Hybrid history

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Science  16 Nov 2018:
Vol. 362, Issue 6416, pp. 789-790
DOI: 10.1126/science.362.6416.789-c

The American crocodile (shown here) has been hybridizing with the Morelet's crocodile for millions of years.


Hybridization between species has long presented a problem for the identification of biological species boundaries and, more recently, for establishing conservation priorities. Although the strict biological definition of a species states that it is reproductively isolated, many clearly defined species regularly hybridize, to the point that new species may emerge. Despite this, classifying hybrids and identifying their conservation status has been problematic. Pacheco-Sierra et al. attempted to address this challenge in the case of two species of crocodile (American and Morelet's), which have been hybridizing for millions of years. Although more “pure” populations of each species exist, there is considerable hybridization throughout their range of overlap. Hence, conservation focus on only the nonhybridized populations would exclude a range of natural, and presumably adaptive, hybrids and millions of years of diversity.

Front. Ecol. Evol. 6, 138 (2018).

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