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The evolution of postpollination reproductive isolation in Costus.
1Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA. yost@biology.ucsc.edu
Sexual Plant Reproduction
|December 25, 2009
Summary
Postpollination barriers in plants, like style length and pollen performance, are key to species diversification. Studies in the Costus genus show these barriers evolve through natural selection, particularly reinforcement, to prevent gene flow between species.
Area of Science:
- Plant reproductive biology
- Evolutionary biology
- Speciation mechanisms
Background:
- Reproductive isolation is crucial for species diversification.
- Postpollination barriers are significant but understudied mechanisms limiting gene flow.
- Understanding the evolution of these barriers provides insight into speciation.
Purpose of the Study:
- To review the role and evolution of postpollination reproductive isolation in plants.
- To evaluate empirical evidence from the plant genus Costus regarding postpollination barriers.
- To test hypotheses on the evolution of reproductive isolation, including by-product and reinforcement.
Main Methods:
- Literature review of postpollination isolation mechanisms and hypotheses.
- Analysis of empirical studies within the Costus genus.
- Examination of barriers related to style length, pollen adhesion, germination, and tube growth.
Main Results:
- Style length differences contribute to reproductive isolation and may be a byproduct of floral morphology selection.
- Reduced pollen adhesion, germination, and tube growth create barriers between sympatric Costus species.
- Geographic variation in barrier strength supports the reinforcement hypothesis.
Conclusions:
- Postpollination barriers play a significant role in plant speciation.
- Evidence in Costus supports both byproduct and reinforcement mechanisms in the evolution of reproductive isolation.
- Further research into cryptic postpollination barriers is warranted.
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