Time-restricted flight ability influences dispersal and colonization rates in a group of freshwater beetles.
Variation in the ability to fly or not is a key mechanism for differences in local species occurrences. It is increasingly acknowledged that physiological or behavioral mechanisms rather than morphological differences may drive flight abilities. However, our knowledge on the seasonal variability and stressors creating nonmorphological differences in flight abilities and how it scales to local and regional occurrences is very limited particularly for small, short-lived species such as insects. Here, we examine how flight ability might vary across seasons and between two closely related genera of freshwater beetles with similar geographical ranges, life histories, and dispersal-related morphology. By combining flight experiments of >1,100 specimens with colonization rates in a metacommunity of 54 ponds in northern and eastern Europe, we have analyzed the relationship between flight ability and spatio-environmental distribution of the study genera. We find profound differences in flight ability between the two study genera across seasons. High flight ability forAcilius(97% of the tested individuals flew during the experiments) and low forGraphoderus(14%) corresponded to the different colonization rates of newly created ponds. Within a 5-year period, 81 and 31% of the study ponds were colonized byAciliusandGraphoderus, respectively. WhileAciliusdispersed throughout the season, flight activity inGraphoderuswas restricted to stressed situations immediately after the emergence of adults. Regional colonization ability ofAciliuswas independent of spatial connectivity and mass effect from propagule sources. In contrast,Graphoderusspecies were closely related to high connectivity between ponds in the landscape. Our data suggest that different dispersal potential can account for different local occurrences ofAciliusandGraphoderus. In general, our findings provide some of the first insights into the understanding of seasonal restrictions in flight patterns of aquatic beetles and their consequences for species distributions.
Freshwater Biological Laboratory Biological Institute University of Copenhagen Copenhagen Ø Denmark; Amphi Consult ApS International Science Park Odense Odense M Denmark.
Lars Lønsmann
LL
Iversen
Institute of Ecology and Earth Sciences University of Tartu Tartu Estonia.
Riinu
R
Rannap
Amphi Consult ApS International Science Park Odense Odense M Denmark.
Lars
L
Briggs
Freshwater Biological Laboratory Biological Institute University of Copenhagen Copenhagen Ø Denmark.
Kaj
K
Sand-Jensen
Coleoptera; aquatic invertebrates; colonization; oogenesis‐flight syndrome