BIS216 Vertebrates Flashcards
(281 cards)
1
Q
Largest group of vertebrates
A
-Osteichthyes
-More than 30,000 sp
-95% of all fish
2
Q
Radiation of osteichthyes
A
-Radiated in Devonian into two groups
-Actinopterygii
-Sarcopterygii
3
Q
Oldest osteichthyes fossil
A
Approx. 400 MYA
4
Q
Actinopterygii
A
-Ray-finned
-Most fish
-Radials made of endochondral bone (cartilaginous precursor that is replaced with bone)
-Long, delicate rays of dermal origin
-Flexible, can be pushed against body and relaxed
5
Q
Sarcopterygii
A
-Lobe-finned
-Have basal, mesomeres and radials
-Fleshy, thicker structures
6
Q
Non-teleost fish
A
-Secondarily lack endochondral bone, bone never comes and is always cartilaginous
-Most show loss of scales
-Upper jaw is not fused to cranium (same as teleosts)
-Have non-respiratory gas bladder (‘’)
-Teleost similarities not homologous
-Includes sturgeons and paddlefish
7
Q
Sturgeon
A
-1-6+ m
-Benthic
-Can be marine water (but breed in freshwater) or can be freshwater
-Scales reduced to scutes
-Protrusible jaw
-Long lived/late maturing
-Late maturity plus exploitation of eggs for caviar threatens them
8
Q
Paddlefish
A
-Paddle structure or rostrum on cranium at anterior end
-Paddle detects electrical impulses for prey catching
-Two species, American and Chinese
-American paddlefish are filter-feeders
-Chinese paddlefish feed on crustaceans etc with protrusible jaw, not seen since 2002 and declared extinct
9
Q
Teleost diversification
A
-Rapid diversification in early history
-Thought to be due to 7 hox gene clusters (due to 3 hox gene duplication events)
-Now thought to be due to the development of the jaw
10
Q
Parts of fish jaw
A
-Lower jaw is mandible
-Upper jaw consists of maxilla and premaxilla
11
Q
Protrusion of fish jaw
A
-Upper jaw not fused to cranium, giving a degree of flexibility and mobility
-This allows for specialisation of feeding mechanisms and ability to exploit a wide range of prey
-protrusion has increased during course of evolution
12
Q
A specialised feeding mechanism allowed by jaw protrusion in fish
A
-As mouth extends, buccal cavity increases in volume and sucks in water
-This allows fish to suck up prey with the water
13
Q
Most diverse fish groups in anterior skull end
A
-Chichlidae and Labridae show huge variations due to feeding adaptations
-These include for digging, piercing, crushing etc
14
Q
How are different modes of feeding enabled?
A
-By pharyngeal jaws, modified from other branchial arches
-Used for prey grinding, tearing or filter-feeding
-Development of these allowed for oral jaws to be free, possibly accounting for diet diversity
15
Q
Moray eel pharyngeal jaws
A
-Raptorial
-Can actually move into back of throat and help pull prey down throat
-This is because moray eels are found in coral reefs, where suction feeding isn’t helpful
16
Q
Features of gnathostomes
A
-Jawed vertebrates
-Show duplication of hox gene complex
-Have muscular neck region
-Have centrum
17
Q
4 groups of jawed fish
A
-Placoderms
-Acanthodians
-Chondrichthyans
-Osteichthyans
18
Q
Placoderms
A
-Early jawed fish
-Body covered in bony plates
-Plates on trunk and head
-Went extinct during Devonian period
-Different forms and sizes
-Show viviparity
19
Q
Clasper
A
-Intromittent organ to transfer sperm to females from males
-In placoderms, clasper present in pelvic region
-Now jawed vertebrates have modified pelvic fin to join the two, not homologous
20
Q
Acanthodians
A
-‘Spiny sharks’
-Stem/basal chondrichthyans
-20cm - 2m
-Toothless
21
Q
What makes an amniote an amniote?
A
Amniotic egg
22
Q
Components of amniotic egg
A
-Three extraembryonic membranes
-Leathery shell as barrier to outside (more specialised in birds with calcium salts) with pores (some need to be buried to stay moist)
-Albumen made of proteins and water (for protection and moisture) and yolk
23
Q
Adaptations related to amniote egg
A
-Internal fertilisation needed
-Intromittent organs homologous (not really in birds), female equivalent is clitoris
-Environmental sex determination after conception (common in reptiles), thought to be ancestral
-No larval stage, so has to be laid on land, with egg laying seen in reptiles, birds and monotremes
24
Q
Amniote extraembryonic membranes
A
-Allantois is for expelling waste products and is also vascularised for gaseous exchange (left behind after development)
-Amnion surrounds embryo
-Chorion surrounds everything including yolk and albumen
25
Tuatura
-Aboriginal for "spines on back"
-Restricted to NZ
-Nocturnal (unusual for reptiles)
-Very diapsid skull with reformed lower bar
-Associated with ground-nesting and burrowing birds
26
Largest turtle
-Leatherback at 2m long
-Can dive down to 1000m
-Tends to feed on jellyfish
27
Longest turtle migratory route
-Green turtles feed off coast of Brazil but lay eggs on Ascension island 2,200 km away
-Also herbivorous (unlike most turtles)
28
Why do hatchling turtles go straight to sea?
-Attracted to light
-Sky above sea looks brighter than sea above land due to reflection
29
Differences between ancestral and modern turtles
-Ancestors had teeth, modern forms just have horny plates for chewing
-Flexible neck can be drawn in, sometimes to the side, in modern forms but not ancestral
-Ancestral forms had longer tails
30
Chordate features
-Notochord, positioned between gut and nerve cord
-Dorsal, hollow nerve cord
-Pharyngeal gill slits, with pharynx at start of gut, used for filter feeding or respiration, also found in deuterostomes
-Post-anal tail
-Endostyle secrets mucus in larval lampreys for filter feeding and is homologous to thyroid, shown by transformation of endostyle to thyroid during lamprey metamorphosis
31
Vertebrae
-Usually replaces notochord in vertebrates as main form of support
-May be of cartilage or bone
-However, not all chordates possess fully formed vertebrate
32
Gnathostome vertebrate structure
-Centrum in middle
-Wraps around nerve cord
33
Chordates without vertebrae
-Hagfish and lampreys have rudimentary vertebral precursors (arcualia)
-Lamprey arcualia along body and dorsal (above notochord)
-Hagfish arcualia at tail region and ventral (below notochord)
-Ancestrally, it was dorsal and ventral
34
Cranium
-Sometimes vertebrates named Craniata
-Can be bony, cartilaginous or fibrous
-Protects brain
-Can be highly specialised
-Cranium and vertebrae make endoskeleton
35
Embryological features of vertebrates
-Duplication of Hox gene (involved in anterior-posterior directioning) complex (homeobox genes)
-Development of neural crest
-Placodes
36
Hox gene duplication in vertebrates
-Invertebrate chordates have 1 hox gene cluster, ancestral jawless vertebrates have 2
-Further duplications associated with evolution of other features e.g., jaw
-Duplication occurred during evolution of teleosts, from 4 to 7
-Another duplication for the salmonoids, 7 to 13
37
Development of neural crest in vertebrates
-Migratory and multipotent
-Specified at boundary of neural plate, which folds to form hollow neural tube, with crests on outside
-Responsible for new structures, especially in head, such as adrenal glands and pigment cells
-Another germ layer, so quadroblastic
-Precursors in invertebrate chordates, similar genes expressed during neural plate development and migratory cells found in Urochordates
38
Placodes and brain division
-Complex sense organs
-Brain of vertebrates larger and has 3 parts (forebrain, midbrain and hindbrain)
-Brain of amphioxus (cephalochordate) not divided but genes similar except development of forebrain (as it has none)
39
Vertebrate size
-Vertebrates have increased body size and activity, cephalochordates up to 10cm long, while jawless vertebrates 10-100cm long
-Can't rely on ciliary action or diffusion
-Higher metabolic rate due to being active
-Can sustain periods of anaerobic respiration, allowing for rapid movement before aerobic respiration can occur
-Transition from filter feeding to active, predaceous mode of life
40
Vertebrate changes to transition to active, predaceous mode of life
-Prescence of tail
-Three-chambered heart
-Muscle blocks (myomeres)
-Development of new organs
41
Mineralised tissues
-Arose in vertebrate evolution but absent at start
-Maximises strength but also provides flexibility
-Unique mineral hydroxyapatite (calcium and phosphorous)
-More resistant to lactic acid after anaerobic respiration
-Six types of tissues can be mineralised
42
What are mineralised tissues made of
-Collagen fibres, proteinaceous tissue matrix and hydroxyapatite
-Gives it a mix of hard and flexible materials
43
Mineralised tissue types
-Mineralised cartilage forms main mineralised internal skeleton of sharks/cartilaginous fishes
-Bone forms internal skeleton of bony fish and tetrapods, highly vascularised and endochondral bone replaces cartilage
-Enamel, enameloid and dentine are associated with teeth, exoskeletons and dermal scales of cartilaginous fishes etc (90-96% mineralised)
-Cementum fastens teeth in sockets (45% mineralised), found in mammals
44
Origin of bone and other mineralised tissues
-No mineralised tissues at start of vertebrate evolution
-Basic units in early vertebrates (odontodes (dermal)), e.g., dermal armour of ostracoderms
-Initially, there was an unmineralised condition, such as in lampreys, but exoskeleton evolved, followed by mineralised endoskeleton
-Bony fish still have exoskeleton-like mineralised tissues (scales and fins), while tetrapods have a reduction of exoskeleton in trunk region, retaining it in the skull
45
Why did mineralised tissues evolve?
-Defensive structure
-Protected electroreceptors
-Storage/regulation of phosphorous and calcium in hydroxyapatite
46
Extinct agnatha
-Ostracoderms
-Approx 500 MYA
-Jawless
-Dermal skeleton of odontodes that could aggrevate to form spine plates
-10-50cm
-Notochord
-Fed on soft bodied prey
-No mineralised internal skeleton
-Dorsal fin, some pectoral fins
-Lived along jawed fish for a time
-Extinct in late Devonian
47
Extinct cyclostome?
-Fossil of Tully monster found (Tullimonstrum)
-Been classed as many things
-Has arcualia and a notochord
-Also has keratin, found in tooth structures of extant cyclostomes
48
Present day cyclostome features
-Jawless
-No mineralised tissue
-No paired fins
-Very ancient group, split from other vertebrates very early
-Lampreys and hagfish
49
How do we know cyclostomes diverged from other vertebrates very early?
-Haemoglobin made of alpha and beta globins
-500 MYA ancestral globin gene duplicated to form these alpha and beta gene clusters
-All vertebrates except jawless vertebrates show this alpha/beta split
-This means that the common ancestor of lampreys and hagfish predates this split and diverged before this
50
Lamprey feeding
-Most predacious
-Latch onto prey but don't usually cause death, but may weaken animal
-Have oral hood with tooth like structures and a tongue with same structures on
-Latches on with jaw hood and grinds at animal, eating blood and tissues
-Has glands that produce anticoagulants
51
Lamprey anadromity
-Males and females build nests with collected stones, releasing egg and sperm within
-Adults find streams by detecting pheremones released by larvae
-Females detect mature males, and adults also avoid some areas, possibly due to alarm cues released
-Adults die after spawning
52
Lamprey alarm cues
-Made up of bile acids (petromyzonol sulphate, petromyzonamine disulphate, petromyzosterl disulphate)
-Detected at low concentrations and produced in large quantities (each larva activates 400L/water/hour)
53
Lamprey features
-Notochord supports body, vertebrae minute (arcualia) and on dorsal surface
-Pineal eye
-Nasohypophyseal opening
-Simple gut
-Tidal ventilation
54
Nasohypophyseal opening of lampreys
-Similar to nostril
-Leads to an olfactory sac
-Several external gill openings
-Shares duct with adenohypopysis, an alternative to anterior pituitary gland
55
Tidal ventilation in lampreys
-Method of breathing
-Can't operate gills while latched on
-Water goes in and out of branchial ducts
56
Larval lampreys
-Ammocoete, as originally thought to be seperate species
-Have endostyle to secret mucus for filter feeding
-Draw water into gills, mucus traps particles
-Endostyle becomes thyroid gland during metamorphosis
-Larval stage can last 5 years in freshwater
57
UK lamprey species
-Brook lamprey, around 20cm and doesn't feed as adult
-River lampreys live in estuaries and coastal regions, sometimes Scottish Lochs
-Sea lampreys about 120cm long and found in coastal areas and the open ocean
58
Hagfish
-Marine and deep sea
-Notochord present
-Arcualia found ventrally in tail region
-Only vertebrates with blood isosmotic to sea
-No larval stage, direct development
-Not a lot known about them
-Exploited in eel skin trade and bycatch
-100:1 biased sex ratio to females, some known to be hermaphrodites
59
Hagfish senses
-Have barbels, sensory devices
-Eyes covered by skin so rely on sensory and olfactory information
60
Hagfish feeding
-Scavengers, feed on dead animals
-Have slime glands that produce copious amounts of slime for protection, but can also clog fish gills, so maybe predaceous
-Can acquire nutrients through skin and gills, unusual for animals
-Can tie themselves in a knot to get rid of slime for feeding, allowing to grip onto prey and pull bits off
61
Advantage of jaw
Ability to feed on a wider variety of prey
62
Vertebrates with jaws are called...
...gnathostomes
63
How did jaws evolve?
-Pharynx became muscular and gill slits now used for respiration instead of feeding, both supported by gill arches
-Jaws evolved from anterior branchial arches (mandibular arches)
-Arch immediately behind mandibular arch is hyoid arch, forming part of jaw but also allowing for suspension of jaw
-Gill reduced to spiracle
-Also involved duplication of Hox gene
64
Why evolve jaw?
-Arch enlargement aided ventilation, not feeding
-Monorhiny vs diplorhiny
65
Arch enlargement aided ventilation
-Functioned in closing and opening entrance to pharynx
-Allows for more activity
-However, mandibular ach doesn't form a functional gill arch in any living vertebrate or fossil, no transition seen from jawless to jawed
-In lampreys, mandibular arch supports velum
-Lamprey and hagfish gill arches found on outside and gills inside, the reverse to gnathostomes, so not good example of transition either
-Mandibular arch has different developmental origin and innervation to rest of arches (the way that nerves control it)
-If hypothesis true, gnathostomes able to suck in prey and grasp it, making jaws selected to be large, leading to feeding
66
Monorhiny vs diplorhiny
-Single or two nostrils
-Hagfish and lampreys have single nostril and single olfactory sac that shares nostril with anterior pituitary gland
-Single nostril could have prevented evolution of upper jaw
-Some transitional forms found with two sacs but only one nostril, shared with AP gland
67
Paired and midline fins in jawed vertebrates
-Midline fins e.g., dorsal fin, anal fin (single) and caudal fin (tail)
-Paired fins not seen on jawless vertebrates, except some ostracoderms had pectoral fins
-Pelvic fins only seen in gnathostomes
-Fins allowed for more manoeuvrability
-Genes responsible for lamprey and dorsal fin are also responsible for midline and paired fins in bony fishes, meaning same genetic mechanism in different location
-Same gene controls limb development
68
Manoeuvrability of fins
-Pitch controlled by pelvic and pectoral (up and down)
-Yaw controlled by dorsal and anal (rolling)
69
Buoyancy in chondrichthyans
-Lipid-filled liver for neutral buoyancy (different method in bony fish (swim bladder))
-Amount of lipid and liver size vary (can be 25% of shark's weight)
-Benthic fish have smaller livers
-High blood urea concentration also aids buoyancy
70
Hyostylic jaw suspension
-Upper jaw suspended from cranium by modified hyoid arch (hyomandibular) at back end
-Front end of upper jaw has ligaments
-Jaw can be flexible
-Seen in most chondrichthyans
71
Groups of chondrichthyans
-Holocephalans
-Elasmobranchs
72
Holocephalans
-Include rat fish Chimaera
-Show holostylic jaw suspension, cranium fused to upper jaw
-Deep sea, feed on crustaceans
-Have tooth plates to crush prey
-Large pectoral fins and whip-like tail
-Oviparous
-Proboscis rich in mechanoreceptors and electroreceptors
-Lateral line system for mechanoreceptors
-Spine on dorsal fin, can be venomous
73
Elasmobranchs
-Sharks, skates and rays
74
Sharks
-Can be split into 2 groups, galeomorphs and squalomorphs
-Range in sizes
-Gut is short
-Heterocercal tail, asymmetrical to maybe help with lifting animal while swimming
-Embedded in skin are teeth-like structures, called denticles, or placoid scales
75
Galeomorphs
-With anal fin
-Tend to be warmer water
-Includes great white shark and whale shark (biggest fish)
-Also includes thresher sharks with asymmetrical tail used as a whip that can stun with pressure or directly hit
76
Squalomoprhs
-No anal fin
-Tend to be in cold water
-Includes spiny dogfish
77
Shark unique species
-Cookie cutter shark uses teeth to eat chunks of prey
-Hammerhead shark thought to have head shape to improve binocular vision, as most sharks have 10% overlap in view, while hammerheads show 48%
78
Shark denticles/placoid scales
-Enameloid on outside, then dentine
-Can be arranged in different ways
-Minimise turbulence, allowing flow of water along body
-All face same way
-Maybe used to help feeding
-Denticles reduced in rays to a barb, and along the dorsal line in skates
79
Skates and rays (Blatoidea)
-Dorso-ventrally flattened
-Ventral side is where gill chambers and mouth located
-Dorsal side is where spiracle located, where water enters
-More diverse than sharks
-Enlarged pectoral fins
-Many benthic, some not such as eagle and manta ray (also can be up to 6m)
-Some produce electric currents, like the electric ray forms in muscle tissue of gills and uses to stun prey, other species produce in tail for communication
-Skates lay eggs, rays give birth live
80
Batoidea feeding
-Many benthic, jaw suspension allows to drop jaw and eat sand animals
-Teeth have flat plates to grind up crustacean and mollusc prey
-May be sexual dimorphism in some species for teeth, as males require sharp teeth for latching on to females during reproductive season, but flat for feeding
-Manta ray filter feeders, using extensions of pectoral fins (cephalic fins) that guide food into mouth, where it is trapped in gills
81
Chondrichthyan teeth whorl
-Not embedded into jaw, but into skin
-Teeth behind replace front ones
-Can kill mammals by exsanguination (bleeding to death)
82
Megaladon
-14-18m long
-Extinct 2.6 MYA
-Thought to be a major pressure on the sizes of baleen whales as were only predator
83
How do chondrichthyans hunt
-With sun behind them
-So that prey do not see them
84
Sensory systems in chondrichthyans
-Mechanoreceptors
-Chemoreceptors
-Electrical impulses
-Vision
-Brain
85
Mechanoreceptors chondrichthyans
-Detect vibrations
-Neuromast organs
-In lateral line
86
Chemoreceptors chondrichthyans
-Acute sense of smell
-Can detect 1 part in 10 billion
-Will turn to side first stimulated
-Sense of smell depends on size of olfactory bulbs, smaller in coral reef sharks
87
Electrical impulses chondrichthyans
-Ampullae of Lorenzini
-Found on head of sharks, pectoral fins of rays and skates, and rostrum of holocephalans
-Impulses produced by prey
88
Vision in chondrichthyans
-Well developed for low light intensities
-Rod rich retina
-Cells with crystals of guanine make up the tapetum luccidium behind retina
-Light reflects off tapetum luccidum back into the retina, maximising light
89
Brains of chondrichthyans
-Brains of sharks are proportionately heavier than brains of other fishes
-Similar brain-to-body mass ratios as some tetrapods
90
Sequence of systems in chondrichthyans
-Olfactory first, particularly if prey wounded
-OR mechanoreception
-Then vision to detect and recognise, may even butt head or gnaw to generate olfactory cues to help recognise
-Nictitating membrane protects eye
-An eyelid over eyes for electroreception
91
Reproduction in chondrichthyans
-May account for their success
-Sexual maturity reached later on in life
-Relied on a lot
-Internal fertilisation
-Male clasper inserted into female cloaca
-Clasper may have hooks and barbs to stay in place
-Sperm released from siphon sac, flowing down a groove and into female reproductive tract
-In smaller sharks, male wraps around female and may bite dorsal fin or flanks to hang on
-Some side by side, and bite pectoral fin
92
Oviparous sharks
-Lay eggs
-Mermaids purse tendrils wrap around vegetation to avoid washing up on shore
-Corckscrew eggs get stuck in rock crevices to ensure survival
-Have connections with outside via pores to ensure freshwater circulates for respiration
93
Ovoviviparous sharks
-Retain eggs in oviduct until hatching
-Nutrition from yolk (lecithotrophy)
94
Viviparous sharks
-Get nutrition from both yolk and female (matrotrophy)
-Some secrete substances such as uterine fluid
-Some continue to ovulate to feed young
-Some larvae eat each other
-Some have yolk sac placenta, yolk sac becomes heavily vascularised (placentotrophic viviparity)
-Once born/lain no parental care, investment is all in eggs or developing embryos
-Lifestyle involving lots of investment
95
Shark maturity
-Reproduce at old age
-White shark matures at 9-10 or 12-14 and produce 2-10 pups, every other year
-Greenland shark lives to 400 years, reproducing at 150
-Hammerhead produce 12-40 pups
96
What percentage of sharks are Critically Endangered
30
97
Actinopterygii features
-Homocercal tail
-Small scales
-Fusiform, torpedo shape effective for swimming
98
Actinopterygii fins
-Dorsal fins split in two
-Have pelvic and and anal fin
-Fins more for steering than movement with alternating contractions of muscles on each side, causing the animal to undulate side by side
-Most fish use back end of body, the caudal peduncle
-Lots of variation in fins
99
Actinopterygii fin variation
-Eels use most of body
-Some use specific fins
-Leafy sea dragons have tiny fins, making it a slow mover
-Guppies have brightly coloured fins for attracting mates and can have a sword that protrudes from fin, also have modified anal fin to form a gonopodium, an intromittent organ
-Flying fish can use fins to glide along surface of water rapidly to evade predation etc
100
Actinopterygii lateral line system
-Neuromast organs
-Detect water displacement
-For vibrations and flow etc
-Many fish that swim in shoals lack neuromast organs or are on head instead to avoid interference from other fish
101
How do actinopterygii achieve neutral buoyancy?
-Through swim bladder
-Thought to have originally been a lung structure
-Homologous with lungs of sarcopterygians
-Primitive fish lungs were ventral but flipped during course of evolution
-5-7% of body volume
-Pressure increases with depth, meaning swim bladder will shrink, causing animal to sink
-Pressure reduces nearer surface, increasing swim bladder and causing animal to rise
-However, for animal to swim wherever it wants, maintaining neutral buoyancy, the animal adjusts volume of gas in swim bladder
-To increase volume of swim bladder, it can gulp air, and to reduce volume, it can burp air out
-However, this is when it is connected to gut, other fish use blood to add or remove air
102
Actinopterygii respiration
-Most solely rely on gills
-Water flows in through mouth and out through gills, passing the operculum (gill covering)
-Gills are made of two columns of lamellae attached to gill arch
-Counter current exchange as blood moves in one direction, and water flows in opposite direction, maximising amount of oxygen taken up
-Some fast-moving fishes show ram ventilation, swimming around with mouth open (includes tunas and other pelagic fish)
-Some can do both ram and buccopharyngeal
103
Regional heterothermy
-Vessels from gills (cold) and vessels from muscles (10C higher than water due to movement) meet and exchange heat, heating gill levels
-Usually done around eye or brain region
-Helps fast-moving fish maintain muscle tissue at higher temperatures due to a countercurrent heat exchange system
104
Fish respiration in low oxygen areas
-May have vascularised anus to breathe oxygen, or thicker lips for gas exchange
-Anabantid fish are obligate air breathers and have gills but also have to breathe atmospheric oxygen by gulping air at surface
-Air enters labyrinth organ, where gaseous exchange takes place to provide supplementary oxygen
105
Eel features
-Studied for 1000s of years
-Lost pelvic fins, only have pectoral
-Typically live in crevices or reedy, grassy places
-Common to see this streamlined body in certain environments
-Also lost svales
-American and North European are distinguishable by number of vertebrae and mtDNA
-Catadromous, return to sea to breed
106
Eel breeding summary
-Discovered by Schmidt
-American and European eels bread in Sargasso sea, producing marine larva (leptocephalus) that metamorphose into glass eels *transition stage) and then again into freshwater eels
-Die after breeding
-Leptocephalus to elver takes 3 years in European, 1 in American due to proximity to Sargasso sea
-Thought that Sargasso sea used to be equidistant, but has changed due to continental drift
107
Sarcopterygian examples
-Lungfish
-Coelacanth
-Those that gave rise to tetrapods
108
Lungfish
-3 genera
-Closer related to tetrapods than coelacanths
-Includes Australian, African, and South American
-Australian have well developed lobe fins and thick scales, not seen in others
-All have lungs (and gills) and in the case of African and S American, use lungs for breathing
-Australian mainly breathe with gills as live in permanent water bodies
-African and S American move in a particular way, using reduced pelvic fins
-S American are not well studied, males have gill-like structures that help gaseous exchange as males look after offspring and can exchange gas with developing embryos
109
African lungfish
-Most well-studied
-Live in areas prone to flooding and drying out
-When area dries up, they burrow into bottom mud to form a cocoon
-Cover themselves in mucus and leave a hole to breathe at top of chamber
-Known as aestivation and is seen in other animals when conditions are unfavourable
-Can stay like this for a while
110
Coelacanths
-Thought to have gone extinct 80 MYA
-However, an extant coelacanth discovered in 1938 by Marjorie Courtenay-Latimer, a curator in a South African museum
-Fished from Comoros islands, Latimeria
-Tried to preserve as best as could
-Another found in Indonesia 1998 in fish market
-Large (2m) deep water nocturnal fish
-Don't use fins as props, swim in undulatory way
-Vestigial fat-filled lung and retain urea in tissues and blood as buoyancy aid
-Electroreceptor organ on top of nose for detection of prey etc
-Viviparous, internal fertilisation
-Suction feeders
111
Tetrapodomorph fishes
-Fishes with tetrapod features
-Osteolepiforms
-Elpistostegalians
-Tiktaalik
-Spiracular region (remains of gill chamber after jaw formation) is different to other fish, the beginnings of tetrapod middle year
112
Osteolepiforms
-Large-bodied fish
-Eusthenopteron is a well-known example with well-developed fins
-Small ribs that point dorsally
113
Elpistostegalians
-More derived
-Panderichthys is a well-known example
-Reduced tail, no dorsal or anal fins
-Eyes on top of head
-Flattened, more pointed head
-Ribs larger and point ventrally
114
Tiktaalik
-Indigenous name
-Found in shallows (hence name)
-Intermediate between above fish and tetrapods
-Even more derived features
-Reduced gill covers, suggesting reduced water flow through gills
-Longer neck and could raise its head and long snout, possibly for snapping up prey
-Ribs large and could lift chest and move head
-Flexible pectoral fins, maybe as props to support animal
-Have wrist bones homologous with tetrapods
-No limbs/digits, but fin rays
115
Early tetrapods
-Acanthostega and Ichthyostega
-Parmastega aelidae
-Aquatic
-Different methods of respiration
116
Acanthostega and Ichthyostega
-Date from 365 MYA
-Found in Greenland
-Primarily aquatic and had gills (but also lungs)
-Had fore and hind limbs
-Hind limbs had contact with vertebral column
-Ichthyostega more specialised
117
Ichthyostega specialised
-More robust skeleton
-Longer ribs
-More robust limbs
-Believed to be able to drag itself into terrestrial environments
-Robustness suggests support
-Paddle-like limbs at back suggest good at swimming
-Hearing apparatus too advanced for water environment
118
Parmastega aelidae
-A more basal tetrapod found 372 MYA
-High head and large orbits
-Nostrils point downwards, must have been underneath water
-Uses nostrils and gills for respiration
-Also has spiracle, suggested for air breathing
-Sharp, fang-like teeth
119
Early tetrapod respiration
-Colosteids have downward nostrils for underwater breathing, no spiracle to take up air
-Temnospondyls have nostrils pointed upwards for air breathing and have lungs, spiracle is now ear (thought to have given rise to amphibians)
-Seymouriamorphs similar to temnospondyls but spiracle becomes ear
120
Early tetrapod aquaticism
-Features initially advantageous to animals in water than on land (feeding, dispersal, basking)
-Would have fed at surface of water
-Evolution of tetrapods and evolution of terrestrial life were 2 separate events
121
Present day fish with aquatic tetrapod features
-Frogfish
-Eel catfish
-Mudskippers
122
Frogfish tetrapod features
-A species of anglerfish
-Uses fins to walk around on floor, moving faster this way
-Well developed pectoral and pelvic fins
-A use of fins by present day fish to move
123
Eel catfish tetrapod features
-Can rise above water due to very flexible neck
-Can reach prey on land
124
Mudskipper tetrapod features
-Can move on land using fins
-Can also climb using fins
-Has flexible neck
-Icthyostega probably walked like this
125
Limbs of early tetrapods
-Polydactyl
-Acanthostega had 8 toes on front and hind feet
-Ichthyostega had 7 toes on hind feet, forefeet unknown
126
Hox genes and limb expression
-Fins and limbs homologous, coded by same set of hox genes
-Two phases of hox gene expression, proximal and radials (or digits)
-In tetrapods, digits form in order 4,3,2,1,5
127
Tetrapods with less than five digits?
-Associated with high speed running
-Ostriches and some artiodactyls (e.g., antelopes) have two toes
-Less branching, so less toes
-Less area for contact with ground allows for faster movement
128
Mechanisms for digit loss in tetrapods
-Reduced gene expression (Ptch 1 gene)
-Cell death, digit starts to form but dies
129
What gave rise to amphibians
-Batrachomorphs
-Temnospondyls either gave rise to all amphibians, or just frogs, toads, salamanders and newts
130
What % of amphibians are threatened?
41
131
Shared derived features of amphibians
-Smooth, moist, permeable skin
-Specific hearing
-Pedicellate teeth
-Vision
-Eye muscles and movement
132
Skin of amphibians
-Can breathe through
-Contains unique vuscularisation that allows for CO2 and O2 exchange
-Thin epidermis, meaning high rates of water loss
-Tied to aquatic or semiaquatic lifestyles
133
Hearing in amphibians
-Use two regions of inner ear for higher and lower sounds
-Papilla amphibiorum sensitive to sounds below 10,000 Hz
-Operculum columella thought to transport vibrations from legs to inner ear
134
Vision in amphibians
-Green and red photoreceptors (only red rods in most vertebrates)
-Acute colour vision even in low-light
135
Amphibian pedicellate teeth
-Only group with these in recent tetrapods
-Complex
-Consists of two calcified dentine layers, crown and base
-Connected by connective tissue
136
Amphibian eye muscles and movement
-6 intrinsing muscles, common to all vertebrates
-Also have retractor and levator bulbi
-Move eyes as a whole
-Can retract eye and cover with nictitating membrane
-Levator bulbi can pull eyeball forward
-Related to food intake as it allows for enlarged buccal cavity
137
Anuran features
-Includes frogs and toads
-Tail-less amphibians
-Most widespread amphibians
-30 families, 5,000 species
-Incredibly diverse in body size and lifestyles
-All carnivorous
-Very specific in terms of morphology
-There are still recent taxonomic discoveries
138
Anuran morphological specificities
-Specific skeleton
-Elongated hind limbs and pelvis for jumping
-Possess urospine, rod-like fusion of the sacral vertebrate resulting in shock absorbing basket
-Reduction of ribs for solid path of energy from limbs when jumping
-Tibia and fibula fused to form tibiofibular
-Radius and ulna also merge
-Forward facing for binocular vision
-Lost some digits, now has 4
-Most lose lateral line
-Anuran body form developed because of advantage in swimming or jumping with hind legs
139
Recent anuran taxonomic discoveries
-Understudied in tropics and sub-tropics
-In 2023, a new species described already, the talking frog, one individual in Ecuador
-New family, Nasikabatrachidae, specialised for burrowing, found in 2003, first since 1926
-In 2014, new species found in NYC wetlands
140
Amphibian reproductive modes
-Ancestral mode is aquatic, still retained in some species
-Big diversity
-Burying live young rare in salamanders, common in Caecealians
-Highest diversity in anurans
141
Anuran reproductive modes
-Generalised lifecycle actually only common in temperate conditions
-Traits such as egg and clutch characteristics vary
-Diversity in oviposition site, larval development, stage and size of hatchling
-Diversity higher in tropics
-Many ways used to protect young against desiccation
-Acoustic communication key
-Less eggs means more costs, and longer developments that require parental care but avoids predation of young
142
Anuran reproductive diversity in tropics
-There has been a progression from aquatic to terrestrial
-More terrestrial reproductive modes where it is warmer and wetter
-Can sustain water-loss
-Aquatic environment also full of predators, making terrestrial species fitter
-Survival of young is main driver of evolving to terrestrial lifestyles
143
Anuran methods of protecting young from desiccation
-Evolved convergently
-Some produce a foam nest through movement of legs and secretions from oviduct, protecting egg and also allows for tadpole development
-Some produce egg clutches folded into large leaves overhanging water, where tadpoles fall into ponds after hatching to develop aquatically
144
Anuran parental modes
-Convergent development of different modes
-Some males guard clutches of eggs
145
Anuran acoustic communication
-Key for reproduction
-Minimal role of pheromones
-Acoustic calls are stereotyped
-Done by inhaling or exhaling air or water
-Only males (some exceptions)
-Vocal sac amplifies the call
146
Trade-offs of acoustic communication in anurans
-Ease of signal variation, can circumvent obstacles and works in dark
-But short lived/distanced, attracts predators, is costly and can be covered by background noise
147
Urodele (Caudata) features
-Includes newts and salamanders
-756 known species
-55% species threatened, 80% of habitat unprotected
-Usually respire using lungs and skin or at surface of mouth
-Variation in courtship displays
-Mostly aquatic eggs and larvae
-Mostly 4 limbs and long tail, except aquatic forms such as sirens, that have lost back limbs
-Move through body undulations
148
Fertilisation in urodeles
-Males will deposit one to many spermatophores, consisting of a gelatinous base with a sperm cap
-Females will intake these into reproductive tract
149
Urodele courtship displays
-Complex behaviour with elaborate secondary sexual characteristics
-Done to make females take up spermatophores
-Mole salamanders will begin with rubbing females, following with movements between both, and pheromone releasing, ending with female taking spermatophore
150
Pheromone transfer in urodeles
-Tail fanning
-Skin slapping
-Biting
-Rubbing
151
Urodele larvae
-Mostly aquatic
-Some purely terrestrial species (viviparous or ovoviviparous) females retain developing embryos or eggs until end of gestation, where she delivers fully developed terrestrial juveniles
-A lot of salamanders and newts are reaching maturity without losing gills
152
Gymnophonia (Apoda) features
-Limbless
-All modern caeciilians
-Have annuli that make them appear segmented, but are just markings
-Mainly found in tropics
-Mainly terrestrial, some aquatic species with specialised reproduction
-Only 215 known species, 35 genera and 10 families
153
Gymnophonia reproduction
-All internal
-Some oviparous, with free-living aquatic larvae
-Some oviparous, with direct development
-Some viviparous, terrestrial and aquatic
-Larvae 60% adult body length
-9 offspring
-Energy first supplied by yolk, then mother
154
Maternal nutrition in gymnophonia
-Oviductal scraping of uterine milk (fatty and rich) in viviparous species
-Skin-feeding (fat rich expanded cells scraped off) in oviparoys, skin regrows every 3 days
-Scraping done with tiny teeth
155
Olms
Cave-dwelling urodeles with reduced eyes
156
Limb differences in anurans
-Long hind and forelimbs are usually walkers and jumpers
-Common toads have short limbs and are more hoppers than jumpers, so tend to move around a lot and can be conspicuous to predators, so have toxins in skin
-Common frogs have longer back legs and are jumpers, with cryptic colouration, and are ambush predators that can jump away from other predators
157
Oldest amphibian fossil
-Permian (approx. 290 MYA)
-Showing urodele and anuran types
158
Derived features of amniotes
-Reduced skin permeability
-Thicker, keratinised skin with more lipids
-Thickening of cranial ectoderm, creating epidermal placodes that lead to scales, hair, feathers
-Costal (rib) ventilation instead of using mouth gaseous exchange
-Rib ventilation means air can be drawn in through a longer distance, allowing for longer necks in amniotes
-More complex nerves controlling forelimb
-Temporal fenestration
159
Temporal fenestration
-Development of holes in skull
-Anapsid skull has no holes
-Synapsid skull found in mammals and have one hole and one arch
-Modified diapsid with one or two temporal bars lost (two in snakes, giving them flexibility)
-Holes evolved independently
-In humans, orbit merged with hole to form one large gap, muscles pass through from bottom of jaw and attach at top of head
160
Why did skull holes evolve?
-Maybe muscles evolved to become larger for more feeding
-Allows for more diversification of jaw movement
161
Diapsids
-Turtles diapsid but look anapsid
-Archosaurs consist of crocodiles, dinosaurs, pterosaurs and birds
-Lepidosaurs include tuatura, snakes and lizards (think tuatura lost lower bar like lizards, but then regrew one secondarily)
162
Chelonia
-Turtles
-Most derived vertebrates
-Body made of carapace (top) and plastron (bottom) covered in scutes (plates of keratin)
-Ribs fused to carapace
-Skull looks anapsid but is modified diapsid
-Odontochelys fossil from 220MYA showed that plastron evolved before carapace, meaning probably emerged in aquatic environment as plastron protects from underneath
163
Chelonia respiration
-Ribs being fused to carapace means difficult breathing
-Lungs attached to gut
-When muscles relaxed, gut moves downwards and lungs fill, inhaling
-When muscles contract, pushing gut upwards, lungs are pushed, causing an exhale
164
Chelonia shape
-Aquatic forms tend to be flatter, terrestrial dome shaped
-Exceptions include pancake tortoise
-Snake neck tortoise can fold neck in sideways
165
Dinosaur brief phylogeny
-Diverse group of reptiles belonging to Dinosauria
-Were part of bigger, monophyletic group, the archosaurs
-Today, archosaurs only represented by crocodilians and birds
-Archosaurs were 'ruling reptiles'
166
Archosaur synapomorphies
-Prescence of calcaneal tuber
-Two skull openings, one between eye socket and nostril, one in lower jaw
-Reduction of the 5th toe
-Secondary palate allows for breathing while eating
-Teeth in sockets (thecodont)
167
Calcaneal tuber
Bony process projecting anteriorly
168
Dinosaur skull opening role
-Lower jaw hole thought to be site for attachment for jaw muscles
-Other hole thought to be an adaptation for reducing skull weight and increasing agility
169
Archosaur branches
-Pseudosuchia
-Ornithodira
170
Pseudosuchia
-Includes crocodilians
-Very high diversity
-Limbs were more erect than primitive reptiles
171
Ornithodira
-Includes birds and dinosaurs
-Single hinge-joint ankle
-Very long hindlimbs
-Longer S-shaped neck
-When dinosaurs first appeared during Triassic, they were not dominant
172
Dinosaur shared derived features
-Semi-erect posture in all archosaurs, even more in dinosaurs
-Upright forelimbs displayed directly beneath
-S-shaped neck (found in birds)
-Pubis bone orientated downwards and backwards, hip structure critical for phylogeny
-Reduced to 3 main toes on foot
-Open acetabulum between ischium, ilium and pubis, where femur would be
-Sacrum, fused vertebrae where pelvis attaches
173
How is dinosaur phylogeny decided
-Hip structure is key criteria
-Hip made of three bones in mammals, birds, reptiles
-Limbs beneath body give semi-erect posture
-Saurichians are 'lizard-hipped', with pubis arranged at front and ischium at back
-Ornithiscians are 'bird-hipped', with pubis and ischium pointing back and down, and ilium has forward facing process
174
Evidence against classic phylogeny
-Birds evolved from theropods that had 'lizard-hipped' structure
-Also, late evolving theropods had a backwards pointing pubis
-In 2017, a publication challenged classic phylogeny, proposing that theropods should instead be a sister group to ornithiscians, forming ornithocelidans
175
Reproduction in dinosaurs
-Most aspects of reproduction and parental care inferred from extant taxa
-All extinct dinosaurs laid eggs
-Known diversity of egg-laying dinosaurs limited to a few groups
176
Dinosaur eggs
-Thought that they had hard calcium carbonate shells instead of the leathery reptile eggs
-Still observed variety of shell microstructures
-Proposed that calcerous eggs convergently evolved at least three times
-Ancestral soft-shelled egg
-Would explain why most eggs found are from Cretaceous period, as early dinosaurs would have been laying soft shell eggs that are not as easily preserved
177
Diversity of dinosaurs
-Originated during late Triassic period, first 30 out of 165 million years of non-avian dinosaurs
-Only 5% excavated from Triassic
-Thought that diversity expanded during Jurassic or Cretaceous
-150 MYA birds evolved from theropods, only group to survive end of Cretaceous
-Around 1850 genera (including those that remain to be discovered)
-Understanding dinosaur diversity will help us understand the extinction of non-avian dinosaurs
178
All birds have...
...-Feathers
-Wings
-Hollow bones for a lighter skeleton
-No teeth, have gizzard to digest food (with stones)
179
Only vertebrates we know the whole phylogeny for
-Birds
-Estimated around 10,000
-Half are passerines (pirching birds)
180
Looking at ratites to help understand bird evolution
-Ratites can be observed in every landmass of Southern hemisphere
-Originated before split of continents
-Was believed for a while, but then found out that they are not a monophyletic group
-They all convergently lost ability to fly
-Probably not root of phylogeny
181
How did birds evolve?
-Some suggest that birds evolved from early archosaur or crocodylomorphs
-Most widely accepted that they evolved from theropods
-Originated in Jurassic, diversified in Cretaceous
182
Theropods
-Ancestrally carnivorous dinosaurs, but now show a range of diets
-Ranged from chicken-sized Compsognathus to Tyrannosaurus rex to the very largest of all theropods, the fish-eating Spinosaurus (around 80m long, 7400kg)
-Idea that birds evolved from theropods first proposed by Thomas Huxley, but was dismissed mainly due to his lack of evidence
183
Dromaeosaurus
-Very well-known
-May have looked more bird-like than portrayed in media
-Feathered and smaller than we thought
-Forelimbs used for grip and for handling prey, modified for flexible seizing function and hunting
-Feathers probably evolved for insulation, not flight, or maybe sexual displays
184
Bird evolution
-Theropod lineage is directly ancestral to birds
-Across 50 million years, there was a tendency to reduce body size
-Skeletal adaptations four times faster than in any other group
-Skull also became larger compared to body
-Lost digits
185
Bird skulls
-Trends towards smaller size were accompanied by trends towards paedomorphic skull
-This means young and adult birds would have similar skull size
-Birds therefore have paedomorphic dinosaur skulls
186
Bird digits
-Ancestral condition was five toes
-This diminished over time due to digit reduction and fusion
187
Bird features common with theropods
-Lay eggs
-Scales (feathers are derived scales)
-S-shaped neck
-Tridactyl foot (not shown by all birds)
-Bipedal
-Toes bearing weight of body (digitigrade posture)
-Wishbone, a fused clavicle
-Fused sternum
188
Archaeopteryx
-"Transitional form" between reptiles and birds
-Iconic late Jurassic fossil, with well-developed feathers (150 MYA)
-12 individuals found, first one found in Germany in 1861, kept in vault of NHM
-Max 1kg, estimated to be size of crow
-Broad wings with rounded ends
-Long tail compared to body size (up to 50cm)
-Reptilian and bird features
189
Archaeopteryx reptilian features
-Thick, sturdy bones, not hollow
-No fusion of vertebrate
-Toothed jaw, not seen in modern birds
-No doubt that it had teeth, clear in fossils
190
Archaeopteryx bird features
-Well-developed feathers
-Three fingers (not same shape as modern birds however)
-S-shaped neck
-Debated whether it belongs to aves or not
191
Archaeopteryx features that help understand evolution
-Asymmetrical feathers, typical for flight (not insulation)
-Found in 2001 that they had similar moulting strategy to preserve maximum flight efficiency (such as in falcons)
-Hind-foot with opposable first toe, similar to modern birds
-Furcula (wishbone), also found in theropods and birds
192
Archaeopteryx flight
-Primitive shoulder girdle that likely limited movement
-Likely lived where there were no big trees
-Didn't climb or perch
-Thus probably flew like pheasants, short distances to hunt or escape
193
11th Archaeopteryx specimen
-Was originally in private collection
-Now allowed to study
-The new specimen shows presence of hyperextendable second toe as seen in dromaeosaurs (not present in modern birds), known as a terrible claw
-Terrible claws were held off ground during locomotion, when muscled contract, claw sweeps down quickly
194
Archaeopteryx vs pigeon
-Pigeon has larger brain case, thought to be because they process spatial information
-Pigeon has 2 digits, not 3 on forearm
-Pigeon has shorter tail
-Large sternum linked to strong pectoral muscles in pigeon
195
Was Archaeopteryx the first bird
-Thought to be for a while
-However, lots of small feathery dinosaurs found in recent times, raising questions about which were direct ancestors and which were cousins
-Xiaotingia zhengi discovered in 2011 in China
-Archaeopteryx in run for first bird, but there are other candidates
196
Xiaotingia zhengi
-From late Jurassic
-Discovered in 2011 in China
-Surrounded by feathers, but also had claws on forelimbs and short teeth
-Not known if true relative to bird
197
Other candidates for first bird, aside from Archaeopteryx
-Aurornis (150-160 MYA)
-Rahonavis (70-65 MYA)
-Scansoriopteryx (130-125 MYA)
198
Advantages to flight
-Flight made birds successful, more birds than other amniote groups and are found everywhere
-Allows to escape predators
-Good for foraging
-Cost-efficient locomotion, such as gliding
-Fast, peregrine falcon 200km per hour
-Colonisation of less accessible habitats such as islands
-Migration across planet to exploit different conditions to feed or breed
-Starling murmurations
199
Constraints of flight
-Requires major physiological and anatomical adaptations
-Rather uniform in morphology
-Limited size and weight range, aerodynamics predict ~12kg, can be bigger if flightless
-Muscle power needed to take off increases by a factor of 2.25 for each doubling of biomass
200
Feather features
-Bird lineage not first to have feathers, some theropods also had feathers, as did many dinosaur groups
-Flight may have also evolved before birds
-Symmetrical for insulation, asymmetrical for flight
-Different types
-Can have colours and patterns
201
Colours and patterns in feathers
-For sexual selection, such as peacocks, house sparrows, great tits etc
-For crypsis
-Combination of pigments, such as melanin (black to grey), phenylamines (red to browns), carotenoids (from diet, as can't be generated (red to yellow))
-For iridescence, created by melanin granules inside feathers casting reflections that cause colour changes when viewed from different angles
202
Feathers as insulation devices
-Heat absorption relies on colour
-Darker wings consistently hotter than light wings
-In white wings with a black tip, temperature difference leads to conductive currents towards tip of wing, leading to an increase in lift as air is moving towards the tip
203
Form and origin of feathers
-First appeared in theropods
-Not for flying, probably insulation or coloration
-Homologues of reptilian scales
-Flight is only one function, also provides insulation, colouration, thermoregulation and waterproofing
-Shaft of feathers have barbules on either side that have little hooks to interconnect with each other
204
Preening in birds
-When birds are preening, they ensure barbules are interlocking to keep waterproofing and insulation
-They also apply oil from preen glands to help maintain waterproofing
205
Different types of feathers
-Down feathers for insulation
-Wing feathers for flight
-Bristle and filoplume feathers detect things
-Semiplume feathers also for insulation
-Countour feathers
206
Common poorwill
-Have bristles around beak to detect prey
-Use torpor in hot conditions to cool body down
-Reduce oxygen consumption by >90%
207
Origin of flight theories
-Cursorial theory
-Arboreal theory
-WAIR (Wing-Assisted Incline Running)
-Pouncing pro-avis hypothesis
208
Cursorial theory
-Wings evolved to help running
-This helped stabilisation and/or catching flying prey
-Favoured theory
209
Arboreal theory
-From the trees down
-Wings helped move around in trees
210
WAIR
-Wing-Assisted Incline Running
-Wings evolved to assist in climbing
-Some young birds do use wings to stabilise movement in branches of trees
211
Pouncing pro-avis hypothesis
-Possible alternative to cursorial
-Ancestral forms would've used wings to pounce on prey
-Helped hunt, not directly to help with movement
-Some would use wings to restrain prey
212
Evidence for cursorial theory
-Ambiguous morphological evidence for climbing abilities
-Lack of trees in locations where Archaeopteryx was found
-Spread of feathered forelimbs was originally probably for stabilisation during running
-Archaeopteryx could glide, but its ability for flapping flight is in doubt due to lack of flexible wrist
213
Evidence against Archaeopteryx ability to fly
-Velocity gap, as max speed of Archaeopteryx was 2m/s and would have needed to be 6m/s to take off
-Not sure that Archaeopteryx could withstand the high energy demands of flight
-Tiny sternum on Archaeopteryx, the point of attach for pectoral muscles, so how did they move off the ground?
214
Evidence for arboreal theory
-Amazon rainforest bird young retain claws to move around in trees
-Pigeon has no claws, Archaeopteryx does, as did dinosaurs
-Amazon rainforest adults lose claw
-Feduccia's claw arc analysis
215
Feduccia's claw arc analysis
-Ground dwellers have shallower and flatter claws
-Climbers have large arcs in claws
-Perchers are inbetween
-Concluded that due to climbing front claw of Archaeopteryx and perching back claw, it must have been an arboreal, climbing bird that glided from heights
216
How do wings work in flight
-Wings follow principle of an aerofoil
-Surface of wing pushes air forward and down
-This creates area of high pressure below the wing and high pressure above
-This results in a lift
-The angle of wing changes direction of forces
-Wing tips (primary feathers) are responsible for thrust, leading to a forward momentum at downward stroke
-Throughout active flight, part of wing closest to body stays pretty much horizontal
-As air passes horizontally over this part, the aerofoil generates an upwards force
-Lift counteracts gravity, keeps bird up
-During downward stroke, wing tip is twisted forward so that the cross section is at a steep angle
217
Wing aspect ratio
-High aspect ratio (longer than wide) for active soarers and high-speed birds, such as albatrosses, gannets, gulls, falcons, ducks, terns and swifts
-Low aspect ratio (wider than long) for passive soarers and ellipticals (very manoeuvrable) such as crows, sparrows, thrushes, storks and eagles
218
Bird respiration
-Unidirectional air flow in lungs
-This means higher oxygen concentration than in mammals
-Additional oxygen supply important for energy requirement of flight
219
What is dispersal?
-Movement from the natal (natal dispersal) or previous breeding site (breeding dispersal) to a new breeding site
-A 3 stop process
-A key life history trait
-Critical for individual fitness
220
3 steps of dispersal
-Decision to leave (emigration)
-Movement (transience)
-Decision to settle (immigration)
221
How is dispersal a key life history trait?
-Gene flow, as dispersal is to breed (different to migration), so after settlement a reproductive event occurs and gene flow is thus impacted
-Spatial distribution
-Population dynamics and genetics
-Speciation and adaption
-Helps us to understand biological invasions
222
Benefits to dispersal
-Mostly after-settlement benefits
-Inbreeding avoidance
-Kin competition avoidance
223
Costs of dispersal
-Mostly during transience and after settlement
-During transience, birds are more likely to cross predators and hostile environments, and food, water and shelter may be hard to find
-After settlement there is lack of familiarity, leading to mortality, exploration costs, competition
-Maladaptation in terms of parasite resistance and mate choice
-Energy and time costly and can't do other activities
-Selecting breeding site is one of most important decisions (as well as mate choice)
224
Collared flycatcher
-Short-lived, whole nesting, migratory passerine bird that exhibits strong sexual dimorphism
-Monitored on an island in Sweden since 1980, so population dynamics known
225
Primate features
-Earliest known potential primate was 66 mya
-250 species, new one found yearly
-Mostly restricted to tropical regions
-Mostly arboreal
-Mostly omnivores but some specialist leaf eaters and need to digest cellulose
226
Recent primate discoveries
-Popa langur discovered in 2020 in Myanmar, endangered due to habitat loss and hunting, with only 250 individuals and was thought to be subspecies of widespread langur species, but is actually independent
-Tapunili orangutan, the first great ape species to be discovered since bonobo in 1929 and threatened mainly by habitat destruction
227
Special primate adaptations to digesting cellulose
-Specialised sacculated stomach
-Special enzymes
-Endosymbiotic bacteria
228
Anatomy of primates
-Retention of clavicle, lost in many mammals but not primates
-Shoulder joint allows limb movement in all direction
-Elbow joint allows rotation of forearm, essential for arboreal movement
-5 digits on fore and hind limbs
-Posterior skull
-Enlarged brain, specifically cerebral cortex, with a reduced nasal region
-Reduced snout and olfactory system
-Reduced number of teeth
-1 young/pregnancy (some exception)
-Nails (modified flattened claws) and fleshy sensitive pads at fingertips
-Bigger orbit size and forward-facing eyes for binocular vision
-Opposable thumbs
229
What is the enlarged brain (specifically cerebral cortex) of primates associated with
-More frugivorous diet
-Needed to be able to discriminate fruits against a background
230
Are twins impossible in primates
No
231
What do nails and the fleshy sensitive pads at the fingertips of primates help with?
-Locomotion
-Grooming (essential for bonding)
-Manipulation of objects
-Dexterity
232
Opposable thumbs in primates
-For grasping (handy for arboreal lifestyle)
-Increases dexterity and allows for finer manipulation of objects
233
Prosimians
-'Before apes'
-Basal primates that branched off early
-Includes lemurs, bushbabies, pottos and tarsiers
-Mostly in mainland Africa
-Small, nocturnal and small brained
-Relatively long nose
-Paraphyletic group
-Tarsiers have a dry nose and are more related to other primate groups than rest of prosimians
234
Anthropoids
-Mostly larger than prosimians
-Larger brain and relatively small olfactory lobes, not a strong sense
-Mainly frugivorous or folivorous
-Different types of locomotion, thought to be due to the shift from foraging at night
-Mostly diurnal
-Includes New and Old World monkeys, and great and lesser apes
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Strepsirrhini vs haplorrhini
-Strepsirrhini means wet nose, haplorrhini means dry nose
-Haplorrhini have shorter nose and forward-facing nostrils
-Also have orbit septum
-Strepsirrhini consist of lemuriformes and lorisoformes, the rest are haplorrhini
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Strepsirrhini species features
-Lemuriformes and lorisoformes, thought to have split 40 MYA
-Usually small, long-snouted and nocturnal
-Frontal bones unfused in middle
-Lower jaw halves unfused
-Open orbit (no septum)
-Distributed across Africa, Asia and Madagascar (one lemur species)
-Generalist diet
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Giant lemurs
-Had lemurs the size of female gorillas in past
-Decline associated with Madagascan colonisation about 2000 years ago
-Decline continues today
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New World monkey features
-Platyrrhini (broad-nosed)
-3 premolars (more primitive state)
-Relatively good sense of smell
-Colonised South America from Africa about 30 MYA
-No terrestrial radiation, only arboreal species, probably due to ground niches in SA being already occupied before colonisation
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Groups of New World monkeys
-Atelidae, consisting of spider monkeys, muriquis, woolly monkeys and howlers, are specialised climbers with prehensile tails
-Aotinae, consisting of owl monkeys, are night monkeys, the only nocturnal higher monkeys
-Cebinae consists of capuchins and squirrel monkeys
-Phitheciinae consists of titis, sakis and uakaris
-Callitrichinae, consisting of marmosets and tamarins, have secondary claws, more than nails and also commonly produce twins
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Old World monkey features
-Catarrhini (narrow-nosed)
-More specialised and species rich, with higher diversity
-No prehensile tail
-2 premolars, a derived feature
-Trichromatic colour vision
-Poor sense of smell, smaller nose, 50% of olfactory genes still active
-Split from NWM and apes around 28 MYA
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Old World monkey groups
-Colobines
-Cercopithecines
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Colobines
-E.g., colobus monkeys, proboscis monkeys, langurs
-Found in Africa
-Folivorous with complex stomachs for digesting cellulose,
-Arboreal with long (non-prehensile) tails
-Back legs bigger than forelimbs
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Cercopithecines
-E.g., vervet monkey, baboons, mandrills, macaques
-Mostly found in Africa (some in Asia)
-Terrestrial with short tail
-Limbs of equal length
-Omnivorous and frugivorous
-Longer thumbs and shorter fingers than Colobines
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Ape groups
-Lesser apes, consisting of gibbons and siamangs
-Great apes, consisting of gorillas, orangutans, bonobos and humans
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Ape features
-Broad thorax, with a dorsal position of scapula, increased curvature of ribs and a centered vertebral column
-This assists balance in a bipedal pose as centre of gravity is near the vertebral column, other primates have to bend knees and lean forward to balance when upright
-Lumbar region of vertebral column is short and caudal vertebrate reduced (no tail)
-Front skull characterised by sinuses
-5 cusps on molars helps with identification
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Social systems
-Female transfer
-Male transfer
-Monogamous
-Solitary
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Female transfer in primates
-Means females leave group that they are born in
-Females in groups aren't relates
-Males form close kin associations as they are all related, but can become territorial
-Small groups
-Seen in chimps, gorillas, baboons and colobus monkeys
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Male transfer in primates
-Males disperse
-Females in group are all related with complex behaviours
-Sometimes males stay and form a dominance hierarchy, so is sometimes referred to as "non-female transfer"
-Large groups
-Seen in most cercopithecines
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Monogamy in primates
-Both sexes participate in defense and parental care
-Seen in gibbons and tamarins
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Solitary primates
-Can be individual, or a female plus offspring
-Male range overlaps with range of >1 females
-Seen in bushbabies and orangutans
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Summary of fitness consequences of dispersal in Collared flycatcher
-Displaced birds and immigrants are less likely to settle and breed
-Non-dispersers and older birds are more likely to return to patch of capture
-Displaced individuals that accepted the displacement raised lighter nestlings
-Mortality not a factor
-Costs of unfamiliarity are non-breeding and early breeding failure
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Long-tailed tit
-Tiny bird
-Spend winters in groups to keep warm
-Split up in March to form pairs and build nests, breeding in May/June
-Habitat of test site in Rivelin Valley, Sheffield (2.5km^2)
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Lepidosaurs
Squamates and tuatura (rhynchocephalia)
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Archosaurs
-Only living members are crocodilians and birds
-Also includes dinosaurs, pterosaurs and extinct crocodilians
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Squamate skulls
-Modified diapsid skull, with lower bar lost in lizards, and both bars lost in skull, making jaw and face more flexible
-Kinetic jaws in most, can have flexibility in diet, but also jaws quite weak (Amphisbaenia have akinetic skull)
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Range of sizes in lizards
-Komodo dragons are 3m, found in Indonesia
-Dwarf geckos 1.6cm, found in Dominican Republic, insectivorous
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Herbivory in large lizards
-Usually are
-Exceptions are monitor lizards and tegus
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Komodo dragon venom
-Due to kinetic jaw, jaw is weak
-Found that komodo dragons have venom glands that run into ducts in teeth, injecting into prey with bite
-Causes prey blood pressure to drop and has an anticoagulant, weakening prey
-Venom also seen in some snakes
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Gular pumping in monitor lizards
-Conflicts between locomotion (undulating) and respiration
-Use back of throat to pump extra air
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Limb reduction in lizards
-Evolved many times in lizard (>60)
-Includes Amphisbaenia, anguinae, pygopodia and serpentes
-Associated with living in crevices, burrowing, or living in long vegetation where limbs are not useful
-Surface dwelling (legless) lizards have short bodies and long tails to move effectively through tall vegetation by more undulations
-Burrowers have short tails and a long body
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Snake evolution
-Essentially specialised legless lizards
-Thought to have branched in Cretaceous
-Thought that during their burrowing stage, their eyes changed
-As they became surface dwellers, their eyes redeveloped and are different to lizard eyes
-Debated
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Snake features
-Short neck and tail, mainly thorax with ribs
-Change in gene expression leads to more thoracic vertebrae
-This gene is thought to be Oct4, as Oct4 in mice, when experimented with, caused increased thorax length and decreased limb development
-Lack pectoral and pelvic girdles (vestigial in pythons and boas)
-Downside of elongated body means a reduced diameter, reducing what it eats
-Snakes avoid this by having a very flexible jaw that can expand to eat something twice the snake's size
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Eupodophis
-Fossil found
-Snake with hindlimbs
-Forelimbs probably lost in snakes first
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Tetrapodophis
-Recent fossil found
-Tiny snake with four limbs
-Probably used limbs to grasp things
-Suggested it was good at burrowing, adding to hypothesis about burrowing stage
-Discovered by chance, teacher with students visited museum in Germany and spotted and recognised it
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Snake jaws
-Multiple points of articulation, up to 8 or more
-Flexibility in many points
-Backward facing teeth that pull prey into throat
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How to snakes subdue prey
-Some produce venom, some constrict
-Constrictors wrap around prey, stopping preys bloodflow to organs
-Snakes can detect heartbeats to know when prey is dead
-Some swallow whole without subduing, risky because it can cause damage
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Crocodilians
-Alligators, gharials and crocodiles
-Part of archosauria
-Diapsid
-Alligators found in freshwater and brackishwater, all in the Americas except the Chinese alligator
-Two gharial species: gharial in India and false gharial in Malaysia and Indonesia
-Crocodiles have a worldwide distribution
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Secondary palate mechanism
-Separates nasal and oral passages
-Crocodiles can feed underwater as long as nostrils are above water
-Can breathe and eat at same time
-Similar mechanism in mammals
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Crocodilian features
-Semi-aquatic predators
-Little limbs, so jaw used for attacking prey and eating etc
-Bumps on jaw are integumentary sensory organs and are pressure receptors as sensitive as fingertips
-Use jaws for lots of things, such as carrying offspring and removing shells from struggling offspring
-Show parental care
-Intelligent, use lures to attract prey, such as sticks on head to attract birds
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Extinct crocodilians
-Only 24 extant species, pretty small
-In past, were far more diverse and widespread
-Include Pakasuchus kapilimai (the size of a cat), Simosuchus clarki (about 60cm long), and Dakosaurus andiniensis, a formidable aquatic predator with serrated teeth
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Crocodilian heads
-Very varied in width
-Was thought to be due to diet
-Gharials have narrow snouts for fish
However, as do false gharials, and they have a mixed diet
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Crocodilian locomotion
-Can move through water via undulations
-Can drag themselves along land, or can walk a bit more upright
-Can gallop at speeds of up to 30km/hr
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Crocodilian social behaviour
-Like birds, they use sounds
-Sounds for territory disputes, mating, and parental care etc
-Even offspring will communicate with adults, and adults can locate and dig them out
-Also show play behaviour, alone or in groups
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Mammal evolution
-Arose from synapsids
-Split from sauropsids early on (late Carbeniferous, early permian)
-Both groups show convergently evolved similar traits, such as holes in skulls, endothermy
-Synapsids first amniote group to radiate on land
-Numbers declined during Triassic, when diapsid reptiles were diversifying
-Therapsids, a more derived synapsid group, along with mammals, survived this decline
-After dinosaur extinction, a second diversification occurs, of mammals
-This is from Cretaceous onwards
-Diversification probably due to many factors, not just dinosaur extinction
-These include the diversification of vegetation
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Pelycosaurs
-Derived synapsid group
-Large-bodied
-Sprawling limbs that stuck out the side
-Include Dimetrodon, that had sails along their back
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Therapsids
-Derived pelycosaurs
-Still large-bodied
-Differentiation of teeth now seen
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Cynodonts
-Arose from therapsids
-Reduction in size
-Change in limbs, now underneath
-Changes in skull and teeth, more variable now
-Some have sabre teeth, some too big for feeding, maybe for display
-Some sabre teeth may have had channels, possibly for venom
-Show a move towards endothermy
-Gave rise to mammals
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What changes occur while moving from synapsids to mammals?
-More upright posture
-More flexible vertebrae
-A reduction in the tail
-Reduction in ribs in lumbar region, they are concentrated in thoracic region
-This indicates presence of diaphragm
-This all suggests a more active lifestyle, and a step towards endothermy
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Diaphragm
-Evolved during course of mammal evolution
-Muscle that separates pulmonary and abdominal cavities
-In relaxed state, it domes, pushing upwards
-This restricts volume in pulmonary cavity, expelling air
-As diaphragm contracts, pulling down, the volume in pulmonary cavity increases, drawing air in
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Changes in jaw and skull that arose in mammals
-Non-mammalian synapsids have all teeth the same, undifferentiated (homodont)
-Some differentiation in intermediate forms, but mammals show much more (heterodont)
-Eye socket combines with hole in skull, forming one hole
-Changes in jaw articulation, dentary (lower jaw bone) is more prominent
-As a consequence, dentary articulates with skull to form a strong dentary/squamosal articulation
-Other jaw bones have become incorporated into the inner ear, with a hammer, stirrup and anvil
-Thought that these bones had vibration detecting mechanics when they were still part of jaw, but as animals became more active, a conflict began between using jaw for feeding or hearing, so these bones joined middle ear
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Mammal limb orientation
-Early synapsids (and lizards) undulate body from side to side, using same muscles for locomotion as are used for respiration and when moving, air is just pushed between lungs, meaning slow movement
-Mammal limbs below body, thoracic cavity kept rigid, with diaphragm to ventilate lung
-Some fast mammal movements actually help respiration, as during the pre-leap position, pressure in the cavity is increased by viscera pushing up on diaphragm, causing an exhale
-As the animal bounds, viscera ease, and pulmonary cavity increases, and air is drawn in
