A population genetic analysis of the Critically Endangered Madagascar big-headed turtle, Erymnochelys madagascariensis across captive and wild populations

Erymnochelys madagascariensis is a Critically Endangered turtle endemic to Madagascar. Anthropogenic activity has depleted the wild population by 70% in the last century, and effective conservation management is essential to ensuring its persistence. Captive breeding was implemented to augment depleted populations in the southern part of Ankarafantsika National Park (ANP), when no genetic data were available for E. madagascariensis. It is unknown how much of the natural population’s diversity is encapsulated in captivity. We used eight microsatellite loci and fragments of two mitochondrial genes to identify the genetic structure of E. madagascariensis in the wild. Captive bred turtles were compared with wild populations in order to assess the representativeness of this ex situ conservation strategy for ANP. Six microsatellite clusters, ten cytochrome b, and nine COI haplotypes were identified across wild populations, with high genetic divergence found between populations in two groups of watersheds. Captive bred individuals represent three out of six sampled microsatellite clusters found in the wild and just one mitochondrial haplotype, possibly due to genetic drift. To improve genetic representation, the strategy of frequent interchange between captive and wild breeders within ANP should be revitalised and, as originally planned, hatchlings or juveniles should not be released beyond ANP

Comparative ecophysiology of a critically endangered (CR) ectotherm: Implications for conservation management

<div><p>Captive breeding is a vital conservation tool for many endangered species programs. It is often a last resort when wild animal population numbers drop to below critical minimums for natural reproduction. However, critical ecophysiological information of wild counterparts may not be well documented or understood, leading to years of minimal breeding successes. We collected endocrine and associated ecological data on a critically endangered ectotherm concurrently in the wild and in captivity over several years. We tracked plasma concentrations of steroid stress and reproductive hormones, body condition, activity, and environmental parameters in three populations (one wild and two geographically distinct captive) of ploughshare tortoise (<i>Astrochelys yniphora</i>). Hormone profiles along with environmental and behavioral data are presented and compared. We show that animals have particular seasonal environmental requirements that can affect annual reproduction, captivity affects reproductive state, and sociality may be required at certain times of the year for breeding to be successful. Our data suggest that changes in climatic conditions experienced by individuals, either due to decades-long shifts or hemispheric differences when translocated from their native range, can stifle breeding success for several years while the animals physiologically acclimatize. We also found that captivity affects stress (plasma corticosterone) and body condition of adults and juveniles differently and seasonally. Our results indicate that phenotypic plasticity in reproduction and behavior is related to environmental cues in long-lived ectotherms, and detailed ecophysiological data should be used when establishing and improving captive husbandry conditions for conservation breeding programs. Further, considering the recent revelation of this tortoises’ possible extirpation from the wild, these data are critically opportune and may be key to the survival of this species.</p></div

Hormone concentrations in sub-adult <i>Astrochelys yniphora</i> populations.

<p>Mean monthly steroid hormone concentrations in sub-adult <i>A</i>. <i>yniphora</i> from all sample populations combined. Smoothing lines included for ease of interpretation, however, no differences between months were significant. Number of samples collected is listed with the number of individuals represented in parentheticals. Error bars represent 1 SE.</p

Wild <i>Astrochelys yniphora</i> in its native habitats.

<p>This “golden tortoise” is near extinct in the wild (EW) due to wildlife smugglers.</p

Hormone concentrations in female <i>Astrochelys yniphora</i> populations.

<p>Mean monthly steroid hormone concentrations in adult female <i>A</i>. <i>yniphora</i> from three sample populations (wild, Madagascar captive, and U.S. captive), collected in 2013 through 2015. Number of samples collected from each population is listed with the number of individuals represented in parentheticals. Error bars represent 1 SE.</p

Observed activity of <i>Astrochelys yniphora</i> populations.

<p>Percent of total observed activity of <i>A</i>. <i>yniphora</i> from three populations (wild, Madagascar Captive, and U.S. Captive).</p

Hormone, morphometric, and environmental data relating to <i>Astrochelys yniphora</i>.

<p>Hormone, morphometric, and environmental data relating to <i>Astrochelys yniphora</i>.</p

Stress hormones in <i>Astrochelys yniphora</i> populations.

<p>Summary of mean circulating corticosterone concentrations in male (M), female (F), and sub-adult (SA) <i>A</i>. <i>yniphora</i> from the wild, a captive population near native range (Madagascar Captive), and a small outgroup, captive population in the U.S from 2013–2015. Error bars = 1SE.</p

Environmental factors associated with <i>Astrochelys yniphora</i>.

<p>Mean air temperature, ground temperature, and ground humidity by month and sex at <i>A</i>. <i>yniphora</i> locations between the two Madagascar populations from 2012–2015.</p