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Intercontinental ecomorph convergence in jumping spiders (Araneae: Salticidae) Piascik, Edyta Katherine

Abstract

The ecomorph convergence hypothesis states that the relationship between morphology and ecology will be similar in independently evolved communities. Molecular phylogenetic studies show that most major groups of jumping spiders (Salticidae) are primarily restricted to one continental region, indicating independent replicate radiations. This study asks whether phylogenetically independent communities of salticids predictably converge in morphospace and how likely are they to be influenced by historical contingencies. To test the ecomorph convergence hypothesis, 281 salticid species were collected in two comparable tropical rainforests in Ecuador and Borneo while recording habitat data. Parsimony methods indicate that there are a minimum of 17 evolutionary transitions that have occurred between foliage, ground, and trunk microhabitats. The transitions among all three microhabitats have occurred independently in a major clade of Euophryines, within the Freyines, within the Marpissoids, and within the Amycines. Most of the diversification occurred within continents as the major clades are largely restricted to continental regions. Strict criteria ensuring sufficient sample size, habitat data, and phylogenetic independence in species comparisons resulted in 36 species for all morphometric analyses. Ecomorphs show signs of clustering in multivariate morphological space and there are significant differences in morphology between microhabitats. Trunk salticids have flatter carapaces with shorter legs than ground salticids while foliage salticids have raised carapaces and longer legs when compared to trunk salticids. The relationship between foliage and ground salticids is not as clear. Foliage salticids exhibit the widest range of body forms when compared to the other two ecomorphs. By combining morphometric measurements with molecular phylogenetic data, I show that independent origins of microhabitat use lead to similar body forms providing evidence for the ecomorph convergence hypothesis. However, I also find differences in convergence patterns between continents in terms of the number of shifts between ecomorph origins and species composition between the three microhabitats. These results provide a rare example of a large scale study of intercontinental community-wide patterns that show a mix between convergence and contingency using a comparative phylogenetic framework while demonstrating quantitatively that large scale continental diversifications can behave as predictably as smaller diversifications.

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Attribution-NonCommercial-NoDerivs 2.5 Canada

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