Does Dispersal Limit Beetle Re-colonization of Restored Fenland? A Case Study Using Direct Measurements of Dispersal and Genetic Analysis

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Abstract

Dispersal ability is known to limit the colonization by many fenland species onto restored habitat but factors determining colonization by wetland invertebrates onto restored fenland have not been previously examined. We used mark-release-recapture and harmonic radar tracking coupled with genetic analysis (ISSR-PCR, inter-simple sequence repeat—polymerase chain reaction) to assess the population structure and colonization of a brachypterous wetland carabid (Carabus granulatus) onto restored fenland. The first two methods were used to determine the dispersal rate of C. granulatus in the absence of barriers, while the genetic analysis was used to examine whether populations were separated by either distance or the water channels and drainage ditches that intersect fenland landscapes. Mark-release-recapture and harmonic radar tracking indicated that the most active 6% of individuals could travel over 25 m in a day and individuals found to be traveling these distances remained atypically active throughout the season. Thus, C. granulatus can disperse at a rate great enough to colonize all areas of restored fenland in the study site within 1 year in the absence of barriers. We found no evidence of genetically distinct sub-populations of C. granulatus showing that distance and water barriers did not limit the movement of individuals from potential source populations to the restored habitat. This research indicates that where fenland is created with nearby established fenland, colonization opportunities should not be considered a limiting factor to colonization by wetland carabids, even where waterways divide sites.

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