Abstract
The snakes Erythrolamprus jaegeri jaegeri and Erythrolamprus poecilogyrus sublineatus are sympatric and syntopic in the coastal region of southern Brazil. Herein, we analyzed the diet composition to evaluate the niche breadth and the prey selection by both species. We examined 192 specimens, and analysis of stomach contents revealed that both species predominantly consume anurans. However, the diet of E. j. jaegeri consists mainly of fish and amphibians, whereas that of E. p. sublineatus is broader, including fish, amphibians, reptiles and mammals. The Standardized Levins Index presented lower values for E. j. jaegeri (BA = 0.17) than for E. p. sublineatus (BA = 0.61), evidencing specialist and generalist strategies for each species, respectively. Regarding prey selection, E. p. sublineatus presented a larger snout-vent length, head, mouth and lower jaw than E. j. jaegeri and fed on larger prey. In addition, positive correlations between the size and weight of predators and prey were confirmed in both species. The results show the development of different mechanisms for co-occurrence of the two species, such as prey selection by size, such that the size of the predator is related to the size of their prey, or by developing different strategies to decrease niche overlap between species.
Highlights
The ecological niche, defined as the set of physical and environmental variables in multi-dimensional space (Hutchinson 1957), encompasses three dimensions: spatial niche, feeding niche and temporal niche (Pianka 1982)
Given the sympatric condition of E. j. jaegeri and E. p. sublineatus in southernmost coastal Brazil, we investigated the diet composition of both species aiming to answer two questions: (1) Does E. p. sublineatus feed on larger prey, seeing that larger predators forage larger prey (Shine 1991)? (2) Considering the high association of E. j. jaegeri with wet habitats (De Lema 2002, Quintela and Loebmann 2009), does this species feed on more prey of aquatic origin compared with E. p. sublineatus?
Erythrolamprus j. jaegeri presented a less diverse diet when compared with E. p. sublineatus, preying only on amphibians and fishes
Summary
The ecological niche, defined as the set of physical and environmental variables in multi-dimensional space (Hutchinson 1957), encompasses three dimensions: spatial niche, feeding niche and temporal niche (Pianka 1982). The feeding niche is one of the most important dimensions among snakes and may influence biological and ecological features such as use of habitat, predatory behavior and period of activity (Toft 1985). By the snakes eating vertebrate and invertebrate animals, we can call them carnivorous anyway (Mushinsky 1987, Greene 1997). This diversity is possible due to the development of morphological and biochemical mechanisms that facilitate snakes’ detection of prey (Pough et al 2008). QUINTELA and DANIEL LOEBMANN vision, heat orientation) and subjugation (strike, constriction, poisoning) (Greene 1997, Burghardt and Krause 1999, Pough et al 2008, De Fraga et al 2013); and occupation of different habitats (Quintela and Loebmann 2009, De Fraga et al 2013)
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