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8 Cards in this Set
- Front
- Back
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Species
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are a fundamental evolutionary unit
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Two individuals are members of the same species if:
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they can exchange genetic material and
produce fertile offspring |
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Morphospecies Concept
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states that members of the same species usually look alike
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Biological Species Concept
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Must test if two species can mate and produce fertile offspring – many limitations
Does not apply to asexual organisms (bacteria), extinct species (fossils) Does not account for genetic exchange in ring species Does not account for hybridization in plants |
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Ecological species concept (ESC)
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suggests that a species can sometimes be characterized by its ecological niche
Niche = the role the species plays in its environment (it’s habitat requirements, nutritional needs, water needs, etc.) |
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Evolutionary species concept (EvSC)
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is the idea that members of a species all share a common ancestry and fate
It requires that all members of a species are descended from a single common ancestor that lived 200 million years ago There are thousands of species of mammals since the common ancestor so long ago, so under this concept, all mammals would be a single species This concept is useful when thinking about asexual species, but beyond that, it is limited |
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Reproductive Isolation
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A condition of the BSC is that the populations must be reproductively isolated in order to be considered separate species.
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Two categories of factors that cause reproductive isolation:
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Pre-zygotic factors (before fertilization)
Behavioral - courtship rituals, songs Physical - incompatible reproductive organs Temporal (time) – different activity times/flowering times Ecological (space) – geographical separation Post-zygotic factors (after fertilization) Genetic incompatibility |
