Browsing by Author "Van De Vliet, M. S."
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- Development and characterization of highly polymorphic microsatellite loci for the Western Spadefoot toad, Pelobates cultripesPublication . Van De Vliet, M. S.; Diekmann, O. E.; Serrão, Ester; Beja, PedroNine highly polymorphic microsatellite markers were isolated and characterized for the Western Spadefoot, Pelobates cultripes. Remarkably, for this amphibian species high numbers of microsatellites were found as part of larger repeat containing regions, making primer design difficult. For nine loci, primers were designed successfully and genotyping of individuals was reliable and consistent. Number of alleles and heterozygosity for these loci ranged from 9 to 34 and from 0.72 to 0.94, respectively. The high levels of polymorphism revealed by our developed loci should provide insight into population genetic structure and levels of dispersal for this typical Mediterranean temporary pond-breeding amphibian.
- Fucus cottonii (Fucales, Phaeophyceae) is not a single genetic entity but a convergent salt-marsh morphotype with multiple independent originsPublication . Neiva, J.; Hansen, G. I.; Pearson, G. A.; Van De Vliet, M. S.; Maggs, C. A.; Serrão, EsterIn low-energy salt-marsh environments, Fucus spp. frequently exhibit an atypical morphology that is characterized by the absence of an anchoring holdfast and a trend towards reduced size and buoyancy, enhanced vegetative proliferation, and often the loss of sexual reproduction. Such forms, often referred to as ecads, presumably derive from typical attached forms, but their affinities are normally difficult to establish with confidence due to their simplified and largely convergent morphology. Minute salt-marsh forms growing partially embedded in the sediment occur on Atlantic and Pacific coasts and have traditionally been recognized as an independent entity, Fucus cottonii. In this study we analyse with four microsatellite loci two F. cottonii populations from salt-marshes of Oregon (NE Pacific) and Ireland (Europe, near the species type locality), as well as local populations of other Fucus spp. that could be considered potential source populations, either directly or via hybridization. Our results show that the F. cottonii from Oregon derive from F. gardneri whereas the Irish population is closer to F. spiralis. We conclude that F. cottonii is not a coherent genetic entity, but an artificial grouping of evolutionarily independent populations that converged into similar morphologies in different salt-marsh habitats.
- Highly polymorphic microsatellite loci for the Parsley frog (Pelodytes punctatus): characterization and testing for cross-species amplificationPublication . Van De Vliet, M. S.; Diekmann, O. E.; Serrão, Ester; Beja, PedroA microsatellite library was developed using genomic DNA of the Parsley frog, Pelodytes punctatus, an amphibian species which inhabits Mediterranean temporary pond systems. Number of alleles and heterozygosity ranged from 10 to 25 and from 0.66 to 0.90, respectively. Crossspecies amplification was successful for 13 of the 15 developed loci for the related species, Pelodytes ibericus. The high levels of polymorphism revealed by these loci will be extremely useful for characterizing the population genetic diversity and structure and to estimate levels of dispersal and gene flow in the species P. punctatus and P. ibericus.
- Highly polymorphic microsatellite markers for the short-snouted seahorse (hippocampus hippocampus), including markers from a closely related species the long-snouted seahorse (hippocampus guttulatus)Publication . Van De Vliet, M. S.; Diekmann, O. E.; Serrão, EsterSpecies of the family Syngnathidae are increasingly being investigated for conservation purposes but also for mating system and genetic parentage studies. The availability of highly polymorphic markers will be of great importance to conduct these kinds of studies. This paper describes the development and characterization of 10 polymorphic microsatellite markers for Hippocampus hippocampus and the utility of nine markers which were developed for a closely related species Hippocampus guttulatus. The number of alleles per locus developed for H. hippocampus ranged from 14 to 30, with levels of heterozygosity between 0.90 and 0.95. Most of the markers were successfully cross-amplified in the sister species, giving clear and unambiguous peaks and maintaining high levels of polymorphism.
- Implications of mating system for genetic diversity of sister algal species: Fucus spiralis and Fucus vesiculosus (Heterokontophyta, Phaeophyceae)Publication . Perrin, C.; Daguin, C.; Van De Vliet, M. S.; Engel, C. R.; Pearson, G. A.; Serrão, EsterThe implications of mating system for genetic diversity were assessed in the sister species Fucus spiralis and Fucus vesiculosus using a combination of ten microsatellite markers. Five new microsatellite markers specific for F. spiralis were developed in order to increase marker resolution and complement the results (i.e. mating system and genetic diversity extended to a larger geographic scale) acquired using five microsatellite loci previously developed from a mixed fucoid seaweed DNA library that excluded F. spiralis. Low genetic diversities observed at the population and species level in F. spiralis using the five new F. spiralis-specific loci described here were consistent with the results obtained previously with non-specific microsatellite loci. Results revealed that selfing is characteristic in F. spiralis across its latitudinal distribution along the Iberian and French Atlantic coasts. Higher levels of within-population genetic diversity were observed in the outcrossing species F. vesiculosus, decreasing towards the southern distributional range of the species. Some cases of significant biparental inbreeding in this species are indicative of short gamete dispersal or mating of spatially or temporally structured populations. In contrast to within-population diversities, higher total genetic diversity among populations was observed in the hermaphroditic species in comparison to the dioecious F. vesiculosus.
- Isolation of highly polymorphic microsatellite loci for a species with a large genome size: Sharp-ribbed salamander (Pleurodeles waltl)Publication . Van De Vliet, M. S.; Diekmann, O. E.; Serrão, Ester; Beja, PedroFourteen highly polymorphic microsatellite markers were developed and characterized for the sharp-ribbed salamander, Pleurodeles waltl. Isolating microsatellites with more than 12 single repeat type units was only successful for a tetranucleotide repeat (ATAG). Compared to microsatellite libraries constructed simultaneously for two anuran amphibian species, a greater number of primer pairs designed for P. waltl had to be discarded, due to consistent amplification problems. Low amplification success rate for P. waltl may be due to its larger genome size. Consequently, to avoid nonspecific binding and to increase amplification success, polymerase chain reaction programmes with touchdown cycles were used. For 14 microsatellite markers, amplification was successful and consistent with number of alleles and expected heterozygosity ranging from seven to 22 and from 0.79 to 0.94, respectively. All 14 microsatellite markers will be extremely useful for metapopulation studies of this unique amphibian species.
- 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.