PLoS ONE (Jan 2010)

Embryos in the fast lane: high-temperature heart rates of turtles decline after hatching.

  • Wei-Guo Du,
  • Bo Zhao,
  • Richard Shine

DOI
https://doi.org/10.1371/journal.pone.0009557
Journal volume & issue
Vol. 5, no. 3
p. e9557

Abstract

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In ectotherms such as turtles, the relationship between cardiovascular function and temperature may be subject to different selective pressures in different life-history stages. Because embryos benefit by developing as rapidly as possible, and can "afford" to expend energy to do so (because they have access to the yolk for nutrition), they benefit from rapid heart (and thus, developmental) rates. In contrast, hatchlings do not have a guaranteed food supply, and maximal growth rates may not enhance fitness--and so, we might expect a lower heart rate, especially at high temperatures where metabolic costs are greatest. Our data on two species of emydid turtles, Chrysemys picta, and Graptemys pseudogeographica kohnii, support these predictions. Heart rates of embryos and hatchlings were similar at low temperatures, but heart rates at higher temperatures were much greater before than after hatching.