title: The first-generation Daphnia magna linkage map.
abstract: BACKGROUND
  Daphnia magna is a well-established model species in ecotoxicology, ecology and evolution. Several new genomics tools are presently under development for this species; among them, a linkage map is a first requirement for estimating the genetic background of phenotypic traits in quantitative trait loci (QTL) studies and is also very useful in assembling the genome. It also enables comparative studies between D. magna and D. pulex, for which a linkage map already exists.
  
  
  RESULTS
  Here we describe the first genetic linkage map of D. magna. We generated 214 F2 (intercross) clonal lines as the foundation of the linkage analysis. The linkage map itself is based on 109 microsatellite markers, which produced ten major linkage groups ranging in size from 31.1 cM to 288.5 cM. The total size of this linkage map extends to 1211.6 Kosambi cM, and the average interval for the markers within linkage groups is 15.1 cM. The F2 clones can be used to map QTLs for traits that differ between the parental clones. We successfully mapped the location of two loci with infertility alleles, one inherited from the paternal clone (Iinb1) and the other from the maternal clone (Xinb3).
  
  
  CONCLUSIONS
  The D. magna linkage map presented here provides extensive coverage of the genome and a given density of markers that enable us to detect QTLs of moderate to strong effects. It is similar in size to the linkage map of D. pulex.
authors.affiliation: Zoologisches Institut, Evolutionsbiologie, Universität Basel, Vesalgasse 1, 4051 Basel, Switzerland. jarkko.routtu@unibas.ch
authors.forename: Jarkko
authors.initials: J
authors.lastname: Routtu
authors.forename: Bastiaan
authors.initials: B
authors.lastname: Jansen
authors.forename: Isabelle
authors.initials: I
authors.lastname: Colson
authors.forename: Luc
authors.initials: L
authors.lastname: De Meester
authors.forename: Dieter
authors.initials: D
authors.lastname: Ebert
mesh_terms: D000483:Alleles; D000818:Animals; D002874:Chromosome Mapping; D003621:Daphnia / Q000235:genetics*; D020224:Expressed Sequence Tags; D005260:Female; D056426:Genetic Loci / Q000235:genetics; D005819:Genetic Markers; D005838:Genotype; D007246:Infertility / Q000235:genetics; D015810:Linkage Disequilibrium / Q000235:genetics; D008126:Lod Score; D008297:Male; D018598:Minisatellite Repeats / Q000235:genetics
chemical_list: D005819:Genetic Markers