SETTLING DECISIONS OF DISPERSING STEGODYPHUS-LINEATUS (ERESIDAE) YOUNG

Dispersal and site selection determine the distribution of organisms i n relation to habitat features. Natal philopatry and specific habitat requirements may result in a clumped distribution that may have import ant consequences for population structure. We investigated dispersal o f young of the web-building spider Stegodyphus lineatus (Eresidae), wh ich has a highly clumped distribution in dry watercourses (wadis) in t he Negev Desert. The young dispersed from maternal nests in late summe r to a median distance of only 2 m, and the dispersal directions diffe red among families and sites. More than 80% of the young settled in fo ur species of perennial shrubs, a distribution that differed significa ntly from expected from the relative abundance of these shrubs in the habitat. Occupied shrubs were taller and had larger surface areas than unoccupied ones nearby. We suggest that the limited movement of young during dispersal and their preference for certain types of shrubs res ults in a clumped distribution.