Research

Rapid Evolution in Atlantic Killifish

My dissertation work with Dr. Douglas Crawford and Dr. Marjorie Oleksiak at the University of Miami focuses on rapid adaptation to changing environmental temperature in a small estuarine fish, Atlantic killifish (Fundulus heteroclitus). These fish are frequently used in physiology and genomics work because they live in large populations (5,000-10,000 fish in a single salt marsh), are highly plastic in response to various environmental stressors (dissolved oxygen, temperature, salinity), and live across a wide geographic range (Northern Florida, USA to New Brunswick, Canada). I am using an interdisciplinary combination of physiology and genomics to investigate acclimation and adaptation to thermal stress. To accomplish this, I have designed and tested high-throughput physiological equipment and used the equipment to measure metabolic and thermal tolerance traits in ~150 adult Fundulus heteroclitus. Traits including whole animal metabolic rate, critical thermal maximum, and cardiac metabolic rate were measured at two acclimation temperatures, which allowed us to address physiological plasticity in response to temperature as well as potentially adaptive phenotypic differences among populations that experience different local temperatures. Genomic and transcriptomic data for these same individuals will be used to associate phenotype, gene expression, and genotype to understand molecular mechanics underlying complex trait evolution.

Environmental Epigenetics

As an undergraduate student I worked with Dr. Christopher Faulk at the University of Minnesota to investigate the impact of environmental stress on the epigenome. Epigenetic changes, like DNA methylation, can alter chromatin structure and gene expression resulting in altered phenotypes despite no change in the underlying genomic sequence. With the Faulk lab I assisted on two major projects: 1) DNA methylation patterns in ultra-conserved non-coding elements among vertebrate taxa and 2) epigenetic changes in response to chronic low-dose decitabine exposure in mice. I also completed a semester long Undergraduate Research Opportunity Project (UROP) where we compared DNA methylation in selectively bred and contemporary populations of milk cows. These projects included using pyrosequencing to assess quantitative DNA methylation and preparing samples for next-generation sequencing. The low-dose decitabine exposure project also required mouse work including inter-peritoneal injections, blood draws, tissue and sperm collection, and imaging. 

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Effects of Ocean Acidification on the Early Life Stages of a Coastal Forage Fish

During the summer of 2017 I was a NOAA Hollings Scholar at the Northeast Fisheries Science Center with Dr. Christopher Chambers. Working with the early life history and recruitment group I collaborated with interns and research scientists to design and test a high-frequency CO2 system (HFCO2). The HFCO2 is a horizontal pipe with an inflow of CO2-striped seawater and CO2 gas, which serves as a manifold that can be tapped to produce up to 20 unique CO2 treatment levels that can be plumbed to rearing containers in a temperature controlled water bath below the pipe. This system was used to assess the shape and scope of physiological response in the early life stages of Atlantic silverside (Menidia menidia) to constant and variable CO2 treatments. Measured responses included body condition, body size, embryonic and larval survival through 14 days post hatch (feeding larvae). 

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Contact

Email: mxd1288@miami.edu

Twitter: @melissakd6