| differences in gene activity in a drosophila species cluster belonging to the obscura group. | the polytene chromosome puffing pattern of drosophila madeirensis was established and compared with those of the related species d. subobscura and d. guanche. a total of 145 loci, active in some of the 12 developmental stages analysed, were described, 38 of which were found to form the puffing pattern characteristic to this species. taking into account the number of puffs as well as the mean puff expression, d. madeirensis shows a similar activity level to d. guanche, both species being less act ... | 1993 | 8314714 |
| insertion polymorphism of retrotransposable elements in populations of the insular, endemic species drosophila madeirensis. | the insertion site numbers of the retrotransposable elements (te) 412, gypsy and bilbo were determined in individuals of five distinct natural populations of the endemic species drosophila madeirensis from the island of madeira. the te distributions were compared to those of the paleartic, widespread and phylogenetically closely related species, d. subobscura. in situ hybridization and southern blots showed that in d. madeirensis the number of insertion sites ranged between 10 and 15, three and ... | 2002 | 11918774 |
| nucleotide variation at the yellow gene region is not reduced in drosophila subobscura: a study in relation to chromosomal polymorphism. | in contrast to drosophila melanogaster and drosophila simulans, the yellow (y) gene region of drosophila subobscura is not located in a region with a strong reduction in recombination. in addition, this gene maps very close to the breakpoints of different inversions that segregate as polymorphic in natural populations of d. subobscura. therefore, levels of variation at the y gene region in this species relative to those found in d. melanogaster and d. simulans may be affected not only by the cha ... | 2000 | 11110911 |
| evolutionary dynamics of the sgm transposon family in the drosophila obscura species group. | sgm (drosophila subobscura, drosophila guanche, and drosophila madeirensis) transposons are a family of transposable elements (tes) in drosophila with some functional and structural similarities to miniature inverted-repeat transposable elements (mites). these elements were recently active in d. subobscura and d. madeirensis (1-2 mya), but in d. guanche (3-4 mya), they gave rise to a species-specifically amplified satellite dna making up approximately 10% of its genome. sgm elements were already ... | 2000 | 11070048 |
| molecular evolution of a duplication: the sex-peptide (acp70a) gene region of drosophila subobscura and drosophila madeirensis. | in drosophila melanogaster, the acp70a gene, which is involved in the postmating reactions of the female, is a single-copy gene. however, in drosophila subobscura, the gene is duplicated and both copies are transcribed. to study the molecular evolution of the duplication, a 2.1-kb fragment encompassing both copies of the duplication was sequenced for 10 lines of d. subobscura and one line of drosophila madeirensis. estimates of the divergence between the two copies of the duplicated region and b ... | 1998 | 9718726 |
| p-element homologous sequences are tandemly repeated in the genome of drosophila guanche. | in drosophila guanche, p-homologous sequences were found to be located in a tandem repetitive array (copy number: 20-50) at a single genomic site. the cytological position on the polytene chromosomes was determined by in situ hybridization (chromosome o: 85c). sequencing of one complete repeat unit (3.25 kilobases) revealed high sequence similarity between the central coding region comprising exons 0 to 2 and the corresponding section of the drosophila melanogaster p element. the rest of the seq ... | 1992 | 1315047 |
| mitochondrial dna evolution in the obscura species subgroup of drosophila. | mitochondrial dna (mtdna) restriction site maps for nine species of the drosophila obscura subgroup and for drosophila melanogaster were established. taking into account all restriction enzymes (12) and strains (45) analyzed, a total of 105 different sites were detected, which corresponds to a sample of 3.49% of the mtdna genome. based on nucleotide divergences, two phylogenetic trees were constructed assuming either constant or variable rates of evolution. both methods led to the same relations ... | 1990 | 2120450 |
| the phylogeny of nine species of the drosophila obscura group inferred by the banding homologies of chromosomal regions. i. element b. | the phylogenetic relationships among nine drosophila species belonging to the obscura group were investigated by establishing the segments displaying banding homologies in their element b (equivalent to the u element of d. subobscura). the phylogenetic ordering of the species was accomplished using overlapping inversions. two african species, d. kitumensis and d. microlabis, were investigated. these species are homosequential for their element b gene arrangement but differ from that of d. obscur ... | 1991 | 1889738 |
| multilocus analysis of nucleotide variation in drosophila madeirensis, an endemic species of the laurisilva forest in madeira. | drosophila madeirensis is an endemic species of madeira that inhabits the island laurisilva forest. nucleotide variation in d. madeirensis is analysed in six genomic regions and compared to that previously reported for the same regions in drosophila subobscura, an abundant species in the palearctic region that is closely related to d. madeirensis. the gene regions analysed are distributed along the o(3) inversion. the o(3) arrangement is monomorphic in d. madeirensis, and it was present in ances ... | 2012 | 22320146 |
| studies of the species barrier between drosophila subobscura and d. madeirensis v: the importance of sex-linked inversion in preserving species identity. | the x chromosome is known to exert a disproportionately large effect on characters related to post-zygotic reproductive isolation. there is also growing evidence about the important role of the chromosomal regions with reduced recombination (such as inversions) in maintaining the identity of closely related species. using molecular markers, we examine the effect of different regions of the x chromosome on determination of hybrid traits (viability, testes size, sperm motility and morphological an ... | 2011 | 21443648 |
| do species converge during adaptation? a case study in drosophila. | adaptation to novel environments is a crucial theme in evolutionary biology, particularly because ex situ conservation forces populations to adapt to captivity. here we analyze the evolution of life-history traits in two closely related species, drosophila subobscura collin and drosophila madeirensis monclus, during adaptation to the laboratory. drosophila madeirensis, an endemic species from madeira, is here shown to have less ability to adapt to the laboratory. early fecundity was the only tra ... | 2010 | 17508331 |
| quantitative genetics of speciation: additive and non-additive genetic differentiation between drosophila madeirensis and drosophila subobscura. | the role of dominance and epistasis in population divergence has been an issue of much debate ever since the neodarwinian synthesis. one of the best ways to dissect the several genetic components affecting the genetic architecture of populations is line cross analysis. here we present a study comparing generation means of several life history-traits in two closely related drosophila species: drosophila subobscura, d. madeirensis as well as their f1 and f2 hybrids. this study aims to determine th ... | 2007 | 17195057 |
| structure and organization of the p element related sequences in drosophila madeirensis. | the p element homologous sequences of the two closely related species drosophila guanche and drosophila subobscura represent a very special case of transposable-element derivatives. although they have lost the regions known to be essential for p transposition by random mutations, all of them have selectively conserved the coding capacity for "p-repressor-like" proteins during the past few millions years. in both species, they are tandemly amplified in a single euchromatic gene cluster at equival ... | 1996 | 8890514 |
| studies of the species barrier between drosophila madeirensis and drosophila subobscura. ii. genetic analysis of developmental incompatibilities in hybrids. | the genetic analysis of two abnormal characters, extra sex combs and abnormal head shape in hybrids between drosophila madeirensis and drosophila subobscura, revealed a major effect of the x chromosome in both cases. autosomes also play a role in determining these abnormalities, the e chromosome in case of extra sex combs, the e and o chromosomes in case of abnormal head shape. autosomes do not cause the two abnormal characters, without interacting with the x chromosome. | 1991 | 1917545 |
| differences in chromosome a arrangement between drosophila madeirensis and drosophila subobscura. | the proximal half of the a (= x) chromosome of d. madeirensis has a gene arrangement very similar to the a1 or a6 inversions found in d. subobscura. polytene chromosome analysis of hybrids between d. madeirensis and strains of d. subobscura homozygous for such inversions shows, however, that d. madeirensis has a gene arrangement different from any known for d. subobscura. these results provide evidence for a greater differentiation of the x chromosome in these species than has previously been de ... | 1989 | 2924882 |
| characterization and evolution of the adh genomic region in drosophila guanche and drosophila madeirensis. | we have sequenced the genomic region of the adh (alcohol dehydrogenase) gene of drosophila guanche and drosophila madeirensis. two genes, adh and adh-dup, whose main features are shared by other drosophila species, are contained in this region. interspecies comparisons of this genomic region of these two species with the region in d. subobscura have been made. our data are in agreement with the phylogenetic relationship of the three species and particularly with the very close proximity of d. ma ... | 1993 | 8081544 |
| a photographic map of drosophila madeirensis polytene chromosomes. | a photographic map of salivary gland polytene chromosomes of drosophila madeirensis has been constructed showing homologies and differences with respect to the standard gene arrangement of d. subobscura. only two paracentric inversions in the x chromosome and some slight minor dissimilarities of one or two bands in the autosomes differentiate the chromosomes of these species. | 2003 | 1795100 |