In the Mediterranean, the parasitic copepod Lepeophtheirus thompsoni Baird, 1850 specifically infests turbot (Psetta maxima L., 1758), whereas L. europaensis Zeddam, Berrebi, Renaud, Raibaut, and Gabrion, 1988 infests brill (Scophthalmus rhombus L., 1758) and flounder (Platichthys flesus L., 1758). Experimental infestation of turbot by copepods from each of the three fish species showed an absence of any physiological incompatibility preventing natural development of the two parasite species, at least on one host species, i.e., the turbot. Moreover, interspecific hybrids were obtained experimentally, which implies that 1) there is no strict genetic barrier between the two species and 2) the natural prezygotic isolation results from a choice of the most favorable habitat. We discuss the origin and possible consequences of the presence, in the Mediterranean, of L. europaensis on brill and flounder, two hosts separated by their taxonomic status and ecobiology.
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"Molecular studies of the diversity of populations of copepods have been applied to both non parasitic and parasitic species. Investigations of non-parasitic copepods have revealed a greater diversity than expected, resulting in the detection of sibling and cryptic species and genetically isolated populations ( Bucklin et al. 2000; Rocha-Olivares et al. 2001; Lee & Frost 2002) For parasitic copepods only a limited number of papers dealing with the population genetics of Caligids were available (Meeus et al. 1990; Isdal et al. 1997; Todd et al. 1997; Shinn et al. 2000). "
"ntrast , S . andegavinus showed no initial choice for any of the two host species , which were seemingly colonized at random . Thus , differences in strength of host preference were detected between the two parasite species . Similar divergent patterns of host preference in closely - related species have been observed in various parasite taxa ( de Meeûs et al . 1990 , 1995 ; Le Brun et al . 1992 ; Du Preez and Kok 1997 ; Du Preez et al . 1997 ; Thresher et al . 2000 ) As described above , preference should evolve according to parasite fitness and dispersal ability . In mites , difference in host preference should occur because the strength of one or both of these conditions ( parasite population dy"
[Show abstract][Hide abstract]ABSTRACT: In parasites, host specificity may result either from restricted dispersal capacity or from fixed coevolutionary host-parasite adaptations. Knowledge of those proximal mechanisms leading to particular host specificity is fundamental to understand host-parasite interactions and potential coevolution of parasites and hosts. The relative importance of these two mechanisms was quantified through infection and cross-infection experiments using mites and bats as a model. Monospecific pools of parasitic mites (Spinturnix myoti and S. andegavinus) were subjected either to individual bats belonging to their traditional, native bat host species, or to another substitute host species within the same bat genus (Myotis). The two parasite species reacted differently to these treatments. S. myoti exhibited a clear preference for, and had a higher fitness on, its native host, Myotis myotis. In contrast, S. andegavinus showed no host choice, although its fitness was higher on its native host M. daubentoni. The causal mechanisms mediating host specificity can apparently differ within closely related host-parasite systems.
"All three hosts are of northern origin (Quignard 1972). They colonized the Mediterranean Sea during the course of the last glaciation events, during which £ounder may have lost their original parasites and become infected with L. europaensis from brill (De Meeuª s et al. 1990). The absence of L. europaensis on £ounder in the Atlantic suggests that parasite competition has a role in determining the host range for these copepods (De Meeuª s et al. 1995), but there is no direct evidence for the e¡ect of such competition. "
[Show abstract][Hide abstract]ABSTRACT: Lepeophtheirus thompsoni and Lepeophtheirus europaensis are two parasitic copepods naturally isolated on their sympatric hosts, i.e. turbot (Psetta maxima L.) and brill (Scophthalmus rhombus L.), respectively They are able to meet, mate and hybridize on turbot experimentally but they are naturally prevented from doing so by a strong host preference when given a choice. Theory suggests that such a pattern is possible, but only under conditions of competition for the resource. In the present study the attachment rates of the two copepods were studied experimentally under various conditions of competition, infectious dose and number of available hosts. The results suggest a greater sensitivity to competition for the generalist species L. europaensis than for the specialist L. thompsoni, which is in agreement with theoretical predictions.
Full-text · Article · Nov 2000 · Proceedings of the Royal Society B: Biological Sciences