Ecological genetics of complex traits: Gene number, environmental-dependence and organismal scale.
Callahan, Hilary*,1, 1 Barnard College, New York, NY
ABSTRACT- In our "post-genomic" age, ecological and other geneticists continue to struggle with mapping relationships between genotypes and phenotypes. When multiple genes rather than a single, Mendelian locus contribute to variation in a phenotypic trait, the mapping of that trait is classically termed quantitative, polygenic or "complex." Using examples from the Arabidopsis thaliana literature, I will discuss sophisticated statistical techniques that can "Mendelize" polygenic traits, including some of the techniques' limitations and whether these limitations reflect scaling issues. In addition, both "simple" and "complex" genotype-phenotype maps are affected by several scaling issues that make them inherently complex in the ecological sense emphasized by this symposium. I will focus on one such issue: phenotypic plasticity. A trait is plastic if an identical genotype produces different phenotype in response to environmental variation, and a trait's phenotypic plasticity influences selection's impact on the trait's mean and variance. Simultaneously, a trait's plasticity itself has a genetic basis and may evolve, depending on the grain and extent of spatiotemporal variables. Surprisingly, information about the grain and extent of environmental variation is seldom available, even though meaningful scales for gathering this information are readily evident (i.e., organismal lifespan, organismal size at various points in the life cycle, dispersal distances of progeny, timing of reproduction, etc.) Using examples from Arabidopsis thaliana and several non-model species, I discuss how careful attention to scaling is essential for designing and interpreting studies of complex, plastic traits.
Key words: quantitative genetics, phenotypic plasticity, environmental heterogeneity, natural selection
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