Genetic diversity in population systems of green frogs (Pelophylax esculentus complex) in waterbodies of Western Ukraine

V O Stakh,I S Khamar,Iu M Strus

doi:10.30970/sbi.1203.575

Abstract

The results of the analysis of the genetic structure in population systems of green frogs on the territory of Lviv and Volyn regions are presented. The material was collected in 2011–2012 in water bodies representing three nature regions of Ukraine – Forecarpathians, Roztochia, and Western Polissia. Three taxonomic groups of green frogs were in a focus of the study: Marsh frog – Pelophylax ridibundus (Pallas, 1771), Pool frog – Pelophylax lessonae (Camerano, 1882) and their hybrid – Edible frog – Pelophylax esculentus (Linnaeus, 1758). DNA was extracted from 91 individuals and analyzed using of 10 pairs of primers: Rrid059, Rrid082, Rrid171, Res5, Res14, Res16, Res22, RlCA1b5, RlCA18, RlCA19. A majority of those are highly polymorphic and diagnostic for species identification. During the analysis, we used programs based on principles of Bayesian statistics and Monte-Carlo Markov Chain algorithms: Structure, BAPS, and NewHybrids. Linkage groups were searched using the GenePop software, and hidden null-alleles were detected using Micro-Checker program. For the first time, in the studied area the genetic structure of populations and population systems were described. After the analysis of genetic diversity of frogs sampled from the Pelophylax ridibundus population and from hemiclonal population systems of mixed R-E-L type, we found that the smallest genetic diversity is observed in the population of Marsh frog from the Nyzhankovychi area (Forecarpathians). More diverse are hemiclonal population systems of green frogs sampled in water bodies of “Cholgynskyi” ornithological reserve (Ukrainian Roztochia) and Shatsk National Nature Park (Western Polissia). Also, for the first time, the hybrid composition of studied localities is described. Hybrids of the first generation (F1) and backcrosses were detected in water bodies of Shatsk National Nature Park and ornithological reserve “Cholgynskyi”.

Highlights

The group of green frogs (Pelophylax) is known because of a specific way of repro duction of hybrid individuals
After the analysis of genetic diversity of frogs sampled from the Pelophylax ridibundus population and from hemiclonal population systems of mixed R-E-L type, we found that the smallest genetic diversity is observed in the population of Marsh frog from the Nyzhankovychi area (Forecarpathians)
Greens frogs sampled from three different localities of Lviv and Volyn regions were in the focus of the study. 31 individuals of Marsh frog were sampled in ponds near Nyzhankovychi town (Starosambirskyi district, Lviv region, Forecarpathians, 49°40′17.7′′N and 22°48′15.3′′E). 42 individuals of green frogs were sampled from reservoirs in the ornithological reserve “Cholgynskyi” (Yavorivskyi district, Lviv region, Roztochia nature zone, 49°55′03.5′′N and 23°26′27.6′′E; 18 Pool frogs, 18 Marsh frogs, and 6 hybrids)

Summary

Introduction

The group of green frogs (Pelophylax) is known because of a specific way of repro duction of hybrid individuals. Berger [3] described an excep tional scheme of hybridization between two species of green frogs – Marsh frog Pelophylax ridibundus (Pallas, 1771) and Pool frog – Pelophylax lessonae (Camerano, 1882) with an Edible frog (Pelophylax esculentus (Linnaeus, 1758)) as a result. These three groups of frogs can exist side by side, freely cross-breed and produce hybrids and hemiclonal population systems (HPS) [47]. After the elimination of one half of a genome, the other half undergoes endoreduplication and is called “clonal” (because of the absence of recombination). Such a way of reproduction is called hemiclonal (Fig. 1)

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