Meeting Abstract

67.1  Sunday, Jan. 6  Genotype-dependent temperature physiology of larvae: Implications for range expansion CUROLE, J.P.*; BERGER, M.S.; MANAHAN, D.T.; University of Southern California; University of Southern California; University of Southern California jcurole@usc.edu

Shifts in the timing of life histories and species' range over the last several decades are well documented. These shifts are expected to continue as global mean temperature increases in the coming decades. There is a need to understand better the relationship of genotype and environment to phenotype in terms of predicting responses by larval forms to environmental change. Specifically, we studied the effect of larval genotype on physiological responses to temperature change. Different families of larvae were produced by controlled crosses of genetically defined lines of the oyster Crassostrea gigas. Growth and respiration rates were measured for reciprocal hybrid and inbred families of larvae reared at 15, 20, and 25°C. Consistent with previous findings, both hybrid families grew faster than inbred families at all temperatures. For the temperature interval of 20-25°C, the Q₁₀ values for growth ranged from 2.1-2.6. In contrast, growth at 15°C was 46-60% slower than predicted from these Q₁₀ estimates. Q₁₀ values for the 15-20°C interval were all higher, ranging from 7.3 to 12.0. Respiratory Q₁₀ values were 2.9-4.8 for the 20-25°C interval; however, family-specific respiration rates were similar between 15 and 20°C. A striking feature of these data is the major genotype-dependent 3-6 fold increase in Q₁₀ growth values at different temperatures. The future use of controlled genetic crosses to produce different phenotypes will enhance understanding of the molecular physiological mechanisms of temperature-dependent growth differences. This, in turn, could provide a predictive basis for identifying thermally-tolerant genotypes that may be at the front end of larval dispersal, range expansion and changing phenologies