Macroevolution-2.4

Macroevolution-2.4 - Lecture outline: Macro-Evolution I....

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Lecture outline: Macro-Evolution I. Overview In previous lectures, we examined microevolutionary processes that concerned evolution within populations. Now we go up one level of biological organization and examine what we mean by a species and the processes that give rise to species. II. The species is the fundamental unit of biological diversity A. Diversity that arises within a species stays in the species (or its descendents) B. Differences that exist among species accumulate after speciation III. There are multiple species concepts A. The morphological species concept defines species as morphologically distinct entities 1. Virtues: reflects how we tell species apart 2. Drawbacks: species differences can be cryptic B. The biological species concept defines a species as an interbreeding unit that is reproductively isolated from other units 1. Virtues: directly addresses what keeps species separate. We will cover these reproductive isolating mechanisms in the next section. 2. Drawbacks: a. It doesn’t apply to asexually reproducing organisms b. Populations might be capable of interbreeding but never do; if geographically remote c. It can be difficult to test: how do you know whether they can interbreed? d.
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This note was uploaded on 11/29/2011 for the course BIOLOGY BIO 187 taught by Professor Capco during the Spring '11 term at ASU.

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Macroevolution-2.4 - Lecture outline: Macro-Evolution I....

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