A Study of Hybridization Between Marmota baibacina and M. sibirica in Their Secondary Contact Zone in Mongolian Altai

Oleg V Brandler,Yansanjav Adiya,Svetlana Yu Kapustina,Viacheslav V Kolesnikov,Alexander A Nikol’Skii,Bair B Badmaev

doi:10.3389/fevo.2021.555341

Abstract

The role of hybridization as one of the factors of speciation in mammals has been underestimated for a long time, but now there is a lot of data on its impact in mammalian evolution. Hybridization of species often occurs in their secondary contact zones, which is a natural model for testing factors that ensure species integrity. Studies of hybrid zones are increasingly revealing the essential role of ecological and behavioral features both in initiating crossbreeding and in maintaining interspecific barriers. We studied the hybridization of two species of marmots Marmota baibacina and M. sibirica in the zone of sympatry in Mongolian Altai Mountains. We used a bioacoustic approach to determine the localization of individuals of different species and their cohabitation sites. Genetic typing with two diploid nuclear markers and one marker each of paternal and maternal lines was used to identify hybrids. Habitat preferences of marmots were studied to understand the conditions for the formation of heterospecific pairs. We found a high proportion of hybrid individuals in boulder screes where conditions for the formation of heterospecific pairs probably exist. Our data indicate the viability and fertility of F1 hybrids and their descendants. We hypothesize that the environmental preferences and behavioral features of both species of marmots are important factors that both create conditions for hybridization and limit hybrid dispersal.

Highlights

The problem of defining species boundaries, their permeability, and estimating the impact of their disturbance for species delimitation is addressed according to the species concept that is a source of long-term discussions in evolutionary biology (Harrison and Larson, 2014; Zachos, 2016)
Our data suggested that frequency-temporal features of M. sibirica and M. baibacina alarm calls from reference populations outside the zone of sympatry correspond to the specific features described earlier for these species (Nikol’skii, 1976, 1984)
Alarm calls of 148 individuals of marmots were analyzed in the study area; 77 of them were identified as M. sibirica and 71 as M. baibacina

Summary

Introduction

The problem of defining species boundaries, their permeability, and estimating the impact of their disturbance for species delimitation is addressed according to the species concept that is a source of long-term discussions in evolutionary biology (Harrison and Larson, 2014; Zachos, 2016). Interspecific hybridization and the breaking down of interspecific barriers can lead to the blurring of species boundaries and, in some cases, Hybridization in Marmots to the extinction of one of the species (Todesco et al, 2016). The hybrid zones formed during secondary contact of previously spatially separated species may exist for quite a long time, appear and disappear periodically, and vary in their location depending on environmental changes (Wielstra, 2019). Formation of robust postzygotic barriers and gametic isolation during independent evolution requires long-term spatial isolation, disruption of which by secondary contacts under some conditions may lead to gene introgression (Abbott et al, 2013)

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