Genetic diversity and structure of an estuarine fish (Fundulus heteroclitus) indigenous to sites associated with a highly contaminated urban harbor

Abstract

Intense selection on isolated populations can cause loss of genetic diversity, which if persistent, reduces adaptive potential and increases extinction probability. Phenotypic evidence of inherited tolerance suggests that polychlorinated biphenyls (PCBs), have acted as strong selective agents on populations of a non-migratory fish, Fundulus heteroclitus, indigenous to heavily contaminated sites. To evaluate population genetic structure and test for effects of intense, multi-generational PCB contamination on genetic diversity, we used AFLP analysis on fish collected from six sites along the east coast of North America that varied widely in PCB contamination. The sites included a heavily contaminated urban harbor (New Bedford, MA), an adjacent moderately contaminated sub-estuary (Buzzards Bay, MA), and an uncontaminated estuary 60 km away (Narragansett, RI). AFLP markers distinguished populations at moderate and small scales, suggesting genetic differentiation at distances of 2 km or less. Genetic diversity did not differ across the study sites. Genome-wide diversity may have been preserved because of large effective population sizes and/or because the mechanism for genetic adaptation to these contaminants affected only a small number of loci. Alternatively, loss in diversity may have been restored with moderate levels of migration and relatively short generation time for this species.

Effects of acid mine drainage on the genetic diversity and structure of a natural population of Daphnia longispina

“…This could indicate that metal contamination acted as a directional selective pressure to change gene frequencies in the exposed population (site I) relative to the references, but this change in frequencies was not reflected by a loss of genetic diversity. These results are in agreement with some of the mentioned studies, which also found that the genetic differentiation between populations of fish (McMillan et al, 2006;Mulvey et al, 2002Mulvey et al, , 2003Roark et al, 2005) and wood-mouse (Berckmoes et al, 2005) was more correlated with environmental contamination than with geographical distance and that these changes reflected selection by contaminants (Ownby et al, 2002).…”

“…In the present study, maintenance of reference levels of genetic diversity in impacted populations could have been due to several factors, as discussed by other authors (McMillan et al, 2006;Mulvey et al, 2003;Weider, 1992), namely: (i) immigration from nearby reference populations and/or the diversity in the subjacent ephippial gene bank was high enough for the recovery of the diversity, (ii) the selection occurred at a limited number of genes, and the reduction of the diversity in these genes was not linked to a reduction in overall diversity; and/or (iii) the loss of genetic diversity due to contamination was of the same magnitude of the loss of diversity caused by clonal dominance in the reference populations. These hypotheses will be discussed separately in the following paragraphs.…”

“…Even though the reduction of genetic diversity in populations inhabiting contaminated areas has been reported in several aquatic and terrestrial species (Belfiore and Anderson, 2001;Bickham et al, 2000), recent studies employing either modern molecular methodologies, such as AFLP analysis (McMillan et al, 2006), microsatellite analysis (Berckmoes et al, 2005) and mitochondrial gene sequencing (Mulvey et al, 2003), or more classical methods, especially allozyme analysis Roark et al, 2005) have found little or no evidence for this effect. Nevertheless, this possible effect is one of the major concerns of modern conservation biology and ecotoxicology (Bagley et al, 2002;van Straalen and Timmermans, 2002).…”

Genetic and growth differences in the outcrossings between two clonal strains of the self-fertilizing mangrove killifish

“…Recently, killifish (Fundulus heteroclitus), the same order as K. marmoratus, was successfully used in AFLP analysis to measure population differentiation and diversity (McMillan et al 2006).…”

Urban driven phenotypic changes: empirical observations and theoretical implications for eco-evolutionary feedback

“…Several model organisms are instructive in their evolutionary responses to landscape modification. For example, heritable tolerance to environmental contaminants associated with urbanization has been observed in mummichogs (Fundulus heteroclitus) [19,20]. Birds are a focus of many studies documenting phenotypic trait changes in response to urbanization; afforestation and increased concentrations of predators in urban areas have influenced wing morphology in urban European starlings (Sturnus vulgaris) [23], traffic mortality may be selecting for narrower wings and associated increased agility in cliff swallows (Petrochelidon pyrrhonota) that nest under bridges [58], house finches (Haemorhous mexicanus) have evolved longer and narrower bills and altered vocal performance in response to anthropogenic noise in urban environments [24], and white crowned sparrows (Zonotrichia leucophrys) have adapted to anthropogenic noise by singing at higher minimum frequencies and with reduced bandwidth [29].…”