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Die Insel Teneriffa (Kanarischer Archipel) wird von zwei Unterarten von Gallotia galloti bewohnt, von denen die Nominatform im Zentrum und im Süden lebt. Für sie wird ein Lectotypus designiert, und die terra typica wird auf das Tal von Güimar restringiert. Die größere und buntgefärbte Form der Anaga-Halbinsel und der Nordküste wird als Gallotia galloti eisentrauti ssp.n. (terra typica Bajamar) beschrieben. Das Vorkommen zweiter distinkter Unterarten, die auch sekundäre Kontaktzonen ausbilden, wird historisch diskutiert und stützt die Hypothese, daß Teneriffa ursprünglich aus mindestens zwei getrennten Teilen bestanden hat. Die Verbreitung von G. galloti auf den vier westlichen Kanaren-Inseln Teneriffa, Gomera, Hierro und La Palma wird mit derjenigen anderer Echsenarten dieser Inseln vergleichend diskutiert.

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Several processes have been described that could explain geographical variation and speciation within small islands, including fragmentation of populations through volcanic eruptions. Massive landslides, or debris avalanches, could cause similar effects. Here we analyse the potential impact of the 0.8 million-year-ago (Ma) Güimar valley debris avalanche on the phylogeography of the lizard Gallotia galloti on the Canary Island of Tenerife.

Distributions of mitochondrial DNA lineages (based on cytochrome b sequences) were analysed on a 60-km southeastern coast transect centred on this area. Three main clades were detected, which can be divided into northern (one clade) and southern (two clades) groups that introgress across the valley.

Maximum-likelihood estimates of migration rates (scaled for mutation rate) revealed highly asymmetric patterns, indicating that long-term gene flow into this region from both the northern and the southern populations greatly exceeded that in the opposite directions, consistent with recolonization of the area.

The ancestral Tenerife node on the G. galloti tree is estimated at 0.80 Ma, matching closely with the geological estimate for the debris avalanche.

Morphological variation (body dimensions and scalation) was also analysed and indicated a stepped cline in female scalation across the valley, although the patterns for male scalation and male and female body dimensions were not as clear. Together these findings provide support for the hypothesis that the debris avalanche has shaped the phylogeography of G. galloti and may even have been a primary cause of the within-island cladogenesis through population fragmentation and isolation.

Current estimates of timing of island unification mean that the original hypothesis that within-island diversity is explained by the secondary contact of populations from the two ancient precursor islands of Teno and Anaga is less plausible for this and some other Tenerife species.

Large-scale landslides have occurred on many volcanic islands, and so may have been instrumental in shaping within-island diversities.

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Microgeographic variation of the vegetarian lizard Gallotia galloti within the island of Tenerife is described using univariate analysis, correlation, multiple group principal component analysis, canonical analysis, transects, and contours. The size varies locally in a mosaic pattern while head shape shows a WNW–ESE cline in the south. The scalation (scale and femoral pore counts) has two facets to its geographic variation, both of which are incongruent with the primary variation in the size and shape. The scalation shows categorical variation (stepped cline) between northern and southern populations and also a strong clinal relationship with altitude. The possible causes of this variation are considered and adaptation to current ecological conditions appears to be implicated for at least the altitudinal variation, although the pertinent factors are not obvious. It is apparent that vertebrate populations distributed across small islands do not necessarily offer the advantage of a discrete homogeneous unit for evolutionary studies but can offer the opportunity for studying microgeographic variation.

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This study of the microgeographic variation in the colour pattern of the lizard, Gallotia galloti, within Tenerife has three facets. One, an analysis of the population distribution and density in relation to physical conditions; two, univariate and multivariate descriptions of the pattern of geographic variation; and three, formal testing of a range of causal hypotheses for these geographic patterns. The range is not divided into separate allotheses high- and low-altitude populations by a inaptitude ring of ground-level cloud although there is a drop in population-density in the middle altitudes. Multiple regression indicates that, or the factors measured, this is primarily due to a decrease in insolation. The pattern of geographic variation in the six independent colour pattern characters is portrayed by contouring the 67 locality means. There is generally good congruence among these patterns and a canonical analysis indicates that the generalized pattern of geographic variation is largely unidimensional and can therefore be represented adequately by (and portrayed by contouring) the first canonical variate. Seven causal hypotheses, from a range of possible and previously suggested causes, are considered. The procedure for testing these hypotheses should depend on their dimensionality and that of the observed pattern. Since all the observed and hypothesized patterns are basically unidimensional the seven hypothesized patterns were simultaneously tested against each observed pattern (individual characters and canonical variate) by partial correlation. All the previously suggested ‘phylogenetic’ hypotheses based on divergence in allopatry are rejected. The hypotheses that the geographic variation in the colour pattern is caused by the topographically determined climate cannot be rejected. The character state changes can be explained by a balance between sexual selection for ‘attractive’ colouration and natural selection, via predation, for cryptic colouration.

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areas in different landscapes and climatic zones. Our special interest was the herpetofauna of this island that is poor in species numbers but nonetheless very interesting. One focus was the search for the Tenerife Speckled Lizard (Gallotia intermedia) in the South and Southwest of the island.

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After a brief overview of the geological processes that shaped Tenerife, the island’s geographical diversity, the distribution of the Tenerife lizard (Gallotia galloti), and the intergradation zones between its subspecies are presented. Based on the collected data, a map was created illustrating the probable intergradation zone between G. g. galloti and G. g. eisentrauti.