title: From the Western Alps across Central Europe: Postglacial recolonisation of the tufa stream specialist Rhyacophila pubescens (Insecta, Trichoptera).
abstract: BACKGROUND
  Dispersal rates, i.e. the effective number of dispersing individuals per unit time, are the product of dispersal capacity, i.e. a species physiological potential for dispersal, dispersal behaviour, i.e. the decision to leave a habitat patch in favour of another, and connectivity of occupied habitat. Thus, dispersal of species that are highly specialised to a certain habitat is limited by habitat availability. Species inhabiting very stable environments may also adopt a sedentary life-style. Both factors should lead to strong genetic differentiation in highly specialised species inhabiting stable environments. These two factors apply to our model species Rhyacophila pubescens a highly specialised freshwater insect that occurs in tufa springs, a very stable habitat.
  
  
  RESULTS
  We examined the genetic population structure and phylogeography using range-wide mtCOI sequence and AFLP data from 333 individuals of R. pubescens. We inferred the location of Pleistocene refugia and postglacial colonisation routes of R. pubescens, and examined ongoing local differentiation. Our results indicate intraregional differentiation with a high number of locally endemic haplotypes, that we attributed to habitat specificity and low dispersal rates of R. pubescens. We observed high levels of genetic diversity south of the Alps and genetic impoverishment north of the Alps. Estimates of migrants placed the refugium and the source of the colonisation in the Dauphiné Alps (SW Alps).
  
  
  CONCLUSIONS
  This is the first example of an aquatic insect with a colonisation route along the western margin of the Alps to the Central European highlands. The study also shows that specialisation to a stable environment may have promoted a behavioural shift to decreased dispersal rates, leading to stronger local population differentiation than in less specialised aquatic insects. Alternatively, the occurrence of highly specialised tufa spring habitats may have been more widespread in the past, leading to range regression and fragmentation among present day R. pubescens populations.
authors.affiliation: Senckenberg, Department of Limnology and Conservation, Clamecystr. 12, 63571, Gelnhausen, Germany.
authors.forename: Christine Hm
authors.initials: CH
authors.lastname: Engelhardt
authors.affiliation: Senckenberg, Department of Limnology and Conservation, Clamecystr. 12, 63571, Gelnhausen, Germany.|Biodiversity and Climate Research Centre (BiK-F) Senckenberganlage 25, D-60325 Frankfurt am Main, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Haase
authors.affiliation: Senckenberg, Department of Limnology and Conservation, Clamecystr. 12, 63571, Gelnhausen, Germany.|Biodiversity and Climate Research Centre (BiK-F) Senckenberganlage 25, D-60325 Frankfurt am Main, Germany.|University of Minnesota, Department of Entomology, 219 Hodson Hall, 1980 Folwell Ave, Saint Paul, MN 55108, USA.
authors.forename: Steffen U
authors.initials: SU
authors.lastname: Pauls