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Keywords:

  • Coenagrion mercuriale ;
  • conservation;
  • dispersal;
  • dispersal types;
  • gene flow;
  • landscape genetics;
  • mark-recapture;
  • Odonata

Abstract

  1. Dispersal is an important process for any organism, but especially for endangered species in fragmented landscapes. To enhance the dispersal of a certain species, connectivity measures are implemented, which require knowledge on the species' dispersal behaviour and habitat. It is often assumed, that the preferred reproductive habitat of a species is also used as the main dispersal habitat. Although this assumption has often been confirmed, there are also cases where it has been disproved.
  2. With a combination of a mark-resight study and genetic analysis conducted in a fragmented agricultural landscape in Switzerland, the dispersal habitats of the threatened damselfly Coenagrion mercuriale were analysed for different distance classes. In addition, maximum dispersal distances were estimated.
  3. The mark-resight study detected movement over short distances (≤500 m) mainly within the reproductive habitat of C. mercuriale (i.e. streams).
  4. In contrast, the genetic study detected both short- and long-distance dispersal. Short-distance dispersal occurred along streams, and discontinuity of streams hindered dispersal. Long-distance dispersal was suggested to happen along more or less straight lines and crossing agricultural land. Genetic analysis also showed that populations were well connected and that few individuals dispersed over larger distances (≤4500 m).
  5. Our study showed that connected reproductive habitat enhanced short-distance dispersal in C. mercuriale. Although short-distance dispersal occurred frequently, long-distance dispersal was rare, but important to connect more isolated populations. Therefore, it would be relevant to differentiate between these two dispersal types when planning connectivity measures.