1 August 2009 Comparative Approaches to the Evolution of Reproductive Isolation: A Comment on
James M. Sobel, April M. Randle
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Speciation can be driven by the evolution of many forms of reproductive isolation. Comparative study is a powerful approach for elucidating the relative importance of individual isolating barriers in the speciation process. A recent contribution by Scopece and colleagues provides comparative data for two groups of deceptive pollination orchids and aims to test hypotheses about which forms of isolation are most important in the two clades. The authors compare pollinator isolation and postmating isolation between the two orchid groups, and conclude that food-deceptive orchid species have less isolation by pollinator specificity than sexually deceptive species, and that postmating isolation is more important in the food-deceptive clade. Although we find this approach to be novel and potentially powerful, these conclusions are called into question by the methods used to define and select species and quantify pollinator isolation. Definition and selection of taxa were performed in a biased manner that undermines the ability to infer general patterns of speciation. Furthermore, pollinator isolation was calculated inconsistently for the two groups under study, effectively nullifying the comparison.

© 2009 The Society for the Study of Evolution.
James M. Sobel and April M. Randle "Comparative Approaches to the Evolution of Reproductive Isolation: A Comment on ," Evolution 63(8), 2201-2204, (1 August 2009). https://doi.org/10.1111/j.1558-5646.2009.00691.x
Received: 17 March 2008; Accepted: 1 November 2008; Published: 1 August 2009

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pollinator isolation
postmating barriers
premating barriers
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