Species range expansion constrains the ecological niches of resident species
(English)Manuscript (preprint) (Other academic)
Changes in community composition resulting from climate change entail modifications of biotic interactions and reshape local species distributions. Such changes are currently occurring in nettle-feeding butterflies in Sweden where Araschnia levana has recently expanded its range northward and is now likely to interact with the resident species (Aglais urticae and Aglais io). Butterfly occurrence data collected over years and across regions enabled us to investigate how a recent range expansion of A. levana may have affected the environmental niche of resident species. We focused on two regions of Sweden (Skåne and Norrström) where A. levana has and has not established, and two time-periods (2001-2006, 2009-2012) corresponding to before and after its establishment. We performed two distinct analyses in each region using the PCA-env and the framework described in Broennimann et al. (2012). We first described the main sources of variation in the environment. Second, we characterized, in each time-period and region, the realized niches of our focal species across topographic and land use gradients. Third, we quantified overlaps and differences in realized niches between and within species over time. We found indications of niche partitioning between native species, although niche differentiation was not clearly associated to specific environmental factors. Looking over time, we found a larger shift in species distributions of the resident species in Skåne than in Norrström. These shifts showed a consistent pattern of avoiding overlap with the environmental space occupied by A. levana, and it was stronger for A. urticae than for A. io. Interspecific interactions play a role in shaping species distributions. It seemed clear that the range expansion of A. levana modified local biotic interactions, and potentially induced shifts in resident species’ distribution. We suggest that parasite-driven apparent competition may mediate niche partitioning in this community.
biotic interactions, community composition, environmental niche model, nettle-feeding butterﬂies, ordination technique, parasite-driven indirect competition, realized niche
Research subject Animal Ecology
IdentifiersURN: urn:nbn:se:su:diva-119717OAI: oai:DiVA.org:su-119717DiVA: diva2:848003