Unexpected sensitivity of the highly invasive spider to soil disturbance in grasslands.

The dwarf spider (Araneae: Linyphiidae), native to North America, has expanded its range over large parts of Europe within less than fifty years. It is notable for occurring in a wide range of mostly agricultural habitats, while most other invasive spiders in Europe are associated with human buildings. As in other invasive invertebrates and plants, the tremendous colonisation success of might be related to anthropogenic habitat disturbance. Here we aim to test if the invasion success of in Europe is associated with high tolerance towards soil disturbance. We sampled spiders from eight grasslands experimentally disturbed with superficial soil tillage and eight undisturbed grasslands without tillage. Opposite to our expectation, densities decrease sharply with soil disturbance. This is in contrast to several native species such as , which becomes more abundant in the fields after superficial soil tillage. Our study suggests that invasion success of is not connected to a ruderal strategy. The ecological and evolutionary processes behind colonisation success of need to be further investigated.