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Ectotherms increase their body temperature in response to ambient heat, thereby elevating their metabolic rate. An often inferred consequence of this is an overall upregulation of gene expression and energetic expenditure, and a concomitant increased production of reactive oxygen species (e.g. superoxide) and, perhaps, a shortened lifespan. However, recent work shows that this may be a superficial interpretation. For example, sometimes a reduced temperature may in fact trigger up-regulation of gene expression. We studied temperature and associated activity effects in male and female Australian painted dragon lizards (Ctenophorus pictus) by allowing the lizards to bask for 4ƒnh versus12ƒnh, and scoring their associated activity (inactive versus active basking and foraging). As predicted, long-basking lizards (hereafter ʻhotʼ) showed heightened activity in both sexes, with a more pronounced effect in females. We then tested for sex-specific effects of basking treatment and activity levels on the increase in net levels of superoxide. In males, short-baskers (hereafter ʻcoldʼ) had significantly more rapidly decreasing levels of superoxide per unit increasing activity than hot males. In females, however, superoxide levels increased faster with increasing activity in the cold than in the hot basking treatment, and females earlier in the ovarian cycle had lower superoxide levels than females closer to ovulation. In short, males and females differ in how their levels of reactive oxygen species change with temperature-triggered activity.

Item Type:	Refereed Article
Research Division:	Biological Sciences
Research Group:	Physiology
Research Field:	Animal Physiology - Systems
Objective Division:	Environment
Objective Group:	Ecosystem Assessment and Management
Objective Field:	Ecosystem Assessment and Management at Regional or Larger Scales
UTAS Author:	Wapstra, E (Associate Professor Erik Wapstra)
ID Code:	77448
Year Published:	2012
Web of Science® Times Cited:	3
Deposited By:	Zoology
Deposited On:	2012-04-16
Last Modified:	2017-11-01
Downloads:	0