Linkage disequilibria between mtDNA haplotypes and chromosomal arrangements in a natural population of Drosophila subobscura
The association between mtDNA haplotypes and chromosomal arrangements in a natural population of Drosophila subobscura from Calvia (Balearic Islands, Spain) was studied in order to search for linkage disequilibria, in an attempt to explain the populational dynamics of the mtDNA haplotypes of this species in nature. The presence of Wolbachia was not detected. Two main haplotypes (I and II) were found, as well as a series of less common ones. The Tajima D-test seemed to indicate some kind of seasonal population bottleneck. An analysis of linkage disequilibrium and factorial analysis of correspondences detected an association between haplotype I and the J(ST) inversion and haplotype II and the…
Population structure and mitochondrial DNA gene flow in Old World populations of Drosophila subobscura
An extensive survey of mitochondrial DNA (mtDNA) restriction polymorphism in 156 isofemale lines from 29 different geographic populations of Drosophila subobscura distributed throughout the Old World was carried out. Ten restriction enzymes were used, five of which revealed restriction site polymorphism. Of the 31 restriction sites detected, 13 were found to be polymorphic. Comparisons with the mtDNA map of Drosophila yakuba indicate that the variable sites are mainly concentrated in protein genes, especially those corresponding to the NADH complex. A total of 13 different haplotypes were observed, two of which (haplotypes I and II) are quite frequent and widely distributed throughout the p…
Assortative mating and fertility in two Drosophila subobscura strains with different mitochondrial DNA haplotypes.
The mating pattern and female fertility on the two main mitochondrial DNA haplotypes (I and II) of Drosophila subobscura were studied, in an attempt to find possible differences between them in relation to sexual selection or isolation that could explain the populational dynamics and the co-existence of these two strains in nature. The mating pattern indicated an assortative mating in population cages, where couples of the same haplotype, mainly those of haplotype I, mated more often. However, the significations detected in laboratory conditions disappeared in wild populations, where random mating was the rule. The female fertility also showed differences in the laboratory compared to the w…
Effect of antiviral treatment and host susceptibility on positive selection in hepatitis C virus (HCV).
Abstract We have conducted a large sequence study of the E1–E2 and NS5A regions of the HCV, subtypes 1a and b, both in patients previously treated with interferon, and untreated patients, who later responded, or not, to a combination therapy based on interferon plus ribavirin. We have examined the role played by the number of positively selected sites on disease progression and its relationship with several variables such as patients’ age, sex and their risk of acquiring the disease. We have detected three groups of patients that respond or not to combination therapy: responders of intermediate age, older non-responders and young non-responders, they possess an increasing average number of …
Unraveling assemblage, functions and stability of the gut microbiota of Blattella germanica by antibiotic treatment
Symbiosis between prokaryotes and eukaryotes is a widespread phenomenon that has contributed to the evolution of eukaryotes. In cockroaches, two types of symbionts coexist: an endosymbiont in the fat body (Blattabacterium), and a rich gut microbiota. The transmission mode of Blattabacterium is vertical, while the gut microbiota of a new generation is mainly formed by bacterial species present in feces. We have carried out a metagenomic analysis of Blattella germanica populations, treated and non-treated with two antibiotics (vancomycin and ampicillin) over two generations to (1) determine the core of bacterial communities and potential functions of the gut microbiota and (2) to gain insight…
The genetic structure of Drosophila subobscura populations from the islands of Majorca and Minorca (Balearic Islands, Spain) based on allozymes and mitochondrial DNA
The genetic structure of seven populations of Drosophila subobscura from different locations on Majorca and Minorca (Balearic Islands, Spain) was studied using two types of markers: allozyme and mitochondrial DNA restriction analyses. Both markers showed congruent results. In the allozyme data, when the Acph-1 locus was excluded from the joint FST statistics, only three out of 21 comparisons were statistically significant, lending support to the hypothesis of low genetic differentiation. The mtDNA restriction analyses showed two haplotypes at a high frequency (more than 40% each), irrespective of the location considered, and a number of endemic haplotypes at very low frequencies (not higher…
Fitness and life-history traits of the two major mitochondrial DNA haplotypes of Drosophila subobscura
Mitochondrial DNA restriction site analyses on natural populations of Drosophila subobscura have proved the existence of two common, coexisting haplotypes (I and II), as well as a set of less frequent ones derived from them. To explain this distribution, experiments to date point practically to all possible genetic mechanisms being involved in the changes of gene frequencies (cytonuclear coadaptation, direct natural selection on mtDNA and genetic drift). In an attempt to find differences that help to understand the dynamics of these haplotypes and to detect the effect of selection, we measured certain fitness components and life-history traits (egg-larva and larva-adult viabilities and deve…
Molecular characterization and cytonuclear disequilibria of two Drosophila subobscura mitochondrial haplotypes.
According to restriction site analyses of mitochondrial DNA, Drosophila subobscura shows a polymorphism that consists of two frequent haplotypes that are evenly distributed all over the Old World and several rare haplotypes never present in more than one locality. To ascertain the causes responsible for such distribution, three different mtDNA fragments from haplotypes I and II sampled in a population from Zürich have been partially sequenced. Only three silent nucleotide changes have been detected in the ND5 gene. One of them implies the loss of the HaeIII restriction site, which differentiates haplotype I from haplotype II. On the basis of these results as well as on others involving the…
Multilocus and morphological analysis of south‐eastern Iberian Wall lizards (Squamata,Podarcis)
The phylogenetic relationships among the wall lizards of the Podarcis hispanicus complex that inhabit the south-east (SE) of the Iberian Peninsula and other lineages of the complex remain unclear. In this study, four mitochondrial and two nuclear markers were used to study genetic relationships within this complex. The phylogenetic analyses based on mtDNA gene trees constructed with ML and BI, and a species tree using *BEAST support three divergent clades in this region: the Valencia, Galera and Albacete/Murcia lineages. These three lineages were also corroborated in species delimitation analyses based on mtDNA using bPTP, mPTP, GMYC, ABGD and BAPS. Bayesian inference species delimitation m…
Mitochondrial DNA effects on fitness in Drosophila subobscura
We tested different fitness components on a series of conspecific mtDNA haplotypes, detected by RFLPs in Drosophila subobscura. Additionally, haplotype VIII, endemic to the Canary Islands, was tested upon its own native nuclear DNA background and upon that of the rest of mtDNAs tested herein. We found that both nuclear and mitochondrial DNA can have a significant effect upon their hosts' fitness, and that negative selection is one of the mechanisms that can intervene in this species' mtDNA haplotype pattern. We discuss the importance of this mechanism in relation to genetic drift, in the form of periodic population bottlenecks, and how the latter can enhance the former. We also detected a s…
Generalized Linear Model (GLM) framework for the association of host variables and viral strains with liver fibrosis in HCV/HIV coinfected patients
Chronic hepatitis C virus (HCV) infection is the main cause of advanced and end-stage liver disease world-wide, and an important factor of morbidity and mortality in Human Immunodeficiency virus-1 (HIV-1) co-infected individuals. Whereas the genetic variability of HCV has been studied extensively in monoinfected patients, comprehensive analyses of both patient and virus characteristics are still scarce in HCV/HIV co-infection. In order to find correlates for liver damage, we sought to analyze demographic, epidemiological and clinical features of HCV/HIV co-infected patients along with the genetic makeup of HCV (viral subtypes and lineage studied by nucleotide sequencing and phylogenetic ana…
Mitochondrial DNA haplotype frequencies in natural and experimental populations of Drosophila subobscura.
Abstract The evolution of Drosophila subobscura mitochondrial DNA has been studied in experimental populations, founded with flies from a natural population from Esporles (Majorca, Balearic Islands, Spain). This population, like other European ones, is characterized by the presence of two very common (>96%) mitochondrial haplotypes (called I and II) and rare and endemic haplotypes that appear at very low frequencies. There is no statistical evidence of positive Darwinian selection acting on the mitochondrial DNA variants according to Tajima's neutrality test. Two experimental populations, with one replicate each, were established with flies having a heterogeneous nuclear genetic back…