Abstract
Two dimensions of the ecological niche (diet and habitat) of a snake assemblage from an endemic rich area in east-central Argentina, the Sierras de Ventania mountain chain, were analyzed. Field data collection was performed in 15-week study periods between 2010 and 2014. Snakes were hand-captured using transect surveys. Field observations on diet were analyzed together with stomach content data from museum specimens. Our results supported the partitioning of the snake assemblage by both habitat use and diet into at least three functional groups: species restricted to microhabitats under rocks and with a diet composed exclusively of ants (Epictia australis); species found mostly in stream microhabitats and feeding mainly upon anurans (Erythrolamprus poecilogyrus and Lygophis elegantissimus); and species found mostly in grassland microhabitats, with specialized diets of terrestrial prey items (Philodryas patagoniensis and Bothrops alternatus). Consistent with previous work, diet was more important than habitat in explaining ecological niche partitioning of this snake assemblage. Our results showed that high overlap values of microhabitat use were compensated by low overlap values of the trophic niche dimension, thus matching the traditional complementary niches hypothesis.
Highlights
Species interactions, such as resource competition and predation, are among the main factors responsible for the structure of communities
We report the most in-depth and detailed analysis of diet, feeding strategies and microhabitat use of five species from a snake assemblage in the Sierras de Ventania low mountain chain
Our data support the partitioning of the assemblage into at least three groups by habitat use and diet
Summary
Species interactions, such as resource competition and predation, are among the main factors responsible for the structure of communities (i.e., resource partitioning: Schoener 1974). The use of community resources is closely linked with the concept of ecological niche (Hutchinson 1957), which includes three main dimensions: food, habitat and time (Pianka 1973, 1975, 1982, Schoener 1974, Toft 1980, 1981, 1985, Jaksic et al 1981). The current structure of an assemblage may be explained by historical and evolutionary changes that affected species interactions over time or, alternatively, by current interactions Thorpe et al 1994, Vitt & Zani 1996) not influenced by phylogeny (Cadle & Greene 1993). According to Vitt & Pianka (2005), resource partitioning may be affected by the current competitive abilities of species, which retain ancestral differences. Historical effects would be maximal and interactions less influential among phylogenetically-distant species, whereas historical effects would
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