Drosophila of Southern California: III. Gene arrangements of Drosophila persimilis

Moore, Betty C.; Taylor, Charles

doi:10.1093/oxfordjournals.jhered.a110248

Cited by 13 publications

(12 citation statements)

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“…The X chromosome is metacentric, incorporating two chromosome arms. The two species differ by fixed large paracentric inversions on the left arm of chromosome X and on chromosome 2 (36,37). The genes associated with isolating mechanisms between D. pseudoobscura and D. persimilis are largely located on these chromosome inversions, with no evidence of major barriers decreasing the potential for gene flow across the other major chromosome arms, just as would be expected according to the suppressed-recombination model of speciation (15,23).…”

Section: Speciation In Drosophilamentioning

confidence: 91%

Chromosome speciation: Humans,Drosophila, and mosquitoes

Ayala

Cóluzzi

2005

Proc. Natl. Acad. Sci. U.S.A.

343

313

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Chromosome rearrangements (such as inversions, fusions, and fissions) may play significant roles in the speciation between parapatric (contiguous) or partly sympatric (geographically overlapping) populations. According to the ''hybrid-dysfunction'' model, speciation occurs because hybrids with heterozygous chromosome rearrangements produce dysfunctional gametes and thus have low reproductive fitness. Natural selection will, therefore, promote mutations that reduce the probability of intercrossing between populations carrying different rearrangements and thus promote their reproductive isolation. This model encounters a disabling difficulty: namely, how to account for the spread in a population of a chromosome rearrangement after it first arises as a mutation in a single individual. The ''suppressed-recombination'' model of speciation points out that chromosome rearrangements act as a genetic filter between populations. Mutations associated with the rearranged chromosomes cannot flow from one to another population, whereas genetic exchange will freely occur between colinear chromosomes. Mutations adaptive to local conditions will, therefore, accumulate differentially in the protected chromosome regions so that parapatric or partially sympatric populations will genetically differentiate, eventually evolving into different species. The speciation model of suppressed recombination has recently been tested by gene and DNA sequence comparisons between humans and chimpanzees, between Drosophila species, and between species related to Anopheles gambiae, the vector of malignant malaria in Africa.genetic divergence ͉ chromosomal rearrangements ͉ human speciation ͉ Drosophila speciation ͉ Anopheles speciation

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Section: Speciation In Drosophilamentioning

confidence: 91%

Chromosome speciation: Humans,Drosophila, and mosquitoes

Ayala

Cóluzzi

2005

Proc. Natl. Acad. Sci. U.S.A.

343

313

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“…Gene order has changed extensively among these species compared to members of D. melanogaster subgroup where ,30 rearrangement events have accumulated among these species and have been considered elsewhere (Ranz et al 2007;York et al 2007). D. persimilis was also excluded from the analysis because the genomic sequence differs from the D. pseudoobscura sequence by four inversion differences (Moore and Taylor 1986) and the inversion events have been analyzed elsewhere Noor et al 2007).…”

Section: Methodsmentioning

confidence: 99%

Chromosomal Rearrangement Inferred From Comparisons of 12 Drosophila Genomes

et al. 2008

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The availability of 12 complete genomes of various species of genus Drosophila provides a unique opportunity to analyze genome-scale chromosomal rearrangements among a group of closely related species. This article reports on the comparison of gene order between these 12 species and on the fixed rearrangement events that disrupt gene order. Three major themes are addressed: the conservation of syntenic blocks across species, the disruption of syntenic blocks (via chromosomal inversion events) and its relationship to the phylogenetic distribution of these species, and the rate of rearrangement events over evolutionary time. Comparison of syntenic blocks across this large genomic data set confirms that genetic elements are largely (95%) localized to the same Muller element across genus Drosophila species and paracentric inversions serve as the dominant mechanism for shuffling the order of genes along a chromosome. Gene-order scrambling between species is in accordance with the estimated evolutionary distances between them and we find it to approximate a linear process over time (linear to exponential with alternate divergence time estimates). We find the distribution of synteny segment sizes to be biased by a large number of small segments with comparatively fewer large segments. Our results provide estimated chromosomal evolution rates across this set of species on the basis of whole-genome synteny analysis, which are found to be higher than those previously reported. Identification of conserved syntenic blocks across these genomes suggests a large number of conserved blocks with varying levels of embryonic expression correlation in Drosophila melanogaster. On the other hand, an analysis of the disruption of syntenic blocks between species allowed the identification of fixed inversion breakpoints and estimates of breakpoint reuse and lineage-specific breakpoint event segregation. D ROSOPHILA research has a rich history in the study of genome rearrangements that now culminates with the analysis of complete genomic sequences. Comparative genomics in Drosophila began when linkage maps of morphological traits were used to establish the homologies of six chromosomal arms in closely related species (Donald 1936;Sturtevant and Tan 1937;Muller 1940;Sturtevant and Novitski 1941). These early studies established the idea that genes are syntenic or conserved on the same chromosome arm among species. One difficulty encountered with these early comparative genomic analyses was that chromosomal arm nomenclatures varied among species (Crew and Lamy 1935;Sturtevant and Tan 1937). Muller (1940) overcame this problem when he developed a standard nomenclature that assigned a letter to each of the chromosomal arms or elements on the basis of the Drosophila melanogaster genome (chromosomal arm equals Muller element: X ¼ A, 2L ¼ B, 2R ¼ C, 3L ¼ D, 3R ¼ E, 4 ¼ F). Sturtevant and Novitski (1941) showed that the conservation of chromosomal elements extended to species across the entire genus of Drosophila.The conservation of the ...

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“…The length of the inverted region (6.8 Mb in D. pseudoobscura and 7.3 Mb in D. persimilis) is proportional to the size of the inversion inferred from salivary chromosomes (Moore and Taylor 1986). The inferred inversion lengths are similar, but not identical, which may reflect differences in the quality of the assemblies between the two species.…”

Section: Ananassae Mapsmentioning

confidence: 96%

“…Kastritsis and Crumpacker (1966) published photomicrographs of complete D. pseudoobscura salivary chromosomes; however, not all sections were labeled in their figures. Moore and Taylor (1986) published photomicrographs of complete D. persimilis salivary chromosomes with all sections indicated. In addition, Moore and Taylor included photomicrographs of the chromosomes of D. pseudoobscura-D. persimilis hybrids, allowing one to precisely map the breakpoints of the inversion differences between the two species.…”

Section: Ananassae Mapsmentioning

confidence: 99%

“…The available cytogenetic maps of the 11 species, however, vary in quality and nomenclature. The D. pseudoobscura and D. persimilis chromosomes depicted in photographic maps contain several bends, making them less than ideal for web-based presentation of the data (Kastritsis and Crumpacker 1966;Moore and Taylor 1986). Two nomenclature problems exist in how the cytogenetic maps were divided into sections and subsections.…”

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confidence: 99%

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Polytene Chromosomal Maps of 11 Drosophila Species: The Order of Genomic Scaffolds Inferred From Genetic and Physical Maps

et al. 2008

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The sequencing of the 12 genomes of members of the genus Drosophila was taken as an opportunity to reevaluate the genetic and physical maps for 11 of the species, in part to aid in the mapping of assembled scaffolds. Here, we present an overview of the importance of cytogenetic maps to Drosophila biology and to the concepts of chromosomal evolution. Physical and genetic markers were used to anchor the genome assembly scaffolds to the polytene chromosomal maps for each species. In addition, a computational approach was used to anchor smaller scaffolds on the basis of the analysis of syntenic blocks. We present the chromosomal map data from each of the 11 sequenced non-Drosophila melanogaster species as a series of sections. Each section reviews the history of the polytene chromosome maps for each species, presents the new polytene chromosome maps, and anchors the genomic scaffolds to the cytological maps using genetic and physical markers. The mapping data agree with Muller's idea that the majority of Drosophila genes are syntenic. Despite the conservation of genes within homologous chromosome arms across species, the karyotypes of these species have changed through the fusion of chromosomal arms followed by subsequent rearrangement events. O NE of the primary strengths of the genus Drosophila as a model system has been the relative ease of generating detailed cytogenetic maps. Indeed, the first definitive mapping of genes to chromosomes Genetics 179: 1601-1655 ( July 2008) was performed in Drosophila melanogaster (Bridges 1916). The subsequent discovery of polytene chromosomes in the salivary glands in this same species (Painter 1934) and their codification into fine-structure genetic/ cytogenetic maps represents perhaps one of the first forays into ''genomics.'' Polytene maps (Bridges 1935;Lefevre 1976) provided an important genetic tool for mapping genes, for detecting genetic diversity within populations, and for inferring phylogenies among related species (Dobzhansky and Sturtevant 1938;Judd et al. 1972;Ashburner and Lemeunier 1976;Lemeunier and Ashburner 1976). Sturtevant and Tan (1937) laid the groundwork for comparative genomics when they established that genes within the chromosomal arms are conserved or syntenic among species. In an insightful melding of the gene mapping and evolutionary studies, H. J. Muller (1940) proposed that the genomes of Drosophila species were subdivided into a set of homologous elements represented by chromosome arms. What Muller (1940) noted, which was subsequently elaborated on by Sturtevant and Novitski (1941), was that the presumed homologs of identified mutant alleles within a chromosome arm of D. melanogaster were also confined to a single arm in other species within the genus where mapping data were available. Using D. melanogaster as a reference, Muller proposed that each of the five major chromosome arms plus the dot chromosome be given a letter designation (A-F) and that this nomenclature be used to identify equivalent linkage groups within the genus.The an...

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Drosophila of Southern California: III. Gene arrangements of Drosophila persimilis

Cited by 13 publications

References 0 publications

Chromosome speciation: Humans,Drosophila, and mosquitoes

Chromosome speciation: Humans,Drosophila, and mosquitoes

Chromosomal Rearrangement Inferred From Comparisons of 12 Drosophila Genomes

Polytene Chromosomal Maps of 11 Drosophila Species: The Order of Genomic Scaffolds Inferred From Genetic and Physical Maps

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