Ch 24 and 25

Ch 24 and 25 - 0. 1. 2. 3. Goals for Chapter 24 : 9-4-07...

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Goals for Chapter 24 : 9-4-07 0. Understand differences between 0. biological and phylogenetic species concept 1. micro and macro-evolution 2. allopatric and sympatric speciation 1. Know examples of each type of isolating mechanism (both pre- and post- zygotic) 2. Understand what is meant by the punctuated equilibrium model 3. Understand 3 ways developmental genes can cause rapid evolution Macroevolution Macroevolution is generation of a new species Can be by anagenesis (slow accumulation of differences) or Cladogenesis (rapid splitting or branching of two new species) Fig. 24.12 What is a species? 0. Biological species concept: 0. Interbreeding populations reproductively isolated from others 1. based on fertility, not similarity 0. Phylogenetic species concept 2. Differences in DNA 3. Different alleles fixed at same locus indicate genetic isolation: 4. AA -- Species 1 5. BB -- Species 2 6. Subunit of biological species, often can’t tell apart morphology Isolating Mechanisms Prezygotic Ecological separation (habitat or temporal) Behavioral (sympatric but differences in mating behavior) Anatomical/physiological barriers Gametic isolation Figure 24.4 A summary of reproductive barriers between closely related species Figure 24.3a Eastern and Western meadowlarks look similar and overlap geographically, but are behaviorally isolated by differences in the male’s courtship song Isolating Mechanisms 1. Postygotic 0. Reduced hybrid survival (frogs) : amphibians 1. Reduced hybrid fertility (horse and donkey produce sterile mule , fig. 24.4 ) 2. Hybrid breakdown (rice, Fig. 24.4 ) 1. Loss of vigor in F 2 (rice, Fig. 24.4 )
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This note was uploaded on 12/02/2009 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.

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Ch 24 and 25 - 0. 1. 2. 3. Goals for Chapter 24 : 9-4-07...

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