Heteropatric speciation

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Heteropatric and heteropatry are terms from biogeography, referring to organisms whose geographical ranges overlap or are even identical, so that they occur together at least in some places, but which occupy ecological niches distinct enough to prevent frequent hybridization. Such organisms are usually closely related (e.g. sister species), their distribution and ecology being the result of heteropatric speciation.

Heteropatric speciation is a special case of sympatric speciation that occurs when different ecotypes or races of the same species geographically coexist but exploit different niches in the same patchy or heterogeneous environment. Thus heteropatric speciation is a refinement of our notion of sympatric speciation in that it represents a behavioral rather than geographic barrier to the flow of genes among diverging groups within a population. The importance of behavioral separation as a mechanism for promoting sympatric speciation in a heterogeneous or patchwork landscape is highlighted in John Maynard Smith's seminal paper on sympatric speciation.[1] In recognition of the importance of this behavioral versus geographic distinction, Wayne Getz and Veijo Kaitala introduced the term heteropatry in their extension of Maynard Smiths' analysis[2] of conditions that facilitate sympatric speciation.

Although some evolutionary biologists still regard sympatric speciation as a highly contentious issue, both theoretical[3] and empirical[4] studies increasingly support sympatric speciation as a likely process in explaining the diversity of life in particular ecosystems. Arguments either implicitly or explicitly implicate competition and niche separation of sympatrically co-occurring ecological variants that through assortative mating ultimately evolve into separate races and then species. Assortative mating most easily occurs if mating is linked to niche preference, as occurs in the apple maggot Rhagoletis pomonella where individual flies from different races use volatile odors to discriminate between hawthorn and apple and look for mates on natal fruit.

In essence, the term heteropatry semantically resolves the issue of sympatric speciation by reducing it to a scaling issue in terms of the way the landscape is used by individuals versus populations. Specifically, from a population perspective, the process looks sympatric, but from an individual’s perspective, the process looks allopatric, once the time spent flying over or moving quickly through intervening non-preferred niches is taken into account.

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References[edit]

  1. ^ J. Maynard Smith, 1966. Sympatric speciation. The American Naturalist 110:637-650.
  2. ^ W. M. Getz and V. Kaitala, 1989. Ecogenetic models, competition, and heteropatry. Theoretical Population Biology 36:34-58.
  3. ^ D. I. Bolnick, 2006. Multispecies outcomes in a common model of sympatric speciation. Journal of Theoretical Biology 241:734-744.
  4. ^ A. A. Forbes, J. Fisher and J. L. Feder, 2005. Habitat avoidance: overlooking an important aspect of host-specific mating and sympatric speciation. Evolution 59:1552-1559.