@article{PAR00007464,
  title = {{M}osa{\¨ie}cism in the {E}uropean zone of sympatry and hybridization of {M}ytilus edulis and {M}. galloprovincialis, as revealed by intron length polymorphism at locus mac-1},
  author = {{B}orsa, {P}hilippe},
  editor = {},
  language = {{ENG}},
  abstract = {{I}ntron-size variation at the actin gene locus mac-1 was used to characterise mussel, {M}ytilus spp., populations in the ~2000-km wide zone of contact and hybridization ('hybrid zone') between {M}. edulis and {M}. galloprovincialis in western {E}urope. {T}wenty-five samples were collected in 1995-1999 in locations within the hybrid zone and from reference populations of each species. {W}e used correspondence analysis on the matrix of allelic frequencies to determine which alleles are characteristic of each species, and to characterise samples along the genetic gradient between {M}. edulis and {M}. galloprovincialis. {I}n the hybrid zone, some samples exhibited mac-1 allele frequencies that were typical of {M}. edulis; other samples were distributed along the {M}. edulis / {M}. galloprovincialis gradient and displayed variable levels of intergradation that were not correlated with geography. {S}ome of the latter samples exhibited significant heterozygote deficiencies. {T}he simple admixture hypothesis ({W}ahlund effect) could not be rejected for two-fifths of the samples. {T}he hybrid zone thus appeared as a mosaic of populations which are either pure {M}. edulis, or hybrid between {M}. galloprovincialis and {M}. edulis, or a mixture of the foregoing with {M}. galloprovincialis individuals. {T}hese results were consistent with published allozyme data, suggesting that they can be extended to the entire nuclear genome. {M}. edulis mac-1 alleles were present at moderate frequency in {A}tlantic {M}. galloprovincialis, and at significantly lower frequency in some {M}editerranean samples. {T}his pattern was homogenous over a broad geographic range within each basin. {I}t was not evident that introgression of {M}. edulis into {M}. galloprovincialis presently occurs south of the zone of contact. {W}e propose that the distinctness of the {A}tlantic {M}. galloprovincialis population results from past introgression by {M}. edulis alleles.},
  keywords = {{M}ytilus edulis ; {M}ytilus galloprovincialis ; hybrid zone ; intron length polymorphism ; heterozygote deficiency ; introgression},
  booktitle = {},
  journal = {{H}eredity},
  volume = {86},
  numero = {},
  pages = {342--354},
  year = {2001},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00007464},
}