Resources influence dispersal and population structure in an endangered butterfly

Abstract

Abstract. 1. The degree of dispersal between patches in a population partly determines its structure. Mark–release–recapture (MRR) studies of an archipelago population of the endangered apollo butterfly (Parnassius apollo, L 1758) revealed that most (79%) adult individuals remained within the patch where they were marked.2. Emigration out of a patch was female‐biased and decreased with the amount of (adult) nectar resources on a patch, but increased with greater proximity to nectar on other patches. Local population numbers positively correlated with total numbers of both emigrants and immigrants. Host‐plant abundance (larval resource) did not influence dispersal.3. The dispersal and population structure of this archipelago population differs pronouncedly from that of a previously studied mainland population where between‐patch dispersal is more frequent even when correcting for differences in habitat structure between the populations, and consequently the population structure is more patchy or open.4. The most prominent environmental factor affecting emigration is nectar resources. Both local patch conditions in terms of nectar on the patch and nectar availability on surrounding patches are important.5. The most important implications for conservation are that resource distribution affects dispersal and hence population‐level processes such as structure, and that emigration and immigration should be viewed as separate processes potentially governed by different environmental factors.