Physiological responses to environmental variability in Mytilus mussels.

摘要

This research addresses the relationship between environmental conditions, ecological patterns, and physiological stress characteristics in two eastern Pacific mussel congeners, Mytilus galloprovincialis and Mytilus trossulus. While M. trossulus is native to the region, M. galloprovincialis is an invasive species introduced to the eastern Pacific nearly a century ago. The two species overlap in range and compete for resources in central California, but species abundances are largely segregated across habitats and latitude. It is thought that differential environmental tolerances may play a significant role in setting the distributions of these species.;Using a combination of field surveys and molecular laboratory analyses, this research correlated environmental conditions with physiological functioning to identify how evolved tolerances map on to ecological patterns. Results support the hypothesis that M. galloprovincialis and M. trossulus differ in their environmental tolerances. The native species exhibited more cool-adapted and euryhaline traits, while the invader suggested a more stenohaline and warm-adapted physiology. These differences were observed in stress response profiles across seasons, habitats, and laboratory acclimations. In Bodega Bay, CA, field surveys also showed the two species to segregate across littoral zones, a pattern which had not previously been reported and has significant implications for future monitoring of these species.;An analysis of field condition across latitude was also undertaken using M. galloprovincialis, intended to measure the extent and nature of acclimatization patterns across large spatial scales. The study found M. galloprovincialis to vary in standing stocks of stress proteins across sites, correlated with relative water temperatures in each region. The relationship between constitutive stress proteins and the inducible "heat shock" response was also explored and results suggested that constitutive proteins may provide a protective role in high-stress environments.;These studies collectively help to characterize the physiological traits that may underlie many of the distribution patterns observed between M. galloprovincialis and M. trossulus. By considering questions of ecology and individual functioning within the context of one another, these types of macro-physiological studies may inform our understanding of the M. galloprovincialis invasion, and perhaps also address larger ecological questions such as species ranges, competition, and responses of organisms to climate change.