Midterm 2 (Lectures 13-24)

Question 1

What are some requirements for locomotion on land?

Answer 1

• streamlining not important in air
• can’t generate thrust by pushing against air
• use legs and feet to transmit backward force to substrate
• gravity requires that skeleton supports body
• limbs must be able to lift body off the ground

Question 2

Skeletal support adjusts to various conditions due to what capability?

Answer 2

Remodeling capacity of bone is important to allow bones to mend and adjust to conditions.

Question 3

External vs internal layers of bones?

Answer 3

External layers: dense and compact (lamellar), strong

Internal layers: porous, light, spongy

Question 4

What is the function of the axial system in fish vs tetrapods?

Answer 4

Axial system: ribs and vertebrae

Fish: for muscle attachment
Tetrapods: for support

Question 5

What is the function of appendages in fish vs tetrapods?

Answer 5

Fish: for steering
Tetrapods: for locomotion

Question 6

Zygapophyses

Answer 6

• on neural arches of vertebrae
• helps lock vertebrae
• articulate to support weight of viscera

Question 7

Which have lost the zygapophyses?

Answer 7

Aquatic tetrapods have lost zygapophyses

Question 8

What is the role of the ribs in skeletal support?

Answer 8

• help retain volume of body cavity in amniotes

- when animal lies down, weight against ground would affect breathing and heart beat

Question 9

What is the role of the pelvic girdle in skeletal support?

Answer 9

• Bears weight of the animal
• connects directly with vertebral column
• connects axial and appendicular skeletons

Question 10

What allowed for a distinct neck region in tetrapods?

Answer 10

• loss of opercular bones
• cervical vertebrae allow independent head movement
• pectoral girdle loses connection to skull*

Question 11

Which costs more energy, locomotion on land or water?

Answer 11

On land is energetically more costly.

Question 12

How did evolution of tetrapod locomotion come about?

Answer 12

1) primitive tetrapod locomotion is still seen in salamanders:
- force from trunk muscles (body undulation)
- feet primarily to provide frictional contact with ground
2) use of limbs more derived trait
- trunk muscles become more important in ventilation
- limbs become more important for locomotion

Question 13

How is eating on land different than eating in water? What is the difference of snouts in fish vs tetrapods?

Answer 13

• in water, food is nearly weightless
• fish: short snouts for suction feeding
• tetrapods: longer snouts to capture prey

Question 14

What was a key innovation for eating on land?

Answer 14

Muscular tongue:

• support from hyoid arch (vs gills in fish)
• manipulate food for chewing and transport
• prey capture in some (projectable tongue evolved independently in frogs, salamanders and chameleons)

Question 15

What is the role of the salivary glands in eating on land?

Answer 15

• moisten food
• saliva with enzymes to begin chemical digestion
• some with venomous secretions (lizards and snakes)

Question 16

What is an example of a venomous mammal?

Answer 16

Northern short-tailed shrew

Question 17

Best breathing methods in water vs air?

Answer 17

Water: gills very efficient, flow through ventilation
Air: gills collapse, tidal ventilation (now possible due to low density and viscosity of air, and high oxygen content)

Question 18

The lung comes from where?

Answer 18

• “Inherited” from fish

- ventral in sarcopterygians (and bichirs)

Question 19

The internal moist membranes in the lungs has what function?

Answer 19

• permits gas exchange

- limits dehydration

Question 20

How are the lungs different in non-amniotic tetrapods (amphibians) vs amniotes?

Answer 20

Non-amniotic tetrapods (amphibians):
-lung ventilation
-positive-pressure buccal pump
-suck air into mouth by expanding oral cavity
-push air into lungs by raising floor of mouth
Amniotes:
-negative-pressure aspiration pump
-create negative pressure in abdominal cavity by expanding rib cage
-draw air into lungs

Question 21

What is the internal structure of the lungs?

Answer 21

• simple sacs in amphibians (supplemented by cutaneous respiration)
• subdivided in amniotes (lobes, alveoli) to increase surface area
• cartilaginous trachea (permits longer necks) and larynx in amniotes

Question 22

What is the difference between blood pumping in fish vs tetrapods?

Answer 22

• fish: in water, blood only needs to overcome fluid resistance to move
  tetrapods:
• require higher blood pressure to push blood upward against gravity, like giraffes with long necks
• higher blood pressure also forces some of the plasma out of vessels into intercellular spaces that is then recovered and returned to circulatory system by lymphatic system

Question 23

How did tetrapod circulation evolve?

Answer 23

• evolution of double circulation
• pulmonary circuit takes deoxygenated blood to lungs
• systemic circuit supplies oxygenated blood to body
• atrium always completely divided

Question 24

What is different about amphibians’ circulation compared to tetrapods?

Answer 24

• atrium always completely divided
• amphibians have no ventricular division, oxygenated blood received in both atria since skin also a major site of gas exchange

Question 25

In the double circulation of blood in amniotes, how is the system divided?

Answer 25

- ventricle divided by a fixed barrier (crocodiles, birds, mammals) or transiently/temporarily separate chambers when heart contracts (turtles, lizards) - deoxygenated blood in right side of heart - oxygenated blood in left side of heart

Question 26

How is oxygen supplied to the heart muscle in amphibians and non-avian reptiles? In mammals and birds?

Answer 26

amphibians and non-avian reptiles: enough oxygen diffuses from blood in ventricle Mammals and birds: thick ventricular muscles, right ventricle with deoxygenated blood

Question 27

What can be said about the evolution of coronary arteries in mammals and birds?

Answer 27

Coronary arteries evolved independently

Question 28

How are the sensory systems in air different than those for water?

Answer 28

- air not dense enough to stimulate lateral line like water does - air does not conduct electricity like water does - air is good for vision, hearing, olfaction of small molecules

Question 29

Sensory systems in air: Vision

Answer 29

- light can be transmitted through air with little disturbance - can be used to sense distance - cornea involved in focusing light on retina - need eyelids and lubricating glands for eyes (due to exposure to air)

Question 30

Sensory systems in air: hearing

Answer 30

- airborne sounds detected by inner ear - fluids in inner ear set in motion by sound waves, stimulate hair cells - middle ear amplified sound with outer membrane (tympanum) - transmits to inner ear through series of bones (stapes) - connected to mouth with Eustacian tube (derived from spiracle) - in Ostariophysan fish, they have Weberian apparatus for hearing

Question 31

Sensory systems in air: olfaction

Answer 31

- airborne molecules that we can detect with our noses - receptors restricted to nasal passage (moist membrane) vs body surface in fishes - mammals have greatest olfaction sensitivity - area of olfactory epithelium increased by turbinates

Question 32

In general mammals have the greatest olfactory sensitivity. What can be said about primates?

Answer 32

- primates have relatively poor sense of smell - short snout - less extensive olfactory epithelium - humans and chimps have poor sense of smell vs dogs who have a really good one

Question 33

What is different about olfaction in snakes?

Answer 33

- Vomeronasal organ on roof of mouth - detects non air-borne molecules - snake flicks tongue to transfer molecules to organ - greatly reduced in primates (humans and chimps)

Question 34

In marine teleosts, how is water lost? What was used to conserve water?

Answer 34

- water lost through body and respiratory surfaces, kidneys | - scales were used to prevent water loss in fish

Question 35

In tetrapod evolution, what happens to scales?

Answer 35

- scales were lost early in tetrapod evolution except for scales on belly - scales were used to prevent water loss in fish

Question 36

How do tetrapods control water conservation?

Answer 36

- epidermis of early tetrapods resembled extant amniotes - keratin produced by epidermal cells - outer layer (stratum corneum) several layers deep to protect against abrasion and some water loss - most water loss reduced by lipids in skin - thin glandular skin of amphibians likely derived

Question 37

Other than dehydration, why is it important for tetrapods to control water loss? How does it compare to aquatic organisms?

Answer 37

- water also needed to get rid of ammonia, a toxic waste product of digestion - kidneys adopt additional role of nitrogen excretion - aquatic organisms get rid of ammonia via gills

Question 38

How does temperature regulation on land differ to water?

Answer 38

- Temperature not as stable on land - But patchier, better for organisms to find different patches of microhabitats (like shade, cave) - And lower heat conductivity means animals can maintain body temperatures different from air (in water, heat is whisked away from body) - Behavioural control of temperature in ectotherms (lizards) - Independent evolution of endothermy in birds, mammals

Question 39

How did tetrapods originate (their precursors)?

Answer 39

- precursors=tetrapodomorph fishes or fishapods - related to sarcopterygian fishes - fishapods=intermediate - With new discoveries, gap between extant fishes and tetrapods narrowing

Question 40

What does "tetrapod" mean?

Answer 40

four feet

Question 41

What are synapomorphies of tetrapods?

Answer 41

- hands and feet with digits | - fin rays lost

Question 42

Name two subdivisions of the "Fishapods." What do they both have in common?

Answer 42

- Osteolepiforms - Elpistostegalids (Panderichthys) - still very fish-like

Question 43

Which has more derived characters, Panderichthys or Osteolepiformes?

Answer 43

Panderichthys more derived due to: - Loss of dorsal and anal fins - reduced caudal fin - Flat heat, long snout with eyes on top of head - Stronger “forelimbs” - Likely shallow water predators

Question 44

Elpistostegalids: characteristics

Answer 44

- likely sister group to tetrapods, not direct ancestor - Still with fin rays, well-developed gills, poorly ossified vertebrae - Loss of operculum (could raise its head) - Lungs and gills still well developed, but no opercular bones - Long snout - Large ribs (could likely support body at least partially on land) - Pectoral fin could bend in middle

Question 45

What is Tiktaalik?

Answer 45

- an Elpistostegalid (a fishapod subdivision) - “Spectacular new find” from Ellesmere Island (2006), transitional fossil - Tiktaalik=“a large freshwater fish seen in the shallows” (Inuktitut)

Question 46

What can be said about the earliest tetrapods and the discoveries made about them?

Answer 46

- with limbs - from late Devonian Trackway - stride length suggests body 85 cm long - no drag marks from tail - ripple marks indicate shallow water

Question 47

Name two Stem Tetrapods.

Answer 47

1) Acanthostega | 2) Ichthyostega

Question 48

Acanthostega: facts

Answer 48

- Stem Tetrapod (not a single lineage; these “fishapods” did not evolve directly into tetrapods) - Likely primarily aquatic - MOST fish-like - Transitional form from water to land

Question 49

Acanthostega: fish-like characteristics

Answer 49

- Caudal fin with dermal rays - Lateral line - Scales - Gills likely internal and covered with soft-tissue operculum

Question 50

Acanthostega: other transitional characteristics

Answer 50

- Had lungs but ribs too short to support chest cavity on land - Scales only on belly - Perhaps some cutaneous respiration - More muscular neck - Morphology of teeth and skull suggest ‘terrestrial-style’ feeding - Webbed digits on each hand and foot - But front foot could not be brought into weight-bearing position, likely more for paddling

Question 51

Ichthyostega: facts

Answer 51

- Stem Tetrapod (not a single lineage; these “fishapods” did not evolve directly into tetrapods) - less fish-like than Acanthostega

Question 52

Ichthyostega: fish-like characteristics

Answer 52

- Caudal fin with dermal rays but reduced - Traces of lateral line and scales - Ear specialized for underwater hearing

Question 53

Ichthyostega: other transitional characteristics

Answer 53

- Limbs likely weight bearing - Pectoral and pelvic girdles better adapted to land (pectoral girdle free of skull) - More supportive ribs, stronger vertebrae with more developed zygapophyses

Question 54

How did tetrapods evolve characteristics in an aquatic environment?

Answer 54

- Tetrapods predated terrestrial vertebrates - Anatomical changes could have been advantageous in shallow water (Air-breathing, Limbs for support and lunging at prey in weedy water, Development of distinct neck and longer, flatter snout) - Ability to migrate overland between adult and juvenile habitats or to deal with drought, bask in sun, etc. * Not “preadaptations” that occurred in anticipation of life on land

Question 55

Who are the non-amniotic tetrapods?

Answer 55

- Extant non-amniotic tetrapods = amphibians - But non-amniotic tetrapods once much more diverse - Larger, more crocodile-like with dermal scales - Uncertain relationships among lineages

Question 56

Why is there uncertainty in the relationships among lineages of the non-amniotic tetrapods?

Answer 56

- Missing critical piece of fossil record for 20–30 my (“Romer’s Gap”) - When major tetrapod groups were undergoing rapid diversification

Question 57

What are the two major lineages of the tetrapods 350 mya?

Answer 57

1) Batrachomorphs | 2) Reptiliomorphs

Question 58

Batrachomorphs

Answer 58

- Major lineage of non-amniotic tetrapods - "frog form" - Flat, immobile (akinetic) skulls - Includes temnospondyls = -Largest and longest-living group of extinct non-amniotic tetrapods

Question 59

Reptiliomorphs

Answer 59

- Major lineage of tetrapods 350mya, both non-amniotes and amniotes - "reptile form" - Taller, narrower (domed) skull and cranial kinesis - Includes “stem amniotes” which were non-amniotic - First possible amniotes in fossil record only 20my after first known tetrapod

Question 60

What are the lepospondyls and what is their relationship with other Tetrapod groups?

Answer 60

- Mostly small, elongate, primarily aquatic tetrapods - Some lizard-like, many limbless - relationship with other tetrapods uncertain - Intermediate characteristics between temnospondyls and “stem amniotes” - Origin of modern amphibians (Lissamphibia) debated - Some suggest that frogs and salamanders derived from temnospondyls and caecilians are derived from lepospondyls

Question 61

Lissamphibians

Answer 61

- Salamanders, anurans (no tail), caecilians - extant amphibians -“Liss=smooth” - Smooth, permeable skin=apomorphic (derived) trait - Many extinct non-amniotes with bony scutes - >6000 extant spp. - Monophyly doubted by some - But generally identified as monophyletic due to presence of several synapomorphies

Question 62

Which of the Lissamphibians based on characteristics is often the "odd man out"?

Answer 62

Caecilians

Question 63

Identify amphibian synapomorphies.

Answer 63

1) thin glandular skin used in cutaneous respiration 2) structural characteristics of inner ear 3) retinal cell (green rods) in eyes 4) levator bulbi muscle of the eye

Question 64

Amphibian synapomorphy: thin glandular skin

Answer 64

- used in cutaneous respiration (gas exchange through skin) - temperature regulation - osmoregulation - escape from predators - but lungs more important when temperatures and activity levels are high - Mucous glands keep skin moist since dry skin less permeable to gases - Only some caecilians with residual scales - Moist skin also important for temperature regulation (overheat if skin dries out=can’t osmoregulate) - sodium uptake at skin (for osmoregulation in freshwater) - Most require moist micro environments

Question 65

Amphibian synapomorphy: structural characteristics of inner ear

Answer 65

a. Papilla amphibiorum - Patch of specialized hair cells in inner ear sensitive to low frequencies b. Operculum-columella complex (equates to Weberian apparatus) - Bones involved in transmitting sounds to inner ear - Connection to pectoral girdle allows low-frequency sounds to be transmitted from ground via forelimbs (frogs and salamanders) * This connection absent in limbless caecilians

Question 66

Amphibian synapomorphy: Retinal cell (green rods) in eyes

Answer 66

- in frogs and salamanders | - lacking in mostly-blind caecilians

Question 67

Amphibian synapomorphy: Structure of levator bulbi muscles of the eye

Answer 67

- Modified in caecilians to retract tentacles | - Outward bulging eyes cause buccal cavity to enlarge

Question 68

Name the three groups of Lissamphibians.

Answer 68

1) salamanders 2) anurans 3) caecilians

Question 69

Class Lissamphibian: Order Caudata or Urodela: Salamanders

Answer 69

-All elongate, most with long tail -caud, uro=tail -Almost all with 4 limbs (exception: some Sirenidae) -Locomotion likely similar to ancestral Tetrapod = undulation of trunk -600 species Ex) Rusty mud salamander

Question 70

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Family Sirenidae

Answer 70

- 4 species - Aquatic salamanders - External gills - Lack pelvic girdle and hind limbs - Have forelimbs

Question 71

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Family Cryptobranchidae

Answer 71

- "hidden gills" - Includes Japanese and Chinese giant salamanders (largest) and North American hellbenders - All are permanently aquatic and paedomorphic (don’t undergo metamorphosis) - have lateral line (only useful in water), no eyelids in adults (only terrestrial) - But without external gills

Question 72

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Family Proteidae

Answer 72

- mudpuppies and European olm (cave dweller) - One in Manitoba, the common mudpuppy - Aquatic, paedomorphic, with external gills - Large due to being aquatic

Question 73

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Congo eels

Answer 73

- 3 species - Aquatic but adults without gills due to well-developed lungs - Can estivate (dormancy during hot or dry periods) for up to 2 years - Have tiny limbs

Question 74

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Mole salamanders

Answer 74

-3 species in Manitoba

Question 75

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Family Plethodontidae

Answer 75

- “Lungless” salamanders - Cutaneous respiration only - 400 spp. - Most fully terrestrial, Some aquatic, Some cave-dwelling, arboreal - Some can drop tail as predator-defense mechanism - Many plethodontids can protrude tongue considerable distances - Have adapted hyobranchial apparatus for feeding (Essential part of buccal pump in other salamanders, Elongated and lightened for protrusion of tongue, Conflicting needs for respiration vs feeding) - good vision to catch moving prey (binocular vision) - Some with direct development

Question 76

How are different families or divisions of Anurans organized?

Answer 76

-organized by their abilities, locomotion, structure, habitat, but NOT based on ancestry

Question 77

Class Lissamphibian: Order Anura: Anurans

Answer 77

- 5400 species - all continents except Antarctica - different groups often distinguished by locomotory specializations

Question 78

Anurans are organized into what subdivisions?

Answer 78

1) frogs 2) toads 3) semi-aquatic frogs 4) tree frogs

Question 79

Class Lissamphibian: Order Anura: Anurans: "Frogs"

Answer 79

- 8 species - specialized for jumping - Long hind legs; tibia and fibula fused - Pelvis attached to stiffened vertebral column - Pelvis and urostyle keep posterior trunk rigid - Forelimbs and pectoral girdle absorb impact - Often sedentary ambush predators - Camouflaged, generally lack chemical defenses

Question 80

Class Lissamphibian: Order Anura: Anurans: "Toads"

Answer 80

-4 species -Not monophyletic -Convergent adaptations to dry environments -Shorter legs, heavy bodies, leathery skin -Wide-ranging predators -Many with poison glands (Cane toad or psychoactive toad)

Question 81

Class Lissamphibian: Order Anura: Anurans: Semi-aquatic frogs

Answer 81

- Streamlined, webbed toes, lateral line in adults - e.g., African clawed frog - Use section to engulf food

Question 82

Class Lissamphibian: Order Anura: Anurans: Tree frogs

Answer 82

- Over 1000 species in many different families - Not monophyletic - Often walk and climb on 4 legs - Enlarged toe disks with mucous glands for adhesion - Surface tension and viscosity - 4 species in Manitoba

Question 83

Class Lissamphibian: Caecilians

Answer 83

- Caecus = blind - Skin or bone over eyes, sometimes without eyes - a.k.a. Gymnophionans (“naked snake”) or apodans (“without feet”) - 170 species - Tropical, generally burrowing - Some species with scales in dermal folds (annuli) - Protrusible tentacles also unique to amphibians - Structures associated with eyes of other amphibians associated with tentacles (Retractor muscles and Lubricating gland) - Feed on small or elongate prey (e.g., termites, earthworms)

Question 84

What are the origins of modern amphibians like the anurans, urodela and caecilians?

Answer 84

- caecilians diverged from anurans and urodela more than 300 mya - clade is consistent with polyphyletic origins from spearated groups of Paleozoic tetrapods

Question 85

Biphasic

Answer 85

has two life stages (one aquatic, one terrestrial)

Question 86

Indirect development vs direct development

Answer 86

Indirect development: has complete metamorphosis in life cycle, has larval stage Direct development: skip larval stage

Question 87

In general. most amphibians have what type of life cycle and reproduction method? However, some amphibians show what other reproductive lifecycles or reproduction method?

Answer 87

general: biphasic lifecycle with indirect development, oviparous others: direct development, paedomorphic, viviparous

Question 88

Paedomorphic

Answer 88

- retain larval characters | - skip metamorphosis

Question 89

Oviparous vs Viviparous

Answer 89

Oviparous: lay eggs on land or in water Viviparous: live birth, retain egg and give birth to metamorphosed young

Question 90

True or false? Some amphibians show sign of parental care?

Answer 90

True. Some carry or guard their eggs or hatchlings

Question 91

What kind of reproduction is seen in Anurans?

Answer 91

- biphasic lifecycle, indirect development 1) aquatic tadpole 2) metamorphosis 3) half tadpole-half frog stage 4) terrestrial adult frog * 20% of anuran species are direct developers

Question 92

How are the tadpoles of Anurans different than the adult frog?

Answer 92

- Aquatic tadpole morphologically, ecologically very different from adult terrestrial frog - Tadpoles of most species filter feeding herbivores, adults carnivores - Exploit seasonal spring bloom of primary productivity, but ponds/algal blooms not reliable year-round

Question 93

How is metamorphosis in Anurans different than lampreys?

Answer 93

Anurans: - stimulated by thyroid hormones - tadpole structures broken down and rebuilt - legs appear, tail regresses - small mouth replaced with large mouth - long gut of herbivore replaced with short gut of carnivore - rapid - indirect development - lay eggs in ponds and then live on land Lamprey: - very slow - Ammoceote larva, so indirect development - lay eggs in freshwater but live in salt water (anadromous)

Question 94

In which phase of the Anuran lifecycle is the organism most vulnerable to predation?

Answer 94

-shortest phase and most vulnerable is the half-tadpole half-frog phase

Question 95

Anuran reproduction: Internal vs external fertilization

Answer 95

- External fertilization in most species since not as successful on land, it relies on water - Internal fertilization in some (on land, ex=tailed frog)

Question 96

Lecithotrophic

Answer 96

Embryo receives no additional nutrition other than that provided by the yolk of the egg

Question 97

Matrotrophic

Answer 97

embryo receives additional nutrition from the mother and yolk of the egg

Question 98

How many Anuran species are known to be matrotrophic?

Answer 98

only two known species

Question 99

In which situation is breeding in Anurans prolonged or explosive?

Answer 99

explosive=in temporary ponds | prolonged=males establish territory and compete for mates by vocalizing

Question 100

Anurans generally produce larger eggs. What advantages and disadvantages come with this?

Answer 100

advantages: better survival disadvantages: require longer to hatch and have greater exposure to predators

Question 101

Anurans have evolved what type of behaviours to protect the eggs and tadpoles?

Answer 101

- tree frogs laying eggs on leaves overhanging water - foam nests produced during amplexus (mating method for external fertilization), tadpoles secrete enzymes that dissolves the foam - in bromeliads (in plants)

Question 102

What are some examples of male Anurans showing parental care?

Answer 102

- African bullfrogs guard eggs and tadpoles - midwife toads gathers strings of eggs around hind legs - Darwin’s frog carries eggs and embryos in vocal pouches; emerge fully-developed

Question 103

What are some examples of female Anurans showing parental care?

Answer 103

- many tree frogs carry eggs on back - eggs covered over by skin of Surinam toad; emerge post-metamorphosis - in stomach of two Australian species (gastric brooding), Both extinct?Possibly because can’t feed while brooding

Question 104

Most salamanders have what type of reproduction? Some others like the Cryptobranchidae and Sirenidae have what type of reproduction?

Answer 104

most: internal fertilization | some like Cryptobranchidae and Sirenidae: external fertilization (due to being aquatic)

Question 105

What method of reproduction do salamanders have that we haven't seen yet?

Answer 105

- use of spermatophores - no intromittent/ external male organ - Females may pick up spermatophore with cloaca - Or male may insert spermatophore into cloaca with feet

Question 106

What are important concepts when salamanders reproduce with each other?

Answer 106

- Courtship patterns, secondary sexual characteristics, and pheromones important - Involves male rubbing pheromones onto nose of the female - Sexual dimorphism within species

Question 107

Sexual dimorphism

Answer 107

the differences in appearance between males and females of the same species, such as in colour, shape, size, and structure

Question 108

Spermatophore

Answer 108

a protein capsule containing a mass of spermatozoa, transferred during mating

Question 109

What are the differences in the aquatic larvae of salamanders who do indirect vs direct development?

Answer 109

Indirect development: Most salamanders lay eggs in water which hatch into gilled aquatic larvae prior to metamorphosis Direct development: Although some families (e.g., Plethodontidae) bypass aquatic larval stage, Gills reabsorbed before hatching, Conflict between larval feeding (suction) and adult feeding (projectile tongue) so loss of the lung

Question 110

Are most salamanders oviparous or viviparous?

Answer 110

- most are oviaprous | - few are viviparous (ex-genus Salamandra)

Question 111

Which paedomorphic (larval characteristics) are retained in a number of salamanders?

Answer 111

- gills | - lateral line

Question 112

What are some examples of obligate and facultative paedomorphic salamanders? What is this dependent on?

Answer 112

- Obligate in Cryptobranchidae, Proteidae, and most cave species - Facultative in some, e.g., mole salamander - depends on environment! - Metamorphic phenotype predominates in temporary ponds - Paedomorphic phenotype in permanent, fishless ponds - Same species = developmental plasticity

Question 113

How do Caecilians reproduce?

Answer 113

- All with internal fertilization with intromittent (external male) organ - Some species lay eggs and females brood the eggs

Question 114

Are Caecilians oviparous or viviparous?

Answer 114

- 25% oviparous | - 75% viviparous

Question 115

How do the young caecilians receive nutrition? How do they develop inside the mother?

Answer 115

- Young feed on special outer layer of mother’s skin = matrotrophic - Embryos get nutrition by scraping oviduct walls with specialized teeth; epithelium produces ‘uterine milk’ - oviduct walls highly vascularized - Gas exchange through close contact with fetal gills and vascularized ovarian walls of the mother - Gills absorbed before birth

Question 116

Caecilians are direct or indirect developers?

Answer 116

all direct developers (no larval stage)

Question 117

Why do amphibians have mucus on the skin and mucous glands?

Answer 117

- to keep skin moist for cutaneous respiration - Antibacterial activity (eg. Xenopus skin secretions) - May make skin slippery (to protect from being captured) - Some species with adhesive mucus (Eg. Some salamanders) - Deters predation - Some species with toxic or irritating mucus secretions

Question 118

Where are poison glands located and what are their functions in amphibians?

Answer 118

- Concentrated on dorsal surface - Primary chemical defense - Some extremely toxic

Question 119

Which is the most toxic amphibian?

Answer 119

-poison dart frogs family Dentrobatidae Golden Dart Frog -Diurnally-active, brightly-coloured frogs -has batrachotoxin (alkaloids) -Single frog with enough poison to kill 10 people if enters body through cut or if eaten raw -Captive-bred animals without significant levels of toxins when fed different diet

Question 120

How are some frogs poisonous?

Answer 120

- over 200 different alkaloids - batrachotoxin from golden dart frog - most alkaloids obtained from prey (ex-ants) - sometimes modified to make more toxin

Question 121

What kind of habitats do most amphibians live in?

Answer 121

- Most amphibians in moist habitats, microhabitats - But some amphibians (especially anurans) in arid habitats - Different families with convergent adaptations

Question 122

What kind of habitat adaptation was taken up by the spadefoot toad in Sonoran and Chihuahuan deserts for water conservation?

Answer 122

- burrowing toads - Spend 9-10 months of year in moist underground - Emerge only during rainy season to feed, grow, reproduce

Question 123

What kind of adaptation was taken up by the tree frogs for water conservation?

Answer 123

- In more humid understory vegetation - many species with skin 1/10th less permeable to water than most other frogs - Some use legs to spread lipid secretions from dermal glands over body (“frog wax”) - Behavioural control of evaporative water loss: water-conserving posture of tree frogs, during dry conditions, they get into smaller posture to reduce surface area and lower the amount of water lost

Question 124

How many amphibian species in Manitoba exist that have overwintering habits?

Answer 124

16 species= 4 Salamanders 12 anurans

Question 125

A manitoban salamander, the Mudpuppy survives the winter how?

Answer 125

- Paedomorphic - Remains active in permanent bodies of water - One that doesn’t freeze to the bottom during the winter

Question 126

How do other amphibian species survive the Manitoba winters?

Answer 126

1) freeze-avoidance: - Aquatic hibernators (northern leopard frog, green frog, mink frog) - Rely on cutaneous respiration all winter in the water - Skin pinker=more blood to skin - Eyes protected by nictitating membrane - Terrestrial hibernators beneath the frost line (salamanders and toads) 2) freeze-tolerance: - 4 frog species (e.g., gray treefrog, wood frog) - Allow ice to form within body wall - But glucose or glycerol prevent vital organs from freezing - Can withstand temperatures as low as -6oC

Question 127

What can be said about the evolution of the first possible amniote?

Answer 127

- in fossil record only 20my after first known tetrapod - small animals - carnivorous on insects - timing of evolution of amniotic eggs (synapomorphy) inferred from branch time between two main amniotic lineages: saurospida (reptiles and birds) and synapsida (mammals)

Question 128

What are the two main amniotic lineages?

Answer 128

1) saurospida (reptiles and birds) | 2) synapsida (mammals)

Question 129

What are some synapomorphies of amniotes?

Answer 129

- amniotic egg - three additional membranes that form outgrowths of embryo body wall (all vertebrates have extraembryonic membranes enclosing yolk sac) - produced by female reproductive tract

Question 130

What are the three additional membranes that form around the embryo body wall in amniotes (egg-laying and viviparous animals)?

Answer 130

1) chorion: outer membrane surrounds entire contents of egg 2) amnion: inner membrane surrounds embryo only 3) Allantois: develops as outgrowth of hindgut, storage for nitrogenous wastes, urinary bladder grows from the base, serves as respiratory organ during later embryonic development, vascularized

Question 131

True or false? Embryonic membranes of placenta in livebearing mammals are analogous with those in amniotic egg.

Answer 131

False. Embryonic membranes of placenta in livebearing mammals are homologous with those in amniotic egg.

Question 132

What are the advantages of amniotic eggs over the amphibian eggs?

Answer 132

- not necessarily essential for development on land but may have allowed for larger egg and embryo size - shell provides mechanical protection while porous for gas exchange and water vapour - albumin and yolk provide water, protein and energy - membranes improve gas exchange and nutrition - intra-egg transport of food and gases allows for larger eggs

Question 133

The three additional membranes in amniotes is a huge advantage in what sense when talking about their overall function?

Answer 133

- membranes improve gas exchange and nutrition | - intra-egg transport of food and gases allows for larger eggs

Question 134

The leathery and flexible shelled eggs are seen in which amniotes? What about the calcified and rigid shells?

Answer 134

- leathery and flexible=lizards, turtles, monotreme | - calcified and rigid=birds and crocodiles

Question 135

What other features are seen in amniotes?

Answer 135

- waterproof skin: thicker skin with keratin and lipids in epidermis, not used for respiration, more skin elaborations (scales, feathers, hair) - costal (rib) ventilation of lungs: negative pressure aspiration pump draws air into lungs, permits longer neck, provides space for elaboration of nerves to forelimb, improves control of forelimbs and ability for manipulation - direct development: no external gills at any point, no lateral line

Question 136

How are amniotes classified?

Answer 136

- classified by patterns of temporal fenestration 1) anapsid 2) diapsid 3) synapsid

Question 137

Anapsid

Answer 137

- "without junction" - solid skull with no temporal fenestrae - in primitive amniotes and turtles - secondary loss of temporal fenestrae in turtles

Question 138

Diapsid

Answer 138

- "two junctions" - two temporal fenestrae - birds and other reptiles - many modifications associated with increased flexibility in snake skull and birds with heavily restructured skull

Question 139

Synapsid

Answer 139

- "shared or joined junction" - single temporal fenestra - mammals and their relatives

Question 140

What is the function of the temporal fenestrae? How did it likely arise?

Answer 140

- provide increased attachment area for jaw musculature - likely arose independently in diapsids and synapsids - different forms likely related to different feeding styles

Question 141

The early division of amniotes resulted in what two lineages?

Answer 141

1) synapsids (mammals) 2) sauropsids (reptiles, dinosaurs, birds) - parallel independent evolution

Question 142

What amniote characteristics had independent parallel evolution during the early division of synapsids and sauropsids?

Answer 142

- rapid, sustained locomotion - powered flight - complex social behaviour - endothermy - but often with different solutions to same challenges of life on land

Question 143

What is the challenge in sustaining locomotion on land?

Answer 143

- need steady supply of oxygen - anaerobic for short sprints - use of axial muscles for bending trunk conflicts with ability to compress rib cage to ventilate lungs - need to keep trunk rigid and use limbs for propulsion

Question 144

What are the solutions in sustaining locomotion on land for synapsids?

Answer 144

1) limbs underneath trunk 2) development of diaphragm (contraction increases volume of pulmonary cavity to draw in air, complements rather than conflicts with locomotion, aided by movement of viscera)

Question 145

Where are the limbs underneath the trunk for locomotion on land first seen?

Answer 145

-first seen in theraspids, non-mammalian synapsids

Question 146

What are the solutions in sustaining locomotion on land for sauropsids?

Answer 146

1) no diaphragm 2) use pelvic movements (crocodilians, movement of liver also helps change volume of trunk, anterior movement of viscera forces air out of lungs) 3) bipedalism (birds, dinosaurs) minimizes trunk movement

Question 147

Bipedalism

Answer 147

-movement on the two rear limbs or feet

Question 148

What are challenges in increasing gas exchange for locomotion on land?

Answer 148

- simple lungs in amphibians so rely on cutaneous respiration for additional supplement of oxygen - due to high levels of activity on land, need more oxygen

Question 149

What are some solutions to increase gas exchange for locomotion on land for synapsids?

Answer 149

- alveolar lungs - tree-like pattern of branching airways ending in alveoli to increase surface area - still tidal ventilation since air is so much less dense than water

Question 150

What are some solutions to increase gas exchange for locomotion on land for sauropsids?

Answer 150

- faveolar lungs - small chambers lining airway - simple in most lizards, although extensive faveolar subdivisions in active monitor lizards - still tidal ventilation

Question 151

How do birds increase gas exchange for locomotion in the air?

Answer 151

- High activity and high altitude (low oxygen content) needs to be more efficient - Pneumatic bone (due to air sacs) makes bones lighter - have system of air sacs - poorly vascularized - store air during parts of respiratory cycle - two cycles required to move unit of air through lung - one way air flow through lung - air capillaries run opposite direction to blood flow =crosscurrent or countercurrent exchange to increase efficiency of gas exchange and allows birds to breathe at high altitudes - one way flow of air through lungs also minimizes dead space or residual air (stale air left in system with each breath) - maintains gradient of oxygen still higher in air than blood (makes it more efficient)

Question 152

Crosscurrent or countercurrent exchange

Answer 152

- air capillaries run in opposite direction to blood flow - increases efficiency of gas exchange - allows birds to breathe at high altitudes - maintains oxygen gradient higher in air than in the blood, making it more efficient

Question 153

What allow birds to breathe at high altitudes?

Answer 153

-crosscurrent or countercurrent exchange (air capillaries run in opposite direction to blood flow)

Question 154

The pneumatic spaces in the saurischian dinosaur fossils suggests that "longnecks" also had what time of respiratory system?

Answer 154

- one-way air flow | - due to amount of dead space that increases with a longer neck, this system minimizes the dead space

Question 155

Which other organism has one-way flow of air like birds and dinosaurs?

Answer 155

crocodilians

Question 156

Why would sauropsids have developed the one-way air flow system?

Answer 156

-sauropsids likely evolved when oxygen levels were low

Question 157

What is a challenge with transporting oxygen to muscles on land?

Answer 157

- high blood pressure needed | - forces plasma from capillaries into air spaces, which reduces gas exchange

Question 158

What is a solution for transporting oxygen to muscles on land by amniotes in general?

Answer 158

- maintain different blood pressures in systemic and pulmonary systems by separation of the ventricle - blood pressure in the left ventricle is higher

Question 159

What is a solution for transporting oxygen to muscles on land by primitive amniotes?

Answer 159

-blood flow likely directed by internal structure (spiral valve)

Question 160

What is a solution for transporting oxygen to muscles on land by extant amniotes?

Answer 160

- transient (short time) separation of oxygenated and deoxygenated blood when heart contracts (turtles and lizards) - fixed barrier (crocodiles, birds, mammals) - anatomical differences in heart suggest that this solution independently derived in two lineages

Question 161

The embryos of both the synapsid and sauropsid lineages have two systemic arches. They are derived from what?

Answer 161

Synapsid: principal systemic arch derived from left aortic arch Sauropsid: derived from right aortic arch

Question 162

Compare the sensory systems and social behaviours of synapsids vs sauropsids.

Answer 162

synapsids: -good olfaction and poor vision (primates are an exception) -reflected in behaviours like scent-marking territorial behaviours in mammals Sauropsids: -good vision but poor smell -territorial displays use colour and pattern (lizards, birds)

Question 163

Why is the class "reptilia" or "reptiles" considered paraphyletic?

Answer 163

- Because it excludes birds - birds also a descendant from common ancestor to all reptiles - crocodiles and birds are sister taxa

Question 164

Sauropsid: Order Testudines: How many turtle species are there?

Answer 164

300 species

Question 165

Sauropsid: Order Testudines: What are the two extant lineages?

Answer 165

1) Pleurodira | 2) Cryptodira

Question 166

Sauropsid: Order Testudines: What is the difference between Pleurodira vs Cryptodira?

Answer 166

Pleurodira: - "side neck," bend neck horizontally to retract head - now only in Southern Hemisphere - ex) Australian snake-necked turtles, South American matamata (lacks horny beak, flaps of skin sensitive to minute vibrations, feeds by suction due to being aquatic) Cryptodira: - "hidden neck" - bend neck in vertical S shape to retract head, contract it under the spine - only Australia without Cryptodires - ex) tortoise=land turtles, Galapagos turtles, Gopher tortoise, pancake tortoise, western painted turtle (Manitoba), snapping turtle (Manitoba, soft shelled turtles (reduced ossification of shell and webbed feet), sea turtles (secondary return to aquatic environment, do migration), Cheloniidae (6 species, retain epidermal scales on shell=loggerhead and green turtles), leatherback turtle (largest extant turtle, dermal ossification reduced to bony platelets in skin, wide distribution, can dive to over 1000m deep, feed largely on jellyfish)

Question 167

Sauropsid: Order Testudines: Cryptodira: What is special about sea turtles?

Answer 167

- particularly specialized for aquatic life (flippers) - Cheloniidae has 6 species like loggerhead and green turtles - retain epidermal scales on shell - secondary return to aquatic habitat - do migration

Question 168

Sauropsid: Order Testudines: Cryptodira: Which is the largest extant turtle?

Answer 168

- A Cheloniidae called the leatherback turtle - dermal ossification reduced to bony platelets in skin - wide distribution - can dive deeper than 1000m - feed largely on jellyfish

Question 169

What is the phylogenetic relationship of Testudines?

Answer 169

- testudines is monophyletic - shell and post-cranial skeleton unique - earliest turtles with shell and beak of derived turtles - 220 million year old fossil turtle found in 2008 with a half-shell, fully formed plastron=lived in water, underside exposed to predators, with teeth) - neck vertebrae specialized for retraction of head - evolved independently in Pleurodira and Cryptodira - relationship with other vertebrates not clear

Question 170

What is the conflict with placing the Testudines on the phylogenetic tree?

Answer 170

- due to anapsid skull, originally thought to be early amniote offshoot - but likely secondary loss of temporal fenestrae - origin from within diapsid reptiles more likely due to molecular data - exact placement within Diapsida uncertain but complete genome suggests turtles sister to birds/crocodilians

Question 171

Is this statement true or false about turtles? Covered in bone, with limbs inside the ribs and teeth.

Answer 171

False. Covered in bone with limbs inside the ribs and horny beaks instead of teeth.

Question 172

Describe the shell and skeleton of the turtle.

Answer 172

- carapace (dorsal shell) consists of dermal bone growing from 59 centres of ossification - 8 dorsal plates fused to neural arches of vertebrae - 8 pairs of costal bones fused to ribs - ribs external to pelvic and pectoral girdles - carapace bones covered by epidermal scales - plastron (ventral shell) formed mostly from dermal ossification - entoplastron and epiplastron derived from interclavicle and clavicle - processes form rigid connection between carapace and plastron - shell kinesis by hinges that allow lobes of plastron to close off openings (evolved many times)

Question 173

What modifications of shells can be seen in different turtles?

Answer 173

- soft-shelled: soft for better swimming in water - leatherback: greatly reduced ossification - pancake: can squeeze in small spaces

Question 174

Carapace vs Plastron

Answer 174

Carapace: dorsal shell that consists of dermal bone (ossification) and covered by epidermal scales Plastron: ventral shell formed from dermal ossification

Question 175

Processes of the turtle's shell

Answer 175

processes form rigid connection between carapace and plastron

Question 176

Shell kinesis of turtles

Answer 176

- hinges allow lobes of plastron to close off openings | - evolved independently many times

Question 177

What two circulatory circuits are seen in turtles?

Answer 177

- pulmonary and systemic circuits (separate systems) - must flow in series in derived sauropsids, synapsids - turtles and lepidosaurs able to shift blood between pulmonary and systemic circuits

Question 178

How is the heart organized in turtles?

Answer 178

- single ventricle with three compartments: cavum pulmonale, cavum venosum and cavum arteriosum - muscular ridge divides cavum pulmonale and cavum venosum when ventricle contracts - cavum venosum and cavum arteriosum connected by intraventricular canal

Question 179

Pulmonale

Answer 179

associated with lungs

Question 180

Describe what happens to the heart of a turtle when the atria contracts.

Answer 180

1) atria contracts 2) atrioventricular valves open (flaps of tissue cover the entry when not contracting) 3) deoxygenated blood (from body) from right atrium flows in cavum venosum 4) oxygenated blood from left atrium flows into cavum arteriosum 5) flaps from atrioventricular valves close intraventricular canal 6) oxygenated blood confined to cavum arteriosum 7) deoxygenated blood in cavum venosum passes over muscular ridge into cavum pulmonale

Question 181

Describe what happens to the heart of a turtle when the ventricle contracts?

Answer 181

1) ventricle contracts 2) blood pressure within heart increases 3) deoxygenated blood in cavum pulmonale flows first into pulmonary circuit where resistance is lower (path of least resistance) 4) muscular ridge closes off passage between cavum venosum and cavum pulmonale 5) right atrioventricular valve closes and no longer blocks intraventricular canal 6) oxygenated blood flows from cavum arteriosum into cavum venosum 7) then into aortic arches 8) blood then goes to body 9) cavum venosum alternately with deoxygenated, then oxygenated blood

Question 182

Turtles can shift blood between pulmonary and systemic circuits. How?

Answer 182

- increase resistance in pulmonary circuit using muscles that narrow blood vessel diameter - some deoxygenated blood bypasses lungs

Question 183

Turtles can shift blood between pulmonary and systemic circuits. Why?

Answer 183

- adjust to changes in respiratory needs - bypass lungs during breath-holding ("ration" out oxygenated blood) - ex) during underwater diving and when drawn into shell

Question 184

How do land turtles do respiration?

Answer 184

- ribs not used to ventilate lungs since they are fused to rigid shell - use contraction of abdominal muscles - lungs attached dorsally and laterally to carapace, and ventrally to connective tissue sheet and viscera (weight of viscera keeps sheet stretched downward) - muscle contraction allows viscera to settle downward, drawing air in - muscle contraction forces viscera upward and air out - but can't inflate lungs when head and legs inside shell (can only do it for so long before they have to breath in again)

Question 185

How do aquatic turtles do respiration?

Answer 185

- hydrostatic pressure helps ventilate lungs - some gas exchange directly from water - especially in pharynx and cloaca - ex) Fitzroy river turtle: rarely surfaces to breathe, fimbriae and microfimbriae give huge surface area

Question 186

Are turtles short or long-lived?

Answer 186

long lived, especially larger species

Question 187

How do terrestrial turtles regulate temperature?

Answer 187

- behaviour helps stabilize body temperature - terrestrial turtles move between shade/sunlight - large turtles heat and cool more slowly (thermal inertia) - can be harder to find large enough microhabitats for them since when hot and dry there can be competition for shade

Question 188

How do freshwater turtles regulate temperature?

Answer 188

- behaviour helps stabilize body temperature - bask on rocks and trees - UV light helps activate vitamin D, necessary for Ca deposition - ex) musk turtles have reduced plastron for climbing

Question 189

How do large marine turtles regulate temperature?

Answer 189

- can maintain body temperature considerably above ambient - ex) green turtles up to 37 in 20 degree water - ex) leatherback turtles with countercurrent arrangement of blood vessels in flippers

Question 190

How do turtles do social behaviour and courtship?

Answer 190

- visual, tactile, olfactory and auditory signals important - species specific colour patterns (species recognition during courtship) - pheromones produced by subdentary glands of tortoises - fecal pellets may serve as territorial markers - biting, ramming, hooking and head movements establish dominance - epiplastrin on males used as a hook to flip over other males

Question 191

How do turtles eat?

Answer 191

- no teeth, have horny beak - can't sick out tongue - good night vision - omnivorous generally but juveniles more carnivorous than adults - Hawksbill turtles feed on sponges - Leatherbacks largely on jellyfish - green turtles only herbivorous sea turtles

Question 192

Are turtles oviparous or viviparous, and indirect development or direct development?

Answer 192

- oviparous, large eggs with 40-60 days to hatch - eggs can have rigid shells (tortoises, softshell turtles) or soft flexible shells (sea turtles, snapping turtles, have faster development) - direct development

Question 193

Diapause

Answer 193

a period of suspended development especially during unfavorable environmental conditions.

Question 194

Diapause in turtles?

Answer 194

- some do | - breed in the fall and hatch during the spring

Question 195

What affects the development of young turtles?

Answer 195

temperature and soil wetness

Question 196

What is temperature-dependent sex determination (TSD) in turtles?

Answer 196

three patterns: 1) males at higher temperatures 2) females at higher temperatures (constant or cycling) 3) females at low and high, males intermediate - can shift from 100% males to 100% females within a narrow range of temperature

Question 197

Why do turtles do temperature-dependent sex determination (TSD)?

Answer 197

- pattern may be related to sexual size dimorphism - higher incubation temperatures produce larger sex - better growth conditions produce sex that benefits more from being large (higher fecundity of females or territorial males) - poorer conditions produce sex penalized less from being small - temperature during middle third of development most critical (second trimester) - narrow range so that both sexes produced in a population under natural conditions (some warmer nests, some cooler nests) - soil moisture can modify temperature effect

Question 198

Which of the following is false? A) The ventricle in the heart of turtles is divided into three compartments, the cavum pulmonale, the cavum venosum, and the cavum arteriosum. B) When the atria contract, a muscular ridge divides the cavum pulmonale and the cavum venosum. C) The cavum venosum and cavum arteriosum are connected by an intraventricular canal; this canal is open when the ventricle contracts. D) Under normal conditions, deoxygenated blood in the cavum pulmonale flows into the pulmonary circuit when the ventricle contracts. E) During diving, increased resistance in the pulmonary circuit causes some deoxygenated blood to bypass the lungs.

Answer 198

B) False. When the VENTRICLE contracts, a muscular ridge divides the cavum pulmonale and the cavum venosum.

Question 199

Why did some conservation efforts of turtles not work in some species?

Answer 199

initial conservation efforts failed when eggs incubated under uniform temperature conditions producing 100% males or females

Question 200

What behaviour is seen in baby turtles?

Answer 200

- no parental care - emergence synchronized to swamp predators, stimulated by vibrations from first hatchlings - "run gauntlet" of predators at night

Question 201

Sexual dimorphism

Answer 201

condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs

Question 202

What behaviours are seen in females during reproduction?

Answer 202

- females may disguise nest site - major breeding sites of sea turtles on isolated islands - often upcurrent from feeding grounds

Question 203

How do sea turtles (green turtles) navigate and migrate in the Carribean and Atlantic Sea?

Answer 203

- move long distances between feeding and breeding areas every 2-3 years - four major nesting sites - no predators on volcanic island, but no food either, so good for nesting site - then females return to their natal beach (Ascension Island 2200km from Brazil - use variety of cues but chemosensory most important (smell of water) - South Atlantic equatorial current flows past Ascension Island toward Brazil - adults swim upstream, up odour gradient to island (hard journey but predator free zone) - piloting (to familiar landmarks) rather than true navigation - back to feeding grounds - newly hatched turtles may drift in current to feeding grounds (takes longer, but downcurrent so less difficult)

Question 204

How do adult loggerhead turtles migrate in the Pacific Ocean?

Answer 204

- 6000 miles - journey may take up to 6 years for hatchlings - adults navigate back to natal Japanese beaches - perhaps in Southern Hemisphere also

Question 205

How do juvenile loggerhead turtles navigate?

Answer 205

- round trip takes approximately 5-7 years - newly hatched turtles in Carribean use at least three cues for orientation: light, wave direction and magnetism 1) light: crawl toward brightest light on emergence, some get confused due to lights of large cities 2) wave direction: swim into waves to lead them into Gulf Stream, drift North along US Coast then east across Atlantic, need to decide which way to go when Gulf Stream divides because don't want to go to cold North Sea 3) Magnetism: to know when to turn to catch southern Gulf Stream, use 3D orientation of Earth's magnetic field to determine direction and latitude

Question 206

Sauropsids: Superorder Lepidosaurs: facts

Answer 206

- 8800 species - "scaly reptiles" - Tuatara (1 species) - Squamata: lizards (5500 species) and snakes (3300 species) - predominantly terrestrial - similarities to ancestral amniotes

Question 207

Sauropsids: Superorder Lepidosaurs: derived characters

Answer 207

- water-impermeable, overlapping epidermal scales | - transverse (horizontal) cloacal slit

Question 208

Sauropsids: Superorder Lepidosaurs: Evolutionary relationships

Answer 208

- monophyletic - traditionally sister group to archosaurs (crocodilians and birds) - but molecular data suggesting that turtles and archosaurs may be sister taxa * turtles are NOT lepidosaurs or squamates (should be in between Archosaurs and Lepidosaurs)

Question 209

Sauropsids: Superorder Lepidosaurs: Tuatara: facts

Answer 209

- maori="spines on back" - once diverse group in Mesozoic - only one species - most unspecialized extant amniote - only on small islands off coast of New Zealand - extirpated from mainland 800 years ago - protected in New Zealand, reintroduced into Karori Sanctuary in 2005 - first wild hatchling discovered in sanctuary in 2008

Question 210

Sauropsids: Superorder Lepidosaurs: Tuatara: characteristics

Answer 210

- one row of teeth on lower jaw - fits between two rows of teeth on upper jaw - parietal (third) eye=photoreceptive, involved in setting circadian and seasonal cycles - feeds on invertebrates, frogs, lizards and seabirds - nocturnal so have limiting ability to raise body temperature (most lizards are diurnal) - territorial - can live more than 100 years - slow metabolic rate, slow growth rate

Question 211

Sauropsids: Superorder Lepidosaurs: Order Squamata: facts

Answer 211

- lizards and snakes - squamates are sister to tuatara - lizards are paraphyletic - lizards are sometimes placed in suborder Lacertilia but it is not monophyletic

Question 212

How do you distinguish a lizard from a snake?

Answer 212

- lack of legs or limbs in the snake is not a good way to distinguish lizards from snakes - since there are legless lizards too - biggest difference is in the skull specializations that allow snakes to swallow prey larger than themselves

Question 213

Sauropsids: Superorder Lepidosaurs: Order Squamata: "Lizards"

Answer 213

- 5500 species - sizes range from 3cm (gecko) to 3m (Komodo Dragon) - families: Iguanidae, Agamidae, Chamaeleonidae, Scincidae, Gekkonidae,Varanidae

Question 214

Sauropsids: Superorder Lepidosaurs: Order Squamata: "Lizards": Iguanidae

Answer 214

- 900 species - green and black iguanas - Anolis lizards (400 species, HUGE diversity!) - many arboreal in South and Central America (in presence of terrestrial predators) - large terrestrial iguanas in West Indies and Galapagos=marine iguana (absence of predators) - Galapagos marine iguana unique

Question 215

What diet do most lizards have?

Answer 215

- most large lizards herbivorous (Marine and black iguanas) - rich gut microflora for digesting cellulose - exception: monitor lizards are carnivorous - small lizards insectivorous (geckos, chameleons)

Question 216

Sauropsids: Superorder Lepidosaurs: Order Squamata: "Lizards": Agamidae

Answer 216

- not monophyletic - dragon lizards, flying lizards (have extended rib cage and no powered flight like birds do), bearded dragon - scales modified into crests, spines, frills - both temperature-dependent sex determination (TSD) and genotypic sex determination (GSD)

Question 217

Sauropsids: Superorder Lepidosaurs: Order Squamata: "Lizards": Chamaeleonidae

Answer 217

- Chameleons - mostly arboreal - zygodactylous feet - most small lizards insectivorous - prehensile tails - projectile sticky tongue - specialized hyoid apparatus (bones that suspend tongue and larynx) - good vision (360 degree field view), eyes can move independently, gauge distance

Question 218

Zygodactylous feet

Answer 218

feet are arranged in pairs where two toes point forwards, and two to the rear

Question 219

Prehensile tail and tongue prehension and jaw prehension

Answer 219

- tail capable of grasping to tree branches when climbing - tongue used to capture prey (grasp them with tongue) - jaw used to capture prey

Question 220

Which lizard families use tongue prehension vs jaw prehension

Answer 220

Tongue prehension: Iguanidae, Agamidae, Chameleonidae (rely on vision for prey detection, tongues for prey capture) Jaw prehension: Varanidae, Scincidae, Gekkonidae (frees up tongue for chemoreception instead of prey capture, able to become nocturnal, invade subterranean habitats)

Question 221

The evolution of legless lizards and snakes evolved how?

Answer 221

- evolved independently | - limb reduction evolved independently 60X in lizards

Question 222

Sauropsids: Superorder Lepidosaurs: Order Squamata: "Lizards": Scincidae

Answer 222

- Skinks - many with reduced limbs (evolved independently several times) - caudal autotomy well-developed - most are terrestrial insectivores - Northern prairie skink (only lizard in Manitoba)

Question 223

Caudal autotomy

Answer 223

dropping of the tail when scared

Question 224

Sauropsids: Superorder Lepidosaurs: Order Squamata: "Lizards": Gekkonidae

Answer 224

- Geckos - 2000 species, wide distribution - smallest lizard, only 16mm long - has species with reduced or no limbs - show caudal autotomy - many nocturnal - use vocalizations rather than visual displays - have vertical pupils - toe pads for climbing - ex) Legless gecko

Question 225

Sauropsids: Superorder Lepidosaurs: Order Squamata: "Lizards": Varanidae

Answer 225

- Komodo dragon and Gila monster - 40 species of monitor lizards - largest lizards, can go up to 3 metres in length - predatory on invertebrates and vertebrates (water buffalo, deer, goats) - hunting shows familiarity with prey's behaviour and local geography, cooperation - lightweight skull (compared to crocodilians) - slashing bite delivers venom (causes hemorrhaging and shock) - uses positive pressure gular pump to supplement negative aspiration using axial muscles to ventilate lungs (pushes and pulls air into lungs) - have higher metabolic rate so need better respiratory system to be more effective in circulating oxygen

Question 226

What is special about the Gila Monster?

Answer 226

- Family Varanidae (Lizards) - venomous - neurotoxin in saliva used medically to treat Type 2 diabetes - feed on rodents, eggs, juvenile birds

Question 227

Sauropsids: Superorder Lepidosaurs: Order Squamata: "Lizards": Mosasaurs

Answer 227

- extinct - Mesozoic lineage of marine lizards - Varanidae lizards or sister groups to varanidae

Question 228

Sauropsids: Superorder Lepidosaurs: Order Squamata: "Lizards": Amphisbaenians

Answer 228

- "worm lizards" - amphi="double" and baen=walk - elongate legless burrowing (fossorial) lizards (squamates, NOT snakes!) - reduced right lung - capable of caudal autotomy - reduced pelvic and pectoral girdles, reduced eyes, heavily ossified skull for burrowing / tunneling - rectilinear locomotion using unique integument (skin) - visible annuli (rings) - little connection to trunk - skin telescopes increasing body diameter - used to push again and anchor against wall of tunnel - body can slide back and forth within integument

Question 229

How does the lung of Amphisbaenians (legless lizards) and snakes compare?

Answer 229

Amphisbaenians=reduced right lung | snakes=reduced left lung

Question 230

Fossorial

Answer 230

burrowing

Question 231

Integument

Answer 231

tough outer protective layer = skin

Question 232

How do you distinguish between a lizard and an amphibian?

Answer 232

- absence of scales in amphibians, have thin permeable mucous skin - a lizard is an amniote

Question 233

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: "snakes": facts

Answer 233

- monophyletic - phylogenetic relationship debated - earliest fossils from Cretaceous but snake skeletons fossilize poorly - hypothesis that snakes evolved from burrowing lizards (with reduced limbs and eyes) - ex) blind snakes, thread snakes (small burrowing (fossorial) snakes with reduced eyes, traces of pelvic girdle,snakelike braincase, represent ancestral condition, suggests that eyes of extant surface dwelling snakes redeveloped so why snakes and lizard eyes are so different)

Question 234

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: "snakes": Genus Titanoboa

Answer 234

- ancient snake as long as a bus | - estimated to be 43 feet long

Question 235

What are the different families of snakes?

Answer 235

1) boidae 2) pythonidae 3) viperidae 4) elapidae 5) colubridae

Question 236

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: "snakes": Boidae

Answer 236

- Boas (ex-Boa constrictor, Red tail boa, Emerald tree boa) - New world - mostly terrestrial - largest ones are usually aquatic or semi-aquatic since water can hold their weight (Anaconda is semi-aquatic) - some arboreal (Amazon tree boa) - more ancestral - a constrictor - vestigial pelvic girdle and residual hind limbs

Question 237

Which is the largest extant snake?

Answer 237

Anaconda - semi-aquatic - from family Boidae

Question 238

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: "snakes": Pythonidae

Answer 238

- Old world pythons - ex) reticulated python - ancestral - vestigial pelvic girdle and residual hind limbs - many use both lungs - have python spurs (remnants of ancestor's limbs) - constrictors

Question 239

What are some derived characteristics for more recent snake families?

Answer 239

- reduced left lung - lost all traces of pelvic girdle - highly kinetic skull - single carotid artery

Question 240

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: "snakes": Viperidae

Answer 240

- ex) pit vipers (have heat sensing pits to sense their prey in the dark), puff adders (heavy-bodied with blunt heads for burrowing), red diamondback rattlesnakes - venomous - erectable long hollow fangs

Question 241

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: "snakes": Elapidae

Answer 241

- ex) Cobras, kraits, mambas, coral snakes, sea snakes ( a terrestrial tetrapod that secondarily loses its limbs and returns to the water, highly specialized for aquatic life) - venomous - hollow fangs - maxillae relatively immobile

Question 242

Some non-venomous snakes mimic the appearance of venomous snakes to confuse predators. How do you know if the snake is venomous or not?

Answer 242

red touching yellow=venomous

Question 243

How are sea snakes so highly specialized for aquatic life?

Answer 243

- tail laterally flattened - ventral scales reduced or absent - dorsal nostrils with valves - lung extends to cloaca, involved in buoyancy regulation - oxygen uptake through skin - most viviparous rather than laying eggs on land

Question 244

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: "snakes": Colubridae

Answer 244

-1700 species -venom glands without specialized hollow fangs -on all continents except Antarctica -consists of all other snakes we don't know where to put -ex) grass snakes, garter snakes, king snakes, milk snakes (trunk musculature secondarily adapted for constriction, crawl slowly, rely on chemoreception), whip snakes, racers (move quickly, visual predators), parrot snakes (elongated arboreal snakes, large eyes)

Question 245

Snakes vs legless lizards (Amphisbaenians): Physical differences?

Answer 245

- snakes have elongation of the body and reduction in diameter due to changes in internal anatomy - left lung reduced in snakes (right lung reduced in lizards) - gall bladder is posterior to liver (lined up instead of side to side like in lizards) - right kidney and gonad anterior to left - snakes have scales

Question 246

Snakes vs legless lizards (Amphisbaenians): Feeding differences?

Answer 246

- legless lizards limited to eating small prey | - snakes have morphological specializations for swallowing prey larger than own diameter

Question 247

What seems to be the trend in Squamata regarding temporal arches?

Answer 247

- first reduction and eventual loss of lower temporal arch (quadratojugal) - after that, further loss of upper temporal arch (squamosal and postorbital) in some lizards and snakes

Question 248

What allowed snakes to open their mouth wider?

Answer 248

- lower and upper temporal arches are lost - creates streptostylic jaw suspension (strepto=twisting) - allows for bigger gape, speed of jaw closure, increases biting force - coupled with more hinge-like suture between frontal and parietal bones (humans have no hinge) - top of head can also bend=cranial kinesis (mesokinesis) - allowed switch to jaw prehension (most extreme in snakes)

Question 249

Mesokinesis

Answer 249

-or cranial kinesis -middle of the skull in snakes can move -allowed switch to jaw prehension -kinesis=movement meso=middle

Question 250

Jaw prehension is seen at the extreme in what organism? But also seen in what other organisms?

Answer 250

- snakes most extreme | - also seen in monitor lizards, skinks, geckos

Question 251

List the organisms in order from least to most amount of motion of the jaw and head. a) gecko b) tuatara c) chameleon d) snake

Answer 251

tuatara (both temporal arches), chameleon (lost lower temporal arch), gecko (lost lower temporal arch and has mesokinesis), snake (lost both temporal arches and has mesokinesis)

Question 252

When a snake closes its mouth, how is this done so that the prey does not come shooting out of the mouth?

Answer 252

- when closing mouth, brings tooth rows parallel | - has a 180 degree gape

Question 253

How many points of movement are in a snake's skull?

Answer 253

8 points

Question 254

What is special about the jaws of a snake?

Answer 254

- left and right of upper and lower jaws attached only by muscles and skin - both sides can move independently from each other - alternately holding and "walking over" prey since have no hands to push their food into mouth - can ingest really large prey!

Question 255

What feeding specializations are seen in snakes?

Answer 255

- usually swallow prey headfirst - presses limbs against body - able to breathe while swallowing (like adult lamprey where it is important to breathe while attached to prey) - contraction of neck muscles moves food toward stomach (bending head sharply pushes prey along)

Question 256

How does a snake eat an egg?

Answer 256

1) wrap their mouth around it 2) draws it into throat 3) flexes muscles to push egg into the bony protrusions on their vertebrae 4) protrusions cause egg to collapse in on itself 5) snake carefully squeezes liquid out of egg 6) regurgitates the crushed egg shell * very efficient and little content of egg is wasted

Question 257

What is the major difference between legless lizards (Amphisbaenians) and snakes?

Answer 257

difference in their skulls!

Question 258

What are two methods used by snakes to immobilize prey?

Answer 258

constriction and venom

Question 259

What features do snakes have to protect themselves from struggling prey?

Answer 259

- rigid braincase | - frontal and parietal bones extend downward to entirely enclose brain

Question 260

Which snakes use constriction? How do they achieve this?

Answer 260

- boas, pythons, some colubrids (secondary development of constriction, lost venom gland) - this is ancestral - hold prey in jaws - wrap one or more coils around it - take up slack, tightening loops each time prey exhales - suffocates or causes heart to stop (doesn't squish it!)

Question 261

What is a consequence for snakes using constriction?

Answer 261

- have short vertebrae and trunk muscles to produce loops of small diameter - will only produce small radius curves during locomotion - slow moving

Question 262

What was a conflict between locomotion and lung ventilation in ancestral amniotes?

Answer 262

- trade off | - use of trunk muscles for lung ventilation conflicted with use for locomotion so started to use legs instead

Question 263

What was a conflict between feeding and lung ventilation in lungless salamanders?

Answer 263

- adaptations to hyobranchial apparatus for feeding using projectile tongue conflicted with its use in lung ventilation - therefore, got rid of lungs and use only cutaneous respiration

Question 264

What is the Mexican black kingsnake?

Answer 264

- a constrictor - powerful body - asphyxiates its prey - lacks venom

Question 265

What are the various venom-delivery systems?

Answer 265

a) opisthoglyphous b) proteroglyphous c) solenoglyphous d) aglyphous

Question 266

Opisthoglyphous snake

Answer 266

- fangs at rear of maxillae - solid fang or with groove - opistho=rear - glyph=sword - hold prey in mouth until it stops struggling - ex) African boomslang (Colubridae*), false viper

Question 267

Which was the first snake family to develop venom?

Answer 267

Colubrids

Question 268

Which is better to have in open habitats in North America, constriction or venom?

Answer 268

-venom because you have a faster-moving body type which is more advantageous out in the open compared to the slow moving constrictor boas that live in jungles

Question 269

How was it discovered that the African boomslang is actually venomous?

Answer 269

- Karl Schmidt died from snake bite of the African Boomslang - was thought to be harmless so when it bit him, he didn't think anything of it - rear-fanged snakes were not considered to be dangerous at the time - he made notes on the effects of the snake's venom as they developed - Schmidt was found dead from respiratory arrest and cerebral hemorrhage - it is now found to be more toxic than front-fanged snakes - one of Africa's most venomous snakes

Question 270

Proteroglyphous snake

Answer 270

- hollow fangs - front of maxillae - protero=front - permenantly errect - short fangs - neurotoxin=fast acting - family Elapidae (cobras, African green mambas, coral snakes, sea snakes)

Question 271

Solenoglyphous snake

Answer 271

- hollow fang - rear of maxillae - erected quickly during strike (swings forward) - soleno=pipe - longer fangs that inject venom deep into tissues - prey runs off and dies - follow scent of injured prey - hemotoxin=slower acting venom - family Viperidae (Red Diamond Rattlesnake)

Question 272

Hemotoxin vs Neurotoxin

Answer 272

Hemotoxin=slower acting venom, inject deep and find prey later (Viperidae=Solenoglyphous) Neurotoxin=fast acting venom, short fangs, hold prey (Elapidae=Proteroglyphous)

Question 273

Aglyphous snake

Answer 273

- have teeth, may have venom but without specialized fangs - unspecialized teeth for holding prey - ex) African pythons, blind snakes, some colubrids

Question 274

What are the contents of venom?

Answer 274

- modified saliva - mixture of enzymes and other components - all venom with proteolytic enzymes to help speed digestion of proteins

Question 275

Most colubrids have small venom glands with venom that isn't fatal to humans. What is the exception to this?

Answer 275

-African boomslang (Opisthoglyphous) that has a potent hemotoxin (slow acting)

Question 276

How is venom injected into the prey of elapidae snakes?

Answer 276

- venom glands are large with tubes that empty into the hollow fangs - compression of adductor superficialis muscle forces venom out - proteroglyphous - spitting cobra can spit out venom at considerable distances (more than a meter), has good aim with help of spiral grooves for greater accuracy (like rifling in barrel of gun)

Question 277

What is used by snakes to detect their prey?

Answer 277

- chemoreception - olfactory epithelium for airborne chemical stimuli - Vomeronasal organ for non-airborne (scent from wounded prey on ground) molecules that is carried to mouth by tongue - forked tongue helps determine direction - no connection between nasal passages and vomeronasal organ - some rely on vision (tree snakes, ambush predators where sticking out the tongue could give you away) - some with pit organs (pit vipers and pythons) that are infrared heat receptors for 180 degree thermal profile of prey, like night vision goggles

Question 278

How do snakes get traction for locomotion on land?

Answer 278

-ventral scales provide traction

Question 279

What are the different types of locomotion seen in snakes?

Answer 279

a) Lateral undulation (serpentine locomotion) b) rectilinear locomotion c) concertina d) sidewinding

Question 280

Locomotion in snakes: Lateral undulation (serpentine locomotion)

Answer 280

- body makes series of curves | - each curve pushes backward to move snake forward

Question 281

Locomotion in snakes: Rectilinear locomotion

Answer 281

- alternate sections of ventral integument lifted off the ground and moved forward - Bends body, lifts off the ground, inches forward = like an inch worm - Much slower than the wide loops in lateral undulation - slow but effective especially on smooth surfaces - used mostly by heavy-bodied snakes (vipers, boas, pythons) - used by some to stalk prey (inconspicuous)

Question 282

Locomotion in snakes: Concertina

Answer 282

- in narrow passages (rodent burrows) - presses loops in posterior part of body against wall to anchor itself - extends anterior part of body forward - best where there is insufficient space to move - forms smaller loops than lateral undulation - much slower

Question 283

Locomotion in snakes: sidewinding

Answer 283

- primarily in deserts where sand substrate slips away during serpentine locomotion - raises body in loops, resting weight on 2 to 3 points - force is exerted downward rather than laterally so snake does not slip sideways - body is extended nearly perpendicular to line of travel - good only for small snakes in areas with few obstacles

Question 284

What is the main mode of reproduction in squamates?

Answer 284

-80% oviparous -oviparity ancestral -produce large eggs relative to non-amniotes -vestigial egg tooth in some livebearers (to break out of the egg) squamates *in manitoba, three of five snakes are vivparous

Question 285

What can be said about the evolution of reproduction in squamates?

Answer 285

- viviparity (with lecithotrophy and matrotrophy) evolved independently more than 100x in squamates - 65x where both egg-layers and livebearers in single genus - *10x where both single species - lecithotrophy and matrotrophy (true viviparous with chorioallantoic placenta)

Question 286

What are some advantages of viviparity in squamates?

Answer 286

- female behaviour can control developmental temperature - particularly in cold climates since mother just has to move herself to warm her young (otherwise if Oviparous, then would have to move all her eggs) - In Manitoba, three of five snakes are viviparous

Question 287

What are some disadvantages of viviparity in squamates?

Answer 287

- generally fewer clutches per year (but if oviparous then there are long incubation times that limit the clutch frequency anyway in cold climates especially - reduced agility of pregnant female

Question 288

Name the squamates that are egg layers.

Answer 288

- most iguanids - most chameleons - almost all geckos - 55% skinks - most amphisbaenians - monitor lizards - Gila monster - *all pythons - milk snakes - rat snakes

Question 289

Name the squamates that are livebearers.

Answer 289

- some iguanids - some chameleons - some geckos - 45% skinks - some amphisbaenians - *all boas - *all vipers - *some sea snakes - *garter snakes

Question 290

All amniotes have direct or indirect development?

Answer 290

direct development

Question 291

All squamates have external or internal fertilization? Why?

Answer 291

- internal fertilization (fertilization necessary before shell deposition) - no external genetalia but males with 2 hemipenes (blind inverted cylinder exerted through vent, stored in base of tail when not in use) - sperm can be stored up to 6 years

Question 292

What are some examples of secondary sex characteristics seen in some squamates?

Answer 292

- Femoral or praenal pores in many male iguanids and geckos - Spurs (vestigial hind limbs) in male boas, pythons (reduced or absent in females) - Chameleon male has horns

Question 293

Is parental care seen in squamates? What are the exceptions?

Answer 293

- no it is rare - female python coils around eggs for protection and temperature regulation by shivering her trunk musculature to generate heat (up to 30 degrees celsius) - parental care in some livebearers like skinks where they are helping neonates escape from birth sacs

Question 294

What can be said about the reproduction of red-sided garter snakes?

Answer 294

- good example of why storing sperm is important in females - not in good physiological state when fasting all winter - hibernate in large numbers in dens - best mating opportunity is when they emerge in spring - males rely on sperm produced in the preceding summer - females store sperm since eggs not yet mature - females mature eggs after they start feeding again following migration to feeding areas in marshes - females bask to increase gestation rate or young born too late in summer would be too small to survive winter - not known where young of year spend first winter - live births late July-October

Question 295

Parthenogenesis

Answer 295

- “Virgin birth”=don’t need to reproduce with male to have young - seen in six lizard families and one snake - viable eggs without fertilization - produces diploid clones of mother (not a haploid egg!)

Question 296

How does parthenogenesis originate?

Answer 296

- originate by hybridogenesis - two species similar enough to permit successful development - dissimilar enough ti disrupt meiosis and genetic recombination - each species may arise independently multiple times - most populations require pseudo-copulation to initiate egg development and maturation - non-gravid (not pregnant) females will assume male role

Question 297

Pseudo-copulation

Answer 297

describes behaviors similar to copulation that serve a reproductive function for one or both participants but do not involve actual sexual union between the individuals

Question 298

Name some advantages of parthenogenesis seen in some squamates.

Answer 298

- reproductive potential twice that of parental species - single female able to colonize new habitat - may also show hybrid vigour (=heterosis) and be superior in intermediate habitats (like rats and raccoons)

Question 299

Heterosis or hybrid vigor

Answer 299

phenomenon that progeny of diverse varieties of a species or crosses between species exhibit greater biomass, speed of development, and fertility than both parents

Question 300

Facultative parthenogensis was seen recently in what squamate?

Answer 300

- Komodo dragon | - given sex-determing system of this species, parthenogenetic offspring are all males

Question 301

If humans were capable of parthenogensis ("virgin birth") the offspring would be all of which gender?

Answer 301

all females

Question 302

Temperature-dependent sex determination is seen in which squamates?

Answer 302

- in skinks, geckos and agamids | - less widespread than what was seen in turtles and crocodilians

Question 303

How does temperature-dependent sex determination seen in the tuatara (a lepidosaur, NOT squamate) have implications in the conservation of its species?

Answer 303

- attempts to establish populations on south end of South Island problematic - cool soil temperatures produce only females - but may benefit from global warming!

Question 304

What are some social behaviours commonly seen in squamates?

Answer 304

- dominance hierarchiesm territorial, courtship - variety of visual (iguanids, chameleons, geckos since more brightly coloured), auditory (geckos), chemical (pheomones) and tactile signals

Question 305

How does the Anolis (Iguanidae) show social behaviour?

Answer 305

- males have brightly coloured gular fans (throat fans) - species-specific colours and head and body movements - similar male territorial and courtship behaviours (Response=Aggression from male or submission from female) - Pheromones important in some iguanids - Femoral pore secretions - Secretions also absorb light in UV spectrum

Question 306

Caudal autotomy

Answer 306

- self-amputation, can cut off their own tail - tuatara, some lizards (geckos and skinks), snakes - at distinctive fracture planes in all but 4-9 anteriormost caudal vertebrae - perforations for easy breaking - contraction of caudal muscles fracture vertebra - arterial sphincter muscles and venous valves close - severed tail twitches (anaerobic metabolism) - usually occurs as far posterior as possible - vertebrae in regenerated tail cartilaginous - without fracture planes - subsequent ruptures only possible anterior to original site

Question 307

What are some costs to autotomy of the organism's tail?

Answer 307

- social: lower in hierarchy | - energetic: tail is site of fat storage

Question 308

What are some adaptations made by desert lizards due to living in an extreme habitat?

Answer 308

- dry and wide temperature fluctuations in the desert - chuckwalla = herbivorous iguanid - relies on water from plants and metabolic water - hibernates during winter in humid crevices - emerges in April to feed on annual plants - gains weight and stores excess water - maintains an osmotic concentration with nasal salt glands - less active in June, July (perennial plants) - some years, weighs less in fall than in April

Question 309

How does the Namib Desert Lizard live in its extreme habitat?

Answer 309

- when moist air blows in from sea | - collects fog droplets off vegetation

Question 310

How does the Namib viper live in its extreme habitat?

Answer 310

- fog forms water beads on snake's body surface | - limited to coastal locations

Question 311

How does the Thorny devil live in its extreme habitat?

Answer 311

- collects dew on body surface | - funnels water between scales to corners of mouth