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.

诸多关于快速演化进程的关键实证均源自群岛与海洋岛屿的研究。城市公园正是这类类似系统：它们营造出地理隔离的绿地斑块，且各斑块在规模、结构与复杂度上均存在显著差异。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、进而促使本土物种发生分化，仍所知有限。本研究针对某城市内4处地理邻近但彼此隔离的城市公园展开分析，为本土蜥蜴（Intellagama lesueurii）的快速遗传与形态分化提供了实证依据。各公园的建成年代跨度为1855年（最久远）至2001年（最新），对应该蜥蜴32个世代至3个世代的演化时长。尽管各公园种群间的两两地理距离极近（<5km），但其遗传分化程度仍较高；相较于非城市种群，其微卫星（microsatellites）标记的分化程度高出2~3倍，线粒体DNA（mtDNA）的分化程度则高出3~33倍。4处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。尤为关键的是，本研究证实，这类分化模式并非仅由奠基者效应或遗传漂变所致。本研究结果表明，城市公园‘群岛’可作为快速演化的实验场，随着时间推移，或可推动适应性分化的发生。