Ch 26 notes - Ch 26- Speciation Speciation- a splitting...

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Ch 26- Speciation Speciation - a splitting event that creates two or more distinct species from a single ancestral group Mutation, selection, and drift begin to act on the populations independently if gene flow between population stops. If new mutation creates an allele that changes the phenotype of individuals in one population, there is no longer any way for the allele to appear in the other population. Therefore, allele frequencies and other characteristics on the populations diverge and over time populations become distinct species. Species - an evolutionarily independent population or group of populations (1) The biological species concept— reproduction isolation from other groups - prezygotic isolation -prevents individuals of different species from mating - postzygotic isolation -offspring of matings between members of different species do not survive or reproduce Disadvantage : No applicable to asexual or fossil species; difficult to assess if populations do not overlap geographically (2) The morphospecies concept —identify independent lineages by differences in size, shape, or other morphological features (likely arise if population are independent and
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This note was uploaded on 10/25/2009 for the course LIFESCI Life scien taught by Professor Lorenz,t.c. during the Fall '09 term at UCLA.

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Ch 26 notes - Ch 26- Speciation Speciation- a splitting...

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