Species History Masks the Effects of Human-Induced Range Loss – Unexpected Genetic Diversity in the Endangered Giant Mayfly Palingenia longicauda

Miklós Bálint,Éva Váncsa,Peter Haase,Jutta Geismar,Szabolcs Lengyel,Carsten Nowak,Kristóf Málnás,László Polyák

doi:10.1371/journal.pone.0031872

Abstract

Freshwater biodiversity has declined dramatically in Europe in recent decades. Because of massive habitat pollution and morphological degradation of water bodies, many once widespread species persist in small fractions of their original range. These range contractions are generally believed to be accompanied by loss of intraspecific genetic diversity, due to the reduction of effective population sizes and the extinction of regional genetic lineages. We aimed to assess the loss of genetic diversity and its significance for future potential reintroduction of the long-tailed mayfly Palingenia longicauda (Olivier), which experienced approximately 98% range loss during the past century. Analysis of 936 bp of mitochondrial DNA of 245 extant specimens across the current range revealed a surprisingly large number of haplotypes (87), and a high level of haplotype diversity (). In contrast, historic specimens (6) from the lost range (Rhine catchment) were not differentiated from the extant Rába population (, ), despite considerable geographic distance separating the two rivers. These observations can be explained by an overlap of the current with the historic (Pleistocene) refugia of the species. Most likely, the massive recent range loss mainly affected the range which was occupied by rapid post-glacial dispersal. We conclude that massive range losses do not necessarily coincide with genetic impoverishment and that a species' history must be considered when estimating loss of genetic diversity. The assessment of spatial genetic structures and prior phylogeographic information seems essential to conserve once widespread species.

Highlights

Freshwater biodiversity is declining much faster than marine or terrestrial biodiversity [1]
While species extinctions have rarely been documented, numerous previously widespread species only persist as small relict populations in refugia which were not subjected to severe habitat alterations
It is expected that these massive range losses have led to considerable losses of genetic diversity [4,5,6], including highly differentiated evolutionary lineages, which can be referred to as cryptic species, or evolutionary significant units (ESU) [7,8]

Summary

Introduction

Freshwater biodiversity is declining much faster than marine or terrestrial biodiversity [1]. Local genetic variants and ESUs might harbor unique evolutionary potential, and provide the source of adaptation to future environmental change [9,10]. These concerns are relevant in freshwater systems, because several species show high levels of differentiation within their ranges, especially along the main catchments [11,12,13], and for species with a limited potential for overland dispersal [14,15,16,17,18]. Existing works suggest that range losses should parallel the loss of genetic diversity [4,5,6], there is still little empirical information on the coupling of these processes, especially in freshwater species

Objectives

Methods

Results

Conclusion