Does reproduction influence temperature preferences in newts?

Abstract

The influence of reproduction on body temperatures preferred in a laboratory thermal gradient has been studied mostly in ectotherms that are either viviparous or oviparous with prolonged egg retention. In this study I investigated whether reproduction influences temperature preferences in the Italian crested newt, Triturus carnifex (Laurenti, 1768), whose females do not carry embryos in utero (strict oviparity). I compared preferred temperatures and locomotor activity among reproductive females, non-reproductive females, and males in an aquatic thermal gradient (5–32.5 °C) over 24 h. Reproductive females preferred mean body temperatures 2.3–4.3 °C higher than those of non-reproductive females and males irrespective of activity level. Females regulated body temperature more precisely when reproductive than when non-reproductive as judged by the narrower range of preferred body temperatures. The study showed that the shift in temperature preferences of reproductive females occurs not only in species with advanced reproductive modes (i.e., viviparity and oviparity with egg retention), but also in a strictly oviparous mode.