The recent history and population structure of five Mandarina snail species from subtropical Ogasawara (Bonin Islands, Japan)
The recent history and population structure of five Mandarina snail species from subtropical Ogasawara (Bonin Islands, Japan)
复制标题
亚热带小笠原（日本小笠原群岛）五种柑橘蜗牛的近期历史和种群结构
作者：
A. Davison;S. Chiba
更新世气候变化对热带和亚热带地区生物的影响知之甚少。因此，我们研究了海洋小笠原（小笠原群岛，日本）的陆蜗牛属Mandarina（Bradybaenidae），目的是使用人口遗传数据，以了解他们最近的历史。我们对五种地面生活物种中600多只蜗牛的线粒体16S核糖体RNA区域的分析表明，Mukoujima，Anejima，Imotojima和Meijima小岛上的种群，以及Hahajima低洼的南部和中部地区，可能经历了最近的瓶颈，然后是随后的扩张。除了主岛端岛和向井岛之间，几乎没有证据表明岛屿之间的基因流，即使这些岛屿通过更新世的陆桥反复连接。在岛屿内，种群结构是严重的，暗示着长期的、低水平的基因流动（在地理上接近的种群中，FST通常大于0.5）。最后，还有一个明显的遗传斑块，这意味着遗传上接近的种群有时会被遗传上遥远的种群分开。这些模式可能是瓶颈扩张、低活跃扩散和罕见的长距离移民造成的创始人效应的结果。不幸的是，避难所和瓶颈的确切性质仍然未知，因为对该地区的古气候知之甚少。确定种群规模变化的年代也是一个挑战，因为分子钟是不确定的。然而，我们认为，干旱条件或森林砍伐引起的大气CO2减少可能是决定人口规模的主要因素。
The effect of Pleistocene climate change on the organisms of tropical and subtropical regions is rather poorly understood. We therefore studied the land snail genus Mandarina (Bradybaenidae) of oceanic Ogasawara (Bonin Islands, Japan), with the aim of using population genetic data to understand their recent history. Our analysis of a mitochondrial 16S ribosomal RNA region from more than 600 snails in five ground‐living species suggests that populations on the small islands of Mukoujima, Anejima, Imotojima and Meijima, as well as on the low‐lying southern and central parts of Hahajima, have probably undergone recent bottlenecks followed by subsequent expansions. Except between the main island of Hahajima and Mukouijima, there is almost no evidence for gene flow among islands even though the islands were connected repeatedly by land bridges through the Pleistocene. Within islands the population structure is severe, suggestive of a long‐term, low level of gene flow (FST is frequently greater than 0.5 among geographically close populations). Finally, there is a marked genetic patchiness, meaning that genetically close populations are sometimes separated by genetically distant populations. These patterns could be a consequence of expansion from bottlenecks, low active dispersal and founder effects caused by rare long‐distance migrants. Unfortunately, the exact nature of the refugia and bottlenecks remains unknown because the palaeoclimate of this region is poorly understood. Dating the population size changes is also challenging because the molecular clock is uncertain. We suggest, however, that arid conditions or deforestation induced by decreased atmospheric CO2 may have been the main factor in determining population size.
影响因子：
3.3
作者：
Yunxin Fu
通讯作者：
Yunxin Fu
影响因子：
3.3
作者：
M. Slatkin;R. Hudson
通讯作者：
M. Slatkin;R. Hudson