Landels-Hill Big Creek Reserve

22 May, 05 AM - 23 May, 05 AM

In recent years, two factors have come to the fore as central issues for furthering our understanding of speciation. First, recognition of the incidental but important contributions of ecological population divergence to reproductive isolation has generated great interest in ?ecological speciation?. Second, the historically controversial notion of ?reinforcement? ? natural selection against low fitness hybrids that results in increased mating discrimination ? has received intriguing support. This support especially derives from comparisons of premating isolation in sympatric/parapatric populations (i.e., those in geographic contact) versus geographically separated (allopatric) populations. To date, studies of these factors have generally treated one or perhaps a few pairs of populations. Such case studies are informative but capture only a single point in the temporally and evolutionarily extended process of speciation. Because no single population comparison can provide a complete picture of the speciation process, a detailed understanding of the factors that initiate, promote, and complete speciation requires the evaluation of the entire ?speciation continuum?. Notably, the evolution of reproductive isolation is expected to continue even after speciation is complete, as ongoing genetic divergence promotes continuing increase in the strength of various reproductive barriers. Thus, the speciation continuum can thought of as extending beyond the species boundary itself. By evaluating dozens of population pairs exhibiting diverse degrees of evolutionary divergence ? from barely differentiated populations through full biological species ? this project provides a rare and uniquely integrated study of the contributions of ecology and geography to speciation, while allowing the evolution of reproductive isolation among populations on both sides of the speciation boundary to be compared. Specifically, it will evaluate pairs of natural populations from at least eight species of host-plant-associated Timema stick insects. These population pairs exhibit a wide range of genetic distance, ecological divergence, geographic relationships, and reproductive isolation. Data from these populations will be analyzed within a single framework, via a comparative approach that has recently been developed by the PI. This approach allows the contributions of ecology and of geography (reinforcement) to speciation to be statistically isolated and quantified. It will further allow the macroevolutionary generality of these contributions to be evaluated across the Timema adaptive radiation. This project will thereby provide a particularly thorough experimental investigation of whether and how ecology and reinforcement drive the entire, complex, speciation process.

Visit #18111 @Landels-Hill Big Creek Reserve

Approved

Under Project # 9669 | Research

Host adaptation and speciation in Timema walking-stick insects

graduate_student - University of California, Santa Barbara

Reservation Members(s)

Daniel Duran May 22 - 23, 2009 (2 days)

Reserve Resources(s) | Create Invoice

Highlands Camp 1 May 22 - 23, 2009