Data from: Effects of fragmentation on plant adaptation to urban environments

Urban ecosystems are relatively recent and heavily human-altered terrestrial ecosystems with a surprisingly high diversity of animals, plants and other organisms. Urban habitats are also strongly fragmented and subject to higher temperatures, providing a compelling model for studying adaptation to global change. Crepis sancta (Asteraceae), an annual Mediterranean wasteland weed, occupies fragmented urban environments as well as certain unfragmented landscapes in southern France. We tested for shifts in dispersal, reproductive traits and size across a rural–urban gradient to learn whether and how selection may be driving changes in life history in urban and fragmented habitats. We specifically compared the structure of quantitative genetic variation and of neutral markers (microsatellites) between urban and rural and between fragmented and unfragmented habitats. We showed that fragmentation provides a better descriptor of trait variation than urbanization per se for dispersal traits. Fragmentation also affected reproductive traits and plant size though one rural population did conform to this scheme. Our study shows the role of fragmentation for dispersal traits shift in urban environments and a more complex pattern for other traits. We discuss the role of pollinator scarcity and an inhospitable matrix as drivers of adaptation.

城市生态系统是一类相对年轻且受人类活动强烈改造的陆地生态系统，其动植物及其他生物的多样性却出人意料地丰富。城市生境普遍存在强烈的破碎化现象，且温度显著高于周边区域，为探究全球变化背景下的生物适应机制提供了极具说服力的研究模型。地中海一年生荒野生杂草Crepis sancta（菊科Asteraceae）在法国南部既分布于破碎化的城市生境中，也见于部分未受破碎化影响的自然景观内。本研究沿城乡梯度开展了扩散特征、繁殖性状及植株体型的变化检测，以明确选择作用是否以及如何驱动城市与破碎化生境中生物生活史的改变。本研究专门比较了城乡生境间，以及破碎化与未破碎化生境间的数量遗传变异与中性标记（微卫星microsatellites）的结构特征。研究结果表明，相较于城市化本身，生境破碎化更能解释扩散性状的变异模式。尽管有一个乡村种群符合该规律，但生境破碎化同样对繁殖性状与植株体型产生了显著影响。本研究证实了生境破碎化在城市环境中对扩散性状转变的驱动作用，而其他性状的变异模式则更为复杂。本研究还探讨了传粉者匮乏与不适宜的景观基质作为生物适应驱动因子的潜在作用。