Abstract Detail

Reproductive Processes

Yomai, Viann Marie [1], Williams, Joseph [2].

Self-compatible plants on Pohnpei self-pollinate more than their outcrossing mainland relatives.

Plant communities on isolated, oceanic islands are expected to be dominated by species that are hermaphroditic, self-compatible, and that have the capacity for autonomous self-pollination. If so, it seems likely that such species are descended from species in mainland source communities that already had the capacity for self-fertilization. Alternatively, shifts in breeding systems may occur after dispersal, during the establishment phase. In this study, we sought to determine the degree to which island species have diverged from their mainland conspecific or nearest-relatives in their breeding and sexual systems. We performed hand-pollinations on 36 flowering plant species on Pohnpei, Federated States of Micronesia to characterize sexual systems and the degree of self-compatibility, autonomous self-fertilization, and outcross/geitonogamous pollen limitation. We then made comparisons to their nearest continental mainland phylogenetic relatives taken from the literature. All 36 Pohnpeian species and all but three of their mainland relatives were self-compatible. All Pohnpeian species were characterized as hermaphroditic, whereas all mainland counterparts had bisexual or rarely, some combination of bi- and/or uni-sexual, flowers on the same plant. Phylogenetic least squares analyses found that the self-compatibility index (SCI-F, based on fruit set) and autofertility index (AFI-S, based on seed set) were 27% (P = 0.0015) and 42% (P < 0.0001) higher in Pohnpeian than mainland species, respectively (N = 33 pairs). A Wilcoxon signed-rank test found that inferred breeding systems on Pohnpei were significantly more autogamous than their mainland counterparts (P = 0.0251; N = 33 pairs). Most Pohnpeian species also displayed high pollen limitation indices. These results suggest that present-day Pohnpei island plant species are most often descended from mixed mating to outcrossing mainland species that are self-compatible and have bisexual flowers. We conclude that successful colonists of this remote oceanic island arrive with the capacity to self-pollinate and subsequently evolve higher levels of self-compatibility and autonomous selfing rates during establishment.

1 - Iowa State University, Ecology, Evolution, and Organismal Biology, 237 Bessey, Ames, Iowa, 50011
2 - University of Tennessee, Knoxville, Ecology and Evolutionary Biology, 1416 Circle Drive, Knoxville, TN, 37996, USA

breeding system
Sexual system

Presentation Type: Oral Paper
Number: RP1004
Abstract ID:557
Candidate for Awards:None

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