Loading...
4 results
Search Results
Now showing 1 - 4 of 4
- Phylogenetic relationships of African green snakes (genera Philothamnus and Hapsidophrys) from São Tomé, Príncipe and Annobon islands based on mtDNA sequences, and comments on their colonization and taxonomyPublication . Jesus, José; Nágy, Zoltan T.; Branch, William R.; Wink, Michael; Brehm, António; Harris, D. JamesMitochondrial sequences (16S rRNA and cytochrome b) of the colubrine snake genera Philothamnus and Hapsidophrys were analysed. Samples were obtained from three volcanic islands in the Gulf of Guinea. The main objective was to infer phylogenetic relationships between the taxa and to trace back the colonization patterns of the group. Both insular species, Philothamnus girardi and Philothamnus thomensis, form a monophyletic unit indicating a single colonization event of one island (probably São Tomé) followed by dispersal to Annobon. Genetic divergence was found to be relatively low when compared with other Philothamnus species from the African mainland, but sufficient to consider the two taxa as distinct sister species. Here we also present evidence on the distinct phylogenetic position of Hapsidophrys sp. from the island of Príncipe, which should be considered as a distinct species, Hapsidophrys principis, a sister taxon of H. smaragdina.
- Phylogeography of the Madeiran endemic lizard Lacerta dugesii inferred from mtDNA sequencesPublication . Brehm, A.; Jesus, J.; Spínola, H.; Alves, C.; Vicente, L.; Harris, D. J.Partial sequences from two mitochondrial DNA genes, cytochrome b and 12S rRNA, were used to assess the phylogenetic relationships of populations of Lacerta dugesii from the volcanic Atlantic islands of Madeira, the Desertas, Porto Santo, and the Selvagens. All four-island groups are genetically distinguishable and populations within each contain similar degrees of genetic diversity. Molecular clock estimates suggest that the islands were colonized much later after their emergence compared to other Atlantic islands, possibly due to their greater geographical isolation. Mismatch analysis of all populations is consistent with exponential growth, as expected after colonization of empty niches. The Selvagens contain genetic substructuring between the islets
- Relationships of Afroablepharus Greer, 1974 skinks from the Gulf of Guinea islands based on mitochondrial and nuclear DNA: patterns of colonization and comments on taxonomyPublication . Jesus, José; Harris, D. James; Brehm, AntónioPartial sequences of three mitochondrial DNA genes, 12S rDNA, 16S rDNA and cytochrome b, and one nuclear gene, c-mos, were used to assess the phylogenetic relationships of species belonging to the genus Afroablepharus from the volcanic islands of the Gulf of Guinea (West Africa) and neighboring continental Africa. Additionally, partial sequences of cytochrome b were used to compare levels of sequence divergence within populations. The three forms from São Tomé, Príncipe and Annobon (one per island) are genetically distinct, with high levels of divergence, supporting the recognition of a distinct species in each island. Populations within each island contain very low levels of genetic diversity. These three forms form a monophyletic group suggesting a single initial colonization followed by radiation to the other islands, possibly from São Tomé to Príncipe and Annobon. This is contrary to what was found in other reptiles from these islands such as Mabuya (sensu lato) and Hemidactylus, which colonized the islands multiple times. Assuming a molecular clock for cytochrome b of about 2% divergence per million years (usually applied to Sauria), the lineage on Annobon island exceeds the age of the island, thus casting further doubt on this widely used divergence estimate. Partial sequences of c-mos showed no variation within islands. Five to seven sites were variable among islands, which is a high value further supporting the treatment of each island form as a distinct species.
- Genetic identity of Pipistrellus maderensis from the Madeira archipelago: a first assessment, and implications for conservationPublication . Jesus, José; Teixeira, Sérgio; Freitas, Tamira; Teixeira, David; Brehm, AntonioAccording to the IUCN global Red List, Pipistrellus maderensis is among the most endangered bat species in Europe. Its populations are scattered across some islands of the Atlantic Ocean, particularly Madeira and the Canary archipelagoes. This geographical pattern is likely to result in significant genetic differences between populations which would have important implications to set conservation priorities. To test this hypothesis, we analyze cytochrome b sequences and compared populations from Madeira and the Canary islands. Five sequences from Madeiran individuals were analysed and compared to 30 sequences extracted from GenBank from Pipistrellus maderensisfrom the Canary islands and Pipistrellus kuhli. Our results indicate a significant divergence between the two groups, smaller than between true species, but higher that intra-group divergence. However, further research on the Madeiran popula tion is needed, including the use of sequences of other mitochondrial markers and nuclear marker and microsatellites