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Unformatted text preview: esult of sympatric and allopatric populations arising from different founder stock (founder effects). Galapagos finches - partitioning of food resources is manifested in the evolution of different beak sizes... leading to reduced competition. Lacking a time machine, these have been difficult prove definitively, but ecologists hypothesize this frequently Species packing: adding new species shrinks the niche width of all species. To compensate species often become more specialized, and more efficient at using a narrower range of resources. Is there a limit to the number of species that can be "packed" into an area? If resources are finite (the niche axis can't be expanded), then adding species will increase the competition coefficent between pairs of species, decreasing the likelihood of coexistence Corollary: as you add species, the probability of establishment of new species should decrease: Invasion success should decrease with increasing numbers of resident species, and successful invaders should be those that are most different from established species (least overlap).
Few species = Many "empty niches", susceptible to invasion. Resource
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- Spring '09