Girinos do quadrilátero ferrífero, sudeste do Brasil: ecomorfologia e chave de identificação interativa

Abstract

Tadpoles use a wide diversity of habitats with different environmental pressures. The existence of highly specialized body shapes is a strong evidence that these organisms were selected to exploit specific habitats. However, little is known about the real morphometric differences and the functionality of these attributes between ecomorphological guilds and between tadpoles that occupy different environmental gradients. Moreover, the extent in which phylogenetic and ecological components influence tadpole external morphology is still poorly understood. This study aimed to explore relationships between form, habitat use/behavior and phylogeny of the larvae of 58 species of frogs belonging to 21 genera and nine families, found in the Quadrilátero Ferrífero region, state of Minas Gerais, Southeastern Brazil. Firstly the species morphological variability was analyzed through ordination techniques. Then the assumptions about the existence of shape patterns in tadpoles of different ecomorphological guilds and environmental gradients were tested by discriminant function analysis. Finally, the influence of ecological and phylogenetic factors on larvae morphology was analized in the range of communities and considering separately families with the greatest number of species. For this, simple and partial Mantel tests were used to test the hypotheses about the existence of correlations between these factors and morphology. The tadpoles presented a great morphological diversity, mainly related to the foraging position in the water column (i.e. nektonic, neustonic, benthic, fossorial, semiterrestrial). There were morphological differences between the groups of species categorized according to this descriptor (Wilks = 0,007; F64,25 = 101,74; p < 0,001), agreeing with the ordination analysis. There were also differences between species with gregarious behavior and the others (Wilks = 0,52; F10,67 = 161,20; p < 0,001) and between species of lentic and lotic environments (Wilks = 0,47; F9,671 = 83,96; p < 0,001). There were no morphometric differences between species that occupy temporary or permanent habitats. Tadpoles morphology was related to habitat use/behavior (r = -0,310, p < 0,001), regardless of species phylogenetic relationships. This overall effect is caused by the predominance of homoplasies and adaptive radiation in the lineges represented in the community. This pattern was not as consistent considering the most representative families. Despite the importance of phylogenetic signal at smaller taxonomic scales (i.e. in some species groups and in the Hylidae and Leptodactylidae families) it is insignificant when superimposed by the general effects resulting from adaptation of tadpoles to the habitats