Vertebral numbers in male and female snakes: the roles of natural, sexual and fecundity selection

R. Shine*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

60 Citations (Scopus)


The relative numbers of trunk (body) and caudal (tail) vertebrae in snakes might be influenced by at least four processes: (1) natural selection for crawling speed, (2) fecundity selection for larger trunk size in females, (3) sexual selection for longer bodies or tails in males and/or (4) developmental constraints (if an increase in the number of body vertebrae requires a decrease in the number of tail vertebrae, or vice versa). These four hypotheses generate different predictions about the relationship between sex differences in the numbers of body vertebrae vs. tail vertebrae. I collated published data to test these predictions, both with raw data and using phylogenetically independent contrasts. Some snake lineages show a negative correlation between the magnitude of sex disparities in trunk vs. caudal vertebrae whereas other lineages show the reverse pattern, or no correlation. Thus, different selective pressures seem to have been important in different lineages. Vertebral numbers in snakes may offer a useful model system in which to explore the conflicts between natural, fecundity and sexual selection.

Original languageEnglish
Pages (from-to)455-465
Number of pages11
JournalJournal of Evolutionary Biology
Issue number3
Publication statusPublished - May 2000
Externally publishedYes


  • Adaptation
  • Comparative analysis
  • Reptile
  • Sexual dimorphism
  • Snake


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