Maintenance of genetic diversity in an introduced island population of guanacos after seven decades and two severe demographic bottlenecks: implications for camelid conservation.

Benito A González,William L Franklin,Rainer Von Borries,Warren E Johnson,Pablo Orozco-Terwengel,Juan C Marín,Taras K Oleksyk

doi:10.1371/journal.pone.0091714

Abstract

Fifteen guanacos were introduced to Staats Island in the Falklands/Malvinas archipelago from Patagonia in the 1930s. Twenty five years later, the population was culled from 300 to 10–20 individuals, but quickly rebounded to a population of almost 400 animals that today retain the genetic signature of the founding event and later bottleneck. The goals of this study were to (i) make a genetic assessment of this island population through comparisons with mainland populations and simulations, and (ii) assess the likely source-population of the introduced guanacos. Genetic variation was estimated from 513 bp of mitochondrial DNA sequence and 15 microsatellite loci among 154 guanacos collected from eight localities, including the adjacent mainland and the islands of Tierra del Fuego and Staats Island. Of the 23 haplotypes observed among our samples, the Staats Island population only contained three haplotypes, all of which were shared with the coastal Monte Leon population in southern Patagonia. Mitochondrial DNA and microsatellite variations on Staats Island were comparable to most mainland populations and greater than those observed on Tierra del Fuego. Patterns of genetic structure suggest that the Staats Island guanaco population was founded with animals from southern Patagonia (as opposed to northern Patagonia or Tierra del Fuego), but that effective reductions in population size lasted only a few generations and that surviving animals were a random sample of the pre-bottleneck genetic variation.

Highlights

Genetic analysis is a well-used tool for the conservation and management of animal populations and can help in determining genetic patterns, differentiating populations, resolving taxonomic uncertainties, and addressing evolutionary questions [1,2,3,4,5]
Of the 23 haplotypes observed among our samples, the Staats Island population only contained three haplotypes, all of which were shared with the Monte Leon population (Table 2, Figure 1)
The Staats Island guanaco population presents a similar amount of genetic variation as continental guanaco populations

Summary

Introduction

Genetic analysis is a well-used tool for the conservation and management of animal populations and can help in determining genetic patterns, differentiating populations, resolving taxonomic uncertainties, and addressing evolutionary questions [1,2,3,4,5]. Genetic studies have had an important management role in describing the effects of demographic changes (e.g. founder effects, bottlenecks) on the genetic variation of populations after capture, translocation, and release of wild individuals [9,10,11,12,13,14,15]. Few studies have genetically surveyed wild or endangered species with well-documented population dynamics in order to test hypotheses about the impact of bottlenecks on genetic variation, and subsequent population persistence [16]. The guanaco (Lama guanicoe) is a native ungulate of South America. It is distributed widely from Peru (8u S) in the north, through Bolivia, Paraguay and Argentina until the southernmost part of Chile (55uS) [17,18]. Besides the Tierra del Fuego population, the only other natural island population occurs on Navarino Island [26], but how guanacos spread from the continent to this island is still unclear [27]

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Conclusion