Differential Survival of Three Mitochondrial Lineages of a Marine Benthic Copepod Exposed to a Pesticide Mixture

Abstract

In South Carolina estuaries, the harpacticoid copepod Microarthridion littorale (Poppe 1881) consists of three distinct mitochondrial lineages (liI, liII, and liIII), whose distributions may be partially explained by the presence of toxic contaminants in the sampled habitats. The frequencies of liII and liIII are greatly diminished and sometimes absent in South Carolina contaminated tidal creeks where liI is omnipresent. In this study, representatives of these lineages or haplotype groups were collected from sediments of an estuarine creek containing low to undetectable levels of toxicants and then exposed to a toxic (approximately LC90) aqueous mixture containing an organophosphate (chlorpyrifos) and organochlorine pesticide (DDT, mixed isomers). A comparison was conducted for the frequency of each of the three haplotypes among the survivors of the exposed animals relative to that among the survivors of the control group. The haplotype group with the highest frequency in contaminated SC estuaries (liI) was statistically higher in frequency in survivors of the pesticide-exposed group than in the control group. The two rarer groups (liII and liIII) were less abundant among the survivors of the pesticide-exposed group than the control group. The frequencies of liI, liII, and liIII did not change significantly among the survivors of the control group. The differential survival of the three haplotype groups in the pesticide mixture may be one of the reasons that some haplotype groups are more likely to be found in clean or contaminated tidal creeks on the South Carolina coast.

Highly Discordant Nuclear and Mitochondrial DNA Diversities in Atka Mackerel

“…Positive selection can produce similar reductions in diversity and departures from neutrality as a population expansion, and the same star-like haplotype genealogy expected for neutral genes in a growing population can appear as low-frequency haplotypes accumulate around a selected haplotype. While this mode of selection appears to account for patterns of mtDNA variation in some species (e.g., Schizas et al 2001;Ballard and Whitlock 2004;Ballard and Rand 2005;Zink 2005) and has been inferred for some fishes (Á rnason 2004;Grant et al 2006;Vigliola et al 2007), the accrual of slightly deleterious mutations in whole-mitogenomic comparisons of several gadid species indicated a nearly neutral pattern of evolution (Marshall et al 2008).…”

Impacts of permethrin contamination on nematode density and diversity: A microcosm study on benthic meiofauna from a Mediterranean coastal lagoon

“…The sensitivity of meiofauna to toxicants has been found to vary with taxonomic group and species, as well as with the toxicant and its concentration and effects tend to be taxon specific. Schizas et al (2001) showed that pesticides caused mortality of harpacticoid copepods. Sánchez-Fortún & Barahona (2005) concluded that meiofauna taxa were affected by permethrin contamination but a very low sensitivity of the rotifer Brachionus plicatilis (Müller, 1786) was detected.…”

Mitochondrial DNA variation and cryptic speciation within the free-living marine nematode Pellioditis marina

“…Experimental studies with harpacticoid copepods indicate that severe bottlenecks can occur in populations exposed to toxicants (Street et al 1998), and environmental history seems to have no effect on their survival ability when copepods are exposed to different concentrations of sediment-associated contaminants (Kovatch et al 2000). In contrast, Schizas et al (2001) observed differential survival of 3 harpacticoid copepod lineages and inferred that this differential survival might explain some of the genetic patterns observed in contaminated habitats.…”