The origin of morphological diversity is a critical question in evolutionary biology. Interactions between the environment and developmental processes have determining roles in morphological diversity, creating patterns through space and over time. Also, the shape of organisms tends to vary with increasing size as a result of those developmental processes, known as allometry. Several studies have demonstrated that the body sizes of anurans are associated with hydric conditions in their environments and that localities with high water stress tend to select for larger individuals. However, how environmental conditions alter those patterns of covariance between size and shape is still elusive. We used 3D geometric morphometric analyses, associated with phylogenetic comparative methods, to determine if the morphological variations and allometric patterns found in Arboranae (Anura) is linked to water conservation mechanisms. We found effects of the hydric stress on the shape of Arboranae species, favouring globular shapes. Also, the allometric patterns varied in intensity according to the water stress gradient, being particularly relevant for smaller frogs, and more intense in environments with higher water deficits. Our study provides empirical evidence that more spherical body shapes, especially among smaller species, reflect an important adaptation of anurans to water conservation in water-constrained environments.

Amazonia harbours a vast biotic and ecological diversity, enabling investigation of the effects of microevolutionary processes and environmental variation on species diversification. Integrative approaches combining phenotypic and genetic variation can improve our knowledge on diversification processes in megadiverse regions. Here, we investigate the influence of environmental and geographic variation on the genetic and morphological differentiation in the Amazonian Boana calcarata-fasciata (Anura: Hylidae) species complex. We analysed the variation of one mtDNA gene from individuals of different forest environments, and assessed their phylogenetic relationships and species limits to define the lineages to perform a phenotypic-environmental approach. We collected morphological data (head shape and size) using 3D models and investigated the phylogenetic signal, evolutionary model and influence of environmental variables on morphology. We verified associations between environmental and geographical distances with morphological and genetic variation using distance-based redundancy analyses and Mantel tests. We found an even higher cryptic diversity than already recognized within the species complex. Body size and head shape varied among specimens, but did not present phylogenetic signal, diverging under a selective evolutionary model. Our results show that diverse factors have influenced morphological and genetic variation, but environmental conditions such as vegetation cover, precipitation and climate change velocity influenced morphological diversification. Possible population-level mechanisms such as parallel morphological evolution or plastic responses to similar environments could account for such patterns in these typical Amazonian treefrogs.

No abstract

Geometric morphometrics were used to analyse ontogenetic trajectories in representatives of the Characiformes, Cichliformes, Cyprinodontiformes, Siluriformes, and Tetraodontiformes. It was not possible to differentiate any allometric growth patterns across groups, indicating that a phylogenetically conserved developmental pattern is widespread throughout Teleostei.