Meeting Abstract
103.4 Sunday, Jan. 6 The evolution of cellular generalization and specialization in natural populations of Drosophila melanogaster COOPER, B.S.*; HAMMAD, L.A.; MONTOOTH, K.L.; Indiana University; Indiana University; Indiana University brascoop@indiana.edu
Changes in the environment can profoundly impact the fluidity of cell membranes. For small insects like Drosophila melanogaster, both changes in temperature and amounts of environmental ethanol perturb membrane fluidity. When environments vary greatly, alleles that enable cellular generalization should be favored by selection. Antagonistic pleiotropy and mutation accumulation, however, can create negative genetic correlations in fitness across environments leading to decreased performance of generalist relative to specialist genotypes. Our previous work has shown that an increased degree of cellular plasticity evolves in an experimentally variable environment, consistent with the selective advantage of an environmentally sensitive allele with associated costs in constant environments. This evolution of increased cellular plasticity enables specialization within generations in environments that vary among generations. Here, we extend this work to natural populations by evaluating the evolution of cellular generalization and specialization in populations of D. melanogaster from Vermont, Indiana, and North Carolina. We use two measures of the lipid composition of cell membranes as indices of physiological plasticity (a.k.a. acclimation) to evaluate the evolution of cellular generalization: (1) change in the ratio of phosphatidylethanolamine (PE) to phosphatidylcholine (PC) and (2) change in lipid saturation in cool (16ºC) relative to warm (26ºC) developmental conditions. We then evaluate the composition of cell membranes within each developmental environment to identify the evolution of cellular specialization in environments that differ in mean temperature. Our results shed light on the mechanisms underlying the evolution of generalization and specialization in environments that differ in mean and variance of temperature.
