Mammal Notes Exam 3

Mammals 4/7

Birds and Mammals Venn Diagram

Mammal Teeth: Hereodont AND Diphyodont

• Canine

• Incisor

• Premolar

• Molar

• 

• Two sets of teeth: baby and adult teeth

• all of teeth are in your skull, kid skulls have teeth above their teeth

• elephant have no canines

Features of Didelphimorphia

• The Opossums

• “2-wombs” — marsupials

• 1 family, about 70 species

• Diverse habits

  • arboreal…aquatic

• Central and South America, Virginia opossum in North America

  • prehensile tails

  • partially opposable thumbs

Virginia Opossum Dental Formula: I 5/4, C 1/1, P 3/3, M 4/4

• most teeth of any North American mammal

• 

• all types of possums very similar-looking

Features of Soricomorpha

• “Shrew-shaped”

• 3 Extant Families → Soricidae (True Shrews), Talpidae (Moles, Shrew-Moles, Desmans), Solenodontidae (Solenodons)

• Broad geographic range

  • Absent only from Australia & Antarctica

  • Abundant and thrive in higher latitudes

    • Species richness increases with increasing elevation

• Fossorial habits

  • Adaptations for burrowing

    • Tapered body; enlarged body; short, powerful limbs.

  • Burrows can be as deep as 150 cm (4-5 cm wide).

• Insatiable appetite

  • High activity levels

Features of Chiroptera

• 2nd most speciose order of mammals

• Extreme species richness in tropics

• Absent only from poles and some remote islands

• Only mammals with true wings, true (powered) flight

Features of Rodentia

• Largest order of mammals

• Worldwide distribution (except Antarctica, New Zealand, and other islands)

• Extreme morphological and ecological diversity

• Shared feature: Incisors for gnawing

• beaver orange teeth is iron

Features of Lagomorpha

• 2 families, 13 genera, 80 species

  • Hares, rabbits, & pikas

• Lifelong growth of incisors

  • Enamel on front & back

    • extends around to the posterior surface of the tooth

    • double layer of incisors on maxilla

• Testes in front of penis (marsupials, too)

• Phylogenetics hotly debated!

  • Recent evidence shows that they might be related to rodents and marsupials

• herbivorous

• looks like bird skulls with fenetrae

Features of Carnivora

• Despite name, diverse food habits

• 13 extant families, ~270 species

• On all major landmasses and oceans

• Teeth → “Carnassial pair”

  

Features of Artiodactyla

• 10 families, 80 genera, 210 species

• Native to all continents except Australia & Antarctica

• Prefer open habitats (grasslands)

• Herbivores (mostly)

• Even toed = run fast and efficient

  

Features of Cetacea

• 2 extant sub-orders

• Baleen whales

• Toothed whales

• 14 families, 46 genera, 83+ species

• Along with bats, considered the most derived mammals

  • most different than other mammals (ocean-dwelling)

    

Features of Sirenia

• 2 extant families with just 4 species

• 6 cervical (neck) vertebrae

• Most mammals have 7

• (Sub)tropical waters

• Will migrate if water temperature dips too low

Mammal Basics

Evolution of Mammals

• Descendants of synapsid reptiles

  • 300 MYA-190 MYA

  • Brain grew

  • Ears more complex

  • More advanced jaws

  • Differentiated teeth

• Therapsids—line that branched to mammals

  • robust skull

  • single large canine

  • Cynognathus

    • limbs beneath trunk

    • jaws similar to modern mammals

    • endothermic? hair?

What makes a mammal and mammal?

• Hair

• Mammary glands

• 3 middle ear bones

• Deciduous and permanent teeth

• Marrow in bones

• Non-nucleated red blood cells

• Muscular diaphragm

• Heterodont dentition

  • molars, incisors, etc

• Endothermic

Subclasses

• Prototheria

  • lay eggs

  • Platypus, Echidna

• Metatheria

  • marsupials

  • born very young, develop in mother’s pouch

  • Kangaroo, koala, opossum

    • live young

    • all other mammals

Mammal Diversity

• 5000 species

• 19-26 orders (depending who you ask)

• DNA technology » changing classifications

• Range in size

  • shrew and bats—as little of 3 grams

  • Blue whale—170 metric tons

• Variety of niches, life history strategies, and modes of locomotion

  • fly, glide, swim, run, burrow, jump

Mammal Physiology

Integumentary System

• Lightweight, waterproof epidermis—variety of environments

  • some have epidermal scales—beaver and rat tails

    • dermal plates—armadillo

• Epidermis gives rise to hair, glands, nails, scales, hooves, baleen, and horns

• Hair—arose from specialized mechanoreceptors in early synapsids

  • guard hair—outer, coarser, longer hair for protection

  • Underfur—inner, finer, shorter, for insulation

  • Hair nonliving, replaced

Molting

• Many molt annually—usually in the fall

• Some molt twice per year—deer, snowshoe hares, short-tailed weasels

  • some change coloration

  • photoperiod combined with melatonin production initiatives molt

  • geographic variation in molting behavior

Horns and antlers

• Reproductive behavior, defense, offense

• True horns—bovine family—cattle, antelope, sheep, goats

  • permanent bony dermal core, epidermal sheath

  • usually not branched, never shed, both sexes

  • grow from base, annual growth rings

• Antlers—branched, solid, dead dermal bone—Cervidae

  • secondary sex characteristics—males only except Caribou

  • testosterone

  • photoperiod signals replacement

  • start growing in spring, full grown in summer—fall, shed mid-winter

  • velvet—skin with blood vessels feed growing antlers, at full growth velvet rubs off

Glands

• Mammary

  • modified swet glands produce milk for young

  • hormone prolactin produced by pituitary

  • number of teats equal to maximum litter size or twice the ave

• Sebaceous—oil glands

  • sebum lubricates hairs

  • antibacterial

• Scent—numerous widely distributed

  • mark territory

  • attract mates

  • defense

  • considered pheomones if they elicit a specific response from the same species

Skeletal System

• Skull

  • single pair of temporal fenestrae

  • syxogmatic arach around orbit

  • more complex ear bones than other vertebrates

• Vertebrae

  • segments: cervical, thoracic, lumbar, sacral, caudal

  • 5 fused sacral vertebrae= sacrum, point of attachment for pelvis

  • ape and human caudal vertebrae fused to form coccyx

Locomotion

• Plantigrade

  • insectivores, monkeys, apes, humans, bears

  • entire surface of food on ground

  • usually have pentadactyl hands and feet

• Digitigrade

  • rabbits, rodents, carnivores

  • bear weight of ends of metacarpals and metatarsals

  • wrists and ankles elevated

  • thumb reduced or lost

  • faster than plantigrade

• Unguligrade

  • weight of body on hooves, modified claws

  • Artiodactyls—cloven hoof, 2 digits function of hoof—deer elk, caribou, giraffes, antelopes, bison, goats, sheep

  • Perissodactyls—1 digit functions as hoof—horses, rhinoceroses

Cardiovascular System

• 4-chambered heart

• Variable heart rate

  • 25 bpm elephant

  • 1000 bpm shrews

• Blood: Erythrocytes, leukocytes, thrombocytes

  • RBCs: non-nucleated, bioconcave discs, carry oxygen

Respiratory System

• Pharynx > trachea (covered by epiglottis) > bronchi > bronchioles > alveoli

• Diaphragm

  • muscle that separates pleural cavities from abdominal cavity

  • dome shaped at rest

  • flattens when contracted and enlarges thoracic cavity

  • lowers internal pressure in pleural cavities so air flows into lungs

  • relaxation of diaphragm—air flows out

Digestive System

• Oral cavity > esophagus > stomach > small inestive > large inestive > rectum > anus

• Diversity in feeding > diversity in digestive anatomy

Dentition

• Diphyodont teeth—2 sets

  • millk teeth or deciduous teeth—before or soon after birth

  • permanent or adult teeth—replace milk teeth

• Heterodont dentition—incisor, canine, premolar, molar

• Diastema

• Carnassial teeth

Nervous System

• Ears

  • Pinna-external, funnels sound to ear canal

  • External auditory meatus—ear canal, sound conveted to eardrum

  • 3 middle ear bones—-malleus, incus, stapes—transmit vibrations from eardrum to inner ear

  • Cochlea—inner ear with hair cells than covnvert mechanical energy into nerve impulses transmitted to brain

• Echolocation—bats, shrews, whales, seals, manatees

  • animal sonar to locate food, communicate, and move

• Eyes

  • similar to other aminotes

  • Some mammals colorblind—whales and seals

  • Many mammals have dichromatic vision—dogs

  • Primates have trichromatic vision—blue, green, red

  • Moles and rats—vestigial eyes

• Nose

  • highly developed olfactory mechanisms

  • large nasal passages

  • especially strong in nocturnal mammals

Mammal Behavior and Reproduction

Mating Systems

• Monogamous—one male and one female

  • 2-4%

  • Often monogamous bonding but extra-pair copulations occur

  • Females widely dispersed or parental care necesssary

  • California mouse mates for life

• Polygamous—more than one mate

  • polygyny most common

  • female elk mate with several males each day of breeding season

• Promiscuous—individuals will mate with any member of opposite sex

  • often not completely promiscuous

  • snowshoe hares

Mate attraction

• Smell

  • scent glands, pheromones—especially in nocturnal spp.

• Sounds

  • howling, bellowing, barking, roaring, squeaking

• Sight

  • Antlers—sex recognition and quality determination

Breeding and Gestation

• Some mammals have no specific breeding season. EX) elephants, rhinos, giraffes, humans

• Seasonal breeders—breed at specific times or year. EX) deer, small mammals

  • increase in photoperiod—small mammals

  • quantity and quality of food—timing and litter size

  • pheromones can effect behavior

• Gestation time: conception to birth

  • opossum = 12.5 days

  • elephant = 24 months

• Madow vole—17 litters/year, elephants 1 per 4-5 years

Delayed implantation

• Mate right after giving birth, implantation doesn’t occur for months later

  • bears, seals, weasels, badgers

• Diapause—period of time when female is holding fertilized embryo but development is suppressed

• Allows young to be born when probability is highest

• Kangaroos—can have embryo in diapause, joey in the pouch, and nursing young kangaroo out of the pouch

Growth and Development—Ovipary

• Duck-billed platypus—Australia, Tasmania

  • 2 eggs incubated 10-14 days

  • Born altricial, drink milk from pools on mother’s stomach

  • Leave burrow after 4 months

• Echidnas—New Guinea, Australia, Tasmania

  • temporary breeding pouch

  • one egg— cloaca to pouch, milk pools in pouch

  • young remain in pouch for 8 weeks after hatching

Growth and Development—Vivipary, Marsupials

• Born super-altricial

• Immediately crawl into marsupium (pouch), attach to nipple

• No baby teeth, no teeth at all until finished suckling

Growth and Development—Vivipary in Therians

• Most mammals develop in amniotic sac—usually ruptures before or during birth

• Parental care universal

  • duration ranges several weeks to several years

    • precocial—hares, cetaceans, ungulates

    • 4 day old pronghorn can outrun human

    • Altricial—born hairless with eyes closed—small mammals

• Sexual maturity

  • several weeks—some rodents

    • female meadow voles breed at 3 weeks

  • 10-15 years—elephants, gorillas, humans

Coyote Natural History

What are coyotes?

• Dog-like canid

• Most closely related to gray wolves

• Smaller than red wolves

• Meso-predator

• Carnivore

Evolutionary Origins Somewhat Unclear

• Have been in North America for 30-60 years

• Unclear if they evolved from another canid or colonized separately

Culturally important for native americans

• Spiritual lore

• Coyote as avatar for humans in the world

• Stories expose human elements through humorous reversal example

Historically restricted to western North America

• rapidly expanded in the last 120 years across the Appalachians and north and south

• wolves and pumas largely extirpated from eastern N.A.

• Hyrbridization with wolves in the northeast

• widespread conversion of forest to agriculture

• intrinsically adaptable, generalists in diet and habitat

What do coyotes eat?

• Small mammals, vegetation, lagomorphs, ungulates, invertebrates, birds, livestock…

  • eat most deer in the winter because less prey available, less vegetation

• Coyotes have more diverse diets where human footprint is larger

• Larger coyotes eat more lagomorphs and ungulates

• Coyotes eat more ungulates where they coexist with wolves

To what extent have coyotes replaced wolves?

• compared dietary ecology in historic wolf range

• compare with ungulate mortality datasets

• coyotes have broader diets than wolves

• coyotes don’t really eat medium herbivores even though gray and red wolves do

• northeastern wolves eat more large herbivores

• coyotes not documented killing moose unlike wolves

• so coyotes have at least partially replaced wolves in southeast

• but they rarely kill key mammals that wolves do: moose, beavers, and nutria. these are ecologically and economically important species

What should managers do about coyotes?

• opportunistic shooting likely has no effect

• even intensive trapping has been shown to be only marginally effective

• Coyote Math: 2-1 = 4… if you remove one, others will come and fight for that territory, adding individuals

• Can fruit reduce predation on fawns?

  • fawns are resource pulses; temporarily available to species

  • if you add a second resource pulse like blackberries, they may change how coyotes respond to fawns

  • do coyotes track pulses? somewhat

  • more fawns predicted to be eaten without blackberries

  • so blackberries seem to decouple normal levels of fawn predation

  • habitat management to promote blackberries and other fruits should be experimented on

Background

• Coyote—Turtle/Bird Conflict

  • Cape Hatteras and Cape Lookout National Seashores established in 1953 to preserve the outer banks natural resources

Research Methods

• Methods were to put high-resolution GPS collars on coyotes, and track the coyotes regularly

• Density estimates were taken by surveying each island four times across 3 distinct surveying seasons, collecting scat, and using spatially explicit capture-recapture methods to estimate population density

Fladry (Flags) Experiment

• Deployed across the width of SCB from June 17th to August 15th

• We set up cameras to video record the interaction

• Goal: document barrier effects given we have collared animals on SCB

Coyotes are Cool

• extremely adaptable, ecological role varies across range

• rapid range expansion—can be problematic in some places

• here to stay—how do we coexist?