MOORE, F. B.-G.; BAGATTO, B.; University of Akron; University of Akron: Evolutioary response to oxygen stress in Zebrafish (Danio rerio): An Experimental Evolution Approach
Measurements of adaptation have traditionally been performed by comparisons between taxa. Inherent in this approach is a confounding of natural selection and other uncontrolled factors. This has led to a criticism of the adaptationist program whereby beneficial traits are assumed to have arisen by natural selection. The fit of an organism to its environment could be either a product of natural selection or the product of such factors as genetic drift, phylogenetic or developmental constraint. One approach for teasing apart these factors is to manipulate history so that replicate lineages see differing selective environments. This experimental evolution approach has occasionally been used to study life history evolution in metazoans and long-term evolutionary dynamics in bacterial systems. Here we use experimental evolution to study the evolution of a broad range of traits in response to hypoxia in a vertebrate. During this ongoing study, zebrafish (Danio rerio) from a common genetic background derived from wild populations are evolving in two environments. One environment is normoxic and the other hypoxic�both with tightly controlled abiotic factors. Multiple replicate lineages are being used to distinguish random from adaptive differentiation. Within each lineage, morphological, physiological and developmental variables are measured within the historical environment and the reciprocal environment. This allows us to determine the evolutionary significance of trait plasticity. Unlike an artificial selection experiment, the populations may respond in a myriad of ways. If we wish to understand the ways in which natural selection molds developmental trajectories, we must allow selection to act in the most efficacious manner. If we want to assert that specific developmental changes are adaptive, then we need to demonstrate that natural selection will act with efficacy on those traits.
