Investigating drivers of marine connectivity in the pink sea fan: implications for its conservation and the designation of Marine Protected Areas

以前，在与自然英格兰合作，我们研究了两种软珊瑚（Eunicella verrucosa;曾经和Alcyonium digitatum; Adig）从英国和爱尔兰周围的网站，并从更远的地方在西北欧。我们开发了新的遗传标记（微卫星），这些珊瑚和分型与面板14（以往）和11个位点（Adig）。我们证明，英国和西北欧沃茨的Ever（粉红色海扇）种群显示出明显的区域遗传结构（Holland & Stevens，2014，2017;图1A）。与此相反，居住在同一地理区域的Adig（死人的手指）的样本出现了panmictic，并没有表现出显着的遗传种群结构。然而，虽然这两个物种在英国西南部和爱尔兰周围的沃茨重叠，但分布图显示，这一地区是Ever的北方界限，而Adig的南方界限。调查可能的驱动程序的人口结构，在以往任何时候都确定了两个基因座的选择下，没有证据的选择，在Adig检测。重要的是，排除选择中的基因座的进一步分析导致了Ever数据集的结构消失（图1B）;这样的发现突出了选择在驱动该物种的表观种群结构中的潜在重要性。观察到的遗传结构的模式是由连接性/连接性障碍或选择驱动的，对于我们理解这些物种的连接性以及海洋保护区的位置和间距，特别是对于世界自然保护联盟列出的物种粉红色海扇，具有重要意义。这两个物种都被认为是传播产卵，幼虫依靠洋流传播，但我们的研究结果表明，在同一地理区域，连通性模式非常不同。迄今为止，人们对这些生物的基本生物学知之甚少，对它们应对热应力的能力知之甚少或一无所知。拟议的项目将调查选择驱动两个物种的种群之间的遗传差异的程度，曾经在其范围的北方限制，Adig在其南部限制。我们将探讨其基本生物学的根本差异，以阐明可能导致观察到的遗传结构的显着不同模式的生物学因素，无论是由于连接或选择的差异。在没有公布的珊瑚基因组的情况下，我们将使用一种称为RAD-seq的分子生物学技术来识别特定于地理区域和/或正在选择的基因座（在埃克塞特）。分子分析将辅之以普通花园实验和可控海洋围隔生态系统（普利茅斯海洋实验室）中的热应激暴露。疣状Eunicella verrucosa是IUCN红色名录，是英国沃茨的保护物种。它被列为受保护的特征，这是2013年和2016年在英格兰西南部指定的许多MCZ的关键因素。了解该物种的多样性和连通性对于保护该物种和指定更多候选MCZ至关重要（Natural England，2016）。我们预计，这项研究将为这两个关键因素提供信息。

Previously, in collaboration with Natural England, we studied two species of soft coral (Eunicella verrucosa; Ever and Alcyonium digitatum; Adig) from sites around Britain and Ireland, and from further afield in northwest Europe. We developed novel genetic markers (microsatellites) for these octocorals and typed them with panels of 14 (Ever) and 11 loci (Adig). We demonstrated that populations of Ever (the pink sea fan) in waters around Britain and northwest Europe showed marked regional genetic structure (Holland & Stevens, 2014, 2017; Figure 1A). In contrast, samples of Adig (dead man's fingers) inhabiting approximately the same geographic area appeared panmictic, and exhibited no significant genetic population structure. However, while both species overlap in the waters around southwest Britain and Ireland, distribution maps indicate that this area is the northern limit for Ever and the southern limit for Adig. Investigation of the possible drivers of population structure in Ever identified two loci as being under selection; no evidence of selection was detected in Adig. Critically, further analysis excluding the loci under selection resulted in the disappearance of structure from the Ever data set (Figure 1B); such a finding highlights the potential importance of selection in driving apparent population structure in this species. Whether the patterns of genetic structure observed are driven by connectivity/barriers to connectivity or by selection has major importance for our understanding of connectivity in these species and for the placement and spacing of marine protected areas, especially for the pink sea fan, an IUCN listed species. Both species are thought to broadcast spawn, with larvae reliant on oceanic currents for dispersal, yet our findings suggest very different patterns of connectivity across the same geographical area. To date, very little is known about the basic biology of these creatures, with little or no knowledge of their ability to deal with thermal stress. The proposed project will investigate the extent of selection driving genetic differences between populations of the two species, Ever at the northern limit of its range, Adig at its southern limit. We will explore fundamental differences in their basic biology to elucidate biological factors that might be contributing to the markedly different patterns of genetic structure observed, whether due to differences in connectivity or to selection. In the absence of published octocoral genomes, we will use a molecular biology technique known as RAD-seq to identify loci specific to geographical regions and/or under selection (at Exeter). The molecular analysis will be complemented by common garden experiments and heat stress exposures in a controllable marine mesocosm (at Plymouth Marine Laboratory). Eunicella verrucosa is IUCN red-listed and is a protected species in UK waters. It is listed as a Protected Feature, a key factor in the designation of many of the MCZs designated in southwest England in 2013 and 2016. An understanding of the diversity and connectivity of this species is essential for both conservation of the species and the designation of further candidate MCZs (Natural England, 2016). We anticipate that this research will inform on both these key factors.