Genetic spatial structure of European common hamsters (Cricetus cricetus) — a result of repeated range expansion and demographic bottlenecks

Abstract

The spatial genetic structure of common hamsters (Cricetus cricetus) was investigated using three partial mitochondrial (mt) genes and 11 nuclear microsatellite loci. All marker systems revealed significant population differentiation across Europe. Hamsters in central and western Europe belong largely to two allopatric mitochondrial lineages south and northwest of the Carpathian and Sudetes. The southern group, 'Pannonia', comprises populations inside the Carpathian basin (Czech Republic, Hungary) while the second group, 'North', includes hamsters from Belgium, the Netherlands, France, and Germany. Isolation of the lineages is maintained by a combination of geographical and ecological barriers. Both main phylogeographical groups show signs of further subdivision. North is separated into highly polymorphic central German and less polymorphic western populations, which most likely split during late glacial expansion (15,000-10,000 bp). Clock estimates based on haplotype distributions predict a divergence of the two major lineages 85,000-147,000 bp. Expansion times fall during the last glaciation (115,000-10,000 bp) corroborating fossil data, which identify Cricetus cricetus as characteristic of colder climatic phases. Despite the allopatry of mt haplotypes, there is an overlap of nuclear microsatellite alleles between phylogeographical units. Although there are strong evidence that Pannonian hamsters have persisted inside the Carpathian basin over the last 50,000 years, genetic differentiation among European hamsters has mainly been caused by immigration from different eastern refugia. Possible source populations are likely to be found in the Ukrainian and the southern Russian plains--core areas of hamster distribution. From there, hamsters have repeatedly expanded during the Quaternary.

Molecular phylogeny of the Cricetinae subfamily based on the mitochondrial cytochrome b and 12S rRNA genes and the nuclear vWF gene

“…A divergence time of 0.8-1.0 MY between Phodopus campbelli and P. sungorus falls exactly in this range implying a strong correlation between quarternary expansion of steppe and migration of Asian hamster populations. Western range extensions during cooler periods of the Quarternary followed by a subsequent disintegration of populations due to deteriorating ecological conditions (cooling or warming maxima) were found to be a key mechanism for genetic subdivision in common hamster populations (Neumann et al, 2005) and most likely accounts for longitudinal speciation. Unfortunately, there are hardly genetic data for other steppe adapted mammals in the Sajan-Altai region to investigate the importance of such a speciation process.…”

“…PCR was run in a thermocycler UNO II, Biometra employing 35 cycles (60 s at 94°C, 60 s at primer specific annealing temperature and 90 s at 72°C) with an initial heating step of 4 min at 94°C and a final extension cycle of 10 min at 72°C. A large portion of cytochrome b (cytb) was amplified and sequenced as described in Neumann et al (2005).…”

The genetic characterization of an isolated remnant population of an endangered rodent (Cricetus cricetus L.) using comparative data: implications for conservation

“…Current genetic structure of C. cricetus is proposed to be an effect of several phenomena, such as partial extinctions, (re-)immigration, bottleneck events, in situ survival in refugia, genetic drift, and different migration routes. The negative consequences of small population size, inbreeding, lack of gene flow, and founder effects are more pronounced in populations from western Europe compared with populations from central and eastern regions (Neumann et al 2005).…”

“…and some central parts of its European range (e.g., Nechay 2000; Neumann et al , 2005Ziomek and Banaszek 2007;Schröder et al 2014;La Haye et al 2014;Reiners et al 2014;Surov et al 2016). Interestingly, the common hamster has shown some potential for recovery following intensive ex situ and in situ conservation actions undertaken recently (e.g., Weinhold 2004;La Haye et al 2010;Villerney et al 2013).…”

“…Neumann et al , 2005 and has generated a compelling picture of its evolutionary relationships and possible migration flows. Current genetic structure of C. cricetus is proposed to be an effect of several phenomena, such as partial extinctions, (re-)immigration, bottleneck events, in situ survival in refugia, genetic drift, and different migration routes.…”