P10-Lecture 2- Patterns in Nature Jan_27

P10-Lecture 2- Patterns in Nature Jan_27 - "This...

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Unformatted text preview: "This view of life": Patterns in Nature s Two patterns in Nature x Apparent "design" x Nested variation s Darwin explained both x Design - the subject of the next set of lectures 3 Inheritance, Natural Selection x Nested variation - Following 3 Phylogeny Design s Organisms are complex Design s Organisms are functionally integrated Design: Form fits function Darwin and "Design" s Natural Selection xLeads to adaptation xExplains design Adaptations vs. Good fit s Not all useful features are adaptations for that use. Adaptations vs. Good fit s Not all useful features are adaptations for that use. Fig. 1.9 Does Natural selection produce perfect adaptations? s NO xEvolutionary history = phylogeny 3At best, natural selection is one generation behind Adaptation and Convergence s Similar circumstances can lead to similar adaptations independently xThis is called convergence xConvergent characters are said to be analogous xConvergence is common Adaptation and Convergence Adaptation and Convergence Mole Mole cricket Groups nested within Groups s Life forms a hierarchy xSmaller groups are nested within larger groups, etc. Groups nested within Groups s Life forms a hierarchy xSmaller groups are nested within larger groups, etc. xE.g. Humans share features with other primates, primates share features with .. Groups nested within Groups Groups nested within Groups Groups nested within Groups Groups nested within Groups s Forms the basis for Linnean classification. x At time was Non-evolutionary x Predates Darwin's ideas x Groups within groups as observed in nature Kingdom Animalia Phylum Chordata DOMAIN EUKARYA Class Mammalia Order Primates Family Hominidae Groups nested within Groups s Darwin explained this pattern very nicely s Phylogenetic Tree s Patterns within patterns can be explained by recency of shared ancestry! Groups nested within Groups s Darwin explained this pattern very nicely s Phylogenetic Tree s Patterns within patterns can be explained by recency of shared ancestry! Homology s Similarity inherited from a common ancestor is called homology. Homology vs. Analogy s Similarities that are independently evolved are called analogous (or convergent). Summary s Organisms are very complex x Natural Selection s Adaptations arise via Natural selection x Not all useful features are adaptations for that use s Natural selection cannot produce perfection x History x Constraint x Compromise Summary s Convergence is common x Similar adaptations under similar circumstances x Independent similarities are called analogous (convergent) s Groups within groups x The basis for Linnean classification x Nested groups are the branches on the phylogenetic tree x Homologous structures are found in a common ancestor For Friday s Read pages: 484-489 s Begin to look over 490 500 which we will discuss in more detail on Monday. ...
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This note was uploaded on 05/11/2010 for the course BIOLOGY 100 taught by Professor Richard during the Spring '10 term at George Mason.

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