Presentation Detail

Adaptation

Cooper, Brandon [1], Hammad, Loubna [2], Montooth, Kristi [1].

Cellular adaptation and the maintenance of fitness in temporally variable environments.

In variable environments, selection should favor generalists that maintain fitness across a range of conditions. However, costs of adaptation can create negative genetic correlations in fitness across environments leading to decreased performance of generalist relative to specialist genotypes. We have been using experimental evolution and comparisons of natural populations of Drosophila melanogaster to test the predictions of models of evolution in variable environments. Specifically, we have been evaluating cellular responses to variable and constant thermal environments and the associated fitness consequences. Temperature greatly perturbs the fluidity of cell membranes leading to decreased cellular performance including impacting the production of ATP. Cells respond to this selection pressure by either adapting their membranes to the mean temperature or by evolving increased cellular plasticity, such that the membrane is remodeled when thermal environments shift. Our results show that increased cellular plasticity during development evolves in variable environments, both in the laboratory and in nature consistent with the selective advantage of an environmentally sensitive allele(s) with associated costs in constant environments. Experimentally evolved populations with greater cellular plasticity also have higher fecundity indicating this cellular response increases this component of fitness. However, these populations also have decreased heat tolerance, a trait that was under relaxed selection throughout the period of experimental evolution suggesting a tradeoff exists between components of fitness. Finally, recent data suggest that 1) natural populations that differ in the degree of developmental plasticity do not differ in the degree of adult plasticity, and that 2) developmental responses of the cell covary genetically with adult responses, but different types of adult responses do not covary. These data indicate that other modifiers of the reaction norm may be specific to certain life stages and/or environments.

1 - Indiana University, Biology, 1001 E. 3rd St., Bloomington, IN, 47405, United States
2 - Indiana University, Chemistry, METACyt Biochemical Analysis Center, Bloomington, IN, 47405, United States

Keywords:
Adaptation
Drosophila melanogaster
Experimental Evolution
phenotypic plasticity
thermal adaptation.

Presentation Type: Regular Oral Presentation
Session: 60
Location: Superior B/Cliff Lodge
Date: Sunday, June 23rd, 2013
Time: 9:00 AM
Number: 60003
Abstract ID:384
Candidate for Awards:W.D. Hamilton Award for Outstanding Student Presentation