Intraspecific variation in the diet of the Mexican garter snake Thamnophis eques
- Published
- Accepted
- Subject Areas
- Conservation Biology, Ecology, Zoology
- Keywords
- ontogenetic, size, sexual variation, Thamnophis
- Copyright
- © 2016 Manjarrez et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2016. Intraspecific variation in the diet of the Mexican garter snake Thamnophis eques. PeerJ Preprints 4:e2442v1 https://doi.org/10.7287/peerj.preprints.2442v1
Abstract
The Mexican Garter Snake (Thamnophis eques) is a terrestrial-aquatic generalist because it feeds on both aquatic and terrestrial prey. We describe size-related variation and slight sexual variation in the diet of Thamnophis eques through analysis of 262 samples of identifiable stomach contents in snakes from 23 locations on the Mexican Plateau. The Mexican Garter Snakes we studied ate prey items mostly fish, followed in lesser amounts, respectively, by leeches, earthworms, frogs, and tadpoles. Correspondence analysis suggested that the frequency of consumption of various prey items differed between the categories of age and sex of snakes, and the general pattern was a reduction of prey item diversity with size of snake. Snake length was correlated positively with mass of ingested prey. Large snakes consumed large prey and continued to consume smaller prey. In general, no differences were found between the prey taxa of male and female snakes, although males ate two times more tadpoles than females. Males and females did not differ in the mass of leeches, earthworms, fishes, frogs and tadpoles that they ate, and males and females that ate each prey taxon were similar in length. We discuss proximate and functional determinants of diet and suggest that the observed intraspecific variation in Mexican Garter Snakes could be explored by temporal variation in prey availability, proportions of snake size classes and possible sexual dimorphism in head traits and prey dimensions to assess the role of intersexual resource competition.
Author Comment
This is a preprint submission to PeerJ Preprints.
Supplemental Information
Mexican garter snakes collected on Central Mexico
Table S1. Collection dates of Mexican Garter Snake during the active reproductive season (February to November) from different years (1980-1986, 1994-1995) at 23 location in Mexican Plateau.