Maloof_5A_TreeApplications

Maloof_5A_TreeApplications - Lecture 5. Tree applications...

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Unformatted text preview: Lecture 5. Tree applications Using trees to better understand evolution Mapping traits on trees: Patterns and modes of evolution Patterns of trait evolution. Case studies: Linanthus; Tortoises Rates of clade diversification Case study: plant defense Biogeography: phylogenies and location Case study: horses Molecular Clocks: phylogenies and time Case studies: snapping shrimps; human clothes Conservation Biology Case studies: invasive grasses; cichlid fishes Wednesday: Microbes and the tree of life (Dave Rizzo) Uses of phylogenies Studying the tempo and mode of evolution How, when and at what rate do characters (morphological, ecological, genetic, etc.) change? Rates of diversification Biogeography The study of the geographical distribution of organisms Molecular Clocks Timing evolutionary or historical events Conservation biology Using phylogenetic criteria to establish conservation priorities Using phylogenies: Mapping traits on trees Many applications ask where an event occurred on a phylogenetic tree. To accomplish this we: 1) use characters (traits) to build a tree--often using DNA. 2) investigate how other traits evolved on this tree. This can involve looking at features of morphology, ecology and behavior. Traits on Trees I: Fertilization in phlox flowers Consider the Linanthus example in your textbook (Life, 8e, page 552). These plants in the phlox family illustrate two different kinds of fertilization systems: (1) self-incompatible flowers (individuals cannot self-fertilize) (2) self-compatible flowers (have ability to self-fertilize) Many flowering plants are self-incompatible. Why? Mapping traits on trees Linanthus phylogeny (based on DNA sequence data) Self-compatibility apparently evolved three times in this group. How do we arrive at this estimate? Are there alternate possibilities? = self-incompatible = self-compatible Mapping traits on trees We reconstruct the evolution of traits on trees in various ways. 1. Use parsimony: minimize the number of changes. 2. Take into account the condition in outgroups 3. Take into account the probability of state changes = self-incompatible = self-compatible Mapping traits on trees We reconstruct the evolution of traits on trees in various ways. 1. Use parsimony: minimize the number of changes. 2. Take into account the condition in outgroup 3. Take into account the probability of state changes (model-based approach) = self-incompatible = self-compatible ! more likely than ! For example: Mapping traits on trees Linanthus phylogeny Why do the self-compatible forms all have the same species name: Linanthus bicolor ? = self-incompatible = self-compatible Mapping traits on trees Linanthus phylogeny Why do the self-compatible forms all have the same species name: Linanthus bicolor ?...
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Maloof_5A_TreeApplications - Lecture 5. Tree applications...

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