Structural variants underlie parallel adaptation following global invasion

Climate change and the global spread of invasive species are currently two of the most significant threats to biodiversity worldwide. Yet the role of adaptation in organismal responses to changing climates or in facilitating species invasions is still poorly understood. We conducted a large-scale trans-continental common garden experiment to understand adaptation to spatiotemporal variation in climate in the native and introduced ranges of a cosmopolitan plant species. Individuals from 96 populations of Trifolium repens (white clover) from both its native (Europe) and introduced (North America) ranges were planted into four experimental common gardens located in northern (Uppsala, Sweden) and southern (Montpellier, France) Europe, and northern (Mississauga, Canada) and southern (Louisiana, USA) North America. We recorded plant sexual and clonal fitness in each common garden and assessed whether plants are best adapted to local climates, whether the strength of local adaptation differed between the native and introduced ranges, and whether populations show evidence of rapid adaptation to recent climate change. Results show that white clover is locally adapted, particularly in lower latitude locations, but also that the most prominent bioclimatic drivers of local adaptation differed by latitude. We also found that strong local adaptation was only evident when populations were transplanted into common gardens located in the same range (native or introduced) from which they originated, indicating rapid local adaptation across a large latitudinal gradient has occurred in T. repens populations in less than 400 years since its introduction to North America. However, we do find some evidence of an adaptation lag in the northern common garden in the introduced range, with plants from historically slightly warmer climates exhibiting the greatest fitness. This indicates that despite evidence of local adaptation to historic climatic conditions and rapid local adaptation post-introduction, white clover populations may be evolving more slowly than climate change is occurring.

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Signatures of selective sweeps in urban and rural white clover populations

Santangelo,

Johnson,

Ness

2024

Preprint

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Urbanization is increasingly recognized as a powerful force of evolutionary change. However, anthropogenic sources of selection can often be similarly strong and multifarious in rural habitats, but these are often ignored in studies of urban evolutionary ecology. Despite numerous examples of phenotypic differentiation between urban and rural populations, we still lack an understanding of the genes enabling adaptation to these contrasting habitats and the genetic architecture underlying urban and rural adaptation. In this study, we conducted whole genome sequencing of 120 urban, suburban, and rural white clover plants from Toronto, Canada. We used these data to identify signatures of selective sweeps across the genome using both SFS and haplotype-based approaches, and characterize the architecture of selective sweeps. We found evidence for selection in genomic regions involved in abiotic stress tolerance and growth/development in both urban and rural populations. Urban and rural populations did not differ in the proportion of hard vs. soft sweeps, though urban populations were characterized by wider sweeps, which may indicate differences in the strength or timescale of selection. In addition, patterns of allele frequency and haplotype differentiation suggest that most sweeps are incomplete. These results highlight how both urban and rural habitats are driving ongoing selection in white clover populations, and motivate future work disentangling the genetic architecture of ecologically important phenotypes, and estimating the strength and timescale of selection underlying adaptation to contemporary anthropogenic habitats.

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Structural variants underlie parallel adaptation following global invasion

Cited by 3 publications

References 58 publications

Altitudinal variation in herbivory resistance and genetic diversity in the naturalized cyanogenic legume

Altitudinal variation in herbivory resistance and genetic diversity in the naturalized cyanogenic legume

A transcontinental experiment elucidates (mal)adaptation of a cosmopolitan plant to climate in space and time

Signatures of selective sweeps in urban and rural white clover populations

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