The restoration of the endangered Sambucus palmensis after 30 years of conservation actions in the Garajonay National Park: genetic assessment and niche modeling.

Priscila Rodríguez-Rodríguez,Pedro A Sosa,Alejandro G Fernández De Castro

doi:10.7717/peerj.4985

Priscila Rodríguez-Rodríguez, Pedro A Sosa + Show 1 more

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https://doi.org/10.7717/peerj.4985

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Abstract

The translocation of individuals or the reinforcement of populations are measures in the genetic rescue of endangered species. Although it can be controversial to decide which and how many individuals must be reintroduced, populations can benefit from reinforcements. Sambucus palmensis is a critically endangered endemic to the Canary Islands. During the past 30 years, the Garajonay National Park (La Gomera) has carried out an intensive program of translocations using cuttings, due to the low germination rates of seeds. To assess the effect of the restorations on the population genetics of S. palmensis in La Gomera, we collected 402 samples from all the restored sites and all known natural individuals, which were genotyped with seven microsatellite markers. In addition, we conducted a species distribution modeling approach to assess how restorations fit the ecological niche of the species. Results show that there is a high proportion of clone specimens due to the propagation method, and the natural clonal reproduction of the species. Nonetheless, the observed heterozygosity has increased with the restorations and there still are private alleles and unique genotypes in the natural populations that have not been considered in the restorations. The population of Liria constitutes a very important genetic reservoir for the species. To optimize future reintroductions, we have proposed a list of specimens that are suitable for the extraction of seeds or cuttings in a greenhouse, as well as new suitable areas obtained by the species distribution models.

Highlights

The preservation of endangered plant species usually involves population restorations, either by reinforcement of the extant populations or the reintroduction of new populations
We developed four new microsatellite markers for S. palmensis to improve the accuracy of the genotypes, coded as Sam_Tet2, Sam_Hex2, Sam_Hex1 and Sam_Tri8 (Supplemental Information 1)
All microsatellite markers used for this study yielded enough polymorphism to identify the possible number of genotypes in the sampling sites analyzed and to detect possible identical genotypes

Summary

Introduction

The preservation of endangered plant species usually involves population restorations, either by reinforcement of the extant populations or the reintroduction of new populations. The biological purpose of the restorations is to increase the species’ survival prospects by recovering its evolutionary potential and autonomous ecological behavior (Godefroid et al, 2011) These measures often involve translocating genotypes across geographic ranges. This is a very controversial practice in which the need to maximize genetic diversity and avoid inbreeding depression is balanced against the maintenance of coadapted gene complexes (outbreeding depression; Storfer, 1999; Hufford & Mazer, 2003; González-Pérez, Sosa & Batista, 2009). The selection of areas for reintroduction is often decided on the basis of intuitive or informal expertise, as the choice of unsuitable habitats is considered a frequent reason for failure (Godefroid et al, 2011)

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