Male Morphs in Tree Lizards Have Different Testosterone Responses to Elevated Levels of Corticosterone

Knapp, Rosemary; Moore, Michael C.

doi:10.1006/gcen.1997.6923

Cited by 99 publications

(40 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Not only could corticosterone play a role in the immediate survival of the animal by helping to mobilize fat and protein reserves, but, as in other taxa, elevated corticosterone levels in reptiles have been shown to inhibit gonadal function (17,19,34,35) and reproductive behaviors (36,37), thereby disrupting reproduction. Severe El Niño events have been shown to exert profound selective pressure on morphological traits (38), and these data suggest that El Niño events may exert selective pressure on physiological traits (i.e., corticosterone release and action) as well.…”

Section: Discussionmentioning

confidence: 99%

Corticosterone levels predict survival probabilities of Galápagos marine iguanas during El Niño events

Romero

Wikelski

2001

Proc. Natl. Acad. Sci. U.S.A.

455

310

View full text Add to dashboard Cite

Plasma levels of corticosterone are often used as a measure of ''stress'' in wild animal populations. However, we lack conclusive evidence that different stress levels reflect different survival probabilities between populations. Galá pagos marine iguanas offer an ideal test case because island populations are affected differently by recurring El Niñ o famine events, and population-level survival can be quantified by counting iguanas locally. We surveyed corticosterone levels in six populations during the 1998 El Niñ o famine and the 1999 La Niñ a feast period. Iguanas had higher baseline and handling stress-induced corticosterone concentrations during famine than feast conditions. Corticosterone levels differed between islands and predicted survival through an El Niñ o period. However, among individuals, baseline corticosterone was only elevated when body condition dropped below a critical threshold. Thus, the population-level corticosterone response was variable but nevertheless predicted overall population health. Our results lend support to the use of corticosterone as a rapid quantitative predictor of survival in wild animal populations.

show abstract

Section: Discussionmentioning

confidence: 99%

Corticosterone levels predict survival probabilities of Galápagos marine iguanas during El Niño events

Romero

Wikelski

2001

Proc. Natl. Acad. Sci. U.S.A.

455

310

View full text Add to dashboard Cite

show abstract

“…Sex hormones are often quantified in conjunction with corticosterone (e.g. Wingfield et al, 1982;Klukowski et al, 1997;Knapp and Moore, 1997;McQueen et al, 1999;Wada et al, 1999;Sorato and Kotrschal, 2006;Kralj-Fišer et al, 2007;Roberts et al, 2007) to investigate interactions between corticosterone and sex hormones across a breeding season. Differences across the sexes within each measure were also investigated; however, this was done in the context of comparing the consistency of the results generated by the different sample types, 6 rather than attempting to elucidate the specific hormonal profiles of each sex.…”

Section: Introductionmentioning

confidence: 99%

Comparing plasma and faecal measures of steroid hormones in Adelie penguins Pygoscelis adeliae

et al. 2009

View full text Add to dashboard Cite

Abstract. Physiological measurements of both stress and sex hormones are often used to estimate the consequences of natural or human-induced change in ecological studies of various animals. Different methods of hormone measurement exist, potentially explaining variation in results across studies; methods should be cross-validated to ensure they correlate.We directly compared faecal and plasma hormone measurements for the first time in a wild free-living species, the Adelie penguin (Pygoscelis adeliae). Blood and faecal samples were simultaneously collected from individual penguins for comparison, and assayed for testosterone and corticosterone (or their metabolites). Sex differences and variability within each measure, and correlation of values across measures were compared. For both hormones, plasma samples showed greater variation than faecal samples. Males had higher mean corticosterone concentrations than females, but the difference was only statistically significant in faecal samples. Plasma testosterone, but not faecal testosterone, was significantly higher in males than females. Correlation between sample types was poor overall, and weaker in females than in males, perhaps because measures from plasma represent hormones that are both free and bound to globulins, whereas measures from faeces represent only the free portion. Faecal samples also represent a cumulative measure of hormones over time, as opposed to a plasma 'snapshot' concentration. Our data indicate that faecal sampling appears more suitable for assessing baseline hormone concentrations, while plasma sampling may best define immediate responses to environmental events. Consequently, future studies should ensure they select the most appropriate matrix and method of hormone measurement to answer their research questions.

show abstract

“…However, the demands of constant territory maintenance against intrusion by male rivals can activate the hypothalamic-pituitary-adrenal (HPA) axis, leading to a rise in adrenal glucocorticoids, particularly corticosterone (B) [Greenberg et al, 1984;Klukowski and Nelson, 1998;Smith and JohnAdler, 1999;Woodley et al, 2000;Summers et al, 2003]. Chronic increases in B can suppress T synthesis and release [Tokarz, 1987;DeNardo and Licht, 1993;Knapp and Moore, 1997], leading to a reduction in the expression of aggressive behavior and loss of the territory [Tokarz, 1987;DeNardo and Licht, 1993;DeNardo and Sinervo, 1994a, b] and resulting in the production of signals indicating submissive status [Crews and Greenberg, 1981;Greenberg et al, 1984;Wingfield and Marler, 1988]. Thus, individual variation in the magnitude of the adrenocortical response to social encounters might ultimately determine individual reproductive success.…”

Section: Introductionmentioning

confidence: 99%

Steroid Correlates of Territorial Behavior in Male Jacky Dragons, <i>Amphibolurus muricatus</i>

Watt

Forster

Joss³

2003

Brain Behav Evol

View full text Add to dashboard Cite

Male jacky dragons, Amphibolurus muricatus, indicate territoriality to rivals during the mating season through the use of stereotyped motor displays. The relationship between corticosterone (B) and testosterone (T) and its effects on territorial display expression were investigated in captive lizards. Results demonstrated that territorial display production was most effectively predicted by elevated baseline T levels. This parallels the heightened T concentrations exhibited by males in the field during the spring mating period. The effect of social interaction on B and T levels was also examined by presenting territory-holding males with a size-matched male intruder. Resident males exhibited clear differences in the level of territorial response evoked by a male intruder, which were correlated with differences in physiological activity. Males that gave no territorial response had moderate B levels that did not change with social interaction, and significantly lower T levels than males that responded to the intruder with territorial displays. Among displaying males, those exhibiting low levels of territorial responses showed no change in B or T. In contrast, high-level territorial responders exhibited acute B increases when faced with an intruder, which might assist in supporting sustained metabolic activity and could possibly reflect differences in the perception of social stress. These same males also exhibited a reduction in T levels at such times, probably due to the acute rise in B. Combined, these results suggest that high circulating T is acting in a preparatory manner to increase the likelihood of producing a territorial response upon engaging in a social encounter. However, once this response has been initiated T may not need to remain elevated to allow continued expression of territorial behavior.

show abstract

Male Morphs in Tree Lizards Have Different Testosterone Responses to Elevated Levels of Corticosterone

Cited by 99 publications

References 25 publications

Corticosterone levels predict survival probabilities of Galápagos marine iguanas during El Niño events

Corticosterone levels predict survival probabilities of Galápagos marine iguanas during El Niño events

Comparing plasma and faecal measures of steroid hormones in Adelie penguins Pygoscelis adeliae

Steroid Correlates of Territorial Behavior in Male Jacky Dragons, <i>Amphibolurus muricatus</i>

Contact Info

Product

Resources

About