Predicting the structure of turtle assemblages along a megatransect in West Africa

Luiselli, L, Akani, GC, Ajong, SN, George, A, Di Vittorio, M, Eniang, EA, Dendi, D, Hema, EA, Petrozzi, F and Fa, John ORCID: https://orcid.org/0000-0002-3611-8487 (2020) Predicting the structure of turtle assemblages along a megatransect in West Africa. Biological Journal of the Linnean Society, 130. pp. 296-309. ISSN 0024-4066

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Abstract

Understanding large- and small-scale patterns as well as the determinants of species richness is central for the study of evolutionary mechanisms. The extent to which species richness in local communities is related to larger scale processes is a pre-eminent topic in ecological and evolutionary research. To investigate how local and regional species richness are related, we sampled freshwater turtle assemblages in seven localities to represent the variation in ecological conditions along a 90km South-North megatransect in Benin, West Africa. In each locality, all turtles captured were identified and measured, and microhabitat classified in which individual turtles were observed. Based on these data we used community diversity metrics to compare turtle assemblages. Spatial autocorrelation did not affect our data. For all localities pooled, only two species (Pelusios castaneus and Pelomedusa olivacea) were the most common, and one species (Trionyx triunguis) the rarest. Analyses of the commonest and more numerous species showed that the abundance of P. castaneus declined with an increase in latitude and longitude, but the opposite was true for P. olivacea. We showed that various microhabitat characteristics were significantly correlated with the abundance of the two common species. We found significant but variable South-North gradients in microhabitat use for different turtle species. Our results highlight the importance of studying interactions between local environments, the ecological requirements of each species, and their synecological relationships.