Another set of important examples of speciation are those that are believed to have speciated as a r

Another set of important examples of speciation are those that are believed to have speciated as a r

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Another set of important examples of speciation are those that are believed to have speciated as a result of isolation in Pleistocene refugia . Glacial advances and retreats during the Pleistocene epoch acted as vicariance events in areas where glaciers were present (Wisconsin ice sheet). Dramatic evidence of this is in the North American bird fauna and the clear faunal break between the east and west, e.g., wood warblers ; Peterson's field guides have an Eastern and Western edition). Climatic changes associated with the glacial advances and retreats altered habitats in the tropics resulting in "islands" of habitat that fluctuated in size and geographic location, leading to
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Unformatted text preview: fragmentation of distributions and contribution to speciation. Believed to one explanation for patterns of speciation in the Amazon . Also a possible explanation for the Larus ring species complex : genus Larus (seagulls) fragmented in Siberia during the Pleistocene. Diverged populations of Larus argentatus (herring gull) colonized eastern Siberia, across the Bering straits, across North America, Iceland and back to Northern Europe becoming increasingly diverged at each step. Hybrid zones exist between successive populations but the ends of the ring are reproductively isolated implying that speciation has gone to completion (an example of geographic speciation)...
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