Jordan P Sinclair, MA, PhD
Sexual Dimorphism, Sex Ratios, and Differential Resource Allocation
Flower size and number, plant size, photosynthetic ability, and nutrient use are a few examples of sexual dimorphisms that have been observed in dioecious plants. How and why the sexes differ can lend insights regarding the evolution of separate sexed individuals. I have previously studied leaf size in the tropical understory tree, Ocetea tenera, and competition in the desert shrub Atriplex bonnevillensis. I also have ongoing work, in collaboration with Gaku Kudo, examining sexual dimorphisms in the summer deciduous shrub Daphne kamtchatica in the forests of Northern Japan.
Biased sex ratios are often seen in dioecious populations and there is little evidence regarding the mechanisms in most species. I have applied sex ratio theory to plant populations and analyzed trends seen in nature with a focus on the importance of pollen and seed dispersal, and life form. I believe there is much more to be done in this area and look forward to revisiting it.
Pollination and Dispersal Ecology
Dispersal ecology is an intricate part of reproduction in plants. Dispersal patterns influence mate choice and seedling success. Pollination ecology describes seed set ratios, self-(in)compatibility rates, and inbreeding depression effects. Through pollen manipulation experiments in the field, genetic analysis using microsatellite markers, and spatial analysis of pollen and seed dispersal events, we can examine the drivers of the evolution of plant mating systems.
The Evolution of Dioecy in Plants
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Why should plants evolve separate sexed individuals? What are the mechanisms behind this evolution? Why is dioecy so rare in Angiosperms, yet has evolved independently in over 100 families? These questions and more have been asked for decades (some for centuries!) and despite enormous effort and attention, much remains unknown. As part of my Ph.D. I developed a computer simulation for the evolution of dioecy which tracks unisexual invasion in a hermaphrodite population. The model is highly dynamic; attempts to simulate natural ecological conditions was a primary focus. The influence of related matings (not just selfing versus outcrossing) was also accounted for. I am currently working on the incorporation of site quality into the simulation, as well as obtaining pollen and seed dispersal data for a variety of species.