Diversity of reptiles in the São Tomé island group: a comparison of colonization events by nonvolant vertebrates in other Atlantic Islands

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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 taxonomy

Publication . Jesus, José; Nágy, Zoltan T.; Branch, William R.; Wink, Michael; Brehm, António; Harris, D. James

Mitochondrial 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.

2009Journal article

Open access

Phylogenetic relationships of Lygodactylus geckos from the Gulf of Guinea islands: rapid rates of mitochondrial DNA sequence evolution?

Publication . Jesus, José; Brehm, António; Harris, D. James

Mitochondrial DNA (12S rRNA, 16S rRNA and cytochrome b) sequences and nuclear sequences (C-mos) were analysed within Lygodactylus thomensis from three volcanic islands in the Gulf of Guinea that have never been connected to the continent. Our aim was to assess interrelationships between the three subspecies to test a recent hypothesis suggesting high rates of mitochondrial DNA (mtDNA) sequence evolution in geckos. Our results indicate, based on mtDNA sequence data, that the three subspecies are genetically differentiated at a level more typically observed between species. However, the forms cannot be differentiated using the nuclear marker C-mos. These results further substantiate the hypothesis of rapid rates of mtDNA sequence evolution in geckos, although the alternative that C-mos is evolving more slowly cannot be discounted. They also suggest that present calibrations for molecular clocks are at the upper limit of divergence over time.

2006Journal article

Open access

Relationships of scincid lizards (Mabuya spp.) from the islands of the Gulf of Guinea based on mtDNA sequence data

Publication . Jesus, José; Brehm, António; Harris, D. James

Relationships of Mabuya lizards from the islands of the Gulf of Guinea where estimated using partial 12S rRNA, 16S rRNA and cytochrome b mitochondrial gene sequences. Mabuya maculilabris from São Tomé and Principe are discreet monophyletic units, highly divergent from each other and from mainland populations, indicating M. maculilabris may be a species complex. Mabuya affinis from Principe is similarly distinct from mainland populations of this species. The relationships of Mabuya ozorii from Annobon are unclear, but the three species in the Gulf of Guinea islands are not closely related, indicating multiple independent colonization events. The recent proposal to partition Mabuya into four genera is premature, since at least five distinct genetic lineages can be identified.

2005Journal article

Open access

Relationships of Afroablepharus Greer, 1974 skinks from the Gulf of Guinea islands based on mitochondrial and nuclear DNA: patterns of colonization and comments on taxonomy

Publication . Jesus, José; Harris, D. James; Brehm, António

Partial 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.

2007Journal article

Open access

Phylogenetic relationships of Hemidactylus geckos from the Gulf of Guinea islands: patterns of natural colonizations and anthropogenic introductions estimated from mitochondrial and nuclear DNA sequences

Publication . Jesus, José; Brehm, António; Harris, D. James

Mitochondrial DNA (12S rRNA, 16S rRNA, and cytochrome b) sequences and nuclear sequences (C-mos and alpha-Enolase) were analyzed within all known Hemidactylus species from all three volcanic islands in the Gulf of Guinea that have never been connected to the continent. These comprise both endemic and widespread species. Our aim was to determine if the widespread species was introduced anthropogenically, to determine the number of distinct genetic lineages within the islands, and to determine if the endemic forms constituted a monophyletic group. Our results suggest that a previously undescribed species on São Tomé is the sister taxon to Hemidactylus newtoni, endemic to Annobon. Genetic variation between populations of Hemidactylus greefii from São Tomé and Principe is very high based on mtDNA sequences, but the forms cannot be distinguished using the nuclear DNA sequences. Hemidactylus mabouia appears to have been anthropogenically introduced to all three islands. The island endemics do not form a monophyletic group, suggesting multiple independent colonizations of the islands.

2005Journal article

Open access