Facultative cardiac responses to regional hypoxia in lizard embryos

Wei Guo Du*, Michael B. Thompson, Richard Shine

*Corresponding author for this work

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

In natural nests, the eggs of squamate reptiles (lizards and snakes) sometimes experience unpredictable shifts in oxygen availability as a function of nest flooding, or the details of egg location within a nest. We experimentally investigated whether embryos can facultatively adjust cardiac function to cope with such challenges by imposing regional hypoxia on developing eggs of the scincid lizard Bassiana duperreyi. To do so, we sealed half of the eggshell surface with tissue adhesive. The embryos rapidly responded by increasing heart rates, which they maintained for long periods. The elevated heart rates enabled the embryos not only to survive, but to maintain "normal" metabolic rates, and to hatch at the usual time with unmodified phenotypic traits (e.g., hatchling size, relative heart mass, locomotor speed, post-hatchling survival and growth rates). Turtles and birds with rigid (highly calcified) eggshells show more dramatic ill-effects from hypoxic incubation, suggesting that the thin (and thus, highly gas-permeable) parchment-shelled eggs of most squamates allow more effective embryonic adjustment of oxygen exchange rates in response to externally-imposed hypoxia.

Original languageEnglish
Pages (from-to)491-494
Number of pages4
JournalComparative Biochemistry and Physiology. Part A: Molecular & Integrative Physiology
Volume156
Issue number4
DOIs
Publication statusPublished - Aug 2010
Externally publishedYes

Keywords

  • embryonic metabolism
  • hatchling
  • heart rate
  • hypoxia
  • reptile
  • squamate

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