Reproductive stage and clutch size incur energetic and oxidative costs in an endangered iguana, Ctenosaura oedirhina

Authors: FRENCH, SUSANNAH - Utah State University; VIRGIN, EMILY - Utah State University; KI, KWANHO - Utah State University; MARYON, DAISY - Kanahau Utila Research And Conservation Facility; Goode, Ashley; PASACHNIK, STESHA - Fort Worth Zoo

Submitted to: Herpetologica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2021
Publication Date: 6/11/2021
Citation: French, S.S., Virgin, E.E., Ki, K.C., Maryon, D.F., Goode, A.B., Pasachnik, S.A. 2021. Reproductive stage and clutch size incur energetic and oxidative costs in an endangered iguana, Ctenosaura oedirhina. Herpetologica. 55(2):192–200. https://doi.org/10.1670/20-099.
DOI: https://doi.org/10.1670/20-099

Interpretive Summary: The Roatán Spiny-tailed Iguana (Ctenosaura oedirhina) is an Endangered species endemic to only two islands in the Bay of Honduras and a few of its surrounding Cays. It is currently threatened by many different impacts including habitat modification, invasive predators, and illegal collection and harvesting. Understanding the reproductive physiology of this and similar species is critical to maintaining healthy, reproducing populations. Physiological indicators provide valuable information regarding the health of animals and populations. Commonly used metrics include circulating hormone concentrations, energetic indicators, and immunological indices. However, these physiological measures can also be difficult to interpret because they are not static and instead vary according to sex, season, reproductive state, and body condition, making interpretation of physiological results complicated. Therefore, to better understand the health status of an individual, it is important to concomitantly measure multiple related and relevant physiological systems, and to examine these responses under different individual and environmental contexts (e.g., reproductive state, site). In the current study, we measured circulating plasma oxidative stress markers and energy metabolites in five populations of Roatán Spiny-tailed Iguanas during the pre-nesting season. We found significant physiological variation in females according to breeding state, and males according to population. Understanding the natural variation in the physiology of free-living animals will allow us to better determine the significance of physiological measures as health indicators in the future and thus better manage these threatened populations.

Technical Abstract: The Roatán Spiny-tailed Iguana (Ctenosaura oedirhina) is an Endangered species endemic to only two islands in the Bay of Honduras and a few of its surrounding Cays. It is currently threatened by many different impacts including habitat modification, invasive predators, and illegal collection and harvesting. Understanding the reproductive physiology of this and similar species is critical to maintaining healthy, reproducing populations. Physiological indicators provide valuable information regarding the health of animals and populations. Commonly used metrics include circulating hormone concentrations, energetic indicators, and immunological indices. However, these physiological measures can also be difficult to interpret because they are not static and instead vary according to sex, season, reproductive state, and body condition, making interpretation of physiological results complicated. Therefore, to better understand the health status of an individual, it is important to concomitantly measure multiple related and relevant physiological systems, and to examine these responses under different individual and environmental contexts (e.g., reproductive state, site). In the current study, we measured circulating plasma oxidative stress markers and energy metabolites in five populations of Roatán Spiny-tailed Iguanas during the pre-nesting season. We found significant physiological variation in females according to breeding state, and males according to population. Understanding the natural variation in the physiology of free-living animals will allow us to better determine the significance of physiological measures as health indicators in the future and thus better manage these threatened populations.