PARENT SESSION
Contributed Oral Session 111: Biodiversity: Genetics and Evolution
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 513 E, Level 5, Palais des congrès de Montréal
Genetic variation in life history traits and its effect on population dynamics of the pea aphid.
van Veen, Frank*,1, Ferrari, Julia1, 1 NERC Centre for Population Biology, Ascot, Berkshire, United Kingdom
ABSTRACT- In most studies of community and population ecology species are assumed to be homogeneous. However, genetic variation in ecologically important traits is widespread in nature. The question is how this genetic variation influences the population dynamics of species within a community. It has previously been shown that genetic variation can significantly alter alga-rotifer dynamics. We are studying genetic variation in life history traits among 10 clonal lineages of the pea aphid with the aim of not only determining its effect on population dynamics, but also to uncover the underlying mechanisms. We have so far found significant variation in resistance to various natural enemies, competitive ability, fecundity and the tendency to produce dispersal morphs. Trade-offs among the traits could provide an explanation for the maintenance of this genetic variation in the population. Interestingly, no clear trade-offs have so far been detected and, if anything, positive correlations appear to be the norm. In order to study the effect of this variation on population dynamics we have performed a field experiment comparing populations consisting of either a single genotype or a mixture of genotypes under late season (high predation) conditions. We found that populations with higher genetic diversity perform significantly better, similar to the familiar biodiversity-ecosystem function grassland experiments. We are now repeating this experiment over an entire season. In addition, a similar experiment is carried in laboratory microcosms with the same genotypes in the absence, and later in the presence, of natural enemies. Results so far indicate that, in the absence of natural enemies, genetic diversity has little or no effect on population size and dynamics, and indeed soon erodes under strong selection for competitive ability. This is a further indication that natural enemies are likely to be a strong driving force in this system.
Key words: biodiversity and ecosystem function, genetic diversity, life history, population dynamics