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Science  25 Jul 2003:
Vol. 301, Issue 5632, pp. 438
DOI: 10.1126/science.301.5632.438c

When humans disturb habitats, the range and distribution of plants can be altered, creating opportunities for hybridization between species heretofore isolated in place or time. Banksia hookeriana and B. prionotes are sister species living in the Australian sandplains and are pollinated by nectar-feeding birds. Under natural conditions they do not cross-fertilize because their flowering seasons do not coincide.

Lamont et al. have discovered that, owing to the greater availability of resources in disturbed vegetation, their flowering seasons expand and overlap; this gives rise to opportunities for cross-pollination. Hybrids between the two species were found in 10% of the disturbed sites investigated, but in none of the undisturbed sites. The hybrids are fully fertile and may prove to have a different range of environmental tolerances than their parent species. Because the disturbances are relatively recent, the aftermath for the genetics and evolution of these species is still uncertain. Nevertheless, this study points to a potentially new consequence of human activity for the biology of species. — AMS

J. Evol. Biol. 16, 551 (2003).

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