Phylogeny, Ecology, and Heart Position in Snakes

@article{Gartner2009PhylogenyEA,
  title={Phylogeny, Ecology, and Heart Position in Snakes},
  author={Gabriel E. A. Gartner and James W Hicks and Paulo Roberto Manzani and Denis V. Andrade and Augusto Shinya Abe and Tobias Wang and Stephen M. Secor and Theodore Garland Jr.},
  journal={Physiological and Biochemical Zoology},
  year={2009},
  volume={83},
  pages={43 - 54}
}
The cardiovascular system of all animals is affected by gravitational pressure gradients, the intensity of which varies according to organismic features, behavior, and habitat occupied. A previous nonphylogenetic analysis of heart position in snakes—which often assume vertical postures—found the heart located 15%–25% of total body length from the head in terrestrial and arboreal species but 25%–45% in aquatic species. It was hypothesized that a more anterior heart in arboreal species served to… 
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