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CHROMOSOMAL EVOLUTION OF ELEMENTS B AND C IN THE SOPHOPHORA SUBGENUS OF DROSOPHILA : EVOLUTIONARY RATE AND POLYMORPHISM
Author(s) -
Papaceit Montserrat,
Aguadé Montserrat,
Segarra Carmen
Publication year - 2006
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.0014-3820.2006.tb01155.x
Subject(s) - biology , subgenus , chromosomal polymorphism , drosophila subobscura , drosophila pseudoobscura , genetics , polytene chromosome , chromosomal inversion , drosophila (subgenus) , hybrid , evolutionary biology , rate of evolution , karyotype , phylogenetic tree , drosophila melanogaster , zoology , genus , chromosome , gene , botany
The locations of 77 markers along the chromosomal elements B (41 markers) and C (36 markers) of Drosophila subobscura, D. pseudoobscura , and D. melanogaster were obtained by in situ hybridization on polytene chromosomes. In comparisons between D. subobscura and D. pseudoobscura , 10 conserved segments (accounting for 32% of the chromosomal length) were detected on element B and eight (17% of the chromosomal length) on element C. The fixation rate of paracentric inversions inferred by a maximum likelihood approach differs significantly between elements. Muller's element C (0.17 breakpoints/Mb/million years) is evolving two times faster than element B (0.08 breakpoints/Mb/million years). This difference in the evolutionary rate is paralleled by differences in the extent of chromosomal polymorphism in the corresponding lineages. Element C is highly polymorphic in D. subobscura, D. pseudoobscura , and in other obscura group species such as D. obscura and D. athabasca . In contrast, the level of polymorphism in element B is much lower in these species. The fixation rates of paracentric inversions estimated in the present study between species of the Sophophora subgenus are the highest estimates so far reported in the genus for the autosomes. At the subgenus level, there is also a parallelism between the high fixation rate and the classical observation that the species of the Sophophora subgenus tend to be more polymorphic than the species of the Drosophila subgenus. Therefore, the detected relationship between level of polymorphism and evolutionary rate might be a general characteristic of chromosomal evolution in the genus Drosophila .