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- Genetic differentiation and gene flow of two sparidae subspecies, Diplodus sargus sargus and Diplodus sargus cadenati in Atlantic and south-west Mediterranean populationsPublication . González-Wangüemert, Mercedes; Pérez-Ruzafa, Á.; García-Charton, J. A.; Marcos, C.A total of nine enzymes coded by 14 loci were assayed for each of six populations (from the north-eastern Atlantic and the Mediterranean) of two sea bream subspecies (Diplodus sargus sargus and Diplodus sargus cadenati). Diagnostic alleles were observed for each subspecies, although there were several common alleles. Estimates of variance in allele frequencies among samples (FST) revealed significant differences (P<0.05) among both subspecies. Genetic divergence was found between Atlantic and Mediterranean samples: values for genetic distances were higher than 0.163. Furthermore, D. sargus cadenati populations displayed a higher mean weight and length than D. sargus sargus populations and significant differences in growth were found among subspecies and populations. These results are discussed in terms of levels of gene flow and its respective relationships with water circulation in the Strait of Gibraltar and geological events.
- Temporal genetic variation in populations of Diplodus sargus from the SW Mediterranean SeaPublication . Gonzalez-Wanguemert, Mercedes; Pérez-Ruzafa, Á.; Cánovas, F.; García-Charton, J. A.; Marcos, C.Population genetic studies on white sea bream Diplodus sargus have revealed different patterns in the subdivision of populations in the Mediterranean Sea. However, the stability of observed allele frequencies over time remains poorly tested. The aim of this study was to show that the genetic structure of D. sargus could significantly change over time by analysing temporal variations in allozymes. In order to determine temporal variation in the genetic structure of 5 natural D. sargus populations in the SW Mediterranean, we screened 14 allozyme loci. Our main finding was the significant genotypic differentiation among cohorts (year-classes) in the Guardamar (FST = 0.012; p < 0.001) and Cape of Palos (FST = 0.008; p < 0.001) populations. The differentiation observed in the present study when considering pair-wise comparisons between cohorts is similar to that of all populations throughout the Mediterranean Sea. Our results suggest that microgeographical variations, also known as ‘chaotic genetic patchiness’, could occur in D. sargus populations from the SW Mediterranean. The recruitment of genetically variable cohorts at 1 site each year may account for these variations. We also discussed alternative explanations for this genetic pattern. This study confirms the importance of understanding the ecology, behaviour and environment of fish populations when investigating population genetic structure. Our results also highlight the importance of incorporating temporal samples when conducting population structure studies.
- Genetic differentiation of Elysia timida (Risso, 1818) populations in the Southwest Mediterranean and Mar Menor coastal lagoonPublication . González-Wangüemert, Mercedes; Giménez-Casalduero, F.; Pérez-Ruzafa, Á.Genetic variation at 10 enzyme loci was analysed in Elysia timida sacoglossan mollusc samples, originating from both coastal lagoon and marine sites. The observed heterozygosity ranged from 0.390 (Los Urrutias) to 0.277 (Tabarca). Marine and coastal lagoon populations were characterised by exclusive alleles. Examination of the spatial structure was performed using Nei’s distances and F-statistics, and indicated significant genetic differences between marine groups and coastal lagoon populations. Multivariate analysis of allele frequencies also suggested that different arrays of genotypes prevail in coastal lagoon samples compared to marine ones.