ANTHRBIO 201 1st Edition Lecture 10I. similarities due to common descent A. forelimbs of dugongs, moles and bats B. patterns of similarity permit hierarchical classification 1. bats resemble mammals II. speciation explains why we can classify organisms hierarchically A. traits due to common ancestry provide the basis for classifyingus with the African apes B. during speciation new species split off from older ones → forms tree C. phylogeny 1. evolutionary relationships among organisms a) represented in tree like form 2. shows branching orders of species 3. timing of speciation events 4. history of events D. species can share features and evolve features independently 1. ancestral traits a) no tails, 5 fingers, forward eyes 2. derived traits a) humans are bipedal b) male chimps have large tests E. relationship between time or separation and similarity III. Why are phylogenies important? A. provide the basis for identifying and classifying organisms ietaxonomy B. explain why species evolve specific adaptations becausethey provide information about ancestral states 1. evolutionary history of humans furnishes insights intothe origin of bipedalism IV. how to reconstruct phylogeniesA. assume that species that are more similar to each other will bemore closely related to each other B. based on myglobin species 1. humans duckbilled platypus, chicken C. problems due to convergence D. analogous characters= similarity due to convergent evolutionE. homologous characters= similarity due to common descent 1. egg laying trait F. ancestral characters= homologous characters that appear early in theevolution of a lineage G. derived characters= homologous traits that appear later in theevolution of a lineage H. ancestral traits: 1. appear early in development 2. appear earlier in the fossil record3. are seen in outgroups V. Phylogenetic reconstruction using genetic distance data A. realign table B. molecular evolution occurs at a relatively constant rate C. molecular clock permits timing speciation events 1. distance=rate x time 2. time= distance / rate VI. TaxonomyA. the scientific system of classifying animals based on the hierarchycreated by evolution B. taxonomy of hominoid primates C. evolutionary taxonomy 1. uses overall similarity as well as evolutionary relationships