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Chromosomal elements evolve at different rates in the Drosophila genome
Josefa González1, José María Ranz, Alfredo Ruiz
1Departament de Genètica i de Microbiologia, Facultat de Ciències-Edifici C, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain.
Genetics
|July 24, 2002
Summary
The genus Drosophila exhibits exceptionally high rates of chromosomal rearrangement, the highest observed in eukaryotes. This study quantifies extensive reshuffling across multiple chromosomal elements, revealing significant evolutionary differences among chromosomes.
Area of Science:
- Genomics
- Evolutionary Biology
- Cytogenetics
Background:
- Previous studies identified high chromosomal rearrangement rates in Drosophila, based on limited chromosomal elements.
- Comparative mapping of Muller's element E in Drosophila repleta and Drosophila melanogaster suggested rapid evolution.
Purpose of the Study:
- To extend the analysis of chromosomal rearrangement rates to additional Muller's elements (A and D) within the Drosophila genus.
- To investigate variations in evolutionary rates among different chromosomes.
- To provide a more comprehensive estimate of genome-wide chromosomal rearrangements.
Main Methods:
- Detailed physical mapping of chromosomes X and 4 in D. repleta using in situ hybridization with 145 DNA probes.
- Comparative analysis of gene arrangements between D. repleta and homologous chromosomes (X and 3L) of D. melanogaster.
- Estimation of fixed paracentric inversions for specific chromosomal elements.
Main Results:
- Chromosomal elements A and D in D. repleta show extensive reshuffling across their entire lengths.
- Estimated fixed paracentric inversions: 118 +/- 17 for element A and 56 +/- 8 for element D.
- Significant variation in evolutionary rates among chromosomal elements was observed, with chromosome X being the most dynamic.
Conclusions:
- The genus Drosophila displays a remarkably high rate of chromosomal rearrangement, confirmed by analysis of multiple elements.
- An estimated 393 paracentric inversions have occurred since the divergence of D. repleta and D. melanogaster.
- The average rate of 0.053 disruptions/Mb/myr underscores the rapid genome evolution in Drosophila.