LIFESCI 1 Chapter Notes - Chapter 22: Adaptive Radiation, Ring Species, Natural Selection
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22. 1 reproductive isolation is the key to the biological species concept. The biological species concept (bsc) states that species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups. page 446. We cannot apply the bsc to asexual or extinct organisms. page 447. Ring species and hybridization further demonstrate that the bsc is not a comprehensive definition of species. page 448. The bsc is nevertheless especially useful because it emphasizes reproductive isolation. page 449. 22. 2 reproductive isolation is caused by barriers to reproduction before or after egg fertilization. Reproductive barriers can be pre-zygotic, occurring before egg fertilization, or post-zygotic, occurring after egg fertilization. page 449. Pre-zygotic isolation may be behavioral, gametic, temporal, or ecological. page 450. In post-zygotic isolation, mating occurs but genetic incompatibilities prevent the development of a viable, fertile offspring. page 450. 22. 3 speciation underlies the diversity of life on earth.
