Abstract Detail



Ecological factors that drive patterns of population genetic structure in plants

Gamba, Diana [1], Muchhala, Nathan [2].

Out of synch: Seasonal asynchrony drives genetic differentiation in tropical plants.

High diversity in the tropics is thought to be due, at least in part, to faster formation of new species through time, but the reasons for this remain obscure. One compelling recent idea, termed the ‘asynchrony of seasons’ hypothesis, has only received a single test to date. Central to this hypothesis is the observation that seasons in the tropics are primarily determined not by temperature but by rainfall patterns, which can vary greatly from site to site. Since most species mate in a limited portion of the year, and mating is often timed to seasons, this implies that reproductive cycles in the tropics may be out of synch across relatively short distances. This, in turn, will limit movement of genes among subpopulations, leading to greater genetic differentiation and faster speciation. To test this hypothesis, we selected two study sites in northern Ecuador with very different rainy seasons, and focused on 12 plant species that occur in both sites. We documented their flowering patterns through bimonthly tracking for one year, and then collected leaf tissue to analyze genetic differences between the sites (subpopulations) for each species using high-throughput sequencing (2b Rad-Seq).  We found a range of phenological synchrony across the species (from complete overlap to asynchrony), and a significant correlation between the amount of overlap and G’ST values: species with greater asynchrony in flowering times had greater genetic differences between sites. This supports the asynchrony of seasons hypothesis, demonstrating that the mosaic of different seasonality across relatively short distances can lead to phenological shifts and greater genetic subdivision within angiosperm species. Such subdivision, in turn, may ultimately increase speciation rates, and thus contribute to the incredible diversity of life found in the tropics.


1 - University Of Missouri - St. Louis, Biology, 223R Research Hall, Biology Department, One University Blvd, St. Louis, MO, 63121, United States
2 - University Of Missouri - St. Louis, Biology Dept., R428 Research Hall, One University Blvd, St. Louis, MO, 63121, United States

Keywords:
Pollination
flowering phenology
tropics
genetic structure
RAD-seq
speciation.

Presentation Type: Colloquium Presentations
Number: 0005
Abstract ID:608
Candidate for Awards:None


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