Patterns of geographic variations (in cladogenesis) T. 26 final exam.txt

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  1. Allopatric speciation
    • Different geographical areas (no bordering Hybrid zones)
    • a. Vicariant: geographic barrier comes AFTER ancestral species arrives.
    • ie brown bears of Kamchatka were present prior to Riss Glacial period. Glaciers moved and formed barrier b/w ancestral asian brown bears & descendents Kamchatka subpopulations. Barrier is the GLACIERS
    • b. Dispersal: aka Peripatric speciation. Barrier comes BEFORE ancestral species arrives.
    • ie Hawaiian islands emerge from Pacific ocean & one species of Drosophila colonize initially. This spawns over 800 new descendent species of Drosophila thru dispersal (island hopping). Barrier is the OCEAN
  2. Parapatric speciation
    • Different geographical areas w/narrow hybridization zones
    • ie, Grass Anthoxanthum odoratum diverged into metal-tolerant and metal-intolerant populations. note, their F1 hybrids don't thrive in either soil, so the 2 populations are classified as 2 species.
  3. Sympatric speciation
    • Exact SAME geographical areas
    • ie, apple maggot fly Rhagoletis pomonella diverged INTO subpopulations feeding on 1. Hawthorn berries and 2. apples. Aquired genetic diff and breeding cycles help make it different
  4. Stasipatric speciation
    • Descendent species originates WITHIN SAME geographic area of ancestral species
    • ie, several chrom inversions have diverged ancestral population of Australian grasshopper Keyacriscurra
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Patterns of geographic variations (in cladogenesis) T. 26 final exam.txt
2011-12-11 16:42:26
geographic variations

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