Low population genetic structuring of two cryptic bat species suggests their migratory behaviour in continental Europe JOSEF BRYJA 1,2 *, PETER KAN ˇ UCH 1,3 , ALENA FORNU ˚ SKOVÁ 1,2 , TOMÁŠ BARTONIC ˇ KA 2 and ZDENE ˇ KR ˇ EHÁK 2 1 Department of Population Biology, Institute of Vertebrate Biology AS CR, 675 02 Studenec 122, Czech Republic 2 Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlár ˇská 2, 611 37 Brno, Czech Republic 3 Institute of Forest Ecology SAS, Štúrova 2, 960 53 Zvolen, Slovakia Received 25 March 2008; accepted for publication 26 April 2008 Although two cryptic pipistrelle bat species, Pipistrellus pipistrellus and Pipistrellus pygmaeus, belong among the most common bat species in Europe, it is still unclear whether they can migrate over long distances between summer and winter roosts. Long-distance migratory species may be expected to show low levels of genetic structuring in large areas due to regular mixing of the gene pool by mating that occurs during migration and/or hibernation. Conversely, the dispersal of gametes in sedentary species is spatially restricted, populations are more genetically structured, and isolation by relatively short distance is visible. By analysing diversity of highly variable microsatellites within and among summer colonies of both studied species in central Europe, we found that differentiation between populations is very weak. Both classical FST and Bayesian clustering approach failed to detect genetic structure among colonies and there was no significant isolation-by-distance pattern. The analyses of relatedness, however, revealed that individuals within colonies are more related than random suggesting philopatry of at least one sex. The results were very similar for the two species. The high level of gene flow among central European populations, even on large geographic distances, is discussed in relation with migrations, dispersal, and mating behaviour. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 103–114. ADDITIONAL KEYWORDS: colony structure – dispersal – gene flow – microsatellites – relatedness. INTRODUCTION Methods of population genetics have become a very important tool for studying the biology of animal populations, especially of those species that are diffi- cult to follow by direct observations. Bats are one of the groups where the use of genetic markers has led to the description and understanding of the peculiari- ties of their social life (e.g. mating systems, roost- ing biology and sex-biased dispersal; McCracken, Lumsden & Kunz, 2006). Population genetic studies in bats have further revealed that geographic genetic differentiation can be affected by a variety of other factors, such as seasonal migrations, geographical barriers, and past processes (Burland & Worthington- Wilmer, 2001). Genetic structure in migratory animals is assumed to be weak across the wide geographical range due to very intense gene flow over long distances and this is especially true in flying species such as birds (Buerkle, 1999; Davis et al., 2006; Hellgren et al., 2008) and bats (McCracken, McCracken & Vawter, 1994; Webb & Tidemann, 1996; Petit & Mayer, 1999, 2000; Russell, Medellín & McCracken, 2005). In temperate bats, the mating usually occurs after the end of reproductive period (i.e. during or after *Corresponding author. E-mail: bryja@brno.cas.cz Biological Journal of the Linnean Society, 2009, 96, 103–114. With 2 figures © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 103–114 103 Downloaded from https://academic.oup.com/biolinnean/article/96/1/103/2447935 by guest on 17 July 2022