The Drosophila montium subgroup species. Phylogenetic relationships based on mitochondrial DNA analysis

Mitochondrial DNA (mtDNA) restriction site maps for three Drosophila montium subgroup species of the melanogaster species group, inhabiting Indian and Afrotropical montium subgroup territories, were established. Taking into account previous mtDNA data concerning six oriental montium species, a phylogeny was established using distance-matrix and parsimony methods. Both genetic diversity and mtDNA size variations were found to be very narrow, suggesting close phylogenetic relationships among all montium species studied. The phylogenetic trees that were constructed revealed three main lineages for the montium subgroup species studied: one consisting of the Afrotropical species Drosophila seguyi, which is placed distantly from the other species, one comprising the north-oriental (Palearctic) species, and one comprising the southwestern (south-oriental, Australasian, Indian, and Afrotropical) species. The combination of the mtDNA data presented here with data from other species belonging to the melanogaster and obscura subgroups revealed two major clusters: melanogaster and obscura. The melanogaster cluster is further divided into two compact lineages, comprising the montium subgroup species and the melanogaster complex species; the species of the other complex of the melanogaster subgroup, yakuba, disperse among the obscura species. The above grouping is in agreement with the mtDNA size variations of the species. Overall, among all subgroups studied, the species of the montium subgroup seem to be the most closely related. Key words : mtDNA restriction site maps, mtDNA size variations, Drosophila, phylogeny.

Comparative restriction site maps of chloroplast DNA of Piceaabies, Piceaglauca, Piceamariana, and Piceasitchensis

Physical maps of chloroplast DNA of four species of Picea Diet, were compared. Restriction site differences occur between species. Four restriction site mutations were mapped, and between species differences in three more were inferred from restriction fragment patterns. Differences observed among species were not sufficient to allow phylogenetic interpretations. No differences in gene order among species were observed. Gene organization in the chloroplast genome of Picea is compared with that of Pinus L. and Pseudotsuga Carr. Gene order is colinear with that of Pseudotsuga with the exception of one inversion. Though the genomes of Picea and Pseudotsuga are colinear over a greater length than those of Picea and Pinus, this does not imply that Picea and Pseudotsuga are more closely related to each other than to Pinus, since these three patterns of gene organization could have evolved by inversion events that differed only in the order in which they occurred.