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EKU - BIO 112 - Class Notes - Week 6

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EKU - BIO 112 - Class Notes - Week 6

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background image BIO 112     Week of February 25,  2018 Homology Different species have similar traits due to a common ancestor. Bat Wing and human arm Genes homologous if derived from ancestral gene Morphological Analysis A systematic study of the morphological features; used to compare extinct  and modern species. Convergent evolution: Similar environments lead to similar traits in different  species. Traits arise independently. This can cause trouble. Called analogous traits Molecular Systematics Genetic homologies are identified and studied to create phylogenetic trees by analyzing genetic data, such as DNA. The more closely related the species’ are, the more closely related the  DNA and amino acid sequences are. Cladistics Compares homologous traits and is based on evolutionary relationships. Shown by phylogenetic trees or cladograms. Chooses the tree that is the  least complex explanation for the data. Can be constructed with gene  sequences. Symplesiomorphy (shared primitive character): Inherited from common  ancestor that isn’t the most recent one and is shared by 2 or more different  taxa.
background image Synapomorphy (shared derived character): Most common ancestor and  shared by 2 or more. Branch Point: Shared derived characters, but there are difference between  species Taxa that share a common ancestor are sister groups Ingroup is the group interested in and the outgroup is the group that diverged before the outgroup species. Outgroup will not have 1 or more of the shared derived character of  ingroups DNA sequence changes due to a mutation is analogous to characteristic  modification. To create a cladogram: 1. Species want to use
2. Characters want to use
3. Character state polarity
a. Primitive? Or derived? To analyze: Higher taxa tips on phylogenetic tree, not at branch point Branch points all have one or more shared derived character, unless  later modified. All appear together ONCE, unless arose independently  during evolution more than 1 time. Most likely cladogram (usually the simplest) Noncontroversial outgroup as root Parsimony Simplest hypothesis preferred (fewest changes). Determining the correct polarity is a challenge: May not be obvious Analysis of fossils

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School: Eastern Kentucky University
Department: Biology
Course: Ecology and Evolution
Professor: Jamie Lau
Term: Summer 2015
Tags:
Name: BIO 112 Week 6
Description: These notes cover what was went over in lecture this week.
Uploaded: 03/02/2018
4 Pages 26 Views 20 Unlocks
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