Journal ArticleDOI
Does interspecific competition with a stronger competitor explain the rarity of an endangered snake on a Mediterranean island
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Overall, this study showed that the two species of whip snakes in Sardinia differed in some aspects of their ecology, but these differences could not be due to competitive interactions.Abstract:
Interspecific competition has been demonstrated to be an important shaping force for snake communities worldwide, but relatively few studies have investigated its occurrence and extent with island assemblages of snakes. In Sardinia (Mediterranean Sea), two species of whip snakes (Colubridae) co-occur, one of them being abundant and widespread (Hierophis viridiflavus) and the other being localized and critically endangered (Hemorrhois hippocrepis). A previous hypothesis suggested that the latter species would be confined to suboptimal habitats by the former species, which is a stronger competitor for food. As a consequence, He. hippocrepis would not only be rare but would also be smaller in body size in Sardinia than in other regions of its range where Hi. viridiflavus does not occur. In 1999–2010, we studied habitat selection, food habits, and body sizes of these two snakes in sympatric populations, applying a suite of statistical tools including null models and Monte Carlo simulations. We observed that dietary habits were different between species (compared to Hi. viridiflavus, He. hippocrepis more frequently preyed upon rodents and less frequently on lizards, and within rodent prey, more frequently upon Rattus and less frequently upon Mus), but not in a way compatible with competitively induced trophic niche partitioning. The two species were similar in terms of prey size and predator-size–prey-size relationships. They also differed in habitat selection (maquis was the preferred habitat for both, but Hi. viridiflavus was found significantly more often than He. hippocrepis in grasslands, cultivations, and artificial pinewoods) but again in a non-competitively directed way. In addition, there was no evidence for the hypothesis that He. hippocrepis was confined to suboptimal habitats. Body sizes were similar between species (with males being significantly larger than females), and Sardinian He. hippocrepis were not smaller than conspecifics inhabiting regions without Hi. viridiflavus. Overall, our study showed that the two species differed in some aspects of their ecology, but these differences could not be due to competitive interactions. The conservation implications of these results are also discussed.read more
Citations
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Journal ArticleDOI
Snake co-occurrence patterns are best explained by habitat and hypothesized effects of interspecific interactions
David A. Steen,Christopher J. W. McClure,Jean C. Brock,D. Craig Rudolph,Josh B. Pierce,James R. Lee,W. Jeffrey Humphries,Beau B. Gregory,William B. Sutton,Lora L. Smith,Danna L. Baxley,Dirk J. Stevenson,Craig Guyer +12 more
TL;DR: It is suggested that current interspecific interactions may influence snake occupancy, challenging the paradigm that contemporary patterns of snake co-occurrence are largely a function of diet partitioning that arose over evolutionary time.
Journal ArticleDOI
Resource partitioning and dwarfism patterns between sympatric snakes in a micro-insular Mediterranean environment
TL;DR: The Mediterranean island of Montecristo, Italy, provides an evolutionary window, where a simplified natural network combined with unusual environmental conditions promote selective processes that trigger rapid changes in biological constituents of a species.
Journal ArticleDOI
The fall of a symbol? A high predation rate by the introduced horseshoe whip snake Hemorrhois hippocrepis paints a bleak future for the endemic Ibiza wall lizard Podarcis pityusensis
TL;DR: The results on the feeding ecology of the snake Hemorrhois hippocrepis are of sufficient concern to justify the maintenance of actions to eradicate this invader.
Journal ArticleDOI
Lizards and the city: A community study of Lacertidae and Gekkonidae from an archaeological park in Rome
TL;DR: It is speculated that the coexistence of ecologically overlapping species at the study area is allowed by a non-limiting availability of resources that would result in the reduction of heterospecific competitive interactions and an overall wide overlap of resource use.
Using local African communities Ecological Knowledge to support scientific evidence of snake declin
TL;DR: In this article, a survey-based participatory approach is described to reinforce the scientific analyses of snake declines in the River Niger Delta, where significant snake declines have been detected over the last decade.
References
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TL;DR: In this paper, the authors define definitions of diversity and apply them to the problem of measuring species diversity, choosing an index and interpreting diversity measures, and applying them to structural and structural diversity.
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