TABLE 1

Synteny statistics (with respect to the D. melanogaster gene order)

SpeciesEstimated time since most recent common ancestor with D. melanogaster A and B (MY)No. of synteny blocksNo. of genes in synteny blocksMaximum synteny block size (no. genes)Average synteny block size (no. genes)No. of singleton genes on same Muller element
D. sechellia5.4, 2.34213,3781,834318.520
D. simulans5.4, 2.313911,8511,07585.269
D. yakuba12.6, 6.111413,175763115.571
D. erecta12.6, 6.16313,403972212.755
D. ananassae44.2, 2069512,66013818.22100
D. pseudoobscura54.9, 24.390811,93210913.14154
D. persimilis54.9, 24.396211,99310912.47151
D. willistoni62.2, 36.31,43011,670888.16383
D. virilis62.9, 39.21,29711,707819.03305
D. mojavensis62.9, 39.21,31211,509738.77328
D. grimshawi62.9, 39.21,33711,217788.39351
  • Synteny statistics (with respect to the D. melanogaster gene order) utilizing assembly scaffolds that were anchored to chromosome arms in various species using experimental and computational data are shown (Schaeffer et al. 2008). Synteny blocks were not artificially broken up by scaffold breaks and were inferred to be continuous when adjacent scaffolds permitted it. The number of synteny blocks and their composition (number of genes and maximum and average size) correspond to the phylogenetic distribution of these species. The number of singleton genes (isolated from their D. melanogaster neighbors) found on corresponding Muller elements in various species increases with evolutionary distance from D. melanogaster—presumed to largely be a result of paracentric inversions. Approximate divergence estimates are from earlier studies: A, Tamura et al. (2004); and B, Russo et al. (1995). We also used a time-independent calibration method for inversion rate estimates. See materials and methods for a discussion regarding selection of approximate divergence times.