Stickleback Story

Stickleback Story - Dr. Susan Foster BIOL 105 Evolution...

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Dr. Susan Foster BIOL 105 – Evolution 9.12.07 The Fish: The Story of Stickleback I) Gasterosteus aculeatus L. 1) Family Gasterosteidae a Close relative of pipefishes and seahorses b Small fish (2-8 cm at maturity) c Can be reared fairly easily in the laboratory d Stickleback pelvis is similar to mammals e Sexually dimorphic (males and females look different): Males assume bright nuptial coloration while females remain drab during reproduction. f Found in temperate oceans and in freshwater in the northern hemisphere 2) Adaptive Radiation a Radiation: diversification of populations or species Darwin’s finches Birds that specialize in different styles of feeding b Adaptive: diversification partly caused by natural selection adjust populations to new environments Different evolutionary adjustments necessary in new environments 3) Oceanic Stickleback (i) Geographically uniform today Oceanic form “always” fully armored, looks like this everywhere Oceanic fish very similar morphologically, and different from more variable freshwater populations (ii) Historically uniform – “living fossil” Miocene oceanic fossils have the same features as extant species (iii) Huge population size - random genetic change unlikely (iv) Stable environment - adaptive change unlikely b Thus oceanic fish are likely to resemble the oceanic fish that gave rise to freshwater populations (i) Provide insight into the ancestral condition
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This note was uploaded on 04/24/2008 for the course BIOL 103 taught by Professor Foster during the Fall '08 term at Clark University.

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Stickleback Story - Dr. Susan Foster BIOL 105 Evolution...

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