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Characterization and isolation of novel microsatellites from the Drosophila dunni subgroup

Published online by Cambridge University Press:  17 February 2003

J. A. WILDER
Affiliation:
Department of Ecology and Evolutionary Biology, Princeton University, Princeton NJ 08544, USA Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
T. DIAZ
Affiliation:
Department of Ecology and Evolutionary Biology, Princeton University, Princeton NJ 08544, USA
R. J. W. O'NEILL
Affiliation:
Department of Ecology and Evolutionary Biology, Princeton University, Princeton NJ 08544, USA Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA.
J. KENNEY
Affiliation:
Department of Ecology and Evolutionary Biology, Princeton University, Princeton NJ 08544, USA Department of Biology, Washington University, St Louis, MO 63130, USA.
H. HOLLOCHER
Affiliation:
Department of Biological Sciences, University of Notre Dame, Notre Dame IN 46544, USA

Abstract

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We have isolated and characterized 77 novel microsatellites from two species, Drosophila dunni and Drosophila nigrodunni, which are closely related Caribbean-island endemics from the Drosophila cardini species group. These species are very distantly related to all other Drosophila from which microsatellites have previously been characterized. We find that the average length of microsatellites isolated in these species is quite small, with an overall mean length of 9·8 repeat units for dinucleotide microsatellites in the two study species. The nucleotide composition of dinucleotides differs between the two species: D. nigrodunni has a predominance of (AC/GT)n repeats, whereas D. dunni has equal numbers of (AC/GT)n and (AG/CT)n repeats. Tri- and tetranucleotide repeats are not abundant in either species. We assayed the variability of eight microsatellites in a closely related third species, Drosophila arawakana, using wild-caught individuals from the island of Guadeloupe. We found the microsatellites to be extremely variable in this population, with observed heterozygosities ranging from 0·541 to 0·889. DNA amplification trials suggest that these eight microsatellites are widely conserved across the D. cardini group, with five of the eight producing amplification products in every species tested. However, the loci are very poorly conserved over greater phylogenetic distances. DNA amplification of the microsatellite loci was unreliable in members of the closely related Drosophila quinaria, Drosophila calloptera, Drosophila guarani and Drosophila tripunctata species groups. Furthermore, these microsatellites could not be detected in the genome of Drosophila melanogaster, despite the conservation of microsatellite flanking regions at some loci. These data indicate that Drosophila microsatellite loci are quite short lived over evolutionary timescales relative to many other taxa.

Type
Research Article
Copyright
© 2002 Cambridge University Press