Browsing by Author "Ferrand, Nuno"
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- Extensive intraspecific polymorphism detected by SSCP at the nuclear C-mos gene in the endemic Iberian lizard Lacerta SchreiberiPublication . Godinho, Raquel; Domingues, Vera dos Santos; Crespo, Eduardo G.; Ferrand, NunoC-mos is a highly conserved intronless gene that has proved useful in the analysis of ancient phylogenetic relationships within vertebrates. We selected the Iberian endemic Schreiber’s green lizard (Lacerta schreiberi) that persisted in allopatric refugia since the late Pliocene to investigate the utility of the Cmos nuclear gene for intraspecific phylogeographic studies. Our combination of DNA sequencing with the high resolving power of single-strand conformational polymorphism (SSCP) effectively discriminated four common alleles showing strong population structuring (FST = 0.46). In addition, reconstruction of allele phylogenetic relationships further improved our understanding of Cmos spatial patterns of variation and allowed a comparison with previously described mitochondrial DNA data. Finally, limited sequencing of an extended Cmos fragment in six additional Lacerta species showed extensive polymorphism, to our knowledge representing a rare example of variation in a highly conserved nuclear gene.
- Genetic characterization of green turtles (Chelonia mydas) from São Tomé and Príncipe: Insights on species recruitment and dispersal in the Gulf of GuineaPublication . Hancock, Joana M.; Vieira, Sara; Taraveira, Lúcio; Santos, Aladino; Schmitt, Vanessa; Semedo, Alcides; Patrício, Ana Rita; Ferrand, Nuno; Gonçalves, Helena; Sequeira, FernandoGenetic studies on green sea turtles (Chelonia mydas) in the Eastern Atlantic have mostly focused on reproductive females, with limited information available regarding juveniles and foraging grounds. Improved understanding of genetic diversity and patterns of connectivity between nesting and foraging grounds is critical to identify management units and delineate suitable conservation strategies. Here we analyzed data from 11 microsatellite markers and sequences of the mitochondrial control region from both juveniles and females sampled in foraging and nesting aggregations around São Tomé and Príncipe islands, in the Gulf of Guinea, West Africa. Both nuclear and mtDNA data were congruent in showing that São Tomé and Príncipe's green turtles population exhibit high levels of genetic diversity, which are similar to those reported for other foraging aggregates in the Atlantic. Although signs of population substructure among foraging and nesting grounds of São Tomé and Príncipe islands were not apparent, our analysis based on mtDNA marker showed that both juvenile and adult turtles were genetically differentiated from other foraging and nesting Atlantic populations. The similar levels of genetic diversity found in both juveniles and females are consistent with the results from mixed stock analyses, which suggested that São Tomé and Príncipe's rookery is the primary source of juveniles to the local foraging aggregation. Taken these aspects in consideration, we argue that São Tomé and Príncipe green turtles show limited dispersal and should be considered an important management unit, and conservation actions in this archipelago must be implemented not only at the level of the rookery but should also include the foraging aggregations.
- Understanding the mechanisms of antitropical divergencein the seabird White-faced Storm-petrel (Procellariiformes:Pelagodroma marina) using a multilocus approachPublication . Silva, Mónica C.; Matias, Rafael; Wanless, Ross M.; Ryan, Peter G.; Stephenson, Brent M.; Bolton, Mark; Ferrand, Nuno; Coelho, Manuela M.Analytical methods that apply coalescent theory to multilocus data have improved infer-ences of demographic parameters that are critical to understanding population divergenceand speciation. In particular, at the early stages of speciation, it is important to implementmodels that accommodate conflicting gene trees, and benefit from the presence of sharedpolymorphisms. Here, we employ eleven nuclear loci and the mitochondrial control regionto investigate the phylogeography and historical demography of the pelagic seabirdWhite-faced Storm-petrel (Pelagodroma marina)bysamplingsubspeciesacrossitsanti-tropical distribution. Groups are all highly differentiated: global mitochondrial ΦST= 0.89(P < 0.01) and global nuclear ΦSTvaries between 0.22 and 0.83 (all P < 0.01). The completelineage sorting of the mitochondrial locus between hemispheres is corroborated by approx-imately half of the nuclear genealogies, suggesting a long-term antitropical divergence inisolation. Coalescent-based estimates of demographic parameters suggest that hemisphericdivergence of P. marina occurred approximately 840 000 ya (95% HPD 582 000–1 170 000),in the absence of gene flow, and divergence within the Southern Hemisphere occurred190000ya(95%HPD96000–600 000), both probably associated with the profound palaeo-oceanographic changes of the Pleistocene. A fledgling sampled in St Helena (tropicalSouth Atlantic) suggests recent colonization from the Northern Hemisphere. Despite thegreat potential for long-distance dispersal, P. marina antitropical groups have beenevolving as independent, allopatric lineages, and divergence is probably maintained byphilopatry coupled with asynchronous reproductive phenology and local adaptation.