Intra- or inter-specific difference in genotypes of Caligus elongatus Nordmann 1832?

Abstract

Two mitochondrial and one nuclear genetic marker were used to study the phylogenetic position of the two reported CO1-genotypes of Caligus elongatus in a group of closely related caligid parasites. Molecular analysis of the two mitochondrial genes (CO1 and 16S), indicate genetic distances of the two C. elongatus genotypes in the lower range of distances previously reported between other crustacean species, but higher than comparable reported within-species differences. Analyses of nuclear 18S sequences indicate no detectable differentiation between these genotypes, but may be due to expected differences in the resolution of these genetic markers. Investigation of two of three selected morphological characters reveals phenotypes supporting the division based on the molecular division. The species status on the two C. elongatus genotypes cannot be drawn conclusively, although the molecular and morphological data presented here suggests the presence of sibling species.

Cytochrome oxidase I sequences reveal possible cryptic diversity in the cosmopolitan symbiotic copepod Nesippus orientalis Heller, 1868 (Pandaridae: Siphonostomatoida) on elasmobranch hosts from the KwaZulu-Natal coast of South Africa

“…The divergence between the two clades (17.44%) is clearly at a level expected for interspecific rather than intraspecific relationships in crustaceans. This value is comparable to the more than 17% and 18% sequence divergence between conspecific populations of the harpacticoid copepods, Tigriopus californicus (Burton, 1998;Burton and Lee, 1994, respectively), is lower than that obtained for conspecific populations of Cletocamptus deitersi (25%) (Rocha-Olivares et al, 2001), but higher than the comparable K2P distance for conspecific populations of the siphonostomatoid Caligus elongatus (12%) (Øines and Schram, 2008). Sequence divergence of 16-22% exists between previously defined Nesippus species (Table 2) which agrees with previous findings of 13-22% sequence divergence in congeneric species of copepods (Bucklin et al, 1999).…”

“…Host occurring sympatrically, both on individual hosts and from the same geographical area (Øines and Heuch, 2005;Øines and Schram, 2008). This is the first report of an intraspecific phylogenetic study of the cosmopolitan N. orientalis based on COI DNA sequences.…”

Estimated Molecular Phylogenetic Relationships of Six Siphonostomatoid Families (Copepoda) Symbiotic on Elasmobranchs

“…These three genes provided independent datasets, with different rates of evolution, with which to infer relationships at various taxonomic levels (Crandall et al, 2000;Daniels et al, 2002;Pérez-Losada et al, 2002;Øines & Schram, 2008). Two microlitres of the diluted DNA solution were added to a 50 μl PCR reaction containing the following: 5 μl 10X Taq buffer, 5-8 μl 25 mM MgCl, 8 μl 10 mM dNTPs, 5 μl each of two 10 mM primers, and 0.3 μl of 1.25 units of Taq polymerase (Promega) and ddH 2 O.…”

Phylogenetic relationships and genetic diversity ofNemesisRisso, 1826 species found on different elasmobranch host species off the KwaZulu-Natal coast, South Africa

“…UMH) and the Nemesis sp. from S. lewini (H13.SCA.RB) (Figure 3, Clade 2), is lower than that of C. elongatus Genotype I, C. elongatus Genotype II (Øines and Heuch 2007) and of Caligus (Øines and Schram 2008), but higher than that of Clade 1 and Clade 2 of N. orientalis (Dippenaar et al 2010), and is thus within the estimated intraspecific range. Therefore it may represent a single species.…”

“…UMZ) and the two individuals from C. brevipinna caught off Park Rynie and Umzumbe (H17.SPN.PAR and H17. SPN.UMZ) (Figure 3, Clade 1) is within the intraspecific divergence of symbiotic copepods (Øines and Schram 2008;Dippenaar et al 2010). Therefore, both S. lewini and C. brevipinna are infected by at least two Nemesis species, and one of those species is common to both hosts.…”