Final Exam Flashcards Preview

EEB388 > Final Exam > Flashcards

Flashcards in Final Exam Deck (183):

Mammalian Diversity

- 6,000-6,500 species
- Largest orders (in order) are Rodentia, Chiroptera, Soricomorpha, Primates
- Total of 28 orders



Two sets of temporal fenestrae in the skull
- Supratemporal
- Infratemporal
Condition of most reptiles



No temporal fenestrae
Condition of turtles



One set of temporal fenestrae in the skull
Condition of mammals



- May be considered the first mammal, depending on the characteristics you use to define mammals
- Small, about 10cm
- Plantigrade
- Nocturnal and insectivorous
- Furred
- Laid small, leathery eggs
- Had two sets of teeth, milk and adult


Special Characteristics of Mammals

- Enhanced intelligence and sensory abilities
- Good sense of smell and hearing
- Endothermic
- Highly efficient reproduction, lactation and social learning
- Efficient food procurement and processing


Mammalian Skull Features

- Single dentary bone makes up the mandible
- Dentary articulates with squamosal
- Quadrate and articular in reptiles have become inner ear bones (incus and malleolus) in mammals
- Pinnae (external ear)
- Epiphyses of the long bones
- Flexible neck (typically 7 cervical vertebrae)
- Two occipital condyles
- Secondary palate separates mouth from nasal cavity


Mammalian Teeth Features

- Thecodont (socketed teeth)
- Heterodont
- Diphyodont (teeth replaced once during development)

All these characteristics are variably present in non-mammals



Teeth are socketed



Different types of teeth (i.e. incisors, canines, premolars, molars)



Teeth are replaced once during development


Mammalian Soft Features - Hair

- Body is typically covered by hair at some stage in development in mammals
- Mainly functions as insulation but can have other uses
- Replaced once or twice a year in a moult
- Colour patterns typically serve as camouflage
- Sebaceous skin glands produce oils to lubricate and maintain hair



Dead epidermal cells that are strengthened by keratin
Grow from living tissue contained in the root



Word used for a mammalian coat of hair



Stiff hairs used as a tactile organ
- Associated with complex facial muscles
- Typically found on the face but sometimes legs as well


Sebaceous Glands

Skin glands that are associated with individual hair follicles
Produce oils that lubricate and help maintain hair


Sweat Glands

Skin glands that secrete water
Used to eliminate waste and promote evaporative cooling
Restricted to certain parts of the body in most mammals


Scent Glands

Skin glands that create odours and pheromones
Used to mark territory and attract mates
May also be used to get rid of pests or predators


Mammary Glands

Modified sweat glands, but produce milk
Possessed by all mammalian females
Male eutherians also have them but they are rudimentary
Vary in number between 2-19
Produce milk when stimulated by things like prolactive
Some mammals do not have nipples to facilitate milk transfer (monotremes, cetaceans)
Milk composition varies between species


Mammalian Soft Features - Internal Features

- Muscular diaphragm facilitates diaphragmatic breathing
- Four chambered heart
- Only the left aortic arch present
- Red blood cells lack nuclei at maturity to increase oxygen carrying capacity
- Brain large
- Optic lobe of brain present



Maintenance of constant internal temperature
Allows for an active lifestyle
Means that in mammals the standard metabolic rate is higher, and there are more capillaries, bigger organs in general
Must be eating constantly and therefore locomoting to find food



Naming and classification of organisms
Determining of the evolutionary relationships between organisms



Ordering and ranking of taxa



Study of the diversity of organisms


Mammalian Classification

- Is related to biogeography; closely related species originated in the same area
- Is changing very rapidly


G.G. Simpson


Presented hypotheses of mammalian origins and relationships that were universally taught until the end of the 20th century



Classifies organisms based off of overall similarity of morphology or other observable traits, regardless of evolutionary relationships


Phylogenetic Systematics

Classification in which organisms are grouped together based on whether or not they have one or more shared unique characteristics that come from the group's last common ancestor and are not present in more distant ancestors.


Reproduction - Prototheria

- Lay eggs that are telolecithal, mesoblastic
- Shell glands in the oviducts secrete a rubbery shell around the embryo
- Reproductive system ends in a cloaca
- No scrotum in males (testes are abdominal)
- Eggs remain in oviduct for ~27 days before being laid
- Sperm is threadlike


Development of Young - Prototheria

- Eggs hatch 10-11 days after being laid
- Young brooded in pouch for a couple months
- Females do not have nipples but secrete milk into grooves on the abdomen, long tufts of hair that young suckle
- Female needs to eat a lot while brooding/lactating


Reproduction - Metatheria

- Females have a paired vaginal canal; two uteruses
- Birth canal opens up between the vaginal canals during the actual birth
- Males have a bifurcated penis and a well-developed scrotum, but it is anterior to the penis
- Urinary, digestive and reproductive tracts are separate (no cloaca)
- Young are retained in the uterus for a very short time, less than an estrous cycle (22-26 days)
- Uterus does not change physiologically as in eutherians
- Shell membrane coating the embryo breaks between 1/3 and 2/3 of development and begins to absorb nutrients through the uterine wall
- Choriovitalline placenta
- Embryo does not obtain much nutrition from mother and oxygen runs out quickly, so young born quickly


Development of Young - Metatheria

- Litters are 1% of mother's body mass
- When born, young crawl to pouch (if pouch exists) using forelimbs, attach to teat
- Very underdeveloped at birth (only 1% of mother's body mass for the whole litter), lack cranial nerves, eyelids, eye/ear pigments, two halves of brain disconnected, hindlimbs buds, fourth chamber of heart hasn't developed yet, cutaneous respiration
- Attached to nipple for much longer than time spent in utero; release around the same time a eutherian would take to gestate
- Composition of milk changes as time passes and infant's nutritional needs change



- Pouch present in 2/3 of marsupials for carrying young
- Made of folds of skin
- Best developed in jumping species


Reproduction in Kangaroos and Wallabies

- Have one young at a time, but go into estrous right away and fertilize an egg
- If egg is fertilized while another is attached to the nipple, egg goes into diapause
- Mother may in fact have three generations on the go: egg in diapause, infant attached to nipple, older joey that is free but comes back for milk
- Each nipple is specialized and gives milk specifically designed for the young using it



Egg in which the yolk is concentrated at one end of the egg and is separate from the growing embryo


Choriovitelline Placenta

Yolk sac supplies a large part of the embryo's nutrition but placenta also attaches to uterine wall and takes nutrients directly from the mother's bloodstream


Reproduction - Eutherians

- Single vagina
- Chorioallantoic placenta
- Young does most of its development in the uterus, born at much more advanced stage than that of metatherians
- Extensive physiological changes to the uterus during pregnancy
- Litters 50% of mothers' body mass


Benefits of Eutherian Reproduction

- Ulimited oxygen supply to embryo
- Unlimited water supply to embryo
- Nitrogenous waste deposited directly into mother's system
- More nutrition provided during development
- Embryo can be protected from parasites/disease/predation


Disadvantages of Eutherian Reproduction

- Can't easily reject the embryo if conditions become bad
- Mother's body may reject the embryo, causing issues for both baby and mother


Chorioallantoic Placenta

- Entirely responsible for fetal nutrition and waste removal
- Chorion and allantois fuse and attach to uterine wall, take nutrients from female's bloodstream
- Erodes away the uterine wall, sometime so extreme allantois is surrounded by a pool of capillary blood
- Secretes a hormone that suppressed female's immune system and prevents rejection of fetus



- Surround an embryo during development and form a large part of the placenta
- Separates embryo from maternal circulatory system


Basic Mammalian Locomotion

- Plantigrade
- Quadrupedal
- Limbs rotated to be under the body



Locomotion with entire manus/pes on the ground
Used for ambulatory locomotion


Increasing Speed

- Lengthening of the limb
- Also increases maneuverability
- Decreases stability (some animals will change their gait with changes in speed to aid in stabilizing)
- In order to lengthen limb, base support becomes smaller



- Used for cursorial locomotion
- Walks and runs only on the digits
- Decreases contact with the ground and also increases the lever arm of the limb



- Used for cursorial locomotion
- Walks and runs on the tips if the distal phalanges
- Most of the muscle mass is located proximally on the limbs
- Basically gives the animal an extra joint


Cursorial Size Limitations

- The longer the limb, the more torque is created during running
- Musculature is usually what counteracts torque, but this is reduced in long limbs
- Larger animals find it harder to mediate velocity, making them less maneuverable; they can go absolutely faster but can't slow down or turn easily


Saltation and Ricochetal Locomotion

- Jumping using the hindlimbs disproportionately
- Quick, unpredictable and maneuverable
- Usually have a long tail and large/long hindlimbs through which forces can act
- Proximal hindlimbs are very muscular
- Origins and insertions of muscles shift to maximize thrust



- Usually on trees, but also rocks
- Need to be able to move in any direction and at any angle
- Have long, curved claws/nails to grasp at substrate
- Can use suction or friction grip
- May have prehensile limbs and tails
- Shorter limbs to aid in balancing
- Tend to be small in size
- Move between trees by jumping, gliding or bridging



Method of transferring between trees by hanging onto first tree with one side of the body, grabbing on to other side and then transferring weight over



- Fusiform body shape
- Reduced and sometimes non-functional eyes
- Reduced pinnae
- Large front feet with big claws
- Short, broad head
- Reduced or absent tail
- Tend to have short hair, density depends on climate
- Can dig with teeth, limbs, even head


Digging with Teeth

Such animals will have enlarged incisors with the fur and skin closing behind them
- Seals incisors off from oral cavity


Digging with the Head

- Done in loose soil
- Use the head as a spade
- Requires powerful, short, broad head with heavy musculature on the back of the neck


Digging via Humeral Rotation

- Orientation of front feet altered to face laterally
- Dig to the side instead of underneath the body


Aquatic Locomotion

- Uses two different methods of swimming: undulatory and oscillatory
- Biggest issue is reducing drag, which can be done by making the body torpedo-shaped and reducing limbs and fur


Undulatory Swimming

- Seen in mammals that are fully aquatic
- Spine and tail are flexed in order to propel the body forward
- Have an enlarged caudal fin
- Best way to swim at speed


Oscillatory Swimming

- Paddle-like propulsion system
- Uses either forelimbs only or forelimbs+hindlimbs
- Not as efficient as undulatory swimming



- Use skin stretched between forelimb and hindlimb as a "parachute" to control movement between trees
- Incapable of powered flight as they can't create the propulsive force to keep momentum going
- Avoid tendencies to pitch/yaw/roll by using the tail and changing the orientation of the gliding membrane
- Stop by stalling intentionally; pull up and use tail to keep from spiralling out of control



- Only seen in bats (mammals), birds and pterosaurs
- In bats, flight occurs by membranes that are stretched over the arm and sometimes between the hindlimbs over the tail
- Double membrane over top and bottom
- Short, broad wings adapted to maneuverable flight
- Low wind loading so generally not adapted for high speeds (some exceptions)


Flight vs. Lift/Drag

Lift is needed to fly
- Created via asymmetry
- Cambered airfoil


Cambered airfoil

When the air moving over the top of an object has a longer distance to travel than the air moving over the bottom
Pressure on the bottom of the wing is greater, so the animal moves upwards


Traditional Definition of Species

Group of inter-breeding, natural populations that are reproductively isolated from one another


Evolutionary Species Concept

Species is a single lineage of populations that maintain their identity from others and have their own evolutionary tendencies and fate

Problem: defining a lineage


Phylogenetic Species Concept

Species is the smallest diagnosable cluster of organisms within which there is a pattern of

Tends to define a lot of different "species"


Morphological Species Concept

Things that look the same are the same



Geographic "races" of a species, happen before speciation
May be temporary


Normal variation

The ordinary range of differences between individuals of a single species
Needs to be determined before assigning something as a subspecies or species


How do you know what an animal eats?

Can usually be determined from dentition



- Ancestral condition for mammals, most common
- Digestive tract is short with no cecum
- Can be terrestrial (shrews), aquatic (platypus), flying (bats), or arboreal (small primates)
- Some mammals are highly specialized insectivores and eat ants or termites; they have reduced or no teeth and elongated rostrums



Pocket at the beginning of the large intestine
Used to digest plant matter



- Smallest evolutionary step from insectivory
- Have a cecum, but it is small
- Also common in mammals - bats, carnivorans, cetaceans, etc.



- Eat BLOOOOOOD (woooooo)
- Seen in all new world vampire bats
- Have a long, complex digestive tract
- Salivary glands produce an anticoagulant
- Stomach rapidly absorbs water, which is excreted before they fly off (otherwise they would be too heavy, awks)
- Kidneys work efficiently with little water



- Much more derived than carnivory
- Seen in artiodactyls, perissodactyls, lagomorphs, etc.
- Have very complex digestive tracts
- Can have an enlarged cecum or a 4-chambered stomach (ruminants; two chambers with high pH, two with low)
- Ruminants regurgitate their food to allow it to be chewed twice
- Have flexible lips
- Teeth have rounded cusps



Eating of faecal pellets in order to maximize nutrient retention from food



- Have very unspecialized guts
- Eat anything, yay!


Sociality in Mammals

- The ancestral condition is for mammals to be solitary
- It just so happens that the social mammals are the most conspicuous


Advantages of Sociality

- Individual vulnerability to predation can be reduced
- Group defence - animals in middle tend to be preyed on less often, warning signs
- Cooperative hunting and food gathering/sharing
- Roost sharing
- Cooperative rearing of young


Food Sharing in Vampire Bats

A vampire bat will starve if it does not eat blood in two days or so. If this begins to happen, an individual will approach another to solicit a meal; the other bat will regurgitate blood to feed the starving one


Disadvantages of Sociality

- Increased competition for resources
- Increased competition of males for females
- More conspicuous to predators
- Increased likelihood of parasitism and disease



Both male and female will have a single mate for one or more breeding seasons
- In extreme cases, one mate for a lifetime



A male will mate with many females each breeding season



A female will mate with many males each breeding season



Mating is just a temporary contact with no durable associations between individuals
Basically, mating happens whenever they happen to be in the same place at the same time



Very rare
Only one or a few individuals actually breed, the rest are there for support and to provide food/rear the young


Male vs. Female Territories

- Females defend only what they need to survive
- Males defend territories with access to as many females as possible
- Male territories tend to be much larger than female territories and often encompass many of them


Density-Dependent Mating Systems

Where the type of mating system a species uses depends on the density of the population
- At peak densities, male lemmings are very promiscuous and a lot of infanticide happens; at low densities, male lemmings are monogamous and are very good dads


Facultative monogamy

Monogamous only when conditions are ideal for it


Social Dispersion

Different species and even populations tend to exhibit different kinds and levels of dispersion from one another; territories are defended and can be static or movingThree systems:
- Dispersed system
- Communal system
- Colonial system


Dispersed System

- Individuals hold exclusive territories
- Territories may abut one another but never overlap (except in the case of male territories overlapping several females)


Communal System

- Individuals occur in groups, usually family
- No set spacing within the group
- The group will defend their territory from other groups
- Groups are not dispersed equally in space
- E.x. elephants, howler monkeys


Colonial System

- Populations are organized into groups
- These groups can sometimes be huge, within which there are clumps of individuals maintaining areas of exclusive use
- E.x. prairie dogs form small groups with females, daughters and sometimes sisters


Males and Polygyny

- Males are generally not involved in parental care
- They tend to mature at the same age or earlier than females
- Produce sperm over their entire lifetime and a variety of environmental conditions
- Stay active for a much longer period of time than females
- Reproductive success of males primarily determined by the dominance hierarchy amongst males; in this case, see a lot of sexual dimorphism


Female Defence Polygyny

- Males fight with one another for access to females
- In some cases, females will form groups with other females and can be antagonistic towards or just tolerant of the males; males defend from other males but are not involved in day-to-day life of the females


Resource Defence Polygyny

- Instead of forcing himself upon a group of females, a male will defend a territory rich in resources in order to attract females
- Males may not even seek females, simply wait for them to arrive


Sexual Dimorphism & Mating Systems

- Can sometimes tell what kind of mating system a species exhibits by the morphology of males vs. females
- Monogamous species tend to have very little sexual dimorphism


Lekking System

Females are widely dispersed but cluster during a season; during this time, males form groups in which they perform mating displays to attract females


Extinction Events

- There have been five major ones
- Events where large number of species died
- Worst one was the Permian-Triassic
- Diversification of mammals happened after the Cretaceous-Tertiary extinction



- Organisms over 100lbs
- Major extinction at the end of glaciation (11 ka) involved a lot of them; pretty much all vanished :(


Mammalian Extinctions

- At least 80 species and 4 families have gone extinct since 1500AD
- Many more before that


Canis lupus - threatened

- Used to roam across all of N.A., but now only really found in the northern parts of Canada and parts of Wyoming where it's now been introduced
- Was recently taken off of the US Endangered Species List even though there are only 300 or so in the wild there


American bison - threatened

- Was in excess of 60 million in 1860 but was considered to be a nuisance by farmers
- US Gov't endorsed the hunting of them in the hopes their loss would weaken the Plains Indians. who relied on them for food
- Were shot and collected in numbers of up to 100,000 per day
- Populations reduced to within the 100s by 1889
- Population has recovered some, now believed to be about 15,000


Factors responsible for decline/extinction of mammal populations

- Human population growth
- Habitat destruction/loss
- Habitat degradation
- Overexploitation
- Cultural and religious beliefs
- Hybridization
- Climate change
- Parasites and disease
- Invasive species

Note: islands are a special case


Human Population Growth & Decline of Mammal Populations

- The more people, the more land and other resources are needed
- Cut forests for crops, fuel and building materials
- Accumulation of waste
- In some cases, armed conflicts can have an effect


Habitat Destruction/Loss & Decline of Mammal Populations

- Deforestation occurs all over the world, but mainly focus on tropical forests
- Secondary growth is a poor substitute for original forest following deforestation
- Opportunistic and often invasive species are generally what appear first
- Can happen to all habitats, not just forests
- Small mammals are usually more affected than others
- E.g. Madagascar has 80% original forests gone; of 60 primate species, 82% are endangered


Habitat Degradation & Decline of Mammal Populations

- Results from things like bioaccumulation of things like pesticides
- Oil spills
- Introduction of predators and other non-native species
- Fragmentation of habitats due to roadways, etc. leads to edge effects


Cultural and Religious Beliefs & Decline of Mammal Populations

- Stems from a belief that animals have "magical" powers, often as aphrodisiacs
- Often leads to poaching of the animals said to have these powers


Hybridization & Decline of Mammal Populations

- Accidental mixing of gene pools that happens when typically separated species come together due to habitat modification or introduction
- That awkward moment when conservation activities can lead to hybridization...
- Domestic animals can also lead to hybridization if they mix with wild populations


Climate Change & Decline of Mammal Populations

- While climate change is a natural process, right now it is happening too quickly for organisms to properly adapt
- Average N.A. temperature is expected to increase by 2-5 degrees by the end of the century, and temperature latitudes will shift 500-800km north
- Entirely new climates may develop
- In order to adapt, species will have to shift ranges or evolve new autecologies


Islands & Decline of Mammal Populations

- 62% of documented mammalian extinctions since 1500 have been of island species
- Ecological islands can also occur - fragments of what were once larger habitats, including parks and reserves
- One of the biggest threats is destructive invasive species


Protected Areas - Biodiversity Hotspots

- Biodiversity hotspot is an area where there is a high total number, or percentage of endemic, species
- Occupy about 16% of Earth's surface
- Home to ~77% terrestrial vertebrate species
- A lot of these occur in areas of high human population densities


Protected Areas - Centres of Imminent Extinction

- Areas with lots of endangered species
- Home to about 800 vertebrate species at serious risk of extinction
- Tend to be in tropical forests, islands, or on mountains
- Tend to occur in areas of rapid development
- E.g. Atlantic forest region of Brazil, which is home to 23 primates, 17 of which are endemic


Canada's Species at Risk Act

- 2002
- Government act that is supposed to protect Canada's threatened species and their habitats
- Creates teams to assess threats to species and habitats
- Only really works if it is implemented properly, which is debatable


IUCN's Red List

- IUCN: International Union for the Conservation of Nature
- Red List assesses the threats to biodiversity and assigns them a category (threatened, endangered, least concern, etc.)



Convention on the International Trade of Endangered Species
- Maintains a list of protected species and regulates the animals and/or animal products that can or cannot be traded



International Whaling Commission
- Formed in 1946
- Regulates whaling, most nations comply but not all
- Criterion to resume whaling is species must attain 50% historical population size, but it's hard to estimate historical population


Biodiversity Market Value

- By ensuring that biodiversity is seen as having market value, governments will be more incensed to protect them


Captive Breeding

Used to reintroduce or supplement wild populations of at-risk species
- Endangered species maintained in captivity while external threat are reduced or removed
- E.g. Arabian oryx was extinct in the wild but was captive bred and reintroduced
- E.g. Black-footed ferret was affected by decline of prairie dogs; Toronto Zoo has been involved in a captive breeding project



- Said that "bats can see with their ears"
- Was interested in how bats & owls could fly at night, so got both to fly in a dark room lit by a single candle and neither had an issue
- When the candle was turned off, the owl wouldn't fly but if forced to would crash, and the bat would be fine


Donald R. Griffin

- Knew of Spallanzani's bat problem, and borrowed a sonic microphone from a physicist to detect bats' noises
- Coined the term "echolocation"
- Wrote a book in 1958 called Listening in the Dark


Low frequency sound

Has more range, but less detail


High frequency sound

Has less range and more detail


Bat Echolocation

- Most pats produce echolocating sounds in the larynx, some do by tongue-clicking
- Bats mix and match high and low frequency sounds depending on their needs
- Bats send out signals and receives them at the same time; signal much weaker on return
- Self deafening: while the sound is being produced, the bat can't register what's coming back
- Dislocate inner ear bones to reduce amplification
- Harmonics increase accuracy


Feeding Buzz

What a bat does when it attacks/catches an insect
- Change in the echolocation call



- Common explanation is that they focus sound as it radiates from the mouth
- This hasn't been well-studied


Low Duty Cycle Echolocation

- Short signal followed by a long period of silence
- Can't send and receive signals at the same time


High Duty Cycle Echolocation

- Long signal followed by a short period of silence
- Can send and receive signals at the same time due to Doppler shift: "flutter detector"
- Bats who use this kind of echolocation have unusually robust ribcages


Echolocation in Non-Insect Feeding Bats

- Some flowers have ultrasonic nectar guides
- Vampire bats also echolocate, maybe to distinguish awake from sleeping prey?


Echolocation & Sociality

- Noises made give away an individual's location, species and possibly age and gender
- Bats may use echolocation for air traffic control and signal jamming
- There is a continuum between calls used for feeding and social calls
- Can recognize group members by listening to echolocation calls; can also find roosts
- Social calls tend to be longer than feeding calls


Mammalian Origins

- Class originates in the Jurassic (nocturnal)
- Very early split between prototherians and therians
- Not much later, split between metatherians and eutherians


Continental Drift & Mammalian Diversification

- When mammals are beginning to really diversify, when continents are Gondwana & Laurasia
- Different mammalian groups occupy different land groups as a result of splitting continents and stuff
- Dispersal of metatherians back and forth over the southern continents (Africa, Australia, S.A.)


Great American Interchange

- 3 MA
- North & South America are joined by a land bridge, the Isthmus of Panama
- Dramatic climatic changes in South America at the same time due to Andes doubling in height
- Mingling of previously separated faunas from both continents; more moved from north to south than vice versa
- Number of extinctions (mostly of highly specialized species) at the same time
- Area is very tectonically active, so Isthmus will probably be gone in ~10 my


South American Rainforest

- Has experienced a lot of retraction and expansion over the past 30 million years
- Results in a lot of endemism between different parts of the expanse


Pleistocene Extinctions

- Northern hemisphere was strongly affected by Pleistocene glaciations and is still recovering (reason for low diversity of mammals in Ontario)
- Rapid environmental change
- Big animals were the first to go
- Over 35 genera of mammals go extinct; 27 global and 8 just N.A.
- Humans arrive 15-10,000 years ago as glaciers retreat
- Humans may have helped push species over the edge of extinction


Human Colonization

- Humans spread across North America and into South American in <1000 years
- Tend to see a reduction in biodiversity as humans colonize
- Humans create patchy environments by modifying habitats
- Extinctions tend to happen in these small, isolated areas


Wallace's Line

- Divides Australasia from Indo-Malay
- Distinct divide between fauna depending on what side of the line an island's on
- Exception is Sulawesi, which has a mixed fauna because it's composed of two continental plates


Changes in Mammalian Diversity

- Higher diversity as latitude decreases; highest in the tropics
- Changes linearly for most mammals, but exponentially for bats
- Higher levels of species endemism tend to be on islands, archipelagos and continental areas with isolated habitats
- Mexico actually has the highest diversity of mammals for its area


Cenozoic Mammals

- Originate in the Jurassic
- Most modern orders have appeared by the Cretaceous
- Early fossil record spotty
- By K/T boundary, continents essentially where they are now but N.A. broken up by shallow seas, N & S not connected


Early Paleocene Mammals

- Eutherian mammals are small, insectivorous and mainly nocturnal
- Multituberculates are the past equivalent of rodents, with comb-like tooth in their lower jaw, most diverse/dominant mammals of the past
- Marsupials
- Condylarths: early eutherians including both herbivores and carnivores; small and raccoon-like now
- Climate cooler than before, wet tropical forests in limited areas
- More temperate forests


Late Paleocene - Early Eocene Mammals

- Mammals still generally small and mainly arboreal
- Still dominated by multituberculates
- Condylarths diversify; insectivores, primates, horses, rodents develop
- Creodonts: early, primitive carnivores
- Archaic ungulate groups
- See beginning of fossil record for bats, sirenians, whales


Late Eocene - Oligocene Mammals

- Drying trend in N. America, appears to be seasonal
- Subtropical forests give way to savannahs and grasslands; first grass pollens
- Rodents, perissodactyls, artiodactyls become more numerous
- Some groups of early herbivores begin to go extinct; marsupials, primates, multituberculates gone from N. America
- First fossils of rabbits


Miocene Mammals

- Early camelids, pig-like artiodactyls
- Still some archaic large herbivores
- Areas of savannah are getting larger; dominated by grasslands and savannahs, especially in the interior continents


Late Miocene - Early Pliocene Mammals

- Elephants, rhinos, hippos
- Antelopes are common
- Many fairly modern rodents appear, some are strange; some burrow deeply with corkscrew shapes that get filled in by mud
- Highest diversity of mammals at any time i history during the mid Miocene
- Glacial cycle begins now; with more rapid cooling, diversity decreases


Pliocene Mammals

- Great American Interchange
- Marsupials and primates reintroduced to North America


Pleistocene Mammals

- Dry steppe climates that don't exist in North America today
- Extensive tundra, temperate forests, interior grassland
- Much dryer and colder than today
- Increase in latitudinal differences in diversity
- Loss of a lot of taxa; generally large herbivores are replaced by smaller ones, some small carnivores lost


Late Pleistocene Mammals

- Woolly rhinos and horses gone from North America, but still have large elephants


General Trends Among North American Mammals

- From fairly uniform tropical broadleaf evergreen forest to more deciduous forests and grasslands with steppes and tundra in the north
- Climates begin very stable but destabilize by the end
- Rates of faunal turnover pretty quick; periods of stability punctuated by periods of loss
- Most modern genera and families don't appear until fairly recently



- Probably the first mammalian herbivores
- Fossil record spans 100 million years
- Highly successful, over 200 species
- Widespread between old and new worlds
- Ecologically equivalent to rodents, with powerfully built lower jaw
- Incisors 2-3/2, some blade-like premolars
- Cheek teeth had several rows of small cusps
- Disappeared in the Paleogene and left no descendants


Overexploitation & Decline of Mammal Populations

- Trapping, hunting, poisoning of agricultural pests
- Trapped for horns, pelts, meat
- Whales: oil, meat, spermaceti, ambergris, etc.
- Sport and trophy hunting
- Illegal hunting
- Over 50% of endangered mammals that are terrestrial and are not rodents are endangered due to human hunting pressure
- Pet trade, research


Solutions to Conservation Problems

- Curtail human population growth
- Preserve & restore habitats
- Establish and maintain reserves
- National laws
- International treaties and agreements
- Educate on the benefits of protecting organisms and habitats; economic benefits through ecotourism
- Captive breeding


Deterring Poaching

- Injecting dye and anti-tick pesticide that is poisonous to humans in order to dissuade use and thwart poaching
- Tracking devices being inserted into horn and linked to database


Sustainability as a key to conservation

Sustainable development meets present needs without compromising the future
Requires us to:
- Maintain biodiversity and essential ecological processes
- Preserve genetic diversity
- Any use of species or ecosystems must be sustainable
- Recycle raw materials and rely on renewable resources
- Sustainable farming conserves soil and water, reduce pollution and energy use, preserve biodiversity


Uses for Echolocation

- Operating under conditions of uncertain or no lighting
- Detecting obstacles
- Detecting, assessing and tracking prey
- Correct orientation for harvesting nectar


Sound Production in Laryngeal Echolocation

Bat vs. normal mammalian larynx:
- Cricothyroid muscle is very large
- Superior laryngeal nerve is very large

Cricothyroid contracts and stretches the membranes over the laryngeal ventricle, which acts as a drum



Capable of maintaining body temperature above that of the external environment



Thermoregulation that maintains a stable internal body temperature regardless of external influence



When an organism can flip between ectothermic and endothermic heat strategies


Benefits of Mammalian Thermoregulation

- Enhances efficiency of capturing prey and escaping predators
- Can extend activity periods over a 24-hour period
- Colonize many environments and ecological niches


Adaptations to Cold

- Body size and metabolism
- Insulation
- Appendages
- Coloration
- Modification of microclamatic regime
- Foraging zone
- Reduction in level of activity
- Reduction of body mass
- Dormancy


Body size and metabolism & Cold Climates

- Larger animals require more food to maintain the body temperature and level of activity
- As size of animal increases, volume and mass change more rapidly than surface area


Bergmann's Rule

- Larger versions of species/genera live in cold climates, and smaller ones in warmer climates


Insulation & Cold Climates

- Most direct method: fat, fur
- Insulation value increases with thickness and length of fur
- However, need to be trade offs


Appendages & Cold Climates

- Legs, tail, ears and nose are potential heat wasters as they cannot be well insulated
- Appendages of many northern mammals can be maintained at comparatively cold temperatures
- Heat conservation also enhanced by reducing length of the exposed extremity


Allen's Rule

Appendages of endotherms are shorter in colder climates that those of the same species found in warmer climates


Coloration & Cold Climates

- Generally see white pelage
- Pigments tend to be paler the closer the species is to the Arctic
- Either remains white year-round or changes for the winter


Gloger's Rule

Races in warm and humid areas are more heavily pigmented than those in cool, dry areas


Modification of Microclimatic Regime & Cold Climates

- Non-hibernating small mammals in northern regions construct elaborate nests and engage in communal nesting
- Especially cricetid ad sciurid rodents
- This conserves body heat


Foraging Zones & Cold Climates

- The thermal regime of an organism's foraging zone is crucial
- Forage in tunnels within soil covered by leaves; in winter this provides a stable, warmer thermal regime
- Snow covered ground insulates the subterranean environment


Reduction of Activity & Cold Climates

- Cached food reserves
- Restricting foraging and nesting to stable microhabitats
- Reduction of daily activities in winter


Reduction of Body Mass & Cold Climates

- Small mammals decline in body mass during the winter
- Decreases caloric needs when food resources are limited
- However, some species gain mass in winter


Dormancy & Cold Climates

- Save energy by temporarily ceasing endothermy: "adaptive hypothermia"
- Have a set point below which the body temperature can't fall; for some species this is just a few degrees above freezing



Period of inactivity with a reduced metabolic rate and lowered body temperature



Lower metabolic rate, body temperature, respiration rate, heart rate
- Can extend for hours to days
- Body temperatures decline but not usually below 15deg
- Bears do shallow torpor, NOT actual hibernation



Torpor during winter for periods of weeks
- Lower body temperature, 2-5deg
- Largest true hibernator is the marmot


Adaptations to Heat

- Challenges are more severe than in cold regions
- Desert mammals need to dissipate heat or avoid it
- Also need to deal with cold nights, scarcity of water/cover, highly variable food supply


Adaptations to Heat - Water Economy

- Kidneys are modified to better conserve water
- Dry faeces, concentrated urine
- Sometime produce highly concentrated milk
- Water obtained from sources other than drinking water
- Subsisting on metabolic water


Adaptations to Heat - Temperature Regulation

Evaporative cooling requires an unlimited supply of water, so limited in deserts
- Water loss through sweat glands; major shortcoming is loss of salts
- Canids cool primarily by panting, providing own airflow over moist surface
- Spread saliva on body parts; less effective than sweating

- Fur minimizes rate of heat absorbed
- Prevents solar radiation from reaching skin
- Sleek, glossy, light-coloured pelage reflects wavelengths of sunlight

Appendages large to dissipate heat (i.e. ears)

Seed eating rodents tend to have low basal metabolic rates

Body size favours small mammals with larger surface area to volume ratio


Adaptations to Heat - Estivation

Period of inactivity in reaction to hot or dry conditions
- Not as well studied as hibernation
- Seen in marsupials, insectivores, most common in rodents
- Animals seem more lethargic than torpid


Adaptations to Heat - Avoidance of High Temperatures

- All desert rodents nocturnal & semifossorial, with exception of ground squirrels/chipmunks
- Retreat to underground burrows during the day; air is cooler and saturated with water vapour
- Diurnal desert rodents move rapidly from one shade patch to another
- Desert ungulates seek shade and change orientation of body to prevent overheating


Evolutionary Taxonomy

Classifies organisms using a combination of phylogenetic relationship and degree of evolutionary changes.


Ancestral Characters

A characteristic that is retained from the last common ancestor


Derived Characters

Characteristic that is different from that of the last common ancestor



Similar characteristics shared between two organisms due to shared ancestry



Similar characteristics shared between two organisms due to convergent evolution rather than shared ancestry