Patterns of genetic variation of a Lessepsian monogenoidean parasite

After the opening of the Suez Canal in 1869 and after the further changes of the water regime of the canal and the near area of the Eastern Mediterranean Sea, the biogeographical barrier existing until that moment, between the Red Sea and the Mediterranean Sea, has been, as time goes by, weakened, allowing the contact between two different biota that was separated for 12 Million years. This work is focused on the mechanisms that set the spread and the colonization of Mediterranean Sea from Glyphidohaptor plectocirra, monogenoidean parasite of rabbit fish Siganus rivulatus (Siganidae), checking also the relationship between the spread of the host species, known to bibliography, and of the parasite, experimentally analysed. Based on available literature, several genetic studies of Lessepsian species often demonstrate the absence of a genetic bottleneck in a wide plethora of taxa, from plants to fish, but information regarding the genetic responses of their parasites in the newly colonized ecosystems is still lacking. In detail, in this work, the genetic flow relationships between five populations was estimated, three from the Red Sea (Nabq and Ismalia, Egypt, and Eilat, Israel) and two from Mediterranean Sea (Rhodes Island, Greece and Tel Aviv, Israel) by sequencing a portion of the mitochondrial CoxI gene. G. plectocirra specimens were extracted from gill arches of S. rivulatus and morphologically identified by analysing haptor sclerotized structures. After the morphological identification of specimens, two DNA regions were amplified, one mitochondrial, about 688 bps long, coding for the Cytochrome Oxidase I (COI) and one nuclear, 681 bps long, coding for the terminal region of the 18S gene, that include the entire ITS1 and a portion of the 5.8S gene, was then amplified using primers S1. The 681 bp alignment of 60 rDNA sequences found in all populations showed only two polymorphic sites, which distinguished only three haplotypes (data not shown). Thus, the low variab