Genetic diversity of Morato's Digger Toad, Proceratophrys moratoi: spatial structure, gene flow, effective size and the need for differential management strategies of populations.

Mauricio P Arruda,Shirlei M Recco-Pimentel,William P Costa

doi:10.1590/1678-4685-gmb-2016-0025

Mauricio P Arruda, Shirlei M Recco-Pimentel + Show 1 more

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https://doi.org/10.1590/1678-4685-gmb-2016-0025

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Abstract

The Morato's Digger Toad, Proceratophrys moratoi, is a critically endangered toad species with a marked population decline in southern Brazilian Cerrado. Despite this, new populations are being discovered, primarily in the northern part of the distribution range, which raises a number of questions with regard to the conservation status of the species. The present study analyzed the genetic diversity of the species based on microsatellite markers. Our findings permitted the identification of two distinct management units. We found profound genetic structuring between the southern populations, on the left margin of the Tietê River, and all other populations. A marked reduction was observed in the contemporary gene flow among the central populations that are most affected by anthropogenic impacts, such as extensive sugar cane plantations, which presumably decreases habitat connectivity. The results indicated reduced diversity in the southern populations which, combined with a smaller effective population size, may make these populations more susceptible to extinction. We recommend the reclassification of P. moratoi as vulnerable and the establishment of a special protection program for the southern populations. Our results provide important insights about the local extinction of southern populations of this toad.

Highlights

The understanding of genetic diversity, population structure, gene flow, and the dispersal capacity of endangered species are fundamental to conservation genetics (Beebee, 2005)
The populations located in the southern portion of the geographic distribution of P. moratoi, that is, on the left margin of the Tietê River, presented lower levels of genetic diversity in comparison with the other populations
While most of these southern populations are represented by small samples, which may explain part of this difference, it is important to note that the Bauru population, represented by more than 20 individuals, was characterized by low levels of diversity, which is typical of the region

Summary

Introduction

The understanding of genetic diversity, population structure, gene flow, and the dispersal capacity of endangered species are fundamental to conservation genetics (Beebee, 2005). Studies of this kind are especially important for elucidating population decline, the definition of conservation status, and the development of management strategies (Beebee, 2005; Funk et al, 2012). The Cerrado is a biodiversity “hotspot” which has suffered high rates of habitat loss, with only 21% of the original vegetation remaining intact (Conservation International, 2011) most of which are small, isolated fragments (Mittermeier et al, 2005). Recent studies have recorded a number of new occurrence localities, especially in the northern part of its original distribution, which have led to considerable debate on its conservation status (e.g. Brasileiro et al, 2008; Carvalho Jr et al, 2010; Rolim et al, 2010; Martins and Giaretta, 2012)

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