Population genomics of emperor penguins using RADseq

Understanding the boundaries of breeding populations is of great importance for conservation efforts and estimates of extinction risk for threatened species. However, determining these boundaries can be difficult when population structure is subtle. Emperor penguins are highly reliant on sea ice, and some populations may be in jeopardy as climate change alters sea ice extent and quality. An understanding of emperor penguin population structure is therefore urgently needed. Two previous studies have differed in their conclusions, particularly whether the Ross Sea, a major stronghold for the species, is isolated or not. We assessed emperor penguin population structure using 4,596 genome-wide single nucleotide polymorphisms (SNPs), characterised in 110 individuals (10 – 16 per colony) from eight colonies around Antarctica. In contrast to a previous conclusion that emperor penguins are panmictic around the entire continent, we find that emperor penguins comprise at least four metapopulations, and that the Ross Sea is clearly a distinct metapopulation. By using larger sample sizes and a thorough assessment of the limitations of different analytical methods, we have shown that population structure within emperor penguins does exist and argue that its recognition is vital for the effective conservation of the species.明晰繁殖种群的边界，对于濒危物种的保护工作与灭绝风险评估均具有重要意义。然而，当种群结构较为隐蔽时，确定此类边界往往颇具难度。帝企鹅（Emperor Penguin）高度依赖海冰，随着气候变化改变海冰的分布范围与质量，部分种群或已濒临险境，因此亟需厘清帝企鹅的种群结构。此前两项相关研究结论存在分歧，尤其是针对该物种的核心栖息地——罗斯海是否存在种群隔离这一问题。本研究针对南极周边8个繁殖群落的110只个体（每个群落取样10至16只），对其4596个全基因组单核苷酸多态性（SNPs）标记进行分型鉴定，以此评估帝企鹅的种群结构。此前有研究认为帝企鹅在整个南极大陆范围内均为泛交种群，本研究结果与此相悖：我们发现帝企鹅至少可划分为4个集合种群（metapopulations），且罗斯海种群明确为一个独立的集合种群。本研究通过采用更大的样本量，并对不同分析方法的局限性进行全面评估，证实帝企鹅内部确实存在种群结构，并主张承认该结构对于该物种的有效保护至关重要。