Adaptive variation in the
Cape girdled lizard

In this project, the Cape girdled lizard (Cordylus cordylus) is used as a model system to investigate how environmental heterogeneity shapes phenotypic, ecological, and genetic variation in natural populations. Cape girdled lizards are endemic to South Africa and have an extensive distribution across the Western, southwestern and Eastern Cape, as well as the southern portions of the Free State and KwaZulu-Natal (Bates et al., 2014). They occur from coastal habitats to high-elevation montane environments exceeding 2,000 m above sea level (Diedericks & Daniels, 2014). The occurrence of Cape girdled lizards is primarily governed by the availability of suitable rocky crevices, with favourable habitats supporting the formation of dense colonies (Branch, 1998). Their occurrence along a broad environmental gradient, combined with locally high population densities, makes the Cape girdled lizard an ideal model system for addressing fundamental questions in evolutionary ecology.

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Multiple data sets are being collected, including detailed morphological measurements, colour-calibrated photography to quantify variation in dorsal and lateral coloration, high-resolution drone imagery to characterise microhabitat structure, mitochondrial genetic data (ND2), and stable isotope analyses to infer ecological differentiation across populations. Sampling is conducted across a pronounced coastal–montane environmental gradient, allowing examination of how climate, habitat structure, and resource use vary spatially and how these factors are reflected in phenotypic and genetic patterns.

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By combining field- and lab-based approaches, this project aims to address key questions in evolutionary ecology, including the drivers of local adaptation, population divergence, and the coupling between phenotype, environment, and genotype in a widely distributed southern African reptile. Genetic samples generated through this project will be archived in a curated research collection and made available for future research that builds upon the present framework. In line with open science principles, all data produced by this project will be made openly accessible through appropriate public repositories to facilitate reuse, synthesis, and comparative research.

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FUNDED BY: Prof. Cang Hui, Mathematical Biosciences Hub, Stellenbosch University