I'm interested in how species with complex life cycles build up their environmental tolerances, ultimately allowing them to cope with climate change. I study how tolerances develop across life stages and between generations.
Development of thermal tolerance across demography in species with complex life cycles
Preparing the next generation for climate change: Are parental effects on larval thermal tolerance adaptive or maladaptive?
The ability of populations to cope with thermal stress may be influenced by conditions experienced by parents, via both genetic changes and transgenerational phenotypic plasticity through epigenetics or maternal provisioning. Adaptive parental effects occur if more stressful parental environments yield more tolerant offspring while the opposite pattern leads to maladaptive effects. This study evaluated the role of parental effects in determining larval thermal tolerances for the intertidal mussel, Mytilus californianus. We tested whether thermal environments across a natural gradient (shoreline elevation) impacted mussel temperature tolerances. Lethal thermal limits were compared for field-collected adults and their larvae. We observed parental effects across one generation, where adult mussels exposed to warmer habitats yielded less tolerant offspring. Interestingly, though parental environments influenced offspring tolerances, we found no clear effects of habitat conditions on adult phenotypes (tolerances). We found indicators of trade-offs in energy investment, with higher reproductive condition and larger egg sizes in low-stress environments. These results suggest parental effects are maladaptive leading to negative effects of thermal stress on the next generation.
Right on time: the effect of critical windows on transgenerational plasticity
Parental effects, or transgenerational plasticity (TGP), occur when the phenotype of an individual is affected by the phenotype or environment of its parent through non-genetic mechanisms. Unlike evolutionary processes, transgenerational effects can be an effective method to prime offspring on a shorter timescale with reversible and more flexible mechanisms, allowing genetic change to catch up. Though TGP is expected to be adaptive for organisms coping with climate change, the timing of environmental stress exposure in parental generations and how that timing relates to a species’ life history may be important in determining the outcomes of transgenerational effects. These critical windows are time periods in a species’ life cycle when exposure to an environmental abiotic stressor ultimately impacts the phenotypes of their progeny. I am using a meta-analysis approach of peer-reviewed literature to investigate the critical windows that induce transgenerational effects and if those differ between species with varying life histories.
A blast from the past: carry-over effects from early life stage experiences on juveniles and beyond
Carry-over effects, where experiences from a previous life stage influence the performance of a later life stage within or across generations, can impact the fitness of species under a changing climate. Little is known about the extent to which field conditions during embryonic and larval development affect juvenile performances, or even the next generation. I will evaluate whether carry-over effects occur in response to natural thermal exposure and how long these effects perpetuate into later life stages in two climate range expanders, Mexacanthina lugubris and Acanthinucella spirata. In the Spring 2022, I will (1) conduct latitudinal surveys (from southern to northern California) to document their range expansion and egg laying microhabitats, and (2) test for carry-over effects of thermal tolerances across life stages by monitoring egg cases in the field and conducting thermal tolerance tests in the laboratory on larvae and hatchlings, and potentially adults as they grow.