Recent research suggests that oxidative stress,via its links to metabolism and senescence,is a key mechanism linking life history traits such as fecundity and growth with survival;however,this has rarely been put unde...Recent research suggests that oxidative stress,via its links to metabolism and senescence,is a key mechanism linking life history traits such as fecundity and growth with survival;however,this has rarely been put under empirical scrutiny within free-living populations.Using a wild population of live-bearing skinks,we explored how plasma antioxidant activity(OXY),reactive oxidative metabolites(ROM),and the estimated oxidative stress index are associated with female and male life history.We found that male skinks have a significantly higher ROM and estimated oxidative stress index than female skinks,but this was not accompanied by a sex difference in mortality.Both sexes showed a non-linear association between OXY and age,indicating that the oldest and youngest individuals had the lowest OXY.Interestingly,female skinks with high OXY showed a decreased probability of survival to the following season.However,we found no significant associations between female reproductive investment(litter size or litter mass)or parturition date(i.e.metabolism)and oxidative status.Combined,our results offer mixed support for a role of oxidative stress in mediating life history traits and suggest that future studies need to explore oxidative stress during vitellogenesis in addition to using an intra-individual approach to understand the cost of reproduction and patterns of aging.展开更多
Recent evidence suggests that many Australian agamids show temperature-dependent sex determination(TSD)with variation in sex determining mechanisms among closely related taxa.However,as shown in other vertebrates,sex ...Recent evidence suggests that many Australian agamids show temperature-dependent sex determination(TSD)with variation in sex determining mechanisms among closely related taxa.However,as shown in other vertebrates,sex ratios can also be influenced by genetic or phenotypic differences among females in their propensity to produce sons or daughters,and these influences might confound any thermal effects of incubation per se.To address these issues,we investigated the determinants of sex ratios in the mallee dragon Ctenophorus fordi,together with a detailed analysis of karyotypes.There was no detectable variation in sex ratios arising from variation among females,clutches or incubation temperatures,which might indicate genetic sex determination for this species.However,there was no evidence of cytologically distinct sex chromosomes using standard banding techniques.The sex ratio pattern in C.fordi strongly contrasts with the results for the congener Ctenophorus pictus,where sex ratios show variation among females.Thus,Australian agamids offer promising opportunities to address fundamental issues in sex ratio biology.展开更多
基金This study was supported financially by the Netherlands Organization for Scientific Research(NWO)that provided a Rubicon post-doctoral fellowship for CI(project no.825.07.004),the Australian Research Council(to MO and EW),the Hermon Slade Foundation(to EW)and the NWO-Vici(to JK).
文摘Recent research suggests that oxidative stress,via its links to metabolism and senescence,is a key mechanism linking life history traits such as fecundity and growth with survival;however,this has rarely been put under empirical scrutiny within free-living populations.Using a wild population of live-bearing skinks,we explored how plasma antioxidant activity(OXY),reactive oxidative metabolites(ROM),and the estimated oxidative stress index are associated with female and male life history.We found that male skinks have a significantly higher ROM and estimated oxidative stress index than female skinks,but this was not accompanied by a sex difference in mortality.Both sexes showed a non-linear association between OXY and age,indicating that the oldest and youngest individuals had the lowest OXY.Interestingly,female skinks with high OXY showed a decreased probability of survival to the following season.However,we found no significant associations between female reproductive investment(litter size or litter mass)or parturition date(i.e.metabolism)and oxidative status.Combined,our results offer mixed support for a role of oxidative stress in mediating life history traits and suggest that future studies need to explore oxidative stress during vitellogenesis in addition to using an intra-individual approach to understand the cost of reproduction and patterns of aging.
基金the field and to Dan Warner for discussions of sex allocation in agamids.All work was carried out in accordance with a National Parks and Wildlife Services permit(S11186)the University of Wollongong Animal Ethics Committee(permits AE04/03-05)the research complies with the laws of Australia.Financial support was provided by the Wenner–Gren Foundations(T.Uller)and the Australian Research Council(T.Uller and M.Olsson).
文摘Recent evidence suggests that many Australian agamids show temperature-dependent sex determination(TSD)with variation in sex determining mechanisms among closely related taxa.However,as shown in other vertebrates,sex ratios can also be influenced by genetic or phenotypic differences among females in their propensity to produce sons or daughters,and these influences might confound any thermal effects of incubation per se.To address these issues,we investigated the determinants of sex ratios in the mallee dragon Ctenophorus fordi,together with a detailed analysis of karyotypes.There was no detectable variation in sex ratios arising from variation among females,clutches or incubation temperatures,which might indicate genetic sex determination for this species.However,there was no evidence of cytologically distinct sex chromosomes using standard banding techniques.The sex ratio pattern in C.fordi strongly contrasts with the results for the congener Ctenophorus pictus,where sex ratios show variation among females.Thus,Australian agamids offer promising opportunities to address fundamental issues in sex ratio biology.
