Tassone Erica E, Miles Lindsay S, Dyer Rodney J, Rosenberg Michael S, Cowling Richard M, Verrelli Brian C
School of Life Sciences Arizona State University Tempe Arizona USA.
Center for the Study of Biological Complexity Virginia Commonwealth University Richmond Virginia USA.
Evol Appl. 2021 Jan 13;14(4):1109-1123. doi: 10.1111/eva.13185. eCollection 2021 Apr.
As human-induced change eliminates natural habitats, it impacts genetic diversity and population connectivity for local biodiversity. The South African Cape Floristic Region (CFR) is the most diverse extratropical area for plant biodiversity, and much of its habitat is protected as a UNESCO World Heritage site. There has long been great interest in explaining the underlying factors driving this unique diversity, especially as much of the CFR is endangered by urbanization and other anthropogenic activity. Here, we use a population and landscape genetic analysis of SNP data from the CFR endemic plant or "common sunshine conebush" as a model to address the evolutionary and environmental factors shaping the vast CFR diversity. We found that high population structure, along with relatively deeper and older genealogies, is characteristic of the southwestern CFR, whereas low population structure and more recent lineage coalescence depict the eastern CFR. Population network analyses show genetic connectivity is facilitated in areas of lower elevation and higher seasonal precipitation. These population genetic signatures corroborate CFR species-level patterns consistent with high Pleistocene biome stability and landscape heterogeneity in the southwest, but with coincident instability in the east. Finally, we also find evidence of human land-usage as a significant gene flow barrier, especially in severely threatened lowlands where genetic connectivity has been historically the highest. These results help identify areas where conservation plans can prioritize protecting high genetic diversity threatened by contemporary human activities within this unique cultural UNESCO site.
由于人为导致的变化消除了自然栖息地，它影响了当地生物多样性的遗传多样性和种群连通性。南非开普植物区系地区（CFR）是植物生物多样性最为丰富的温带地区，其大部分栖息地被列为联合国教科文组织世界遗产地而受到保护。长期以来，人们一直热衷于解释驱动这种独特多样性的潜在因素，尤其是因为CFR的大部分地区受到城市化和其他人为活动的威胁。在这里，我们以CFR特有植物或“普通日照松果菊”的SNP数据进行种群和景观遗传分析为模型，来探讨塑造广阔CFR多样性的进化和环境因素。我们发现，高种群结构以及相对更深和更古老的谱系是CFR西南部的特征，而低种群结构和更近的谱系合并则描绘了CFR东部的情况。种群网络分析表明，在海拔较低和季节性降水量较高的地区，遗传连通性得到促进。这些种群遗传特征证实了CFR物种水平的模式，与西南部更新世生物群落的高度稳定性和景观异质性一致，但东部则存在同时发生的不稳定性。最后，我们还发现了人类土地利用作为重要基因流动障碍的证据，特别是在严重受威胁的低地，那里的遗传连通性在历史上是最高的。这些结果有助于确定保护计划可以优先保护这一独特的联合国教科文组织文化遗址内受当代人类活动威胁的高遗传多样性区域。
