Population Genetics of Bathyal and Abyssal Organisms

Abstract

Publisher Summary Bathyal and abyssal environments are characterized by relatively stable physical parameters, especially temperature, salinity, oxygen concentration, and hydrostatic pressure. Exceptions to this stable environment are found within hydrothermal vent fields, hydrocarbon seeps, groundwater seeps, subduction seeps, and oxygen-minimum zones (OMZs). Organisms may also exhibit enzymatic, metabolic, and morphological adaptation to conditions of low oxygen concentrations and/or the presence of high concentrations of naturally occurring toxic compounds. At present, there are no data on the effects of such adverse environmental factors on the genetics of deep-sea species. Biochemical techniques have been used in the majority of genetic studies on deep-sea species and populations. These techniques have the disadvantage that they require fresh tissue for enzyme extraction but the advantage that enzyme loci are functional proteins and can demonstrate environmentally driven selection. Molecular genetic techniques have the disadvantage that they are expensive and generally require a long period of optimization for a particular study. However, these techniques can utilize tissues preserved in alcohol or buffering solutions, which is a major consideration when deep-sea cruises are of long duration and in remote locations. Biochemical and molecular genetic techniques can be applied at different systematic levels of genetic separation, but molecular techniques have a broader spectrum of application. Analysis of the relationship between genetic identity and systematic separation for deep-sea taxa demonstrate that levels of genetic identity between conspecific, congeneric, and confamilial populations are broadly similar between deep-sea organisms and those from other habitats. These data imply that speciation may occur at a similar rate in the deep sea in comparison to that in other environments, and that approximate times of evolutionary divergence for species and genera are three million and 25 million years, respectively.