Evolutionary History Our place in nature- homo sapiens Kingdom: Animalia Phylum- Chordata (Subphylum- vertebrata) Class- Mammalia (Subclass- eutheria) Order- Primates Family- Hominidae Genus- Homo Classification and Evolutionary Relationships Compare characteristics -ancestral, primitive (old) -derived (modified) from ancestral condition -shared derived* 2 Ways to Shared Traits 1) Homologies -shared due to common ancestry 2) Analogies -shared, but through independent evolution (homoplasy) Humans have a shared ancestor with chimps- last common ancestor. Chimps and bonobos (knuckle walkers) likely shared due to LCA= homology Bipedality is derived in hominids. Analogy- shared trait, independent evolution (process of homoplasy) What is a species? -biological species concept (E. Mayr) -says species are reproductively isolated, evolutionary dead ends -many other species concepts -20+ species concepts -Phylogenetic species concept- reproductive isolation may or may not be an outcome of evolutionary processes -evolutionary significant units -population that has a genetic/behavioral/etc distinction that you want to save -Endangered species Interpreting Variation -tell whether it?s a variation within a species, or whether it?s a whole new species Primate Specialist Group, IUCN, Taxonomic Revisions Split species with distinct populations top conserve maximum diversity -added new taxonomies Criteria: -morphology -genetics -physiology -behavior Species in the Fossil Record ?Splitters? versus ?lumpers? Within versus between species variation -levels of sexual dimorphism -biologically meaningful traits (those under selection) Speciation -macroevolutionary process -reproductive (genetic) isolation -geographic -behavioral Tempo and mode of speciation** Phyletic Gradualism- over time a species starts to accumulate differences, still recognizable as the same species, however, over time the species becomes a new species. *Slowly over time? Species A ---> under drift or selection----> Species B Punctuated Equilibrium- period of stasis (stable), then something happens (usually major environmental change), then you have rapid change and a completely new species Species A------> Stasis-----> Rapid Change-----> Species B Adaptive Radiation- occurs during punctuated equilibrium, lots of species explodes from a single species (branches out), species diversify during the rapid change in PE, diversify into new ecological niches Adaptive Potential*** Generalized -broad ecological niche -wide geographic distribution -diverse habitats Specialized -narrow ecological niche -geographically limited -distinct habitat needs -Which is most likely to have high genetic variation? -Generalized -Which is most at risk under climate change? -Specialized
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