Diversity and evolution of macrohabitat use, body size and morphology in a monophyletic group of Neotropical pitvipers (Bothrops)

Abstract

The Neotropical pitviper genus Bothrops comprises about 40 species, which occur in all main ecosystems of cis-Andean South America. We explored the relationships of body size and form (tail length and stoutness) with macrohabitat use in 20 forms of Bothrops. Semi-arboreal habits appeared only in forest forms. Semiarboreals are signi®cantly more slender and have longer tails than terrestrials; body size is not signi®cantly different between terrestrials and semi-arboreals. Within Bothrops, independent contrasts for macrohabitat use were signi®cantly correlated with contrasts of tail size (positively) and stoutness (negatively); thus, the more arboreal the species, the longer its tail and the more slender its body. Contrasts of adult body size seems to remain constant over the lower range of macrohabitat use, but to decrease in species of Bothrops which are more arboreal. Reconstructions of character states indicate that: (1) the ancestor of Bothrops was a small, stout, terrestrial species; (2) semi-arboreal habits appeared one to three times in the genus; (3) a decrease in stoutness and an increase in tail length occurred along with an increase in arboreality in some clades. Although macrohabitat use seems to be important in determining body form in Bothrops, our results also indicate that tail size, stoutness and body size may also be affected by selective agents other than macrohabitat use. The selective agents responsible for the shifts in macrohabitat use in Bothrops are still uncertain, although they may have included prey availability and/or predation pressure. The plasticity of macrohabitat use, morphology and body size described in this study may have been key features that facilitated the highly successful ecological diversi®cation of Bothrops in South America.

Ecologia e história natural de uma taxocenose de serpentes no Núcleo Santa Virgínia do Parque Estadual da Serra do Mar, no sudeste do Brasil

“…Foram obtidas as seguintes informações: conteúdo do tubo digestivo, número de itens alimentares e condição reprodutiva. Uma espécie foi considerada de dieta especializada quando um tipo de presa representou 75% ou mais do total de presas registradas (Martins et al 2001). O comprimento rostro-cloacal do menor macho maduro e da menor fêmea madura de cada espécie serviu para diferenciar indivíduos adultos de imaturos (Shine 1977, Marques 1996, Hartmann & Marques 2005.…”

“…Apresenta variação ontogenética na dieta, com filhotes apresando principalmente anuros e os adultos consumindo mamíferos (Martins et al, 2001).…”

Répteis em fragmentos de Cerrado e Mata Atlântica no Campo das Vertentes, Estado de Minas Gerais, Sudeste do Brasil

“…Na revisão taxonômica desse complexo, Silva & Rodrigues (2008) detectaram que B. neuwiedi (considerando as 12 subespécies) é, na verdade, formado por sete espécies plenas. Pelo grande número de registros, aparentemente, B. neuwiedi é mais comum do que Bothropoides jararaca na área de estudo, considerando que grande parte das espécies do grupo neuwiedi é típica de áreas abertas (Valdujo et al 2002), ao passo que B. jararaca ocorre primordialmente em áreas florestadas (Martins et al 2001).…”

Richness, abundance, and mass in snake assemblages from two Atlantic Rainforest sites (Ilha do Cardoso, São Paulo) with differences in environmental productivity

“…At this time we do not know if this tendency may be a result of an ecological incompatibility of these Bothrops species, although a similar segregation in occurrence has been suggested for some species of Micrurus (Henderson et al 1979). However, alternatively, we must consider that actually these two Bothrops species are not closely related, and actually belong to distinct clades (species groups) within Bothrops (Martins et al 2001) and this may explain the differences in macrohabitat use.…”