Is dispersal promoted at the invasion front? Morphological analysis of a ground beetle invading the Kerguelen Islands, Merizodus soledadinus (Coleoptera, Carabidae)

Abstract

As a biological invasion proceeds, the spread of the alien may promote dispersal ability at the front by direct and indirect selection, thereby altering the dynamics of the invasion. Morphology correlates with dispersal in numerous taxa, and represents a relevant integration of temporal or geographical changes in dispersal. Using data from Laparie et al. (Biol Invasions 12:3405-3417, 2010) in a ground beetle introduced to a single location of the Kerguelen Islands in 1913, we examined the quantitative relationship between distance in residence time and morphological distance (computed from a multivariate combination of parameters). A consistent relationship depicted a quantitative match between differences in morphology and residence time. Body size increased from the founder population to successive child populations (femur, thorax, abdomen and head), which may indicate increasing dispersal ability along the colonization history of the species. The morphological differentiation may result from a combination of both dispersal pattern and residency effect in former populations, the latter leading to decreasing size when residence time increases, due to alteration of trophic conditions following invasion by the beetle. Our results offer a fertile ground for investigating spatial selection and promotion of dispersers on front margins, as they highlight the dynamic fashion of dispersal ability during invasions. © 2013 Springer Science+Business Media Dordrecht.