The evolutionary history of Sphaerodactylus fantasticus (Sauria: Gekkonidae) and its close relatives

Abstract

The evolutionary history of the Lesser Antillean gecko species Sphaerodactylus fantasticus was studied using both molecular and morphometric techniques. Genetic sequence of the mitochondrial gene, cytochrome b was used to create gene trees describing relationships within the S. fantasticus species complex and gene trees describing relationships between all Lesser Antillean Sphaerodactylus species. Analysis of sequence divergence identified saturation of AG substitutions at around 10% sequence mismatch. This observation was used to select weighting rationales for parsimonious phylogeny reconstruction.
The intraspecific gene tree for S. fantasticus identified several clades with defined geographic boundaries, combined with geologic evidence this allowed the inference of a between-clade colonisation sequence and the calibration of a 2.49 - 2.96 % per million year molecular clock. It is recommended that, as the basal Les Saintes clade fits the criterion of the evolutionary species concept, it should be classified as a new species S. phyzacinus.
Patterns of phenotypic geographic variation in S. fantasticus on the island of
Guadeloupe were described using univariate and multivariate methods. Characters showing significant variation were regressed against alternative causative hypotheses via partial matrix correspondence tests. These controlled for the interaction of local adaptation (represented by environmental clines) evolutionary history (represented by patristic distances obtained from
phylogenetic reconstruction) and gene flow (represented by geographic proximity hypotheses). Of the hypotheses tested, those invoking local adaptation were shown to have the greatest association with phenotypic variation.
The interspecific gene tree reconstructed revealed division of Lesser Antillean
endemic species into two clades, one in the north of the region comprising the species S. sputator, S. e/egantulus, S. sabanus and S. fantasticus, and one in the south, comprising the species S. microlepis, S. vincenti and S. kirbyi. These relationships, combined with geologic evidence, were used as a basis to infer a colonisation sequence for the Lesser Antillean region.

Date of Award	Sept 1999
Original language	English
Awarding Institution	University of Wales, Bangor