RESUMO
Chemical pollutants include the harmful effects of various substances on soils, water bodies, and biodiversity. Amphibians are one of the most endangered groups of vertebrates and are impacted by chemical pollutants in various ways due to their complex life cycles. Since trace pollutant concentrations vary across environments, different frog ecomorphs (classified by their microhabitat use) may have different exposures. We aimed to determine the association between frog ecomorphs and the occurrence of histopathological hepatic lesions (HHLs) as an indicator of contaminant exposure. We focused on small forest streams near a large urban region in Brazil, heavily polluted in the 1980s. We examined 104 frog specimens from various families. All specimens exhibited HHLs, with melanomacrophages being the most common (n = 99). Arboreal frogs exhibited more vascular congestion, while terrestrial frogs showed structural hepatic damage. Higher cobalt levels were linked to increased liver necrosis in arboreal frogs and structural issues in both arboreal and terrestrial frogs. Cadmium was associated with hepatitis in terrestrial frogs. Although metal levels had no significant effects on rheophilic frogs, the prevalence of hepatitis and necrosis indicated complex exposure pathways. Iron and aluminum were linked to fewer lesions in rheophilic frogs, suggesting resilience. The high prevalence of HHLs signals an ongoing issue, with variations among ecomorphs suggesting differential exposure to pollutants and posing a complex challenge for community conservation.
RESUMO
The breast-shoulder apparatus (BSA) is a structurally and kinematically complex region of lizards. Compared with the pelvic region it has received little attention, even though its morphological variation is known to be extensive. This variability has seldom been the focus of functional explanation, possibly because the BSA has been difficult to explore as a composite entity. In this study we apply geometric morphometric techniques to the analysis of the BSA in an attempt to more fully understand its configuration in relation to differential use in locomotion. Our approach centers upon the Jamaican radiation of anoline lizards (genus Norops) as a tractable, small monophyletic assemblage consisting of species representing several ecomorphs. We hypothesized that the different species and ecomorphs would exhibit variation in the configuration of the BSA. Our findings indicate that this is so, and is expressed in the component parts of the BSA, although it is subtle except for Norops valencienni (twig ecomorph), which differs greatly in morphology (and behavior) from its island congeners. We further found similarities in the BSA of N. grahami, N. opalinus (both trunk-crown ecomorphs), and N. garmani (crown giant). These outcomes are promising for associating morphology with ecomorphological specialization and for furthering our understanding of the adaptive response of the BSA to demands on the locomotor system.
Assuntos
Osso e Ossos/anatomia & histologia , Lagartos/anatomia & histologia , Ombro/anatomia & histologia , Animais , Evolução Biológica , Fenômenos Biomecânicos , Osso e Ossos/fisiologia , Clavícula/anatomia & histologia , Clavícula/fisiologia , Feminino , Lagartos/fisiologia , Locomoção , Masculino , Filogenia , Análise de Componente Principal , Escápula/anatomia & histologia , Escápula/fisiologia , Fatores Sexuais , Ombro/fisiologia , Especificidade da Espécie , Coluna Vertebral/anatomia & histologia , Coluna Vertebral/fisiologia , Tórax/anatomia & histologia , Tórax/fisiologiaRESUMO
Escape by Anolis lizards is influenced by microhabitats and fight initiation distance increases with predation risk. Differences in microhabitat use among ecomorphs affect escape behavior, but only two studies have reported ecomorphological differences in flight initiation distance among Greater Antillean species. I studied effects of predation risk and microhabitats on escape behavior by conducting field experiments using two species of anoles, Anolis lineatopus and A. grahami, on the campus of the University of the West Indies at Mona, Jamaica. Because ecomorphological variation of anoles has evolved independently within each island of the Greater Antilles, but relationships between ecomorphs and escape behaviors are poorly known, I characterized microhabitat use and escape tactics, and determined relationships between flight initiation distance and two risk factors, habituation to human presence and perch height, in Anolis lineatopus, a trunk-ground anole and A. grahami, a trunk-crown anole. Sample sizes for A. lineatopus and A. grahami were 214 and 93, for microhabitat use and escape destinations, 74 and 34 for human presence and 125 and 34 for perch height. The two species occurred in similar microhabitats and exhibited similar escape tactics, but exhibited key differences expected for their ecomorphs. Both species were sighted frequently on the ground and on trees, but A. lineatopus were more frequently on ground and were perched lower than A. grahami. Both species escaped from ground to trees and when on trees hid on far sides and escaped without changing climbing direction with equal frequency. The frequency of fleeing upward was greater for A. grahami than A. lineatopus. Both species exhibited habituation by having shorter flight initiation distances in areas with more frequent exposure to people. In both species flight initiation distance increased as perch height decreased because, lizards had to climb farther to be out of reach when perched lower. The relationship between flight initiation distance and perch height may apply to other anole ecomorphs that flee upward when low perched on trees. Rev. Biol. Trop. 58 (4): 1199-1209. Epub 2010 December 01.
El escape de las largarijas Anolis está influenciado por el microhábitat y la distancia de iniciación de escape incrementa el riesgo de depredación. Las diferencias en el uso de microhábitats entre ecomorfos afecta el comportamiento de escape, pero sólo dos estudios han reportado diferencias ecomorfológicas en la distancia de iniciación de escape entre las especies de las Antillas Mayores. Se estudió el efecto de riesgo de depredación y la influencia del microhábitat en el comportamiento de escape, mediante la realización de experimentos de campo con Anolis lineatopus y A. grahami, en el campus de la Universidad West Indies en Mona, Jamaica. Debido a que las variaciones ecomorfológicas de Anolis han evolucionado independientemente en cada isla de las Antillas Mayores, la relación entre ecomorfos y el comportamiento de escape son pobremente conocidos. Se caracteriza el uso del microhábitat y las tácticas de escape, se determinan las relaciones entre la distancia de iniciación de escape y los dos factores de riesgo (habituación a presencia humana y altura a la que se posan) de Anolis lineatopus, una lagartija que habita en troncos-tierra y A. grahami, una lagartija de troncos-partes más altas. Los tamaños de muestra para A. lineatopus y A. grahami fueron: 214 y 93, para uso del microhábitat y destinos de escape 74, para presencia humana 34 y para perchas altas 125 y 34. Las dos especies se presentan en microhábitats similares y mostraron tácticas de escape parecidas, pero exhibieron diferencias claves esperadas para sus ecomorfos. Ambas especies fueron vistas con frecuencia en el suelo y en los árboles, pero A. lineatopus fue encontrada más frecuentemente en el suelo y debajo de A. grahami. Ambas especies escaparon del suelo a esconderse en los árboles y huían con igual frecuencia sin cambiar de dirección. La frecuencia de huir hacia arriba fue mayor para A grahami. Ambas especies mostraron habituación al tener distancias más cortas de iniciación de escape en zonas con exposición frecuente a la gente y la distancia de iniciación de escape incrementa cuando la altura de la percha disminuye, porque las lagartijas tienden a subir más al estar fuera de nuestro alcance cuando se posan en la parte baja. La relación entre la distancia de iniciación de escape y altura de la percha puede aplicar a otros ecomorfos de Anolis que huyen hacia arriba cuando están posados en las partes bajas de los árboles.