Wolz Marina, Klockmann Michael, Schmitz Torben, Pekár Stano, Bonte Dries, Uhl Gabriele
1Zoological Institute and Museum, General and Systematic Zoology, University of Greifswald, Greifswald, Germany.
2Masaryk University, Brno, Czech Republic.
Mov Ecol. 2020 Jan 7;8:2. doi: 10.1186/s40462-019-0182-4. eCollection 2020.
Dispersal and reproduction are key life-history traits that jointly determine species' potential to expand their distribution, for instance in light of ongoing climate change. These life-history traits are known to be under selection by changing local environmental conditions, but they may also evolve by spatial sorting. While local natural selection and spatial sorting are mainly studied in model organisms, we do not know the degree to which these processes are relevant in the wild, despite their importance to a comprehensive understanding of species' resistance and tolerance to climate change.
The wasp spider has undergone a natural range expansion - from the Mediterranean to Northern Europe during the recent decades. Using reciprocal common garden experiments in the laboratory, we studied differences in crucial traits between replicated core (Southern France) and edge (Baltic States) populations. We tested theoretical predictions of enhanced dispersal (ballooning behaviour) and reproductive performance (fecundity and winter survival) at the expansion front due to spatial sorting and local environmental conditions.
Dispersal rates were not consistently higher at the northern expansion front, but were impacted by the overwintering climatic conditions experienced, such that dispersal was higher when spiderlings had experienced winter conditions as occur in their region. Hatching success and winter survival were lower at the range border. In agreement with theoretical predictions, spiders from the northern leading edge invested more in reproduction for their given body size.
We found no evidence for spatial sorting leading to higher dispersal in northern range edge populations of . However, reproductive investment and overwintering survival between core and edge populations differed. These life-history traits that directly affect species' expansion rates seem to have diverged during the recent range expansion of . We discuss the observed changes with respect to the species' natural history and the ecological drivers associated with range expansion to northern latitudes.
扩散和繁殖是关键的生活史特征，它们共同决定了物种扩大分布范围的潜力，例如在当前气候变化的背景下。已知这些生活史特征会受到当地环境条件变化的选择，但它们也可能通过空间分选而进化。虽然局部自然选择和空间分选主要在模式生物中进行研究，但尽管它们对于全面理解物种对气候变化的抗性和耐受性很重要，我们并不清楚这些过程在野外的相关程度。
黄蜂蜘蛛在近几十年经历了自然分布范围的扩张——从地中海地区扩展到了北欧。通过在实验室进行互作共园实验，我们研究了复制的核心种群（法国南部）和边缘种群（波罗的海国家）在关键特征上的差异。我们测试了由于空间分选和当地环境条件，在扩张前沿扩散增强（气球状行为）和繁殖性能（繁殖力和冬季存活率）的理论预测。
在北部扩张前沿，扩散率并非一直更高，但受到所经历的越冬气候条件的影响，使得当幼蛛经历了其所在地区的冬季条件时，扩散率更高。在分布范围边界，孵化成功率和冬季存活率较低。与理论预测一致，来自北部前沿的蜘蛛在给定体型下对繁殖的投入更多。
我们没有发现证据表明空间分选导致黄蜂蜘蛛北部分布范围边缘种群的扩散增加。然而，核心种群和边缘种群之间的繁殖投入和越冬存活率存在差异。在黄蜂蜘蛛最近的分布范围扩张过程中，这些直接影响物种扩张速率的生活史特征似乎已经发生了分化。我们根据该物种的自然史以及与向北纬度范围扩张相关的生态驱动因素，讨论了观察到的变化。
