Mixed population genomics support for the central marginal hypothesis across the invasive range of the cane toad (Rhinella marina) in Australia

Understanding factors that cause species' geographic range limits is a major focus in ecology and evolution. The central marginal hypothesis (CMH) predicts that species cannot adapt to conditions beyond current geographic range edges because genetic diversity decreases from core to edge due to smaller, more isolated edge populations. We employed a population genomics framework using 24 235–33 112 SNP loci to test major predictions of the CMH in the ongoing invasion of the cane toad (Rhinella marina) in Australia. Cane toad tissue samples were collected along broad-scale, core-to-edge transects across their invasive range. Geographic and ecological core areas were identified using GIS and habitat suitability indices from ecological niche modelling. Bayesian clustering analyses revealed three genetic clusters, in the northwest invasion-front region, northeast precipitation-limited region and southeast cold temperature-limited region. Core-to-edge patterns of genetic diversity and differen...

解析物种地理分布范围限制的成因，是生态学与进化生物学领域的核心研究议题。中心边缘假说（Central Marginal Hypothesis, CMH）指出，物种无法适应现有地理分布范围边缘以外的环境条件，其机制在于边缘种群规模更小、隔离程度更高，进而导致遗传多样性从分布核心向边缘逐渐衰减。本研究采用群体基因组学研究框架，依托24235至33112个单核苷酸多态性（Single Nucleotide Polymorphism, SNP）位点，针对澳大利亚境内正在扩散入侵的海蟾蜍（Rhinella marina），对该假说的核心预测开展检验。研究团队沿其入侵分布区的跨尺度核心-边缘样带采集了海蟾蜍组织样本；通过地理信息系统（Geographic Information System, GIS）与生态位模型生成的生境适宜性指数，明确了该物种的地理与生态核心分布区。贝叶斯聚类分析结果显示，海蟾蜍可划分为三个遗传类群，分别对应西北入侵前沿区域、东北降水限制区域以及东南低温限制区域。遗传多样性与分化的核心-边缘分布模式及……