Complex tourism and season interactions contribute to disparate physiologies in an endangered rock iguana

Abstract

To promote survival and fitness, organisms use a suite of physiological systems to respond to both predictable and unpredictable changes in the environment. These physiological responses are also influenced by changes in life history state. The continued activation of physiological systems stemming from persistent environmental perturbations enable animals to cope with these challenges but may over time lead to significant effects on the health of wildlife. In the present study, we tested how varying environmental perturbations driven by tourism and associated supplemental feeding affects the energetics, corticosterone and immunity of six discrete populations of the northern Bahamian rock iguana (Cyclura cychlura inornata and Cyclura cychlura figginsi). We studied populations within and outside the reproductive season and quantified tourist numbers during sample collection. Specifically, we measured clutch size, body condition, plasma energy metabolites, reactive oxygen species, baseline corticosterone concentrations and immune function of male and female iguanas from each population to address whether (i) disparate physiologies are emerging across a gradient of tourism and feeding, (ii) both subspecies respond similarly and (iii) responses vary with season/reproductive condition. We found significant effects of tourism level, season and their interaction on the physiology of both C. c. inornata and C. c. figginsi, supporting the idea that tourism is leading to the divergence of phenotypes. Specifically, we found elevated plasma energy metabolites, oxidative stress and a measure of innate immunity (bactericidal ability), but reduced corticosterone concentrations with increasing tourism in both subspecies of rock iguanas. These physiological metrics differ according to the level of tourism in both subspecies and persist across seasons despite variation with natural seasonal and reproductive changes. These findings suggest that anthropogenic disturbance results in disparate physiologies in northern Bahamian rock iguanas.

Invading nonnative frogs use different microhabitats and change physiology along an elevation gradient

“…Furthermore, glucose may be important in helping coqui at high elevations meet energetic demands under suboptimal temperatures. However, glucose levels respond rapidly to environmental changes such as acute stress (French et al, 2022; Gangloff et al, 2017; Kelley et al, 2021; Romero & Beattie, 2022), and previous work has demonstrated that stress may mask inherent glucose differences among populations (Hudson, Lidgard, et al, 2020). In support of this idea, previous research by Marchetti et al (2023) found a strong positive relationship between elevation and glucose in coqui, but also that stress immediately after capture could obscure these results.…”

Feather corticosterone is lower in translocated and historical populations of the endangered Laysan duck ( Anas laysanensis )

“…Brief elevations in GCs following a perturbation are typically beneficial and help to restore homeostasis; however, repeated or prolonged elevations can lead to wear and tear on the organism and pathological effects [13]. GCs have been used to investigate the impacts of anthropogenic disturbance and changes in habitat quality in mammals [14,15], birds [16][17][18][19], reptiles [20][21][22], amphibians [23][24][25][26] and fish [27][28][29], and they have been linked to changes in demography (reviewed in [6]).…”