Low but contrasting neutral genetic differentiation shaped by winter temperature in European great tits

Abstract

Gene flow is usually thought to reduce genetic divergence and impede local adaptation by homogenising gene pools between populations. However, evidence for local adaptation and phenotypic differentiation in highly mobile species, experiencing high levels of gene flow, is emerging. Assessing population genetic structure at different spatial scales is thus a crucial step towards understanding mechanisms underlying intraspecific differentiation and diversification. Here, we studied the population genetic structure of a highly mobile species – the great tit Parus major – at different spatial scales. We analysed 884 individuals from 30 sites across Europe including 10 close‐by sites (< 50 km), using 22 microsatellite markers. Overall we found a low but significant genetic differentiation among sites (FST = 0.008). Genetic differentiation was higher, and genetic diversity lower, in south‐western Europe. These regional differences were statistically best explained by winter temperature. Overall, our results suggest that great tits form a single patchy metapopulation across Europe, in which genetic differentiation is independent of geographical distance and gene flow may be regulated by environmental factors via movements related to winter severity. This might have important implications for the evolutionary trajectories of sub‐populations, especially in the context of climate change, and calls for future investigations of local differences in costs and benefits of philopatry at large scales.

Repeated genomic signatures of adaptation to urbanisation in a songbird across Europe

“…Boyce and Perrins 1987; Table S1). This is in line with previous studies of the species (Perrier et al 2018;Laine et al 2016;Lemoine et al 2016;Spurgin et al 2019). In addition, the levels of heterozygosity were similar between urban and rural populations, although slightly lower in some of the urban populations (see Table S1 for details; Wilcoxon test: W=30, P = 0.377).…”

Great tits and the city: Distribution of genomic diversity and gene–environment associations along an urbanization gradient

“…First, Lemoine et al. () found an F st of 0.018 between Montpellier City and La Rouvière Forest. Second, F st among close sites in Barcelona City ranged from 0.018 to 0.19 (Björklund et al., ).…”

“…Specifically, the first aim of this study was to test the impact of the local level of urbanization on the extent of genomewide genetic diversity and structure in urban great tits. Although small genetic differentiation was expected given recent empirical findings in this species (Laine et al., ; Lemoine et al., ), we hypothesized that significant population structure and reduction in diversity may occur among populations found in areas with different levels of urbanization (Björklund et al., ), potentially resulting from the interplay between reduced dispersal and population size, habitat choice, and local adaptation. The second aim was to search for genomic footprints of divergent selection between sites with different levels of urbanization, and gene–urbanization associations, that may be implicated in adaptation to urban life (Harris et al., ).…”

“…Great tits are widespread and abundant across Eurasia and can be found in a wide variety of environments, from natural forests to highly urbanized cities. Previous studies based on microsatellite loci showed relatively small genetic differentiation across Europe, yet higher differentiation among southern populations (Lemoine et al., ) as well as within the city of Barcelona (Björklund et al., ). Studies comparing the life history and physiology of great tits in forest versus city habitats have recently revealed that, compared to their forest conspecifics, urban great tits lay earlier and smaller clutches, they display faster breath rates and faster exploration scores in a novel environment, have higher levels of neophilia, and their offspring fledge in poorer condition (Bailly et al., ; Charmantier, Demeyrier, Lambrechts, Perret, & Gregoire, ; Marzluff, ; Sprau, Mouchet, & Dingemanse, ; Torné‐Noguera, Pagani‐Núñez, & Senar, ; Tryjanowski et al., ).…”

Flexibility of co-evolutionary patterns in ectoparasite populations: genetic structure and diversity inApodemusmice and their lice

“…The generally accepted view holds that species occupying large interconnected habitats tend to possess larger, more diverse populations, whereas species with isolated populations and/or recently bottlenecked species show reduced diversity (Allendorf et al 2013). However, even in continental, highly mobile species, the level of local genetic diversity may differ and gene flow between the populations may be affected by moderate environmental differences (Lemoine et al 2016).…”