48.1 Saturday, Jan. 5 Physiological mechanisms of pleiotropy revealed by the accelerating effect of temperature HOEKSTRA, LA*; SIDDIQ, M; MONTOOTH, KL; Indiana University email@example.com
Organisms respond to environmental change with coordinated changes in metabolic processes. Plasticity in metabolic performance can create a dynamic context for the effects of mutations, particularly for mutations affecting energy use. Here we use Drosophila melanogaster nuclear genomes paired with divergent Drosophila mitochondrial genomes to explore the effects of mitochondrial-nuclear genetic variation across different thermal environments. Previously, an incompatibility between a particular D. melanogaster nuclear genome and D. simulans mitochondrial genome was identified that significantly impacts several life history traits when reared under normal laboratory conditions. Mapping the causal mutations revealed that this incompatibility compromises mitochondrial protein translation and oxidative phosphorylation activity. Here we demonstrate that the phenotypic effects of this mitochondrial-nuclear incompatibility are conditional on environmental temperature. Development time and pupation height, both traits associated with energy state, are adversely affected by interactions between mitochondrial-nuclear genotype and increasing developmental temperature. Using flow-through respirometry to measure larval metabolic rate, we find that mitochondrial-nuclear genotype significantly affects the ability of larvae to match their metabolic rate to their thermal environment. Overall we find that the deleterious effects of mitochondrial-nuclear incompatibility increase with temperature, but also that developmental plasticity provides some homeostasis for metabolic rate. Together these results demonstrate thermodynamic constraint on performance via energy limitation, such that inefficiencies in metabolic processes are revealed when temperature accelerates the rate of life.