Why do most tropical animals reproduce seasonally? Testing hypotheses on an Australian snake

G. P. Brown, R. Shine*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

87 Citations (Scopus)
3 Downloads (Pure)

Abstract

Most species reproduce seasonally, even in the tropics where activity occurs year-round. Squamate reptiles provide ideal model organisms to clarify the ultimate (adaptive) reasons for the restriction of reproduction to specific times of year. Females of almost all temperate-zone reptile species produce their eggs or offspring in the warmest time of the year, thereby synchronizing embryogenesis with high ambient temperatures. However, although tropical reptiles are freed from this thermal constraint, most do not reproduce year-round. Seasonal reproduction in tropical reptiles might be driven by biotic factors (e.g., peak periods of predation on eggs or hatchlings, or food for hatchlings) or abiotic factors (e.g., seasonal availability of suitably moist incubation conditions). Keelback snakes (Tropidonophis mairii, Colubridae) in tropical Australia reproduce from April to November, but with a major peak in May-June. Our field studies falsify hypotheses that invoke biotic factors as explanations for this pattern: the timing of nesting does not minimize predation on eggs, nor maximize food availability or survival rates for hatchlings. Instead, our data implicate abiotic factors: female keelbacks nest most intensely soon after the cessation of monsoonal rains when soils are moist enough to sustain optimal embryogenesis (wetter nests produce larger hatchlings, that are more likely to survive) but are unlikely to become waterlogged (which is lethal to eggs). Thus, abiotic factors may favor seasonal reproduction in tropical as well as temperate-zone animals.

Original languageEnglish
Pages (from-to)133-143
Number of pages11
JournalEcology
Volume87
Issue number1
DOIs
Publication statusPublished - 1 Jan 2006
Externally publishedYes

Bibliographical note

Copyright 2006 by the Ecological Society of America. Originally published in Brown, G. P., & Shine, R. (2006). Why do most tropical animals reproduce seasonally? Testing hypotheses on an Australian snake. Ecology, 87(1), 133-143. https://doi.org/10.1890/04-1882

Keywords

  • Australia
  • climate
  • developmental plasticity
  • hydric
  • oviposition
  • predation
  • reptile
  • Tropidonophis mairii

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