BIOC51H3 Lecture 7: BGYB51H3 Lecture 7 Notes Oct 1
11 Aug 2010
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BGYB51H3 Lecture 7 Notes
-without evolutionary knowledge, hypotheses about macroevolutionary changes v[
tested (refer to testes example)
-control of phylogeny is the evolutionary history of an organism
-phylogenies are hypotheses that can be tested
-a branch is a single taxonomic group through time
-nodes show a common ancestor for branches and are the sites of a split in lineage
-terminal node is most recent single taxon descendant
-sister taxa share more recent common ancestor
-traits are scored as discrete or distant data
-discrete data have only certain states possible
-distance data has consistent range of values
-phylogenetic trees should minimize homoplasies because they are misleading
-homoplasy is a trait similar because of convergent evolution or reversal (usually occurs when
two different species are grown up in similar environments)
-finding more traits eliminates homoplasies because certain organisms will become more
similar to each other than others as more traits are analyzed
-unidentified homoplasies will have a less effect on phylogenetic trees
-traits that define branches on a phylogenetic tree are synapomorphies
-synapomorphies are distinct similar traits found between two species and is considered a
more broad trait
-in evaluating hypotheses about the order of phylogenetic events, parsimony is used in
alternative explanations
-parsimony involves minimizing the total amount of complexity by using the most simple
explanation
-parsimony always assumes that the reasonable phylogenetic tree is the one with the least
evolutionary changes
-macro or microevolution questions allow researchers to test the logic of hypotheses and
identify where further study is needed
www.notesolution.com
Document Summary
Control of phylogeny is the evolutionary history of an organism. A branch is a single taxonomic group through time. Nodes show a common ancestor for branches and are the sites of a split in lineage. Terminal node is most recent single taxon descendant. Traits are scored as discrete or distant data. Phylogenetic trees should minimize homoplasies because they are misleading. Homoplasy is a trait similar because of convergent evolution or reversal (usually occurs when two different species are grown up in similar environments) Finding more traits eliminates homoplasies because certain organisms will become more similar to each other than others as more traits are analyzed. Unidentified homoplasies will have a less effect on phylogenetic trees. Traits that define branches on a phylogenetic tree are synapomorphies. Synapomorphies are distinct similar traits found between two species and is considered a more broad trait. In evaluating hypotheses about the order of phylogenetic events, parsimony is used in alternative explanations.
