Abstract Detail

Sexual selection in flowering plants: traits, processes, and estimation

Williams, Joseph [1].

Pollen competition in a comparative context.

With the origin of pollination in ancient seed plants, the male gametophyte (“pollen”) began to evolve a new and unique life history stage, the progamic phase, a postpollination period in which pollen sexual maturation occurs in interaction with sporophyte-derived tissues. Pollen performance traits, such as the speed of pollen germination, sperm development, and pollen tube growth, mediate the timing of the fertilization process, and often evolve under competition from other pollen genotypes. Studies of pollen development rarely address the issue of performance evolution, which involves linking variation in developmental rates to relative fitness within populations or to adaptations on a macroevolutionary scale. Changes in floral biology that affect fertilization timing and changes in the intensity of pollen competition affect the direction and strength of selection on pollen performance. Hence, pollen developmental evolution is always contextual—it involves both the population biology of pollen reaching stigmas and the co-evolution of sporophytic traits, such as pollen tube pathway structure and physiology or the mating system. For most species, performance evolution generally reflects a wandering history of periods of directional selection and relaxed selection, channeled by developmental limitations, a pattern that favors the accumulation of diversity and redundancy in developmental mechanisms and the underlying genetic machinery. Developmental biologists have been focused on finding universal mechanisms that underlie pollen function, but these are largely mechanisms that have evolved through their effects on performance. Comparative studies provide the historical framework needed to interpret developmental evolution of pollen performance traits. They also provide insight into evolutionary mechanisms, but disentangling the roles of natural and sexual selection on performance is complicated by the fact that both predict similar historical patterns.

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Information about Williams lab

1 - University Of Tennessee, Ecology And Evolutionary Biology, 1406 Circle Drive, Hesler 341, Knoxville, TN, 37996, United States

Keywords:
Pollen germination
pollen
Pollen tube growth rate
Pollen competition
Evolution of development
Gametophyte biology
macroevolution
reproductive biology.

Presentation Type: Colloquium Presentations
Session: CO08, Sexual Selection in Flowering Plants: Traits, Processes, and Estimation
Location: Tucson H/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 1:45 PM
Number: CO08002
Abstract ID:663
Candidate for Awards:None