Abstract

Ex situ management strategies play an important role in the conservation of threatened species when the wild survival of the species cannot be ensured. Molecular markers have become an outstanding tool for the evaluation and management of captive breeding programs. Two main genetic objectives should be prioritized when planning breeding programs: the maintenance of maximum neutral genetic diversity, and to obtain “self-sustaining” captive populations. In this study, we use 24 microsatellite loci to analyze and evaluate the genetic representativity of the initial phases of the captive breeding program of the Montseny brook newt, Calotriton arnoldi, an Iberian endemic listed as Critically Endangered. The results show that the initial captive stock has 74–78% of the alleles present in the wild populations, and captures roughly 93–95% of their total genetic diversity as observed in a previous study on wild newts, although it does not reach the desired 97.5%. Moreover, the percentage of unrelatedness among individuals does not exceed 95%. Therefore, we conclude that the genetic diversity of the captive stock should be improved by incorporating genetic material from unrelated wild newts. In recognition of the previously described significant genetic and morphological differentiation between eastern and western wild populations of C. arnoldi, we suggest maintaining two distinct breeding lines, and we do not recommend outbreeding between these lines. Our comparisons of genetic diversity estimates between real and distinct sample-sized simulated populations corroborated that a minimum of 20 individuals are needed for each captive population, in order to match the level of genetic diversity present in the wild populations. Thus, the current initial stock should be reinforced by adding wild specimens. The captive stock and subsequent cohorts should be monitored in order to preserve genetic variation. In order to avoid genetic adaptation to captivity, occasionally incorporating previously genotyped individuals from the wild into the captive populations is recommended.

Highlights

  • There is general agreement among scientists that we are in the midst of the sixth great mass extinction

  • We evaluated whether the levels of genetic diversity observed in the initial captive stock are comparable to the genetic diversity observed in the wild populations, and if this diversity is sufficient to be maintained over time

  • A total of 140 alleles were identified in the 42 captive individuals analyzed, compared to the 170 alleles identified in the 160 individuals analyzed from the wild populations by Valbuena-Ureña et al (2017)

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Summary

Introduction

There is general agreement among scientists that we are in the midst of the sixth great mass extinction. Captive breeding programs are typically associated with many limitations: high economic costs, adaptation to captivity (Araki, Cooper & Blouin, 2007; Williams & Hoffman, 2009), poor success in reintroductions (Harding, Griffiths & Pavajeau, 2015; McCleery, Hostetler & Oli, 2014) and more (see below) have been reported The need for such programs is justified only when it is essential for species’ survival, and should be implemented only after a careful evaluation of costs and benefits of all conservation alternatives (Dolman et al, 2015; McGowan, Traylor-Holzer & Leus, 2016). Without excluding other in situ actions, captive breeding can play a crucial role in the recovery of some species for which effective alternatives are unavailable in the short term (Frankham, 1995; Griffiths & Pavajeau, 2008; Ralls & Ballou, 1986; Snyder et al, 1996; McGowan, Traylor-Holzer & Leus, 2016)

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