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What is the most important factor that holds a gene pool of a species together and prevents speciation? |
Gene flow – Gene flow refers to the transfer of alleles among populations. As long as populations are exchanging alleles, speciation is unlikely. |
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Two animals are considered members of different species if they _____. |
cannot mate and produce viable, fertile offspring. – If two individuals cannot interbreed and produce viable, fertile offspring, they are members of different species. |
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According to the phylogenetic species concept, what is a species? |
a set of organisms with a unique genetic history |
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Which of the following is the first step in allopatric speciation? |
geographic isololation – Allopatric speciation occurs when a population of organisms is geographically separated long enough for significant changes to occur. After a period of time, the populations may no longer be able to interbreed. |
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Which of these is an example of temporal isolation? |
One species is nocturnal, and the other species is not. – In temporal isolation, two species that breed during different times of the day cannot mix their gametes. |
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Sympatric speciation is _____. |
the appearance of a new species in the same area as the parent population – It is due to a radical change in the genome. |
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Hybrid zones provide an opportunity to investigate _____. |
the evolution of reproductive isolation – A hybrid zone allows researchers to see what happens when closely related species come together. Reproductive barriers may be strengthened or weakened, depending on environmental and genetic factors. |
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A certain species of salamander was split into two populations by a wide, dry valley, and the populations began to diverge from each other. After a period of time, some members of the two populations began to interbreed in a hybrid zone at the southern end of the valley. Only weak reproductive barriers existed by this time, so the two populations could freely interbreed and re-establish gene flow. This outcome in a hybrid zone is known as _____. |
– fusion Fusion refers to the weakening of reproductive barriers, allowing the two populations to fuse and remain (or become) one species. |
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According to the _____ model, evolution occurs in spurts; species evolve relatively rapidly then remain unchanged for long periods. |
punctuated equilibrium – This is the definition of punctuated equilibrium. |
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Which of the following has been shown to cause speciation most rapidly? |
autopolyploidy – Autopolyploidy has been shown to produce nearly instantaneous speciation in plants. |
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