Genetic diversity of a marine foundation species, Laminaria hyperborea (Phaeophyceae Laminariales), along the coast of Ireland

Worldwide, kelp populations are stressed by warming, increased storms and
other man-driven disturbances. Marine population distributions
are projected to retreat poleward with climate change if they cannot adapt
to changing conditions, which would potentially lead to a regime shift in
subtidal habitats. In Northern Europe, Laminaria hyperboreais a
subtidal ecosystem engineer whose distribution has shifted over millennia,
leaving predicted areas of high genetic diversity from the last glacial
maximum (LGM) near its southern distribution limit in the Iberian
Peninsula. In Ireland, L. hyperborea structures
communities by supporting diverse faunal assemblages and producing large
quantities of organic carbon throughout the year. We investigated the
genetic diversity of eight populations ranging from the southern coast to
the northwest of Ireland using nine microsatellite loci. Diversity was
found to be highest in Lough Hyne, a Special Area of Conservation (SAC),
near the predicted climate refugium. We found evidence of isolation by
distance, with high connectivity between populations that were
geographically close, likely driven by short range dispersal
of L. hyperboreapropagules. Genetic diversity (measured as
expected heterozygosity and allelic richness) was highest at Lough Hyne,
and decreased northwards, as predicted from past range shifts. Expected
heterozygosity was highest at Lough Hyne (0.706) and decreased northward,
with the lowest value at Bridges of Ross (0.283). Based on these patterns,
further fine-scale investigation into population diversity, dispersal and
potential resilience in Irish kelp forests are necessary as warming and
non-native species are observed more and more frequently.

全球范围内，海带（kelp）种群正受到气候变暖、风暴频发及其他人为扰动的胁迫。若海洋种群无法适应环境变化，其分布预计将向极地退缩，这可能引发潮下带栖息地的生态系统转型。在北欧，掌状海带（Laminaria hyperborea）是一类潮下带生态系统工程师，其分布在数千年来发生了变迁，在伊比利亚半岛南部分布边界附近，遗留有末次冰盛期（Last Glacial Maximum, LGM）预测的高遗传多样性区域。在爱尔兰，掌状海带通过支撑多样的动物群落、全年产生大量有机碳来构建群落结构。本研究利用9个微卫星位点（microsatellite loci），对爱尔兰南部海岸至西北部的8个种群开展了遗传多样性调查。结果显示，位于预测气候避难所附近的海恩潟湖（Lough Hyne）——一处特殊保护区（Special Area of Conservation, SAC）——的遗传多样性最高。研究发现了距离隔离效应的证据：地理邻近的种群间连通性较强，这大概率由掌状海带繁殖体的短距离扩散所驱动。以期望杂合度和等位基因丰富度衡量的遗传多样性在海恩潟湖最高，并随纬度向北逐渐降低，与过去种群分布变迁的预测结果相符。其中，期望杂合度在海恩潟湖达到峰值（0.706），并向北逐步降低，在罗斯桥（Bridges of Ross）处降至最低（0.283）。基于上述研究模式，鉴于气候变暖和外来物种的观测频次日益增加，有必要对爱尔兰海带林的种群多样性、扩散能力及潜在恢复力开展进一步的精细尺度研究。