title: Distribution and population genetic variation of cryptic species of the Alpine mayfly Baetis alpinus (Ephemeroptera: Baetidae) in the Central Alps.
abstract: BACKGROUND
  Many species contain evolutionarily distinct groups that are genetically highly differentiated but morphologically difficult to distinguish (i.e., cryptic species). The presence of cryptic species poses significant challenges for the accurate assessment of biodiversity and, if unrecognized, may lead to erroneous inferences in many fields of biological research and conservation.
  
  
  RESULTS
  We tested for cryptic genetic variation within the broadly distributed alpine mayfly Baetis alpinus across several major European drainages in the central Alps. Bayesian clustering and multivariate analyses of nuclear microsatellite loci, combined with phylogenetic analyses of mitochondrial DNA, were used to assess population genetic structure and diversity. We identified two genetically highly differentiated lineages (A and B) that had no obvious differences in regional distribution patterns, and occurred in local sympatry. Furthermore, the two lineages differed in relative abundance, overall levels of genetic diversity as well as patterns of population structure: lineage A was abundant, widely distributed and had a higher level of genetic variation, whereas lineage B was less abundant, more prevalent in spring-fed tributaries than glacier-fed streams and restricted to high elevations. Subsequent morphological analyses revealed that traits previously acknowledged as intraspecific variation of B. alpinus in fact segregated these two lineages.
  
  
  CONCLUSIONS
  Taken together, our findings indicate that even common and apparently ecologically well-studied species may consist of reproductively isolated units, with distinct evolutionary histories and likely different ecology and evolutionary potential. These findings emphasize the need to investigate hidden diversity even in well-known species to allow for appropriate assessment of biological diversity and conservation measures.
authors.affiliation: Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, CH-8600, Dübendorf, Switzerland. marie.leys@eawag.ch.|Institute of Integrative Biology, ETH-Zürich, CH-8092, Zürich, Switzerland. marie.leys@eawag.ch.
authors.forename: Marie
authors.initials: M
authors.lastname: Leys
authors.affiliation: Department of Clinical Research, University of Bern and Swiss Institute of Bioinformatics, CH-3010 Bern, Switzerland.
authors.forename: Irene
authors.initials: I
authors.lastname: Keller
authors.affiliation: Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, CH-8600, Dübendorf, Switzerland.|Institute of Integrative Biology, ETH-Zürich, CH-8092, Zürich, Switzerland.
authors.forename: Katja
authors.initials: K
authors.lastname: Räsänen
authors.affiliation: Musée cantonal de Zoologie, Palais de Rumine, Place de la Riponne 6, CH-1014, Lausanne, Switzerland.|Department of Ecology and Evolution, University of Lausanne, Biophore, CH -1015, Lausanne, Switzerland.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Gattolliat
authors.affiliation: Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, CH-8600, Dübendorf, Switzerland.|Institute of Integrative Biology, ETH-Zürich, CH-8092, Zürich, Switzerland.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Robinson
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001499:Bayes Theorem; D044822:Biodiversity; D005075:Biological Evolution; D004272:DNA, Mitochondrial / Q000235:genetics; D017753:Ecosystem; D065133:Ephemeroptera / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics*; D014644:Genetic Variation; D005828:Genetics, Population; D018895:Microsatellite Repeats; D010802:Phylogeny; D013557:Switzerland; D061350:Sympatry
chemical_list: D004272:DNA, Mitochondrial
keywords: Alpine biodiversity; Cryptic species; Mitochondrial DNA; Nuclear microsatellites; Sympatry