TY - JOUR

T1 - Hierarchical genetic structuring in the cool boreal kelp, Laminaria digitata: implications for conservation and management

AU - King, Nathan

AU - McKeown, Niall

AU - Smale, Dan

AU - Bradbury, Sunny

AU - Stamp, Thomas

AU - Juterbock, Alexander

AU - Egilsdóttir, Hrönn

AU - Groves, Emily

AU - Moore, Pippa

PY - 2020/9/1

Y1 - 2020/9/1

N2 - Kelp are foundation species threatened by ongoing warming trends and increased harvesting pressure. This emphasizes the need to study genetic structure over various spatial scales to resolve demographic and genetic processes underpinning resilience. Here, we investigate the genetic diversity in the kelp, Laminaria digitata, in previously understudied southern (trailing-edge) and northern (range-centre) regions in the Northeastern Atlantic Ocean. There was strong hierarchical spatial structuring with significantly lower genetic variability and gene flow among southern populations. As these span the area of the Hurd’s deep Pleistocene glacial refuge, the current low variation likely reflects a fraction of previous levels that has been eroded at the species southern edge. Northern variability and private alleles also indicate contributions from cryptic northern glacial refugia. Contrary to expectations of a positive relationship between neutral genetic diversity and resilience, a previous study reported individuals from the same genetically impoverished southern populations to be better adapted to cope with thermal stress than northern individuals. This not only demonstrates that neutral genetic diversity may be a poor indicator of resilience to environmental stress but also confirms that extirpation of southern populations will result in the loss of evolved, not just potential, adaptations for resilience.

AB - Kelp are foundation species threatened by ongoing warming trends and increased harvesting pressure. This emphasizes the need to study genetic structure over various spatial scales to resolve demographic and genetic processes underpinning resilience. Here, we investigate the genetic diversity in the kelp, Laminaria digitata, in previously understudied southern (trailing-edge) and northern (range-centre) regions in the Northeastern Atlantic Ocean. There was strong hierarchical spatial structuring with significantly lower genetic variability and gene flow among southern populations. As these span the area of the Hurd’s deep Pleistocene glacial refuge, the current low variation likely reflects a fraction of previous levels that has been eroded at the species southern edge. Northern variability and private alleles also indicate contributions from cryptic northern glacial refugia. Contrary to expectations of a positive relationship between neutral genetic diversity and resilience, a previous study reported individuals from the same genetically impoverished southern populations to be better adapted to cope with thermal stress than northern individuals. This not only demonstrates that neutral genetic diversity may be a poor indicator of resilience to environmental stress but also confirms that extirpation of southern populations will result in the loss of evolved, not just potential, adaptations for resilience.

U2 - https://doi.org/10.1093/icesjms/fsaa055

DO - https://doi.org/10.1093/icesjms/fsaa055

M3 - Article

VL - 77

SP - 1906

EP - 1913

JO - ICES Journal of Marine Science

JF - ICES Journal of Marine Science

SN - 1054-3139

IS - 5

ER -