@article{KangSchartlWalteretal.2013,
  author    = {Ji Hyoun Kang and Manfred Schartl and Ronald B. Walter and Axel Meyer},
  title     = {Comprehensive phylogenetic analysis of all species of swordtails and platies (Pisces: Genus Xiphophorus) uncovers a hybrid origin of a swordtail fish, Xiphophorus monticolus, and demonstrates that the sexually selected sword originated in the ancestral lineage of the genus, but was lost again secondarily},
  journal   = {BMC Evolutionary Biology},
  volume    = {13},
  number    = {25},
  doi       = {10.1186/1471-2148-13-25},
  year      = {2013},
}