Conserved Ecological Niches

Abstract

In their report “Conservatism of ecological niches in evolutionary time” (20 Aug., p. [1265][1]), A. T. Peterson et al. demonstrate that geographically isolated sister taxa show little differentiation in ecological niche. Their results imply that ecology diverges slowly in allopatry (the geographic isolation of species), and the authors therefore conclude that speciation most commonly occurs without significant ecological change. However, this conclusion seems to contradict the observation that sympatric sister taxa (species living in the same or overlapping locations) generally do show divergent ecology. Indeed, many sympatric ecological races are so closely related that hybridization still occurs regularly ([1][2]). We suggest two possible explanations for this discrepancy. First, as mentioned in the News of the Week article by Bernice Wuethrich (20 Aug., p. [1190][3]), the analysis considered only four physical factors in defining the niche of each species. Certainly, biotic factors such as feeding strategy, host plant use (in the case of butterflies), mutualisms, and predation are also important in defining the niche of a species. Thus, it may be that the analysis was simply too crude to show ecological divergence over a relatively short time scale. Alternatively, if Peterson et al. are correct and ecological divergence does in fact proceed rather slowly in allopatry, then we need another explanation for the frequent occurrence of sympatric, ecologically divergent sister taxa. Sympatric speciation, when it occurs, is likely to proceed rapidly because disruptive selection plays a direct role in driving divergence ([2][4]). In contrast, models of allopatric speciation do not generally invoke a direct role for natural selection and might thus be expected to proceed more slowly. By showing that allopatric divergence does not lead to rapid ecological change, Peterson et al. may have provided some of the best evidence that sympatric sister species have evolved in situ. 1. [↵][5]1. M. R. Orr, 2. T. B. Smith , Trends Ecol. Evol. 13, 502 (1998). [OpenUrl][6][CrossRef][7][PubMed][8][Web of Science][9] 2. [↵][10]1. U. Dieckmann, 2. M. Doebeli , Nature 400, 354 (1999). [OpenUrl][11][CrossRef][12][GeoRef][13] [1]: /lookup/doi/10.1126/science.285.5431.1265 [2]: #ref-1 [3]: /lookup/doi/10.1126/science.285.5431.1190a [4]: #ref-2 [5]: #xref-ref-1-1 View reference 1 in text [6]: {openurl}?query=rft.jtitle%253DTrends%2Bin%2BEcology%2B%2526%2BEvolution%26rft.stitle%253DTrends%2Bin%2BEcology%2B%2526%2BEvolution%26rft.aulast%253DOrr%26rft.auinit1%253DM.%2BR.%26rft.volume%253D13%26rft.issue%253D12%26rft.spage%253D502%26rft.epage%253D506%26rft.atitle%253DEcology%2Band%2Bspeciation.%26rft_id%253Dinfo%253Adoi%252F10.1016%252FS0169-5347%252898%252901511-0%26rft_id%253Dinfo%253Apmid%252F21238408%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [7]: /lookup/external-ref?access_num=10.1016/S0169-5347(98)01511-0&link_type=DOI [8]: /lookup/external-ref?access_num=21238408&link_type=MED&atom=%2Fsci%2F286%2F5438%2F239.5.atom [9]: /lookup/external-ref?access_num=000077403800010&link_type=ISI [10]: #xref-ref-2-1 View reference 2 in text [11]: {openurl}?query=rft.jtitle%253DNature%253B%2BPhysical%2BScience%2B%2528London%2529%26rft.stitle%253DNature%253B%2BPhysical%2BScience%2B%2528London%2529%26rft.volume%253D400%26rft.issue%253D6742%26rft.spage%253D354%26rft.epage%253D357%26rft.atitle%253DOn%2Bthe%2Borigin%2Bof%2Bspecies%2Bby%2Bsympatric%2Bspeciation%26rft_id%253Dinfo%253Adoi%252F10.1038%252F22521%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [12]: /lookup/external-ref?access_num=10.1038/22521&link_type=DOI [13]: /lookup/external-ref?access_num=1999055575&link_type=GEOREF