Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
CNRS, Sorbonne Université, UMI 3614, Evolutionary Biology and Ecology of Algae, Station Biologique de Roscoff, CS 90074, Place G. Tessier, 296888, Roscoff, France.
J Phycol. 2020 Dec;56(6):1575-1590. doi: 10.1111/jpy.13046. Epub 2020 Aug 18.
Molecular studies have reported the coexistence of two species of Agarophyton in New Zealand: the newly described A.transtasmanicum with an apparently restricted distribution to some sites in the North Island, and the more widespread A.chilense. Here, we compared the distribution, genetic diversity, and structure of both Agarophyton species throughout the archipelago using sequences of the nuclear Internal Transcribed Spacer 2 (ITS2) marker. Agarophyton chilense's distribution was continuous and extensive along the North and South Islands, Stewart Island, and Chatham Island, and the genetic clusters were mostly concordant with boundaries between biogeographic regions. In contrast, specimens of A.transtasmanicum were collected in four sites broadly distributed in both the North and South Islands, with no clear spatial structure of the genetic diversity. Populations, where the species co-occurred, tended to display similar levels in genetic diversity for the two species. Demographic inferences supported a postglacial demographic expansion for two A.chilense genetic clusters, one present in the South Island and the eastern coast of the North Island, and the other present in northern South Island. A third genetic cluster located on the western coast of the North Island had a signature of long-term demographic stability. For A.transtasmanicum, the skyline plot also suggested a postglacial demographic expansion. Last, we developed a new molecular tool to quickly and easily distinguish between the two Agarophyton species, which could be used to ease future fine-scale population studies, especially in areas where the two species coexist.
分子研究报告称，新西兰存在两种琼脂藻：新描述的 A.transtasmanicum ，其分布显然局限于北岛的一些地点，以及分布更广的 A.chilense 。在这里，我们使用核内转录间隔区 2（ITS2）标记的序列比较了这两个琼脂藻种在整个群岛中的分布、遗传多样性和结构。Agarophyton chilense 的分布在北岛和南岛、斯图尔特岛和查塔姆岛沿续且广泛，遗传聚类大多与生物地理区域的边界一致。相比之下，A.transtasmanicum 的标本分布在北岛和南岛的四个地点广泛分布，遗传多样性没有明显的空间结构。两个物种共存的种群往往表现出两种物种相似水平的遗传多样性。人口推断支持两个 Agarophyton chilense 遗传聚类的后冰河时代人口扩张，一个存在于南岛和北岛东海岸，另一个存在于南岛北部。位于北岛西海岸的第三个遗传聚类具有长期人口稳定的特征。对于 A.transtasmanicum ，天际图也表明了后冰河时代的人口扩张。最后，我们开发了一种新的分子工具，可以快速轻松地区分这两种琼脂藻，这可以用于简化未来的精细种群研究，特别是在两个物种共存的地区。
