Background: Divergent natural selection between ecologically different environments often drives speciation. An unanswered question concerns the importance of sexual selection in generating sexual isolation during this process. We illustrate that four distinct mechanisms can drive sexual isolation: (I) divergent sexual selection, (II) uniform sexual selection, (III) intrapopulation assortative ...

Major evolutionary innovations can greatly influence subsequent evolution. While many major transitions occurred in the deep past, male live-bearing fishes (family Poeciliidae) more recently evolved a novel body plan. This group possesses three-region axial skeleton, with one region—the ano-urogenital region—representing unique region accommodating genitalic structures (gonopodial complex). Her...

Here we review the literature of a male poecillid's sexually dimorphic body plan, behavior, and nervous system, including work dating from the mid 1800s to the mid 1990s as well as work in press or in preparation for publication. Rosa-Molinar described the remodeling of the sexually dimorphic anal fin appendicular support, confirmed earlier claims about the development of the male and female se...

1 This study used an experimental model of a constructed wetland to evaluate the risk of 2 mercury methylation when the soil is amended with sulfate. The model was planted with 3 Schoenoplectus californicus, and the sediments were varied during construction to 4 provide a control and two levels of sulfate treatment. This allowed characterization of 5 sulfate’s effect on mercury bioaccumulation ...

Two previous mesocosm studies showed changes in glucosephosphate isomerase-2 (Gpi-2) allele frequencies in mosquitofish populations exposed to mercury for 111 d or two years. A previous selection component analysis of single-generation populations exposed for 111 d to 18 microg/L Hg suggested that female sexual selection and fecundity selection could contribute to changes in Gpi-2 allele freque...

Previous laboratory studies have demonstrated that estrogenic and antiandrogenic chemicals can alter several sexual characteristics in male poeciliid fishes. Whether similar disturbances occur under field conditions remains to be confirmed. Lake Apopka, Florida, is contaminated with numerous chemicals, some of which possess endocrine-disrupting activity. Male mosquitofish (Gambusia holbrooki) w...