Phenotypic structure of Pelophylax esculentus complex population in urbanized landscapes in the South Central Russian Upland

Abstract

Background. Morphological features are one of the most important markers for bioindication. Among them, the polymorphism of phenotypic traits occupies a special place. In tailless amphibians, dorsal colouration variability is widespread: the presence or absence of a light dorsomedial stripe or dark spots. The phenotypic composition is known to change in the impacted areas. The purpose of the study was to analyze the phenotypic structure of Pelophylax esculentus complex populations in the urbanized landscapes in the South Central Russian Upland. This study is a part of the comprehensive analysis of the population structure of green frogs in the South Central Russian Upland. Materials and methods. A total of 748 individuals were sampled from 35 localities in the South Central Russian Upland. Collection points differed in the degree of anthropogenic pressure. Dorsal coloration variations were analyzed according to the generally accepted grading. Analysis of phenotypes diversity was performed according to the indicators proposed by L.A. Zhivotovsky. Results. Four main phenotypes “Maculata” (M), “Striata” (S), “Punctata” (P), “Burnsi” (B), and their combinations SM, SP and SMP were registered in the study area. The highest phenotypic diversity was observed in natural or sparsely disturbed biotopes “Sazon” (6.815 ± 0.251), “Aidar” (6.527 ± 0.306), “Goluboi Dunai” (6.43 ± 0.418), while under anthropogenic pressure an increase in the proportion of rare phenotypes was observed. The principal component analysis has demonstrated the phenotypic similarity of most of the populations. At the same time, unique groups were found in both impact and natural habitats, which may indicate an effective compensatory response of the green frog populations in the study area to anthropogenic pressures. Conclusions. The results obtained confirm the data of the previous studies on the phenotypic polymorphism of green frogs, according to which the phenotypic diversity declines and the proportion of rare phenotypes increases under conditions of anthropogenic pressure. In addition, in a number of populations, both in urbanized and relatively clean biotopes, unique combinations of phenotypic frequencies are observed, indicating active adaptation of green frogs to changing environmental conditions.

Keywords

• the south central russian upland
• pelophylax esculentus complex
• population structure