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92 Cards in this Set
- Front
- Back
late pleistocene extinctions
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60-10 mya, correlates with arrival of humans (agriculture), disproportionally affected large vertebrates, first suggested by Richard Owen
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Madagascar
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much endemicity, used to be huge lemurs that are mostly extinct now, correlate with arrival of humans
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La Brea
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fossil deposits in LA, many well-preserved mammals, both herbivores and carnivores
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smilodon
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state fossil, ambush carnivore, not sure how fragile canines were used
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basal synapsids
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broad lineage of reptile-like mammals, dominated late triassic
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Milestones in synapsid evolution
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1. finer regulation of body temp
2. control of internal environment 3. reorganization of mastication, 2ndary palate to separate breathing/swallowing 4. reorientation of pectoral/pelvic girdles for upright limbs 5. evolution of inner ear |
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Dimetrodon
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basal synapsid, skin-covered fin thought to help regulate temperature
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Evolution of jaw joint and inner ear
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only 1 jaw bone now: most vertebrates have several bones in lower jaw that take part in hearing by sensing vibration --> incus/malleus/stapes only in mammals because old jaw bones migrated up to inner ear and still serve the same purpose, just different location
- movement can be followed in fossil record |
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Mesozoic mammaliforms
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Dino period, mostly shrew-like mammals scuttling in bushing after insects, nocturnal, relied on smell/hearing, weak vision, good metabolic control, lactation, more precise dental occlusion and jaw control, parental care
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Hadrocodium
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Lower Jurrassic period in China, found intact skull
- possible challenges with endothermy because of high surface area and high metabolic rate |
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Castorocauda
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Middle Jurassic period, fur indentations, skeleton suggests burrowing/swimming adaptations; dentition = sharp triangular molars, piscivorous; diurnal, semiaquatic carnivore
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Fruitafossor
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Upper Jurassic period, reconstructed as scratch-digging myrmecophage, armadillo dentition
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Repenomamus
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lower cretaceous period, carnivorous teeth, ate dinosaurs, found remains in stomach
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Monotremata
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- only egg-laying mammals
- one orifice for intestinal, genital, and urinary tracts - 3 extant species - make milk through fur, no nipples |
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Marsupialia
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- short gestation period, longer lactation period )too long in the mother, more likely immune system senses embryo and attacks)
- good hands to climb into mother's pouch - baby stuck to swollen nipple until big enough - thecodont and heterodont teeth |
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Juramaia sinensis
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earliest eutherian
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Eomaia scansoria
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early eutherian
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Placental radiation
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- rapid explosion and radiation, made mammal supertree to determine time of radiation/waves
- long-fuse model (2 pulses) vs. traditional explosion (more supported in recent paper) - by Eocene, most familiar lineages had appeared |
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Origin of Cetaceans
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4-limbed ancestors
- first thought to be derived from mesonychids (wolf-like carnivores), but later shown to be descended from artiodactyls and connected via DNA evidence and double-trochleated ankle (skeletal match found) - renamed cetartiodactyla |
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Mammalia characteristics
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- 3 ear ossicles
- fised atlas vertebrate - hair - mammary glands - epiphyses - muscular diaphragm |
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Theria characteristics
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- viviparity
- molar tribosphenic teeth - modified hips and ankle bones |
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Afrotheria
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Afrosoricida
Macroscelidea Tubulidentata Hyracoidea Sirenia Proboscidea |
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Afrosoricia
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Tenrecs, golden moles
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Macroscelidea
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Elephant shrews
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Tubulidentata
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Aardvark
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Hyracoidea
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Hyraxes
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Sirenia
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Dugongs, manatees
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Proboscidea
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Elephants
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Xenarthra
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Cingulata
Pilosa |
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Cingulata
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Armadillos
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Pilosa
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Sloths, anteaters
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Euarchonoglires
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Lagomorpha
Rodentia Scanentia Dermoptera Primates |
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Scandentia
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Tree shrews
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Dermoptera
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Flying lemurs
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Laurasiatheria
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Lipotyphla
Pholidora Carnivora Chiroptera Perissodactyla Artiodactyla |
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Pholidota
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Pangolins
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Perissodactyla
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Odd-toed ungulates
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Mammal Skull
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Cranium and mandible (1 bone)
- hyoid apparatus connected via cartilage/tissue |
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Masticatory apparatus
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- tongue
- muscles for chewing (tempralis, masseter, pterygoids) |
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Teeth
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- cemented into bone
- inorganic enamel - nerves and blood vessels via pulp cavity - mammals are heterodonts (functional diversity) - diphyodont = baby teeth replaced by permanent teeth |
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Rodent teeth
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2 gnawing incisors, self-sharpening chisels
- diastema - gap without canine - red-brown patina = iron, layer of enamel - murid rodents = 3 cheek teeth, no premolars |
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Bones
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long bones: diaphyses and epiphyses elongate bone until epiphyseal plate is fused
- determinate growth = rapid growth, then levels off - fibula and ulna often fused or lost - limbs evolved from tetrapodomorphs with paired aquatic (webbed) feet - mammal dexterity associated with brain development |
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Baculum
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penis bone
- primates, rodents, insectivores, chiroptera, carnivora, colugos |
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tapetum lucidum
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reflects light back into retina for another look
- more rods in nocturnal mammals |
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Brain characteristics
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well-developed finger sensitivity
- echolocation mapping with hearing vibbrissae implanted in blood sinus that amplifies movement, directly connected to brain (mystacial = around nose) |
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Hairs
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- made of keratin, arrector pili muscles
- non-living tissue, but bulb is living/growing - pigment granules in medulla - melanin for UV protection - seasonal or age molts - facial masks: medium mammals warning larger mammals away, almost exclusively terrestrial |
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Scansoriality
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climbing, mostly small branches
- sharp claws, in trees |
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Arboreality
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Locomotion via trees
- highly mobile limbs, long sharp claws - prehensile tail often - some climb headfirst and turn ankle sideways for better grip (pes reversal), aka raccoon |
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Gliding
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flying squirrels
- skin flaps and outstretched limbs - tall canopy tree areas, often scansorial |
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Volancy
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true flight (bats)
- radius makes up most of forearm -thin, flexible patagium -short/broad wings for maneuvering, not long-distance |
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Cursoriality
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running
- reduce distal weight, loss/fusion of bones - spinter = bursts of speed - stayer = slow start, but can run for longer periods - springing ligament = inserts at sesamoid bone, cocked and loaded when animal is standing - gazelle pronk = bounding - altruism? boasting? |
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Ungulate manus structure
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Paraxony = axis b/w digit 3 and 4
mesaxony = axis through digit 3 - plantigrade (human), digitigrade (dog), unguligrade (hoof) - graviportal - pillar limbs, stacked vertically - digital vs. metapodial pads |
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Retractile claws
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pulled back for walking (cats)
- flexor muscle relaxes, retractor ligament holds claw in retracted position - cheetahs have semi-retractable claws for extra grip |
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Ricochetal saltators
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jumpers (kangaroos)
- bipedal vs. quadripedal - elongate plantigrade pes, reduced forelimbs, long tail |
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Saxicoly
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rock dwelling
- rubber pads on feet deliver secretions that give them traction on rocks |
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Fossorial
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toothdiggers and scratchdiggers
- lips behind incisors in some mole = builds mole hills vole = open holes, tunnel without grass cover gopher = plug holes |
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Eskers
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Tubular deposits of earth produced by rodents in winter
- thomomys leaves thick tubes - microtus leaves narrow tubes |
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ambulatory
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flat-footed, all 5 toes on ground
- hedgehogs, porcupines to hide short legs |
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Bipedality
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functional or obligatory
- often begins with wading through water - only a few true bipedal primates |
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Ecomorphology of gut
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- directly relates to diet
- teeth are very key, diagnostic to species (dental enamel provides chemical info related to ecology/geology) - herbivore has enlarged cecum and massive colon for hindgut fermentation - ruminant = multiple-chambered stomach, foregut fermentation |
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Insectivory
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invertebrates
- priginal diet of mammals - tribosphenic teeth ideal (possum) to pierce chitinous exoskeleton and crunch it up |
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Myrmecophagy
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social insects (ants, termites)
- hyenid = premolars specialized for crushing |
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Vermivory
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earthworms
- easy to digest, use long/narrow skulls - scat will have citae or gizzard (undigestable) |
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Piscivory
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fish
- long sharp teeth - many homodonts |
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Hunting Association
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- coyote and badger team up to hunt ground squirrels, curious companionship
- mesovertebrate predators often have defense mechanisms (quills, gas) - large vertebrate predators often hunt in large packs |
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Osteophagy
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bone marrow
- requires powerful jaw muscles and dense skull bones, strong blunt teeth - hyenas |
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Sanguivory
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lap up blood, vampire bats (3 sp)
- sharp incisors, anticoagulant in saliva - can eat their body mass in blood in one night - share blood |
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Zooplanktivory
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baleen whales filter krill from water
- gulpers and skimmers - crab-eater seals have seive-like teeth |
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Frugivory
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fruit
- seasonal, trees separated and require long traveling times between patches - arboreal or terrestrial |
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Granivory
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seeds
- ever-growing incisors for chiseling -high water content of seeds - cheek pouches (Dipodomys) |
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Graminivory
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Grazing
- hypsodont = high-crowned - hypselodont = ever-growing teeth leads to high-crowned - bambusivory = bamboo eating |
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Folivory
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browsing leaves, not as course as grass, teeth are lower-crowned and not evergrowing
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Gummivores
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nectar-feeding, pollinators
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Lignivore
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bark and pith, lichen, fungi
- beavers and elephants |
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coprophagous
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eat wet clusters of cecal pellets (bunnies)
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Durophagy
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hard-shelled invertebrates
- puffy teeth = hyperbunodonty - wetland = dextrous hands, big brain, powerful jaws, extractive foraging |
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Migration
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- for food, temp, breeding
- cetaceans and bats are long-distance - don't migrate if large or have low metabolism, or too small to handle distance - mule deer is local migrator |
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Hibernation
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denning in cold weather
- some torpor - bears are slightly active, no torpor - some prepare food caches (pika) - small mammals dump heat against burrow walls, won't be very active = estivation |
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Olfaction funcitons
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- trigger reproduction
- indicate when female is ready - pregnancy blocker (Bruce effect) - copulation inducer - sexual maturation - recognition |
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Monotreme/marsupial reproduction
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monotreme: uteri enter urogenital tract
marsupial: 2 vagina, uteri enter vaginal sinus |
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Estrous cycle
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when females are sexually active; follicular and luteal phases
estrogen = stimulates development of endometrium, peaks at ovulation progesterone = maintains endometrium, withdraws during luteal phase monestrous vs. polyestrous - fertilization can be delayed after successful breeding - postpartum = next litter born while still lactating, heavy impact on female |
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Fertility factors
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- number of estrous event per year
- litter size - population-level pregnancy rate - time to sexual maturity - lifespan |
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Reproductive strategies
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- female takes more of the cost, more incentive to be choosey
- pays for males to mate with as many as possible monogamy = rare, evolves with low population density - may work to defend territory together (beavers) polygyny = female defense or resource defence |
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Canid social systems
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Canis lupus = dominant male and female, previous offspring are helpers, division of labor, sub-dominants don't reproduce as much
Canis latrans = fems/males share home range, may form pairs across seasons Vulpes vulpes = fems/males have separate territories, form short bond for mating and raise young independently |
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infrasound
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travels long distances, low Hz (elephants, tigers)
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ultrasound
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very fast, must be slowed down for us to hear, high Hz, (peromyscus californicus)
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Group foraging
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requires highly social animals
- humpback whales bubblenet feed, blow bubbles under fish to draw them up - canids work together in relay fashion to take over long-distance prey - dolphins/fish.birds |
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Tool use
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- otters use stones to hammer abalone open
- bottlenose dolphins use sponges on nose to probe for prey, only females, from mother to daughter, taught or observed? |
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cognitive flexibility
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subadults learn more easily, more risk-taking
- older individuals take longer to learn - japanese macaques and sweet potatoes |
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Great apes and tools
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- chimps fish for termites with grass stems
- orangutans and gorillas too |
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Culture
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- sum total of all shared, learned experiences in a given time/place
- tool use - cultural behavior = passed down through social interaction - Gorillas use sticks to test water depth - unknown if other organisms use tools to make tools |
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Social rank
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80% prediction based on gene expression
- lower ranking individuals have increased immunity due to stress - baboons |