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6 Cards in this Set

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While benthics and limnetics can interbreed and produce fertile hybrids, they don't. What ecological hypotheses did McPhail propose to reconcile these facts?
1. intermediate characteristics of hybrids mean that offspring can't feed efficiently in either environment
2. While they *can* interbreed, they don't. Hybrids make up less than 1% of population. (cultural differences.) Both were true.
McPhail discovered other sets of benthic limnetic pairs that varied morphologically in other lakes in BC. He concluded that he was dealing with a pattern or process - what was he referring to?
"variations on a theme," the pairs were like an experiment repeated independently and yielding similar results. It wasn't random or isolated, but a process of nature.
double invasion hypothesis support?
-looking at fish in nearby lakes, geological and fossil evidence for circumstances, supporting evidence around globe in similar environments, genetic evidence and base pair sequencing
experiment McPhail used to determine difference between benthic and limnetics? what were the possibilities?
Possibilities: polymorphism, or two species. Bred like kinds to like kinds for several generations, bred true, so not polymorphs. Then interbred to see what happened, and got fertile hybrid, so not different species, but speciation occurring.
describe two ways in which evolution proceeds
Traditional view of evolution - one organism changing into another type of organism very gradually over time at a rate so slowly as to be imperceptible on a human scale. Speciation - branching of one species into two or more species over time. Can happen quite rapidly, and may be responsible for much of the variety of life.
anatomical differences between benthic and limnetic sticklebacks?
benthic - fat, weak and small dorsal and pelvic spines, no pelvic girdle. Limnetic - skinny, small, have dorsal and pelvic spines.