(Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2017-02)
Bors, Eleanor K.
Every genome tells a story. This dissertation contains four such stories, focused on shared themes
of marine population dynamics and rapid change, with an emphasis on invasive marine species.
Biological invasions are often characterized by a range expansion, during which strong genetic
drift is hypothesized to result in decreased genetic diversity with increased distance from the center
of the historic range, or the point of invasion. In this dissertation, population genetic and genomic
tools are used to approach complex and previously intractable fundamental questions pertaining
to the non-equilibrium dynamics of species invasions and rapid range expansions in two invasive
marine species: the lionfish, Pterois volitans; and the shrimp, Palaemon macrodactylus. Using
thousands of loci sequenced with restriction enzyme associated DNA sequencing in these two
systems, this research tests theoretical predictions of the genomic signatures of range expansions.
Additionally, the first chapter elucidates patterns of population genetic connectivity for deep-sea
invertebrates in the New Zealand region demonstrating intimate relationships between genetics,
oceanographic currents, and life history traits. Invasive shrimp results extend our understanding of
marine population connectivity to suggest that human-mediated dispersal may be as important—
if not more important—than oceanographic and life history considerations in determining genetic
connectivity during specific phases of marine invasions. In invasive populations of lionfish,
measures of genomic diversity, including a difference between observed and expected
heterozygosity, were found to correlate with distance from the point of introduction, even in the
absence of spatial metapopulation genetic structure. These results indicate a signal of rapid range
expansion. The final study in this dissertation uses an innovative temporal approach to explore
observed genomic patterns in the lionfish. In all, this dissertation provides a broad perspective
through the study of multiple species undergoing superficially parallel processes that, under more
intense scrutiny, are found to be mechanistically unique. It is only through comparative approaches
that predictable patterns of population dynamics will emerge.
