Zoologisches Forschungsmuseum A. Koenig, Centre of Taxonomy and Evolutionary Research, Adenauerallee 160, 53113, Bonn, Germany.
Glob Chang Biol. 2017 May;23(5):1988-2004. doi: 10.1111/gcb.13616. Epub 2017 Jan 31.
Today, indigenous forests cover less than 0.6% of South Africa's land surface and are highly fragmented. Most forest relicts are very small and typically occur in fire-protected gorges along the eastern Great Escarpment. Yet, they hold a unique and valuable fauna with high endemism and ancient phylogenetic lineages, fostered by long-term climatic stability and complex microclimates. Despite numerous studies on southern African vegetation cover, the current state of knowledge about the natural extension of indigenous forests is rather fragmentary. We use an integrated approach of population-level phylogeography and climatic niche modeling of forest-associated chafer species to assess connectivity and extent of forest habitats since the last glacial maximum. Current and past species distribution models ascertained potential fluctuations of forest distribution and supported a much wider potential current extension of forests based on climatic data. Considerable genetic admixture of mitochondrial and nuclear DNA among many populations and an increase in mean population mutation rate in Extended Bayesian Skyline Plots of all species indicated more extended or better connected forests in the recent past (<5 kya). Genetic isolation of certain populations, as revealed by population differentiation statistics (GST'), as well as landscape connectivity statistics and habitat succession scenarios suggests considerable loss of habitat connectivity. As major anthropogenic influence is likely, conservational actions need to be considered.
如今,南非的本土森林仅占其陆地面积的不到 0.6%,且高度碎片化。大多数森林遗迹都非常小,通常出现在东部大断崖沿线受防火保护的峡谷中。然而,它们拥有独特而有价值的动物群,具有高度的特有性和古老的系统发育谱系,这是由长期的气候稳定性和复杂的小气候所促成的。尽管对南部非洲植被覆盖进行了大量研究,但目前对本土森林自然延伸的了解仍然相当零散。我们采用种群水平系统地理学和与森林相关的鳃金龟物种气候生态位建模的综合方法,评估自末次冰盛期以来森林栖息地的连通性和范围。当前和过去的物种分布模型确定了森林分布的潜在波动,并基于气候数据支持了更广泛的潜在当前森林延伸。许多种群中存在大量的线粒体和核 DNA 遗传混合,以及所有物种的扩展贝叶斯天空线图中平均种群突变率的增加,表明在最近的过去(<5 千年),森林的范围或连通性更好。某些种群的遗传隔离,如种群分化统计(GST')、景观连通性统计和栖息地演替情景所揭示的那样,表明栖息地连通性有相当大的损失。由于主要的人为影响是可能的,因此需要考虑保护行动。