High genetic diversity in the remnant island population of hihi and the genetic consequences of re-introduction

Abstract

The maintenance of genetic diversity is thought to be fundamental for the conservation of threatened species. It is therefore important to understand how genetic diversity is affected by the re-introduction of threatened species. We use establishment history and genetic data from the remnant and re-introduced populations of a New Zealand endemic bird, the hihi Notiomystis cincta, to understand genetic diversity loss and quantify the genetic effects of re-introduction. Our data do not support any recent bottleneck events in the remnant population. Furthermore, all genetic diversity measures indicate the remnant hihi population has retained high levels of genetic diversity relative to other New Zealand avifauna with similar histories of decline. Genetic diversity (N(A) , alleles per locus, allelic richness, F(IS) and H(S) ) did not significantly decrease in new hihi populations founded through re-introduction when compared to their source populations, except in the Kapiti Island population (allelic richness and H(S) ) which had very slow post-re-introduction population growth. The N(e) /N(c) ratio in the remnant population was high, but decreased in first-level re-introductions, which together with significant genetic differentiation between populations (F(ST) & Fisher's exact tests) suggest that extant populations are diverging as a result of founder effects and drift. Importantly, simulations of future allele loss predict that the number of alleles lost will be higher in populations with a slow population growth, fewer founding individuals and with nonrandom mating. Interestingly, this species has very high levels of extra-pair paternity which may reduce reproductive variance by allowing social and floater males to reproduce a life history trait that together with a large remnant population size may help maintain higher levels of genetic diversity than expected.

High variance in reproductive success generates a false signature of a genetic bottleneck in populations of constant size: a simulation study

“…Genetic methods for bottleneck detection are useful because: (1) historical (and current) census sizes are rarely known; (2) even when census size ( N c ) is known, cryptic bottlenecks (change in effective size, N e , without change in N c ) may occur; and (3) bottleneck outcomes are highly stochastic, meaning that genetic diversity following the bottleneck is somewhat unpredictable even when the demographic history is known [11,12]. It is therefore important to evaluate the statistical performance of these methods, especially as these tests are key components of many evolutionary, molecular ecology, and conservation genetic studies [13-16]. …”

“…In addition, factors such as the mutation model and the rate of post-bottleneck recovery may also play an important role [9,13,16-18]. Also, the methods do not always show similar power.…”

“…Remarkably, in spite of frequent use of bottleneck tests, and the conservation decisions that are based on them, little is known about their type I error rates when assumptions of the biological model are violated. For example, the influence of mating patterns [13], age structure [14], and reproductive success [21,22] is rarely known.…”

Long-distance translocations to create a second millerbird population and reduce extinction risk

“…Ongoing study on Laysan will shed light on the life history, ecology, and genetics of this new millerbird population (Conant, 1988;Michel et al, 2010;Brekke et al, 2011;Wright et al, 2014). In addition, the millerbird translocation is an example of the application of established guidelines for translocation under unique circumstances, and this project provides a general model of project planning that can be adapted for use in other longdistance conservation translocations of endangered species.…”

Genetic monitoring to evaluate reintroduction attempts of a highly endangered rodent

“…Moreover, captive breeding is mostly started in species with already highly threatened populations with low numbers (Frankham et al 2002;Allendorf et al 2013), which may result in ex-situ populations with small genetic variation. Together with limitations in the number of individuals available for reintroduction (Van Houtan et al 2009;Brekke et al 2011;Tracy et al 2011) it seems almost inevitable that reintroductions initially result in small populations, with a poor genetic status (Spielman et al 2004;Tracy et al 2011;Pacioni et al 2013). Despite these disadvantages, reintroduction has become an important and frequently applied strategy for the conservation of a broad variety of mammals, ranging from small mammals (Ottewell et al 2014;McCleery et al 2014) till large carnivores (Hayward et al 2007).…”