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BIO 301M Notes for Test 3

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BIO 301M

BIO Test 3 Sexual selection: ­ Males: if you don’t try and mate, you wont leave any offspring ­ Females: whychoose males with traits or behaviors that are detrimental to survival? The handicap principle: ­ any male that is capable of surviving in spite of having living with a huge handicap must carry superior genes ­ ex: the ability for peacocks to show off without getting attacked by prey the parasite hypothesis: ­ bright colors of males are costly extravagance and signals males that are more parasite free ­ ex: ability to make colors light red or green=healthy bodies the sensory exploitation hypothesis: ­ males evolved colors that females are predisposed to pay attention to ­ ex: males use colors to their advantage the sexy son hypothesis: ­ females chose extravagant males because they know they wil produce extravagant sons which will be successful in the next generation natural selection and sexual selection work in opposite directions why does any variation persist at all? ­ diploidy ­ heterozygote advantage: some people survive better ­ neutral variation: eye color and hair color doesn’t help with survival ­ frequency dependent selection: fishies want the rarer guy ­ environmental hetetrogeneity Why are organisms not perfect? ­ mutations not arise from demand; chance ­ adaptions are compromises; either or. Such as more offspring or large offspring in rats ­ historical constraints: bats wish they had light bones birds have but they haven’t been flying as long as birds have Alfred Wegener ­ 1910 after Darwin ­ continental drift and plate tectonics Evidence for continental drift ­ coastlines of continents fit together ­ geological features on one continent often match those of another when they are fit together ­ fossils of extinct animals and plants do not match the environment where they are found; fish on the mountains, tropical plants inAntarctica ­ there are many cases of extinct species; their ranges span across continents that were once together ­ gigantic land mass called pangea, which broke ­ we are still moving today. 2cm/year ­ evidence of plate tectonics, san andres fault what is a species? ­ many ways to define a species: species concepts ­ what about two organisms that look alike but will not interbreed? ­ What about different looking but don’t interbreed ­ What about different but do interbreed ­ What if they cannot reproduce sexually Biological species concept ­ organisms may be considered the same species if they belong to populations that actually or potentially interbreed in nature morphological species concept ­ organism may be considered the same species if they can be identified by morphological features sex video: ­ lizards that have eggs without having sex and the eggs are a literal copy of them ­ males can be annoying and females don’t really need or want them ­ males still paly a big role and sex is important ­ no asexual cloning ­ most speacies use sexual reproduction; why? ­ The fish with spots were mostly the ones that were asexual and no the sexual ones ­ Evolution is a race; the red queen ­ After the drought the spots were only on the sexual fish and not the clones ­ Taking the asexual fish and putting them in the parasite pool with sexual fish, then the parasite went back to the asexual fish ­ All about competition ­ Young survive ­ Behavior and physical traits are very important ­ Free of parental care; females can produce more eggs ­ Humans closest to chimps Species problem: ring species ­ a species where the range wraps around some geographic feature so big that where the range meets on the other side, individuals seem to be different species ­ ex. Salamander; greenish warbler reproductive isolation ­ prezygotic: before fertilization ­ postzygotic: after fertilization prezygotic: habit isolation ­ different areas ­ ex. Different species of garter snakes may live in the same area but one lives under water and the other doesn’t prezygotic: temporal isolation ­ different times ­ ex. Eastern and western spotted skunk ranges overlap but eastern skunks breed in winter and western in summer prezygotic: behavioral isolation ­ different courtship ­ ex. Blue-footed boobies can interbreed with other related species but don’t recognize them without their blue feet prezygotic: gametic isolation ­ molecular incompatibility of gametes ­ ex. Sperm don’t recognize eggs of different species postzygotic: reduced hybrid fertility ­ infertile hybrids ­ ex. Donkeys and horses can interbreed but sterile mules adaptive radiation ­ sudden burst in speciation activity ­ causes: colonization of new areas, extinction of compe
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