Dowd Lab @ LMU: Research
Research overviewPeopleTeachingPublications
 
    Ecological and evolutionary physiology of the environmental stress response

We are interested in the interactions among physiology, ecology, behavior, and evolution in coastal marine and estuarine fishes and invertebrates. These animals frequently encounter dramatic spatial and temporal variation in biotic and, especially, abiotic conditions such as dissolved oxygen, temperature, and salinity. These challenges can occur over several time scales (tidal cycle, seasonal, interannual, stochastic) and to varying intensities. Coastal habitats such as estuaries and the intertidal zone are also some of the most likely to be impacted by anthropogenic global change, and both the frequency and severity of environmental stress events are projected to increase. Consequently, extreme events and the capacities of organisms to cope with them (or not!) are likely to play a significant role in driving ecological and evolutionary patterns in these habitats.

We take an integrative approach to organismal function, with the ultimate goal of evaluating the ecological and evolutionary implications of environmental stress physiology. To this end, we examine physiological responses to environmental stress at multiple levels of organization, from molecules to whole organisms, and from both mechanistic and evolutionary perspectives. We combine laboratory and field studies whenever possible. We use proteomics (the study of global protein expression and modification patterns) in concert with traditional biochemical methods (e.g., enzyme activity assays, immunochemistry), organismal physiology (e.g., metabolic rate measurement, osmolyte analyses), and environmental monitoring to more fully characterize the response to environmental stress. When appropriate, we also borrow research techniques from animal behavior, such as long-term acoustic telemetry of animal movements in the wild, to understand how and when physiology and behavior interact in the face of environmental challenges. Recently, we have also been delving into evolutionary models of thermal tolerance in dynamic and changing environments. We are particularly interested in the relative importance of temporal vs. spatial environmental variation.

We anticipate that this work will provide insight into how the functional molecular phenotype (the proteome: a product of the genome, posttranslational modification, and alternative transcript splicing) integrates with other levels of organization, with the individual's history of exposure, and with ecological factors to determine the organismal outcome in the face of environmental stress. Ultimately, we hope to elucidate how this functional phenotype influences the distribution and evolution of organisms both within and among species in the context of a changing world.

 

Our work aims to answer three broad and complementary questions (with examples):

1. What physiological (and/or behavioral) mechanisms allow some species or subpopulations to persist in dynamic, ‘stressful’ habitats, while others exhibit narrow tolerance ranges?

  • Mechanisms of osmoregulation in estuarine leopard sharks: physiological and behavioral tradeoffs
  • Molecular mechanisms of extreme hypoxia and anoxia tolerance in the epaulette shark

2. How do physiological mechanisms (or limitations) contribute to current patterns of differential species success, and what are the implications in the face of global climate change and species invasions?

  • Thermal stress physiology of Mytilus mussel congeners with different thermal optima: targets of oxidative protein damage and behavioral responses to heat stress episodes

3. How do patterns of physiological variability among individuals interact with spatial and temporal patterns of environmental variation to contribute to ecological and evolutionary trajectories?

  • Intra-population variation in both temperature exposure and food availability: relationships to patterns of enzyme activity, function, and regulation in intertidal mussels
  • Inter-individual variation in body temperatures of intertidal mussels: Biophysical determinants and physiological consequences (focus of our 2013-2017 NSF IOS award)
  • Modeling the impacts of spatial and temporal environmental variability on the evolution of thermal tolerance in intertidal limpets
  • Physiological performance of the tidepool copepod Tigriopus californicus in the face of dynamic co-variation in temperature, salinity, pH, and dissolved oxygen (focus of our 2017-2020 NSF IOS award)

 



©2011-2017 W. Wesley Dowd • last updated February, 2017 LMU Biology Tides Weather MyLMU