Oklahoma Biological Survey and Department of Biology, University of Oklahoma, Norman, Oklahoma, United States of America.
PLoS One. 2020 Aug 28;15(8):e0234830. doi: 10.1371/journal.pone.0234830. eCollection 2020.
Residential yards constitute a substantive biodiverse greenspace within urban areas. This biodiversity results from a combination of native and non-native species and can contribute to biotic homogenization. Geographical climatic patterns affect the distribution of native species and may differently affect non-native species. In this study, we examined biodiversity and biotic homogenization patterns of yard-dwelling land snails across 12 towns in Oklahoma and Kansas (USA). The 3 x 4 array of towns incorporated a N-S winter temperature gradient (mean low January temperature range = -8.4 to 0.1°C) and an E-W annual rainfall gradient (annual rainfall range = 113.8 to 61.3 cm/yr). Ten yards per town were surveyed. We hypothesized that mild winter temperatures and greater annual rainfall would be associated with greater snail abundance and richness, and that the presence of non-native species would contribute to biotic homogenization. Non-native snails were present and often abundant in all towns. Snail communities varied with both rainfall and cold temperature. Contrary to our prediction, snail abundance was inversely related to annual rainfall-likely because drier conditions resulted in greater yard watering that both augmented rainfall and maintained moist conditions. Sørensen similarity between towns for the entire land snail community and for only non-native species both showed distance-decay patterns, with snail composition becoming less similar with increasing distance-patterns resulting from species turnover. The biotic homogenization index also showed a distance-related pattern, such that closer towns were more likely to have biotic homogenization whereas more distant towns tended to have biotic differentiation. These results support the concept that biotic homogenization is more likely regionally and that climatic changes over distance result in species turnover and can reduce spatially broad biotic homogenization.
居住庭院构成了城市中具有实质性生物多样性的绿地。这种生物多样性源自于本地和非本地物种的结合，可能导致生物均质化。地理气候模式影响本地物种的分布，可能对非本地物种产生不同的影响。在这项研究中，我们调查了俄克拉荷马州和堪萨斯州（美国） 12 个城镇庭院栖息的陆生蜗牛的生物多样性和生物均质化模式。这些城镇的 3x4 排列组合包含了一个南北向的冬季温度梯度（1 月平均最低温度范围为-8.4 至 0.1°C）和一个东西向的年降雨量梯度（年降雨量范围为 113.8 至 61.3cm/yr）。每个城镇调查了 10 个庭院。我们假设温和的冬季温度和更大的年降雨量将与更多的蜗牛数量和丰富度相关，并且非本地物种的存在将导致生物均质化。非本地蜗牛在所有城镇都存在且往往很丰富。蜗牛群落随降雨量和低温而变化。与我们的预测相反，蜗牛数量与年降雨量呈反比关系，这可能是因为干旱条件导致更多的庭院浇水，既增加了降雨量，又保持了潮湿的条件。整个陆生蜗牛群落和仅非本地物种的城镇间 Sørensen 相似性都表现出距离衰减模式，随着距离的增加，蜗牛的组成变得越来越不相似，这是由于物种更替导致的。生物均质化指数也表现出与距离相关的模式，因此距离较近的城镇更有可能发生生物均质化，而距离较远的城镇则倾向于发生生物分化。这些结果支持了生物均质化更可能是区域性的，并且距离上的气候变化导致物种更替并减少空间广泛的生物均质化的概念。
