| dc.description.abstract | Understanding how anthropogenic activity impacts the health and viability of wildlife
populations is one of the most important tasks of environmental biology. A key concern
related to bi-products of human activity is the accumulation of environmental pollutants
within aquatic environments. Pollutants such as endocrine disruptors and heavy metals
have the potential to impact both human and wildlife populations in contaminated areas.
While much research has focused on how these compounds impact natural selection
processes, such as viability and reproduction, their effect on sexual selection processes is
not as clear. The goal of this dissertation was to address how environmental
contaminants impact sexual selection processes in a sex-role reversed pipefish and
evaluate how these effects may impact long-term population viability. Here we show
that short periods of exposure to environmentally relevant concentrations of a synthetic
estrogen result in male pipefish with female-like secondary sexual traits. While these
males are capable of reproduction, exposed males are discriminated against by females
in mate choice tests. In natural populations, this type of discrimination could reduce male mating opportunities, potentially reducing their reproductive success. In an
additional component of this dissertation, it was discovered that pipefish populations
around Mobile Bay, specifically Weeks Bay, are currently being exposed to significantly
elevated levels of mercury. These populations are genetically distinct from coastal
populations but moderate levels of gene flow occur among sites, and gene flow between
contaminated and non-contaminated population may be influencing how environmental
contaminants are impacting genetic diversity and population viability. In the case of
endocrine disruptors, migration between contaminated and non-contaminated sites may
negatively impact population viability. Morphological traits induced with exposure to
contaminants may be maintained for extended periods of time, therefore, the effect the
exposed phenotype has on mating dynamics and sexual selection could be carried to
non-contaminated sites if exposed individuals move to new populations. On the other
hand, immigration of individuals from non-contaminated sites into contaminated areas
may help maintain genetic diversity within exposed populations. In conclusion, the
work presented in this dissertation shows that the presence of environmental toxins can
significantly impact sexual selection processes, which in turn can have profound effects
on the viability and future evolutionary trajectory of populations. Future work in this
area should not only address how these toxins impact individual fitness, but should also
address how population structure may be influencing the severity of these compounds on
natural populations. | en |
