Genetic variation and population structure of the carpet shell clam Ruditapes decussatus along the Tunisian coast inferred from mtDNA and ITS1 sequence analysis

ArticleinBiologia 65(4):688-696 · August 2010with7 Reads
Impact Factor: 0.83 · DOI: 10.2478/s11756-010-0069-8

    Abstract

    Surveys of allozyme polymorphisms in the carpet shell clam Ruditapes decussatus have revealed sharp genetic differentiation of populations. Analysis of population structure in this species has now been
    extended to include nuclear and mitochondrial genes. A partial sequence of a mitochondrial COI gene and of the internal transcribed
    spacer region (ITS-1) were used to study haplotype distribution, the pattern of gene flow, and population genetic structure
    of R. decussatus. The samples were collected from twelve populations from the eastern and western Mediterranean coasts of Tunisia, one from
    Concarneau and one from Thau. A total of twenty and twenty-one haplotypes were detected in the examined COI and ITS1 regions
    respectively. The study revealed higher levels of genetic diversity for ITS1 compared to COI. The analysis of haplotype frequency
    distribution and molecular variation indicated that the majority of the genetic variation was distributed within populations
    (93% and 86% for COI and ITS1 respectively). No significant differentiation was found among eastern and western groups on
    either side of the Siculo-Tunisian strait. However, distinct and significant clinal changes in haplotypes frequencies between
    eastern and western samples were found at the most frequent COI haplotype and at three out of five major ITS1 haplotypes.
    These results suggest the relative importance of historical processes and contemporary hydrodynamic features on the observed
    patterns of genetic structure.

    Key wordsRuditapes decussates-COI-ITS1-Tunisia