Data from: Archipelagos of the Anthropocene: rapid and extensive differentiation of native terrestrial vertebrates in a single metropolis

Some of the best evidence for rapid evolutionary change comes from studies of archipelagos and oceanic islands. City parks are analogous systems as they create geographically isolated green spaces that differ in size, structure, and complexity. Very little, however, is known about whether city parks in single urban centres drive selection and result in the diversification of native species. Here, we provide evidence for the rapid genetic and morphological differentiation of a native lizard (Intellagama lesueurii) at four geographically close yet unconnected parks within one city. Year of establishment of each city park varied from 1855 (oldest) to 2001 (youngest) equating to a generation time range of 32 to three generations. Genetic divergence among city park populations was large despite the small pairwise geographic distances (< 5km) and found to be two to three times higher for microsatellites and three to 33 times higher for mtDNA relative to non-urban populations. Patterns of morphological differentiation were also found to be most extensive among the four city park populations. In contrast to non-urban populations, city park populations showed significant differentiation in relative body size, relative head and limb morphology and relative forelimb and hindlimb length. Crucially, we show that these patterns of differentiation are unlikely to have been caused by founder events and/or drift alone. Our results suggest that city park ‘archipelagos’ could represent theatres for rapid evolution that may, in time, favour adaptive diversification.

快速演化变化的最佳实证之一，源自对群岛与海洋岛屿的相关研究。城市公园便是与之类似的系统：它们打造了地理上相互隔离的绿地空间，且在规模、结构与复杂度上各有差异。然而，目前学界对单一城市中心内的城市公园是否会驱动自然选择，并促成本土物种的分化，仍知之甚少。本研究针对某一城市内四座地理相近却互不连通的公园，为本土蜥蜴（Intellagama lesueurii）的快速遗传与形态分化提供了实证依据。四座公园的建成年代跨度为1855年（最悠久）至2001年（最新），对应该蜥蜴种群的世代数跨度为32代至3代。尽管各城市公园种群间的两两地理距离极近（<5km），但种群间的遗传分化程度却十分显著：相较于非城市种群，其微卫星（microsatellites）位点的分化水平高出2~3倍，线粒体DNA（mtDNA）的分化水平则高出3~33倍。四座城市公园种群间的形态分化模式同样最为显著。与非城市种群相比，城市公园种群在相对体型、相对头部与肢体形态，以及相对前肢、后肢长度上均呈现出显著分化。至关重要的是，本研究证实，此类分化模式并非仅由奠基者效应（founder events）与/或遗传漂变所致。本研究结果表明，城市公园‘群岛’可作为快速演化的研究场景，且随着时间推移，或可助力适应性物种分化。