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- Multilocus genetic analyses provide insight into speciation and hybridization in aquatic grasses, genus RuppiaPublication . Martínez-Garrido, Jose; Serrão, Ester; Engelen, Aschwin H.; Cox, C. J.; García-Murillo, Pablo; Gonzalez-Wangueemert, MercedesAquatic plants of the genus Ruppia inhabit some of the most threatened habitats in the world, such as coastal lagoons and inland saline to brackish waters where their meadows play several key roles. The evolutionary history of this genus has been affected by the processes of hybridization, polyploidization, and vicariance, which have resulted in uncertainty regarding the number of species. In the present study, we apply microsatellite markers for the identification, genetic characterization, and detection of hybridization events among populations of putative Ruppia species found in the southern Iberian Peninsula, with the exception of a clearly distinct species, the diploid Ruppia maritima. Microsatellite markers group the populations into genetically distinct entities that are not coincident with geographical location and contain unique diagnostic alleles. These results support the interpretation of these entities as distinct species: designated here as (1) Ruppia drepanensis, (2) Ruppia cf. maritima, and (3) Ruppia cirrhosa. A fourth distinct genetic entity was identified as a putative hybrid between R. cf. maritima and R. cirrhosa because it contained a mixture of microsatellite alleles that are otherwise unique to these putative species. Hence, our analyses were able to discriminate among different genetic entities of Ruppia and, by adding multilocus nuclear markers, we confirm hybridization as an important process of speciation within the genus. In addition, careful taxonomic curation of the samples enabled us to determine the genotypic and genetic diversity and differentiation among populations of each putative Ruppia species. This will be important for identifying diversity hotspots and evaluating patterns of population genetic connectivity. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 00, 000–000.
- Highly polymorphic microsatellite markers for the Mediterranean endemic fan mussel Pinna nobilisPublication . Gonzalez-Wanguemert, Mercedes; Costa, J.; Basso, L.; Duarte, C. M.; Serrão, Ester; Hendriks, IrisPinna nobilis is an endemic bivalve of the Mediterranean Sea whose populations have decreased in the last decades due to human pressure; as a consequence, it was declared a protected species in 1992. Despite its conservation status, few genetic studies using mitochondrial markers have been published. We report on the isolation and development of 10 microsatellite loci for the fan mussel, Pinna nobilis. All loci (2 di-nucleotide, 5 tri-nucleotide, 2 tetra-nucleotide and 1 penta-nucleotide) are characterized by high levels of polymorphism in 76 individuals tested from two populations in the Balearic Islands (Spain, Western Mediterranean Sea). The number of alleles ranged from 4 to 24 and expected heterozygosity ranged from 0.4269 to 0.9400. These microsatellites could be very useful for the assessment of the genetic diversity and connectivity patterns of P. nobilis and the establishment of new conservation strategies.
- Genetic evidence for polygynandry in the black-striped pipefish Syngnathus abaster: A microsatellite-based parentage analysisPublication . Hübner, K.; Gonzalez-Wanguemert, Mercedes; Diekmann, O. E.; Serrão, EsterSexual selection theory predicts that, in organisms with reversed sex roles, more polyandrous species exhibit higher levels of sexual dimorphism. In the family Syngnathidae (pipefish, seahorses, and seadragons), males provide all parental care by carrying developing embryos on their ventral surfaces, and females develop secondary sex characters. Syngnathids exhibit a variety of genetic mating patterns, making them an ideal group to test predictions of sexual selection theory. Here, we describe the mating system of the black-striped pipefish Syngnathus abaster, using 4 highly variable microsatellites to analyze parentage of 102 embryos. Results revealed that 1) both sexes mate multiple times over the course of a pregnancy (polygynandrous mating system), 2) eggs are spatially segregated by maternity within each brood pouch, and 3) larger females have higher mating success (Kolmogorov–Smirnov test; P < 0.05). Together with similar studies of other syngnathid species, our results support the hypothesis that the mating system is related to the intensity of sexual dimorphism.
- Genetic signature of a recent invasion: the ragged sea hare Bursatella leachii in Mar Menor (SE Spain)Publication . Gonzalez-Wanguemert, Mercedes; Domínguez-Godino, J.; Giménez-Casalduero, F.; Serrão, EsterIn the last years, bioinvasions are increasing their ecological and economic impacts on different habitats all over the world, and are therefore becoming the target of much recent research (Ricciardi et al., 2004; Bernardi et al., 2010; Zenetos et al., 2012). The leading hypothesis for the origin of invasions is that colonization by invasive species is most often associated with founder events of introduction by occasional windows of opportunity (Montefalcone et al., 2010; Zhan et al., 2010), although distinct invasion processes might occur simultaneously in different parts of the invaded range, and some can create local accumulation of genetically distinct invaders. In a typical invasion scenario, however, the few founders are then the source of rapid demographic expansions in the new habitats. Such processes result in extreme genetic diversity loss. Biological invasions thus contradict the paradigm of genetic diversity being essential for adaptation to novel habitats.
- West versus East Mediterranean Sea: origin and genetic differentiation of the sea cucumber Holothuria poliiPublication . Valente, Sara; Serrão, Ester; Gonzalez-Wangueemert, MercedesWe studied the genetic structure of the sea cucumber Holothuria (Roweothuria) polii (Delle Chiaje 1823) by analysing the mitochondrial DNA variation in two fragments of cytochrome oxidase I (COI) and 16S genes. Individuals were collected in seven locations along the Mediterranean Sea, which cover a wide range of the species distribution. We found high haplotype diversity for COI and moderate diversity for 16S, and low nucleotide diversity for both genes. Our results for the COI gene showed many recent and exclusive haplotypes with few mutational changes, suggesting recent or ongoing population expansion. The Western and Eastern Mediterranean populations exhibited slight but significant genetic differentiation (COI gene) with higher genetic diversity in the East. The most ancient haplotype was not present in the westernmost sampling location (SE Spain). The oldest expansion time was observed in Turkey, corresponding to mid-Pleistocene. Turkey had also the highest genetic diversity (number of total and exclusive haplotypes, polymorphisms, haplotype and nucleotide diversity). This suggests that this region could be the origin of the subsequent colonizations through the Mediterranean Sea, a hypothesis that should be assessed with nuclear markers in future research.
- Genetic evidence for polygynandry in the black-striped pipefish syngnathus abaster: a microsatellite-based parentage analysisPublication . Huebner, Kerstin; Gonzalez-Wanguemert, Mercedes; Diekmann, O. E.; Serrão, EsterSexual selection theory predicts that, in organisms with reversed sex roles, more polyandrous species exhibit higher levels of sexual dimorphism. In the family Syngnathidae (pipefish, seahorses, and seadragons), males provide all parental care by carrying developing embryos on their ventral surfaces, and females develop secondary sex characters. Syngnathids exhibit a variety of genetic mating patterns, making them an ideal group to test predictions of sexual selection theory. Here, we describe the mating system of the black-striped pipefish Syngnathus abaster, using 4 highly variable microsatellites to analyze parentage of 102 embryos. Results revealed that 1) both sexes mate multiple times over the course of a pregnancy (polygynandrous mating system), 2) eggs are spatially segregated by maternity within each brood pouch, and 3) larger females have higher mating success (Kolmogorov–Smirnov test; P < 0.05). Together with similar studies of other syngnathid species, our results support the hypothesis that the mating system is related to the intensity of sexual dimorphism.
- New highly polymorphic microsatellite markers for the aquatic angiosperm Ruppia cirrhosa reveal population diversity and differentiationPublication . Martínez-Garrido, J.; Gonzalez-Wanguemert, Mercedes; Serrão, EsterRuppia cirrhosa is a clonal monoecious plant phylogenetically associated to seagrass families such as Posidoniaceae and Cymodoceaceae. It inhabits shallow waters that are important for productivity and as a biodiversity reservoir. In this study, we developed 10 polymorphic microsatellite loci for R. cirrhosa. Additionally, we obtained cross-amplification for two microsatellites previously described for Ruppia maritima. These 12 markers were tested in four R. cirrhosa populations from the southwest of Europe. The number of alleles per locus was high for most of the markers, ranging from 4 to 13. Two populations (Sicily and Cádiz) showed heterozygote deficit (p < 0.001). The four populations (Sicily, Murcia, Cádiz, and Tavira) were significantly differentiated (FST ≠ 0; p < 0.001), corroborating the usefulness of these microsatellites on R. cirrhosa population genetics.