BB 3140 Course Outline Chapter 3

BB 3140 Course Outline Chapter 3 - BB 3140 Course Outline...

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BB 3140 Course Outline Chapter 3 Patterns of Evolution I. Common changes occurring in systematics (classification of taxa) are referred to as patterns of evolution A. Systematics uses characteristics of organisms to classify them 1. When compared with phylogenies of the same organisms, history of changes in characters can be inferred. 2. For example, phylogeny of humans from first organism shows synapomorphies as changes in character states (Fig. 3.1). 3. Using this information, can infer the character state present in ancestral taxa B. Examples of character evolution 1. Evolution of opposable vs nonopposable toes in primates (Fig. 3.3) a. Other apes have opposable toes b. Humans have nonopposable toes c. Suggests that common ancestor of humans and chimpanzees had opposable toes d. Humans lost opposable toes after divergence from chimpazees 2, Evolution of host range in HIV (Fig. 3.4) a. HIV related to lentiviruses in cats and other mammals b. Phylogeny suggests that HIV-1 evolved at least twice from chimpanzee virus (SIV) c. HIV-2 evolved from sooty mangabey 3. Visual pigment rhodopsin a. Found in all vertebrates with eyes b. Can infer sequence of rhodopsin in dinosaur ancestor of birds and alligators (which are both considered allosaurs) c. Made synthetic dinosaur rhodopsin and showed that it performed correct function (visible light absorption) II. Patterns of Evolutionary Change Inferred from Systematics A. Most features have been modified from pre-existing features 1. Homology is defined as a character or character state found in two species if both inherited it from a common ancestor 2. Wings of birds, bats, and pterodactyls all evolved from forelimbs having the same numbers and arrangements of bones in all tetrapod vertebrates (Fig. 3.5) a. forelimbs are homologous, even though the different kinds of wings are not 3. Characters may be homologous but a given character state may not be homologous a. toes are homologous in vertebrate hindlimbs
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b. having a certain number of toes is not homologous
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This note was uploaded on 09/01/2010 for the course BB 10294 taught by Professor Politz during the Spring '10 term at WPI.

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BB 3140 Course Outline Chapter 3 - BB 3140 Course Outline...

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