Bio200 Week 11 Notes
Bio200 Week 11 Notes BIO 200LLB
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This 4 page Class Notes was uploaded by Nicole on Friday November 13, 2015. The Class Notes belongs to BIO 200LLB at University at Buffalo taught by Lindqvist, C in Fall 2015. Since its upload, it has received 29 views. For similar materials see Evolutionary Biology in Biological Sciences at University at Buffalo.
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Date Created: 11/13/15
November 9, 2015 Lecture 23 Mammals -Smallest class of invertebrates -Includes the largest terrestrial animals -70% of mammals are relatively small (rodents, bats) -Ancient mammals were mostly small, shrew-like, insectivorous, arboreal and nocturnal -Mammals likely survived the extinction of the dinosaurs due to endothermy Mammals are unified by Five Traits: 1.) Hair a. Generally have a dense overcoat of fur covered by an overcoat b. Used as camouflage c. Sensory uses (whiskers) d. Defense, quills are simply thick, sharpened hair 2.) Mammary glands a. Milk is calorie and fat rich, allowing for the development of the baby’s brain 3.) Endothermy a. 4-Chambered heart b. Higher metabolic rates c. Homoplasious in mammals and birds (has evolved separately) 4.) Sweat glands a. Cool mammals via evaporation 5.) Placentas a. Most mammals have internal gestation b. Placenta allows developing baby’s blood to come into close enough contact to mother’s blood to absorb nutrients, but bypass waste Mammalian Development -Highly Specialized teeth-we can tell what a mammal eats simply by it’s teeth -Mammals have symbionts that allow them to digest cellulose -Have used keratin to develop hooves and horns -Certain mammals are capable of powered flight (bats) Two Groups of Mammals 1.) Prototherians (Monotremes)-movie 2.) Therians (Marsupials and Eutherians) a. Marsupials often have pouches b. Though they have amniotic eggs, no shell develops c. Most species of mammals are eutherians (Includes humans) i. Much more developed babies than Marsupials ii. Huge size range iii. Diverged quickly after the mass extinction of dinosaurs iv. Diverged as the continents broke apart during the late Mesozoic Movie: A winning Design -Carries an egg the size of a marble on the underside of her fur carrying a young achina Platypus-rubbery beak-feeds on small invertebrates -Grinds them to a pulp -Senses tiny electric currents given off my living things with beak Birds hunt alongside platypus because fish are attracted -Platypus-milk oozes through the skin Primates -Two traits in common: Grasping fingers & toes -Binocular vision (gives us depth perception), important for hunting Two Main Groups of Primates we usually recognize 1.) Prosimian-before the apes a. Paraphyletic group b. Strepsirrhini (Wet-nosed) 2.) Anthropoids-includes apes a. Haplorrhini (dry-nosed) Hominidae (Hominids): -Comprises the great apes and humans -Humans and their direct ancestors are hominins Hominids vs Hominins Traditional Classification Family: Pongidae (great apes) Family: Hominidae (modern humans and our close extinct relatives) New Classification Family: Hominidae (Great apes AND humans) Subfamily: Homininae (gorillas, chimpanzees, and humans) Tribe: Hominini (humans & our close extinct relatives) Strepsirrhini (wet-nosed) primates are the most ancient primates -Includes Lemurs, bush baby, Loris -Some lemurs do not act like other Strepsirrhini; some are diurnal (awake during the day), very social and live in matriarchal societies Haplorrhini (dry-nosed) primates -Have developed color vision to adapt to daytime living -Extended parental care allows for longer learning time & more brain development Platyrrhines (New World Monkeys) -Live in South & central America Catarrhines gave Rise to two groups: 1.) Old World monkeys a. Tailless, include Rhesus macaque and Olive baboons 2.) Apes (hominids) a. Gibbons b. Hominids (great apes and humans) c. Asian apes & orangutans diverged first, though neither group is especially closely related to humans d. African apes and humans evolved most recently e. Humans vertebral column is more curved, and our pelvis is more oval shaped to push our center of gravity over our legs Where did We Come From? 1.) Bipedalism is the only trait that distinguishes humans from other apes a. Allow for us to grasp other things b. Ardipitithecus may have been mostly arboreal i. Bipedal, allowing her to walk upright (though not for very long periods) c. Australopithecines is the first hominin group we have many fossils from i. Earliest Australopithecines were gracile 1. They could walk upright, but had much smaller brains 2. Lucy was an Australopithecus, her feet & leg bones were almost identical in function to those in humans ii. Second group of Australopithecines was most robust: Paranthropus d. All members of the genus Homo are called humans i. Australopithecus sebida may be the lineage Homo evolved from ii. First Homo species we recognize is Homo habilis 1. Much larger brain chamber than ancestors, but still only ~50% the size of modern humans 2. Short with long arms iii. Homo erectus 1. Nearly the height of an average modern male with 75% brain size of modern humans 2. Hunter-gatherers, first species to master fire, and first to leave Africa iv. Modern humans originated around 600,000 years ago 1. Short & stocky, moved to Europe & developed complex rituals 2. Homo sapiens come to dominate around 34,000 years ago 2.) Where did Homo neanderthalensis go? a. Assimilation Hypothesis i. Excessive hybridization led to single population b. Out of Africa theory i. Separate lineages evolved & competition determined current population ii. Current evidence supports this theory iii. Genomic data from archaic hominins suggest that our development may be more complex than this theory: Neanderthals and Denisovans
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