ABSTRACT
Internal organs of ectotherms have melanin-containing cells that confer different degrees of coloration to them. Previous experimental studies analyzed their developmental origin, role in immunity, and hormonal regulation. For example, melanin increases with ultraviolet radiation (UV) and temperature in frogs and fish. However, little is known about how environmental variables influence the amount of coloration on organs among amphibian species over a large spatial extent. Here, we tested how climatic variables (temperature, UV, and photoperiod) influence the coloration of internal organs of anurans. We recorded the level of melanin pigmentation using four categories on 12 internal organs and structures of 388 specimens from 43 species belonging to six anuran families. Then, we tested which climatic variables had the highest covariation with the pigmentation on each organ after controlling for spatial autocorrelation in climatic variables and phylogenetic signal in organ coloration using the extended version of the RLQ ordination. Coloration in all organs was correlated with the phylogeny. However, the coloration of different organs was affected by different variables. Specifically, the coloration of the heart, kidneys, and rectum of hylids, Rhinella schneideri, some Leptodactylus, and Proceratophrys strongly covaried with temperature and photoperiod, whereas that of the testicle, lumbar parietal peritoneum, lungs, and mesenterium of Leiuperinae, Hylodidae, Adenomera, and most Leptodactylus had highest covariation with UV-B and temperature. Our results support the notion that melanin pigmentation on the surface of organs of amphibians has an adaptive function conferred by the protective functions of the pigment. But most importantly, internal melanin seems to respond differently to climatic variables depending on the lineage and locality in which species occur.
ABSTRACT
Salinity is the primary driver of osmoregulatory evolution in decapods, and may have influenced their diversification into different osmotic niches. In semi-terrestrial crabs, hyper-osmoregulatory ability favors sojourns into burrows and dilute media, and provides a safeguard against hemolymph dilution; hypo-osmoregulatory ability underlies emersion capability and a life more removed from water sources. However, most comparative studies have neglected the roles of the phylogenetic and environmental components of inter-specific physiological variation, hindering evaluation of phylogenetic patterns and the adaptive nature of osmoregulatory evolution. Semi-terrestrial fiddler crabs (Uca) inhabit fresh to hyper-saline waters, with species from the Americas occupying higher intertidal habitats than Indo-west Pacific species mainly found in the low intertidal zone. Here, we characterize numerous osmoregulatory traits in all ten fiddler crabs found along the Atlantic coast of Brazil, and we employ phylogenetic comparative methods using 24 species to test for: (i) similarities of osmoregulatory ability among closely related species; (ii) salinity as a driver of osmoregulatory evolution; (iii) correlation between salt uptake and secretion; and (iv) adaptive peaks in osmoregulatory ability in the high intertidal American lineages. Our findings reveal that osmoregulation in Uca exhibits strong phylogenetic patterns in salt uptake traits. Salinity does not correlate with hyper/hypo-regulatory abilities, but drives hemolymph osmolality at ambient salinities. Osmoregulatory traits have evolved towards three adaptive peaks, revealing a significant contribution of hyper/hypo-regulatory ability in the American clades. Thus, during the evolutionary history of fiddler crabs, salinity has driven some of the osmoregulatory transformations that underpin habitat diversification, although others are apparently constrained phylogenetically.
Subject(s)
Biological Evolution , Brachyura/genetics , Osmoregulation , Phylogeny , Salt Tolerance , Animals , Brachyura/classification , Brachyura/physiologyABSTRACT
The correct identification of species is a common impediment for studies of conservation, management and environmental licensing. Currently, 37 species from five families of anuran amphibians are recorded in the region that includes the Turvo-Grande, São José dos Dourados and parts of the Low Pardo, Low Tietê and Tietê-Batalha Hydric Resources Management Unit (UGRHIs). Despite of being studied since de mid-1960's, none identification key that included all the species recognized was available. Although developed for a regional anuranfauna, this key has wide application because the species found in the studied region are associated to open areas and have wide geographical distribution. This study aims to fill this gap presenting an illustrated list about species' biology, and a dichotomous key that comprises 37 anuran species.
A correta identificação de espécies normalmente é um obstáculo para estudos de conservação, manejo e licenciamento ambiental. Atualmente 37 espécies de cinco famílias de anfíbios anuros são registradas na área que abrange integralmente as Unidades de Gerenciamento dos Recursos Hídricos (UGRHIs) do Turvo-Grande e São José dos Dourados e parte das UGHRIs do Baixo Pardo, Baixo Tietê e Tietê-Batalha. Embora esta fauna venha sendo objeto de estudos quase ininterruptos desde a metade da década de 1960, nenhuma chave de identificação que incluísse todas as espécies reconhecidas na região estava disponível. Embora desenvolvida para uma anurofauna regional, esta chave tem ampla aplicação porque as espécies encontradas na área de abrangência do estudo são associadas à áreas abertas e apresentam ampla distribuição geográfica. Este estudo visa preencher esta lacuna e apresentar uma lista ilustrada e uma chave dicotômica artificial para as 37 espécies de anuros conhecidas para esta região.
