Chapter 22

Chapter 22 - Chapter 22 Reconstructing and Using...

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Chapter 22: Reconstructing and Using Phylogenies 22.1 – What is phylogeny? o Phylogeny is the evolutionary history of relationships among organisms and their genes o A phylogenetic tree is a diagram that portrays a reconstruction of that history o Each split or node in a tree represents a divergence of lineages o The common ancestor of all the organisms in a tree is called the root of the tree o Any group of species to which we designate a name is called a taxon o A taxon that includes all of the evolutionary descendants of a common ancestor is called a clade o Two species that are each other’s closest relatives are called sister species o Two clades that are each other’s closest relatives are called sister clades o Systematics is the study and classification of biodiversity o Biologists use phylogenies to make comparisons and predictions about shared traits across genes, populations, and species o The complete evolutionary history of life is known as the tree of life o Homologous traits are received due to common ancestry trait that was already present in the ancestor of the group is called an ancestral trait o A derived trait is a trait found in the descendants, but not in the ancestors o Derived traits that are shared by a group of organisms that can be used as evidence for evolution are called synapomorphies o Not all similar traits are evidence of relatedness:
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This note was uploaded on 09/08/2011 for the course LS 1 taught by Professor Thomas during the Summer '05 term at UCLA.

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Chapter 22 - Chapter 22 Reconstructing and Using...

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