Do post-pollination processes contribute to assortative mating among species?
Do post-pollination processes contribute to assortative mating among species?
Michael Wunsch's research focuses on this question.
In experimental sympatry plots that Anthony Ippolito set up in situ in Brazil, hummingbirds almost always visited N.forgetiana, and hawkmoths preferred N. alata. Hawkmoths' preferences weren't absolute; they visited N. forgetiana ~16.5% of their total visits. We then grew the progeny from these plots and counted the hybrids that were produced. Hybrids were fewer in number than we would have expected based on the rate of interspecific movements by hawkmoths and 97% of hybrids had an N. forgetiana plant as their maternal parent. Both of these observations suggest post-pollination processes were operating.
Micahel used three appraoches to investigate these phenomena. First, he pollinated plants of both species with pollen from con- and hetero-specific sources. He then scored the % fruit set and seed set. In a second set of similar crosses, he fixed styles at three successive times post-pollination and measured pollen tubes. Third, he pollinated plants of each species with a 50/50 mixture of pollen and then grew the resulting progeny to see how many of them were hybrids. These data are being written up for AJB but we present some highlights below.
