Landels-Hill Big Creek Reserve

18 Apr, 08 AM - 20 Apr, 04 AM

Evolution of Parthenogenesis and Maintenance of Sexual Reproduction Project Background: The maintenance of sexual reproduction has puzzled biologists for over a century. The production of sons by sexual females creates a two-fold cost of sex that should culminate in its rapid elimination. The predominance of sexual reproduction in spite of this ??cost of males?? means that sex must confer major advantages that have yet to be fully understood. We investigate the processes underlying the evolution of parthenogenesis and the maintenance of sex in insects, especially Timema stick insects. These groups are characterized by many independent transitions to parthenogenesis including both recent and very old ones. We are currently examining the possibility for asexual lineages to revert back to sexual reproduction. The potential for reversals to sexuality depend on the rate at which traits specific to sexual reproduction would regress in asexuals. Many traits involved in sexual reproduction are expected to become useless or even maladaptive in asexually reproducing species. For example, pheromones used for mate-attraction in sexual species lose their utility in asexuals; they may even become maladaptive if also used by predators to locate their prey. Thus, such non-functional, yet expressed traits can be selected against and degenerate over evolutionary time whereby the rate of trait vestigialization should depend on whether the traits are neutral or under negative selection. Proposed Project: We are testing whether asexual Timema stick insects display regression of sexual-reproduction traits, and whether the level of trait regression depends on the age of the asexual lineage (i.e., how long ago the transition from sexual to asexual reproduction occurred). Sexual Timema use a combination of pheromones and cuticular hydrocarbons as cues to identify suitable mates. We will test whether asexual species still emit pheromones that are attractive to males of the sexual species, whether sexual males persist in mating with asexual females and whether asexual species display a shift in hydrocarbon profiles relative to their sexual sister species. Two sexual Timema species occur in the Big Creek reserve (Timema knulli and T. landelsensis). We will use males of these two species to test for their attraction to females of the two asexual species T. shepardi and T. douglasi. Approximately 30 males of each sexual species will be captured by shaking host plant branches into a sweep net. These males will be used for behavioural assays (tests of their attraction to asexual females in a Y-maize and measurements of their copulation propensity with asexual females). Ten males of each sexual species will be preserved for subsequent analysis of hydrocarbon profiles; the remaining individuals will be released on the spot where they were collected. Note: This project is a continuation of a project initiated a few years ago when I was a postdoctoral fellow at Simon Fraser University in British Columbia (and when I first visited the Big Creed reserve). I have since then moved to a new position in the Netherlands, which is why my affiliation has changed between my current and previous applications.

Visit #28211 @Landels-Hill Big Creek Reserve

Approved

Under Project # 8334 | Research

Evolution of parthenogenetic lineage in Timema stick insects

research_scientist - University of Groningen

Reservation Members(s)

Tanja Schwander Apr 18 - 20, 2012 (3 days)
Tanja Schwander Apr 18 - 20, 2012 (3 days)

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