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Community assembly

Community assembly rules and resource partitioning in Malagasy chameleon communities : a critical test of the ectomorph concept?

PhD Proposal

Understanding the formation and coexistence of communities of closely related species is crucial for conservation. Previous research, mainly focused on lizards of the genus Anolis, has highlighted the importance of evolutionary convergence and the ecomorph concept in structuring these communities. However, validation of these concepts in other lizards remains limited. The chameleons of Madagascar offer a unique opportunity to explore these ideas, as they present complex communities on the island, although the data needed to do so is currently lacking. We therefore propose an integrative project focusing on the morphology, performance and ecology of chameleon communities to better understand how these species allocate resources.

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Ecological niches modeling

Using data from the previous chapters, we will model ecological niches to assess the ability of Vohimana communities to persist under various climate change scenarios. We will establish mechanistic niche models taking into account the biology and physiology of species, providing more accurate predictions than traditional models. We will calculate response surfaces based on temperature and body size of chameleons, which we will use to predict their future distribution in Madagascar.

Source: Galante, Peter J., et al. (2018). The challenge of modeling niches and distributions for data-poor species: a comprehensive approach to model complexity. Ecography, vol. 41, no 5, p. 726-736.

Axes of differentiation

Using collections from the National Museum of Natural History in Paris and elsewhere, we will compare chameleon communities from five regions of Madagascar. We will assess their community composition (species diversity) and morphological occupation (morphological diversity) to test if the concept of ecomorph, observed in Caribbean Anolis, applies to chameleons. We will examine the morphology of 30 individuals of each species at each site, where possible, to understand intra- and interspecific variation.

Photo: Martin Etave

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Form – function relationships

To understand how morphological variation can allow for niche partitioning among chameleons, we will study the species in the Vohimana reserve. We will measure their physical performances, such as bite and grip strength, as well as sprint speed. We will also film prey capture and quantify tongue projection performance using high-speed wearable cameras. Finally, we will examine their thermal dependence and measure physiological limits for each species.

Source: Ekhator, Chukwuyem, et al. (2023). Locomotor characteristics of the ground-walking chameleon Brookesia superciliaris. Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, vol. 339, no 6, p. 602-614.

Field data collection

We will quantify the use of ecological niches for the 13 species of chameleons that make up the community in the Vohimana reserve, Madagascar. This community is of interest due to its specific and morphological diversity. Additionally, it includes the largest (Calumma parsonii) as well as some of the smallest chameleons (Brookesia). We will analyze their habitat, feeding, and thermal preferences using non-invasive methods. These unprecedented data will be crucial for considering both in situ and ex situ conservation projects.

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3 years

150 000 CHF


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