Search results for " hybridization"

Inter- and intraspecific hypervariability in interstitial telomeric-like repeats (TTTAGGG)n in Anacyclus (Asteraceae).

2017

BACKGROUND AND AIMS: Interstitial telomeric repeat (ITR) sites, consisting of tandem repeats of telomeric motifs localized at intrachromosomal sites, have been reported in a few unrelated organisms including plants. However, the causes for the occurrence of ITRs outside of the chromosomal termini are not fully understood. One possible explanation are the chromosomal rearrangements involving telomeric sites, which could also affect the location of other structural genome elements, such as the 45S rDNA. Taking advantage of the high dynamism in 45S rDNA loci previously found in Anacyclus (Asteraceae, Anthemideae), the occurrence and patterns of variation of ITRs were explored in this genus wit…

Chironomus riparius(Diptera) genome sequencing reveals the impact of minisatellite transposable elements on population divergence

2016

AbstractActive transposable elements (TEs) may result in divergent genomic insertion and abundance patterns among conspecific populations. Upon secondary contact, such divergent genetic backgrounds can theoretically give rise to classical Dobzhansky-Muller incompatibilities (DMI), a way how TEs can contribute to the evolution of endogenous genetic barriers and eventually population divergence. We investigated whether differential TE activity created endogenous selection pressures among conspecific populations of the non-biting midgeChironomus riparius,focussing on aChironomus-specific TE, the minisatellite-likeCla-element, whose activity is associated with speciation in the genus. Using an …

High and uneven levels of 45S rDNA site-number variation across wild populations of a diploid plant genus (Anacyclus, Asteraceae)

2017

The nuclear genome harbours hundreds to several thousand copies of ribosomal DNA. Despite their essential role in cellular ribogenesis few studies have addressed intrapopulation, interpopulation and interspecific levels of rDNA variability in wild plants. Some studies have assessed the extent of rDNA variation at the sequence and copy-number level with large sampling in several species. However, comparable studies on rDNA site number variation in plants, assessed with extensive hierarchical sampling at several levels (individuals, populations, species) are lacking. In exploring the possible causes for ribosomal loci dynamism, we have used the diploid genus Anacyclus (Asteraceae) as a suitab…

Not that clean: Aquaculture-mediated translocation of cleaner fish has led to hybridization on the northern edge of the species' range

2021

Translocation and introduction of non-native organisms can have major impacts on local populations and ecosystems. Nevertheless, translocations are common practices in agri- and aquaculture. Each year, millions of wild-caught wrasses are transported large distances to be used as cleaner fish for parasite control in marine salmon farms. Recently, it was documented that translocated cleaner fish are able to escape and reproduce with local wild populations. This is especially a challenge in Norway, which is the world's largest salmon producer. Here, a panel of 84 informative SNPs was developed to identify the presence of nonlocal corkwing wrasse (Symphodus melops) escapees and admixed individu…

An exhaustive phylogeny of the combtooth blenny genus Salaria (Pisces, Blenniidae) shows introgressive hybridization and lack of reciprocal mtDNA mon…

2019

A comprehensive phylogeny of the genus Salaria based on mitochondrial and nuclear markers grouped the extant species of the genus in well-characterised marine and freshwater clades, thus rejecting the hypothesis of a polytypic origin of the freshwater Salaria populations and supporting the occurrence of a single invasion event of the inland waters by the genus. Based on both mitochondrial and nuclear DNA datasets, the Salaria species of the freshwater clade proved to be vicariant taxa originating from a common ancestor which could possibly spread throughout the circum-Mediterranean inland waters during the late Miocene Messinian salinity crisis, then experiencing a process of allopatric dif…

2020

Turtles, a speciose group consisting of more than 300 species, demonstrate karyotypes with diploid chromosome numbers ranging from 2n = 26 to 2n = 68. However, cytogenetic analyses have been conducted only to 1/3rd of the turtle species, often limited to conventional staining methods. In order to expand our knowledge of the karyotype evolution in turtles, we examined the topology of the (TTAGGG)n telomeric repeats and the rDNA loci by fluorescence in situ hybridization (FISH) on the karyotypes of two emydids: the Sicilian pond turtle, Emys trinacris, and the yellow-bellied slider, Trachemys scripta scripta (family Emydidae). Furthermore, AT-rich and GC-rich chromosome regions were detected …

Unravelling the scientific debate on how to address wolf-dog hybridization in Europe

2019

Anthropogenic hybridization is widely perceived as a threat to the conservation of biodiversity. Nevertheless, to date, relevant policy and management interventions are unresolved and highly convoluted. While this is due to the inherent complexity of the issue, we hereby hypothesize that a lack of agreement concerning management goals and approaches, within the scientific community, may explain the lack of social awareness on this phenomenon, and the absence of effective pressure on decision-makers. By focusing on wolf x dog hybridization in Europe, we hereby (a) assess the state of the art of issues on wolf x dog hybridization within the scientific community, (b) assess the conceptual base…

Karyotype variability and inter-population genomic differences in freshwater ostracods (Crustacea) showing geographical parthenogenesis

2018

Transitions from sexual to asexual reproduction are often associated with polyploidy and increased chromosomal plasticity in asexuals. We investigated chromosomes in the freshwater ostracod species Eucypris virens (Jurine, 1820), where sexual, asexual and mixed populations can be found. Our initial karyotyping of multiple populations from Europe and North Africa, both sexual and asexual, revealed a striking variability in chromosome numbers. This would suggest that chromosomal changes are likely to be accelerated in asexuals because the constraints of meiosis are removed. Hence, we employed comparative genomic hybridization (CGH) within and among sexual and asexual populations to get insigh…

Erwinia carotovora subsp. odorifera subsp.nov., associated with odorous soft rot of chicory (Cichorium intybus L.)

1992

Eleven strains of Erwinia carotovora that were isolated mainly, but not exclusively, from slimy rot of witloof chicory and were previously designated “atypical” E. carotovora subsp. atroseptica strains were characterized and compared with strains of E. carotovora subsp. carotovora, E. carotovora subsp. atroseptica, and Erwinia chrysanthemi (including the type strains). The 11 atypical E. carotovora subsp. atroseptica strains produced a typical bananalike odor when they were inoculated onto witloof chicory leaves. DNA-DNA homology experiments, biochemical tests, tests to determine carbon utilization patterns, and tests to identify the volatile metabolites produced from rotting witloofs were …

Immunity and other defenses in pea aphids, Acyrthosiphon pisum

2010

Background Recent genomic analyses of arthropod defense mechanisms suggest conservation of key elements underlying responses to pathogens, parasites and stresses. At the center of pathogen-induced immune responses are signaling pathways triggered by the recognition of fungal, bacterial and viral signatures. These pathways result in the production of response molecules, such as antimicrobial peptides and lysozymes, which degrade or destroy invaders. Using the recently sequenced genome of the pea aphid (Acyrthosiphon pisum), we conducted the first extensive annotation of the immune and stress gene repertoire of a hemipterous insect, which is phylogenetically distantly related to previously ch…