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by 123 chapter 24 - CHAPTER 24: The Origin of Species...

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CHAPTER 24: The Origin of Species Microevolution - changes over time in allele frequencies in a population Macroevolution - the broad pattern of evolution over long time spans Species - a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring—but do not produce viable, fertile offpsirng with members of other such groups Reproductive isolation - the existence of biological factors (barriers) that impede members of two species from producing viable, fertile offspring Hybrids - offspring that result from interspecific mating Prezygotic barriers - barriers that impede mating or hinder fertilization if mating does occur o Habitat isolation - two species that occupy different habitats within the same area may encounter each other rarely, if at all, even though they are not isolated by physical barriers such as mountain ranges o Temporal isolation - species that breed during different times of the day, different seasons, or different years cannot mix their gametes o Behavioral isolation - courtship rituals that attract mates and other behaviors unique to a species are effective reproductive barriers, even between closely related species. Such behavioral rituals enable mate recognition—a way to identify potential mates of the same species o Mechanical isolation - mating is attempted, but morphological differences prevent its successful completion o Genetic isolation - sperm of one species may not be able to fertilize the eggs of another species. For instance, sperm may not be able to survive in the reproductive tract of females of the other species, or biochemical mechanisms may prevent the sperm from penetrating the membrane surrounding the other species’ eggs. Postzygotic
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by 123 chapter 24 - CHAPTER 24: The Origin of Species...

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