Does Sexual Selection Accelerate or Slow Speciation in Arctic Shorebirds?

性选择通常被认为促进物种形成，因为它通常与一种性别对其配偶特别挑剔有关，这加强了生殖隔离(Lande，1981)。然而，D‘Urban-Jackson等人最近的研究。(2017)发现，在滨鸟中，一夫多妻制交配系统中发现的较高水平的性选择与减少生殖隔离水平有关。作者认为，这是由于一夫多妻制对基因流动的更直接影响--通过交配、继续前进和再次交配，一个个体可以在每个季节将其基因混合到多个种群中。生态因素也与交配系统和基因流动有关，这些都混淆了之前的研究(包括D‘Urban Jackson等人，2017年的研究)。这项计划中的研究将比较约10种受系统发育控制的北极滨鸟的种群结构，这些物种的繁殖范围和栖息地几乎相同，但存在不同程度的性别选择。将首次在没有生态混乱的情况下调查性选择在生殖隔离中的作用。在CASE合作伙伴北京基因组研究所的支持下，将使用高通量基因组学对生殖隔离进行分析。这项计划中的分析将需要北极的多个野外季节以及合作(在国家海洋和大气科学研究所的支持下)，预计要到博士学位接近尾声时才能完成样本采集。更直接的计划是：1)分析交配系统对性别偏见基因表达的影响，首次使用野生鸟类(见Harison等人，2015年在半驯养鸟类中进行的此类分析)。以及2)首次分析北极鸟类环鸟的时间遗传多样性变化(见Boessenkool等人，2010年，企鹅的类似方法)。计划中的研究与国家环境研究委员会的目标有明确的关系，因为了解生殖隔离的因素可以帮助自然资源保护者预测哪些物种面临最大的灭绝风险。这一点尤其适用于所研究的鸟类所在的北极地区，那里的许多物种已经在迅速减少，气候变化的影响感受最强烈(在Meltofte，2007年进行了回顾)。Boessenkool，S.，Star，B.，Seddon，P.J.，&Waters，J.M.(2010)。时间遗传样本表明，濒危黄眼企鹅的有效种群规模很小。《保护遗传学》，11(2)，539-546.D‘Urban Jackson，J.，Dos Remedios，N.，Maher，K.H.，Zefania，S.，Haig，S.，Oyler-McCance，S.，...&Kper，C.(2017)。一夫多妻制减缓了滨鸟的种群分化。《进化》，71(5)，1313-1326.哈里森，P.W.，赖特，A.E.，齐默，F.，Dean，R.，蒙哥马利，S.H.，POINT，M.A.，&Mank，J.E.(2015)。性选择推动了男性基因表达的进化和快速更替。《国家科学院院刊》，第112(14)期，第493-4398页。多基因性状的性别选择物种形成模型。《国家科学院院刊》，78(6)，3721-3725.Meltofte，H.(2007)。气候变化对北极滨鸟繁殖生态的影响博物馆图斯库拉纳姆出版社。

Sexual selection has often been assumed to promote speciation, as it is typically associated with one sex being particularly selective about their mate, which enhances reproductive isolation (Lande, 1981). However recent research by D'Urban-Jackson et al. (2017), found that in shorebirds, the higher levels of sexual selection found in polygamous mating systems were associated with reduced levels of reproductive isolation. The authors suggest this is due to a more direct effect of polygamy on gene flow - by mating and moving on and mating again, an individual can mix its genes into multiple populations every season. Ecological factors are also associated with both mating system and gene flow, and these have confounded previous investigations (including that of D'urban Jackson et al., 2017). The planned research will compare population structure in ~10 phylogenetically controlled species of Arctic Shorebird, with almost identical breeding ranges and habitats, but with varying levels of sexual selection present. For the first time the role of sexual selection in reproductive isolation will be investigated in the absence of ecological confounds. Reproductive isolation will be analysed using high-throughput genomics, with support from CASE partner the Beijing Genomics Institute. This planned analysis will require multiple Arctic field seasons as well as collaboration (with support from ÉLVONAL), and sample collection is not expected to be complete until towards the end of the PhD. More immediate plans are: 1) to analyse the effect of mating system on sex-biased gene expression, for the first time using wild birds (see Harrison et al., 2015 for such an analysis in semi-domesticated birds). And 2) to analyse temporal genetic diversity changes for the first time in an Arctic bird, the Ringed Plover (see Boessenkool et al., 2010, for a similar methodology in penguins). The planned studies have a clear relation to the National Envrionment Research Council aims, as understanding the factors underlying reproductive isolation can help conservationists predict which species are most at risk of extinction. This is particularly applicable given the Arctic location of the birds studied, where many species are already in rapid decline and where the effects of climate change are felt most keenly (reviewed in Meltofte, 2007). Boessenkool, S., Star, B., Seddon, P. J., & Waters, J. M. (2010). Temporal genetic samples indicate small effective population size of the endangered yellow-eyed penguin. Conservation Genetics, 11(2), 539-546.D'Urban Jackson, J., Dos Remedios, N., Maher, K. H., Zefania, S., Haig, S., Oyler-McCance, S., ... & Kupper, C. (2017). Polygamy slows down population divergence in shorebirds. Evolution, 71(5), 1313-1326.Harrison, P. W., Wright, A. E., Zimmer, F., Dean, R., Montgomery, S. H., Pointer, M. A., & Mank, J. E. (2015). Sexual selection drives evolution and rapid turnover of male gene expression. Proceedings of the National Academy of Sciences, 112(14), 4393-4398.Lande, R. (1981). Models of speciation by sexual selection on polygenic traits. Proceedings of the National Academy of Sciences, 78(6), 3721-3725.Meltofte, H. (Ed.). (2007). Effects of climate variation on the breeding ecology of Arctic shorebirds. Museum Tusculanum Press.