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- Characterization of 15 polymorphic microsatellite loci in the temperate reef fish Lepadogaster lepadogaster, developed using 454-sequencingPublication . Teixeira, Sara; Candeias, Rui; Klein, Maria; Serrão, Ester; Borges, R.Abstract The clingfish, Lepadogaster lepadogaster is a reef fish species, abundant in temperate nearshore rocky reefs of the Eastern Atlantic and central and Eastern Mediterranean. To study genetic variability and population connectivity of this species, we developed fifteen polymorphic microsatellite markers. These were tested in one population and all but one, showed no departure from Hardy–Weinberg equilibrium. Average overall observed heterozygosity was 0.66 and allelic richness was 8.9. Two primer pairs revealed possible linkage disequilibrium. These markers open perspectives for population genetic studies of this species to unravel connectivity and population biology, vital information for future conservation studies.
- Vicariance patterns in the Mediterranean Sea: East-west cleavage and low dispersal in the endemic seagrass Posidonia oceanicaPublication . ARNAUD-HAOND, Sophie; Migliaccio, M.; Diaz-Almela, E.; Teixeira, Sara; Van De Vliet, M. S.; Alberto, F.; Procaccini, G.; Duarte, C. M.; Serrão, EsterAim The seagrass, Posidonia oceanica is a clonal angiosperm endemic to the Mediterranean Sea. Previous studies have suggested that clonal growth is far greater than sexual recruitment and thus leads to low clonal diversity within meadows. However, recently developed microsatellite markers indicate that there are many different genotypes, and therefore many distinct clones present. The low resolution of markers used in the past limited our ability to estimate clonality and assess the individual level. New high-resolution dinucleotide microsatellites now allow genetically distinct individuals to be identified, enabling more reliable estimation of population genetic parameters across the Mediterranean Basin. We investigated the biogeography and dispersal of P. oceanica at various spatial scales in order to assess the influence of different evolutionary factors shaping the distribution of genetic diversity in this species. Location The Mediterranean. Methods We used seven hypervariable microsatellite markers, in addition to the five previously existing markers, to describe the spatial distribution of genetic variability in 34 meadows spread throughout the Mediterranean, on the basis of an average of 35.6 (± 6.3) ramets sampled. Results At the scale of the Mediterranean Sea as a whole, a strong east–west cleavage was detected (amova). These results are in line with those obtained using previous markers. The new results showed the presence of a putative secondary contact zone at the Siculo-Tunisian Strait, which exhibited high allelic richness and shared alleles absent from the eastern and western basins. F statistics (pairwise θ ranges between 0.09 and 0.71) revealed high genetic structure between meadows, both at a small scale (about 2 to 200 km) and at a medium scale within the eastern and western basins, independent of geographical distance. At the intrameadow scale, significant spatial autocorrelation in six out of 15 locations revealed that dispersal can be restricted to the scale of a few metres. Main conclusions A stochastic pattern of effective migration due to low population size, turnover and seed survival is the most likely explanation for this pattern of highly restricted gene flow, despite the importance of an a priori seed dispersal potential. The east–west cleavage probably represents the outline of vicariance caused by the last Pleistocene ice age and maintained to this day by low gene flow. These results emphasize the diversity of evolutionary processes shaping the genetic structure at different spatial scales.
- Polymorphic microsatellite markers in the brown seaweed Fucus vesiculosusPublication . Candeias, Rui; Casado-Amezúa, Pilar; Pearson, G. A.; Serrão, Ester; Teixeira, SaraBackground: Fucus vesiculosus is a brown seaweed dominant on temperate rocky shores of the northern hemisphere and, is typically distributed in the mid-upper intertidal zone. It is an external fertilizer that reproduces sexually, providing an excellent model to address conflicting theories related to mating systems and sexual selection. Microsatellite markers have been reported for several Fucus species, however the genomic libraries from where these markers have been isolated, have originated from two or more species pooled together (F. vesiculosus and F. serratus in one library; F. vesiculosus, F. serratus and Ascophyllum nodosum in a second library), or when the genomic DNA originated from only one species it was from Fucus spiralis. Although these markers cross-amplify F. vesiculosus individuals, the level of polymorphism has been low for relatedness studies. Findings: The microsatellite markers described here were obtained from an enriched genomic library, followed by 454 pyrosequencing. A total of 9 microsatellite markers were tested across 44 individuals from the North of Portugal. The mean number of alleles across loci was 8.7 and the gene diversity 0.67. Conclusions: The high variability displayed by these microsatellite loci should be useful for paternity analysis, assessing variance of reproductive success and in estimations of genetic variation within and between populations.
- Characterization of 15 polymorphic microsatellite loci in Rimicaris exoculata, and cross-amplification in other hydrothermal-vent shrimpPublication . Teixeira, Sara; Serrão, Ester; ARNAUD-HAOND, SophieAbstract Rimicaris exoculata is an alvinocarid shrimp endemic to the hydrothermal vents of the Mid-Atlantic Ridge. In order to study genetic variability and connectivity in this species, we developed fifteen polymorphic microsatellite markers. The markers were tested on one population and, except for one, all showed no departure from Hardy–Weinberg equilibrium, with an average overall observed heterozygosity of 0.63. Two primer pairs revealed possible linkage disequilibrium, and 14 crossamplified at least one of the three co-occurring shrimp species tested (Alvinocaris muricola, Alvinocaris markensis and Mirocaris fortunata). These markers therefore open perspectives for population genetic studies of hydrothermal vent shrimp species in order to unravel connectivity and evolution of populations, and to add information on possible future impact studies.
- Polymorphic microsatellite DNA markers in the mangrove tree Avicennia albaPublication . Teixeira, Sara; ARNAUD-HAOND, Sophie; Duarte, C. M.; Serrão, EsterLike most species of mangrove trees of the genus Avicennia , A. alba is widely distributed among tropical and subtropical coasts around the world. Mangroves play an essential role in ecosystem dynamics but are reported to be regressing as human pressure increases on coastal zones. Hypervariable genetic markers are useful for population genetics studies, to estimate the level of impact and the populations potential for recovery. Microsatellite markers for A. alba were obtained by screening a partial genomic library enriched for micro-satellite dinucleotide repeats. Among 20 primer pairs defined, six amplified polymorphic microsatellites with a satisfying level of variability.