Effects of parasitic infection and reproduction on corticosterone plasma levels in Galápagos land iguanas, Conolophus marthae and C. subcristatus. Issue 15 (5th July 2017)

• Record Type: Journal Article
• Authors: Onorati, Michela; Sancesario, Giulia; Pastore, Donatella; Bernardini, Sergio; Cruz, Marilyn; Carrión, Jorge E.; Carosi, Monica; Vignoli, Leonardo; Lauro, Davide; Gentile, Gabriele
• Is Part Of: Ecology and evolution. Volume 7:Issue 15(2017:Aug.)
• Page Start: 6046
• Page End: 6055
• Publication Date: 2017-07-05
• Subjects: baseline levels -- ELISA -- glucocorticoids -- hemoparasites -- Hepatozoon -- parasitemia -- pink iguana -- Wolf volcano; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.3077
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: In vertebrates, one main feature of stress response is the release of glucocorticoids (corticosterone in reptiles), steroid hormones whose synthesis is regulated by the hypothalamic–pituitary–adrenal axis (HPA). In the Galápagos Islands, populations of land iguanas are differentially impacted by a tick‐transmitted apicomplexan hemoparasite of genus Hepatozoon, which could cause diseases and ultimately reduce fitness. Using competitive enzyme‐linked immunosorbent assays (ELISA), we examined baseline plasma corticosterone levels of two syntopic and highly parasitized populations of the land iguana species Conolophus marthae and C. subcristatus in Wolf volcano (Isabela Island). We also used a poorly parasitized population of C. subcristatus from the same island (Bahia Urbina) as a reference. To better interpret the observed glucocorticoids patterns, we simultaneously performed the count of white blood cells (WBCs) in all individuals and investigated the reproductive status of females. We did not find evidence in support of either a positive or negative relationship between the tick load, hemoparasite infection, and glucocorticoid plasma concentration in C. marthae and C. subcristatus at Wolf volcano. The comparison between parasitized and non‐parasitized sites (V. Wolf and Bahia Urbina) would instead suggest an inverse relationship between corticosterone and parasites. Our findings support association between corticosterone plasma levels and reproduction. Abstract : We investigated the effects of parasites on plasma corticosterone levels of two syntopic species of Galápagos land iguanas and related glucocorticoids patterns to the reproductive state of females. Ticks and parasitemia did not explain the variance of corticosterone plasma levels in both males and females of both species. Corticosterone levels variation was explained by reproductive stage.