New insights into the coexistence ofContracaecum rudolphiiA andContracaecum rudolphiiB (Nematoda: Anisakidae) inPhalacrocorax carbosinensis from Sardinia: genetic variability and phylogenetic analysis

Abstract

AbstractContracaecumsp. nematodes are important parasites of fish eating birds that can cause animal health problems. In the present study, specimens ofContracaecum rudolphiisensu lato, from the great cormorantPhalacrocorax carbo sinensisfrom Sardinia, were characterized based on morphological and molecular data. The morphological analysis allowed to identify all the fourth stage larvae (n= 1918) asContracaecumsp., and adults, male (n= 5845) and female (n= 8312), asC. rudolphiisensu lato. Population genetics and phylogenetic relationships were inferred based on mitochondrial and nuclear markers. Multiple sequence alignment of the ribosomal internal transcribed spacer showed the coexistence ofC. rudolphiiA (n= 157),C. rudolphiiB (n= 22) and a rare heterozygote of these species. Moreover, mitochondrial markers, namely NADH dehydrogenase subunits I (nad1), cytochrome c oxidase subunit (cox1 and cox2) and small subunit of rRNA (rrnS), showed that the studiedC. rudolphiiA populations had undergone bottleneck, or founder effect event, subsequent to a rapid population growth and expansion. The observed heterozygote is with a mitochondrial pattern ofC. rudolphiiB. Although, bothContracaecumspecies showed high genetic diversity, no genetic structure between localities was detected. Phylogenetic reconstructions supported the paraphyly of the avianContracaecumspecies includingC. ogmorhini(parasite of otariids).