LISA T. CRUMMETT
Ecology and Evolutionary Biology, UC Irvine
Ph.D., University of Florida, 2008, Zoology
I am evolutionary ecologist broadly interested in understanding the ecological and evolutionary factors that shape the distribution of a species over time and space. Secondarily, I am interested in the coevolutionary dynamics of host-parasite interactions. I am particularly drawn to the marine environment and I have significant graduate training and research experience working in the intertidal zone. I am an enthusiastic lecturer with a diverse teaching background. I have taught General Biology, Ecology, Zoology, Environmental Science, Evolution & Biodiversity, Molecular Biology, Genetics, Anatomy, and Physiology.
Factors that influence the distribution of a species
For my Master’s research, I used genetic tools to show that Lottia digitalis, a common California limpet (intertidal snail) that was previously thought to exhibit a wide geographic range, was actually composed of a northern (L. digitalis) and southern (L. austrodigitalis) cryptic species pair (Crummett and Eernisse 2007). The MDH (malate dehydrogenase) locus, which we used as a diagnostic marker for the cryptic species pair, was later shown to produce allozymes that differed in their thermal stability (Dong and Somero 2009). Thus, these allozymes are likely associated with observed latitudinal species distributions as well as observed vertical (low-intertidal versus mid-intertidal) species distributions in the zone of sympatry (Crummett and Eernisse, 2007). These diagnostic allozymes may also be associated with the recent contraction of the southern range of L. digitalis and the northward range expansion of L. austrodigitalis (Crummett and Eernisse 2007); a probable result of global climate change.
For my doctoral research, I examined the hypothesis that ecological stressors interact with genetic features to influence the local distribution of sexual versus asexual populations of the freshwater snail, Campeloma limum. Finite asexual populations that produce clonal progeny are predicted to accumulate deleterious mutations over time. I provided evidence that local environmental stressors (low dissolved oxygen and microbial pollutants) may be interacting with mutation load to limit the distribution of clonal populations to relatively pristine habitats (Crummett et al. in Press). I also examined female fecundity and embryo size in asexual versus sexual populations of C. limum. I provided empirical support for the evolutionary hypothesis that asexual populations should have twice the reproductive rate of their sexual counterparts if all else is equal, known as the “two-fold cost of sex” (Crummett and Wayne, 2009). Examining snail parasites (flukes, mites, and leeches) during my doctoral work sparked my interest in host-parasite interactions, which led to my current postdoctoral work.
Currently, for my postdoctoral research, I am examining lytic marine viruses that infect the abundant marine cyanobacteria, Synechococcus, which contributes up to 25% of the primary production in pelagic waters. Through lysing their hosts, these marine viruses control bacterial abundance, affect community composition, and impact global biogeochemical cycles (nutrient flow through the marine food web). Since marine viruses control the abundance of marine cyanobacteria, we need to understand what factors control the abundance of these viruses. I am performing experiments to determine what viral characteristics (decay rate, latency period, burst size) interact with the local environment to influence local viral abundance. There is also a genetic component to this work. Interestingly, the viruses that infect Synechococcus carry a variety of genes, termed “host-derived genes” that originated in the host but were co-opted by the virus. I am examining whole genomes from viral isolates to determine if there are patterns in the specific assemblage of host-derived genes carried by a viral isolate and its location or phylogeny. With this current research, I hope to begin to understand what viral characteristics (phenotypic and/or genetic) interact with the environment to influence their abundance and distribution in the oceans.