Speciation160-page10

Speciation160-page10 - habitat Today we often discuss loss of habitat but this loss is generally not a physical loss of geography but a change in

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Methods of Speciation - 10 Both gradualism and punctuated equilibrium have merit. Evolution can, and does, result from selection pressures. Evolution also takes place in "jumps" consistent with punctuated equilibrium and random events. The differences are in the interpretation of the forces that shape evolution, not in process of evolution as the underlying foundation of biology. Extinction Before we leave the subject of life, just as we have new species, we have species that decline in numbers and eventually die out altogether. We discussed a several examples of successful adaptations in this section. What about species that lack adaptations in their environment, and lose to those who are better adapted? Adaptations can affect not just populations of one species, but natural selection can also lead to the loss of a species by extinction. When we look at extinction, the most significant cause of extinction is change in
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Unformatted text preview: habitat. Today we often discuss loss of habitat, but this loss is generally not a physical loss of geography, but a change in that habitat which results in an area no longer suitable for the individuals who originally lived there. Humans have done much in the past few centuries to alter habitat, to the detriment of thousands of species. Species that have narrow gene pools (are highly specialized) and/or have restricted distribution are more vulnerable to changing environments. Those who are large-dimensioned and have greater resource demands are more vulnerable. Equally vulnerable are species perceived by humans as physically threatening, in particular the large carnivores, and most particularly cats, wolves and bears. Karner Butterfly – Lupine restricted Devil's Hole Pupfish – One Nevada Location...
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This note was uploaded on 12/29/2011 for the course BIO 151 taught by Professor Edwards during the Spring '10 term at SUNY Stony Brook.

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