Larsson Dennis, Šarhanová Petra, Paun Ovidiu, Schneeweiss Gerald M
Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria.
Department of Botany and Zoology, Masaryk University, Brno, Czech Republic.
Mol Ecol. 2025 Feb;34(3):e17624. doi: 10.1111/mec.17624. Epub 2024 Dec 13.
Understanding the causes of restricted geographic distributions is of major interest to evolutionary and conservation biologists. Inferring historical factors has often relied on ad hoc interpretations of genetic data, and hypothesis testing within a statistical framework under different demographic scenarios remains underutilised. Using coalescent modelling on RAD-sequencing data, we (i) test hypotheses about the origin of Phyteuma gallicum (Campanulaceae), a range-restricted endemic of central France sympatric with its widespread congener Ph. spicatum, and (ii) date its origin, irrespective of its mode of origin, to test the hypothesis that the restricted range is due to a recent time of origin. The best supported model of origin is one of a dichotomous split of Ph. gallicum, confirmed as distinct species, and the Central European Ph. nigrum with subsequent gene flow between Ph. gallicum and Ph. spicatum. The split of Ph. gallicum and Ph. nigrum is estimated at 45-55,000 years ago. Coalescent modelling on genomic data not only clarified the mode of origin (dichotomous speciation instead of a previously hypothesised hybridogenic origin) but also identified recency of speciation as a sufficient, although likely not the sole, factor to explain the restricted distribution range. Coalescent modelling strongly improves our understanding of the evolution of range-restricted species that are frequently of conservation concern, as is the case for Ph. gallicum.
了解地理分布受限的原因是进化生物学家和保护生物学家主要关注的问题。推断历史因素通常依赖于对基因数据的临时解释，而在不同人口统计学情景下的统计框架内进行假设检验仍未得到充分利用。利用RAD测序数据进行溯祖建模，我们（i）检验关于法国中部分布范围受限的特有物种法国蓝盆花（桔梗科）起源的假设，它与其广泛分布的同属物种穗花蓝盆花同域分布，（ii）确定其起源时间，无论其起源方式如何，以检验分布范围受限是由于起源时间较近这一假设。得到最佳支持的起源模型是法国蓝盆花的二分分裂模型，它被确认为一个独特的物种，与中欧的黑蓝盆花二分，随后法国蓝盆花和穗花蓝盆花之间存在基因流动。法国蓝盆花和黑蓝盆花的分裂估计发生在45000 - 55000年前。基于基因组数据的溯祖建模不仅阐明了起源方式（二分物种形成而非先前假设的杂交起源），还确定物种形成的近期性是解释分布范围受限的一个充分因素，尽管可能不是唯一因素。溯祖建模极大地增进了我们对分布范围受限物种进化的理解，这些物种常常受到保护关注，法国蓝盆花就是如此。
