Data from: Assessing risks of invasion through gamete performance: farm Atlantic salmon sperm and eggs show equivalence in function, fertility, compatibility and competitiveness to wild Atlantic salmon

Adaptations at the gamete level (a) evolve quickly, (b) appear sensitive to inbreeding and outbreeding and (c) have important influences on potential to reproduce. We apply this understanding to problems posed by escaped farm salmon and measure their potential to reproduce in the wild. Farm Atlantic salmon (Salmo salar) are a threat to biodiversity, because they escape in large numbers and can introgress, dilute or disrupt locally adapted wild gene pools. Experiments at the whole fish level have found farm reproductive potential to be significant, but inferior compared to wild adults, especially for males. Here, we assess reproductive performance at the gamete level through detailed in vitro comparisons of the form, function, fertility, compatibility and competitiveness of farm versus wild Atlantic salmon sperm and eggs, in conditions mimicking the natural gametic microenvironment, using fish raised under similar environmental conditions. Despite selective domestication and reduced genetic diversity, we find functional equivalence in all farm fish gamete traits compared with their wild ancestral strain. Our results identify a clear threat of farm salmon reproduction with wild fish and therefore encourage further consideration of using triploid farm strains with optimized traits for aquaculture and fish welfare, as triploid fish remain reproductively sterile following escape.

配子（gamete）层面的适应性具备三大特征：(a) 演化速率较快；(b) 对近交（inbreeding）与远交（outbreeding）敏感；(c) 对繁殖潜能具有显著影响。我们将这一认知应用于逃逸养殖鲑鱼引发的相关问题，并对其野外繁殖潜能展开评估。养殖大西洋鲑（Salmo salar）会对本地生物多样性构成威胁：它们会大量逃逸，并可通过基因渐渗、基因库稀释或破坏本地适应性野生种群的基因库。过往基于全鱼个体的实验显示，养殖个体的繁殖潜能可观，但相较于野生成体仍显逊色，雄性个体的差距尤为突出。本研究采用在相同环境条件下饲养的实验个体，通过模拟自然配子微环境的实验条件，对养殖与野生大西洋鲑的精子、卵子的形态、功能、受精能力、兼容性及竞争能力开展细致的体外（in vitro）比较分析，以此评估配子层面的繁殖表现。尽管养殖种群经历了定向驯化且遗传多样性有所降低，但本研究发现，养殖个体的所有配子功能性状均与野生祖先种群无显著差异。本研究结果证实，养殖鲑鱼与野生鲑鱼存在交配繁殖的明确风险，因此建议进一步考量使用兼具水产养殖优良性状与鱼类福利优化的三倍体（triploid）养殖品系——此类三倍体个体逃逸后仍可保持繁殖不育性。