lecture21 - BioEE 278 Evolutionary Biology CASE HISTORIES...

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BioEE 278 Fall 2007 Evolutionary Biology Lecture 21 CASE HISTORIES OF SPECIATION Reading: A. Adaptive radiations on “islands” 1. Examples: Darwin’s finches, Hawaiian radiations (many insects and plants), cichlids in African Rift Lakes 2. What is it about islands? 3. What are the advantages of studying islands? B. Hawaiian Silverswords 1. Geographic context of Hawaii 2. Mainland origins and monophyletic group with 3 genera 3. Rapid diversification in ~5 MY 4. Rapid evolution of regulatory genes involved in flower differentiation and photosynthesis 5. Morphological differentiation by habitat – convergent evolution 6. Allopatric vs. sympatric speciation – basal species on Kaui (oldest island); degree of sympatric speciation declines with island age. C. Hawaiian “spiny-leg” spiders in genus Tetragnatha 1. Monophyletic clade in the genus 2. Four “ecomorphs” associated with different predation habit 3. Island distribution of ecomorphs 4. How many times have ecomorphs evolved and what was the geographic context?
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This note was uploaded on 09/28/2008 for the course BIOEE 2780 taught by Professor Geber during the Fall '07 term at Cornell.

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lecture21 - BioEE 278 Evolutionary Biology CASE HISTORIES...

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