Jean-Pierre Quignard

Molecular phylogeography of western Mediterranean dusky grouper Epinephelus marginatus

Intraspecific sequence variation in a portion of the gene coding for cytochrome b in the dusky grouper (Epinephelus marginatus Lowe 1834), an endangered fish species in various regions of the Mediterranean sea, was examined in 29 individuals from the western Mediterranean sea. Sixty-four phylogenetically informative nucleotide positions were present in a 353-base pair cytochrome b sequence, amplified using the polymerase chain reaction. Statistical analysis of the sequence data using a variety of tree-building algorithms separated the taxa into one group of dusky groupers corresponding to some of the Algerian individuals and another regrouped set of fishes originating in France, Tunisia and the remaining Algerian specimens. Although, on the basis of their morphology, E. marginatus are now considered as a single species, our results suggest that a subgroup of the Algerian dusky grouper constitutes a cryptic (undescribed) species. These results suggest that morphological and genetic evolution may be uncoupled in dusky grouper, resulting in morphological similarity between species despite extensive genetic divergence. In addition, we cannot rule out the possibility of gene introgression with other species of grouper. A more in depth phylogenetic analysis (i.e. between and within the different Epinephelus species) would likely affect many conservation management decisions about this assemblage of groupers.

Microsatellite length variation in candidate genes correlates with habitat in the gilthead sea bream Sparus aurata

The genetic basis and evolutionary implications of local adaptation in high gene flow marine organisms are still poorly understood. In several Mediterranean fish species, alternative migration patterns exist between individuals entering coastal lagoons that offer favourable conditions for growth and those staying in the sea where environmental conditions are less subject to rapid and stressful change. Whether these coexisting strategies are phenotypically plastic or include a role for local adaptation through differential survival needs to be determined. Here, we explore the genetic basis of alternate habitat use in western Mediterranean populations of the gilthead sea bream (Sparus aurata). Samples from lagoonal and open‐sea habitats were typed for three candidate gene microsatellite loci, seven anonymous microsatellites and 44 amplified fragment length polymorphism markers to test for genotype–environment associations. While anonymous markers globally indicated high levels of gene flow across geographic locations and habitats, non‐neutral differentiation patterns correlated with habitat type were found at two candidate microsatellite loci located in the promoter region of the growth hormone and prolactin genes. Further analysis of these two genes revealed that a mechanism based on habitat choice alone could not explain the distribution of genotype frequencies at a regional scale, thus implying a role for differential survival between habitats. We also found an association between allele size and habitat type, which, in the light of previous studies, suggests that polymorphisms in the proximal promoter region could influence gene expression by modulating transcription factor binding, thus providing a potential explanatory link between genotype and growth phenotype in nature.

Molecular Phylogeny of Mugilidae (Teleostei: Perciformes)

Molecular phylogenetic relationships among five genera and twelve Mugilidae species were investigated us- ing published mitochondrial cytochrome b and 16S rDNA sequences. These analyses suggested the paraphyly of the genus Liza and also that the separation of Liza, Chelon and Oedalechilus might be unnatural. Moreover, all the species of the genus Mugil plus orthologs of Crenimugil crenilabis clustered together; however, molecular analyses suggested possible introgressions in Mugil cephalus and moreover, that fish identified as Mugil curema could correspond to two different species as already shown by karyotypic analyses.

Spinal deformities in the black-striped pipefish Syngnathus abaster (Pisces, Syngnathidae) from the Tunis North Lake, Tunisia.

Spinal deformities are seen in fishes. Deformities in the family Syngnathidae is rarely reported. Spine curvatures in natural population of pipefish, Syngnathus abaster are reported from the Tunis North Lake. The species is euryhaline and occurs along the Mediterranean coasts. Four hundred specimens of S. abaster were collected from January 2006 to December 2007 from the Tunis North Lake. Two specimens with skeletal abnormalities were described for the first time. X-rays radiographies revealed several vertebral deformities for each deformed specimen, especially at five curvation places of the caudal part. Several factors are believed to be the cause of spinal deformities of S. abaster in the Tunis North Lake, such as environmental disturbances, parasitism infection and nutritional factors.

Recruitment and demographic variability in a lagoonal population of the blenniid fish Lipophrys pavo

The demography of a lagoonal population of Lipophrys pavo over a four year period is described. This population exhibited high variability in recruitment and mortality and as a result, in age structure and density. During the study the average size at a given age decreased. This decrease was not linked to growth variation. Changes in demography and length structure are interrelated and could be linked to stressful environmental conditions and to reproductive patterns of this species. Lipophrys pavo (Risso, 1810) is a common species in shallow waters of the rocky littoral of the Mediterranean sea (Zander, 1972; Patzner, 1984). This species differs from other Blenniidae by its ability to colonize biotopes where hard substrates are scarce (Moosleimer, 1980; Almada et al., 1994; Ruchon, 1995), and by its great euryhaline and eurythermal tolerance limits (Marion, 1890; Paris & Quignard, 1971; Zander, 1972; Muller et al., 1973; Moosleitner, 1988; Patzner & Seiwald, 1988). This euryvalence has allowed L. pavo to colonize brackish and soft-bottom lagoons of the Gulf of Lion where it is the single Blenniidae present (personal observation). Lipophrys pavo is a gonochoric species exhibiting strong sexual dimorphism (Zander, 1975; Papaconstantinou, 1979). Males are territorial nest breeders during the spawning season (Patzner et al., 1986), and females are batch spawners (Fishelson, 1963a; Patzner, 1985a).