scholarly journals Reproductive isolation in a nascent species pair is associated with aneuploidy in hybrid offspring

2015 ◽  
Vol 282 (1802) ◽  
pp. 20142862 ◽  
Author(s):  
Anne-Marie Dion-Côté ◽  
Radka Symonová ◽  
Petr Ráb ◽  
Louis Bernatchez
Keyword(s):  
Reproductive Isolation ◽  
Chromosome Numbers ◽  
Chromosomal Instability ◽  
Diploid Number ◽  
Chromosomal Rearrangements ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Mitotic Instability ◽  
Two Populations

Speciation may occur when the genomes of two populations accumulate genetic incompatibilities and/or chromosomal rearrangements that prevent inter-breeding in nature. Chromosome stability is critical for survival and faithful transmission of the genome, and hybridization can compromise this. However, the role of chromosomal stability on hybrid incompatibilities has rarely been tested in recently diverged populations. Here, we test for chromosomal instability in hybrids between nascent species, the ‘dwarf’ and ‘normal’ lake whitefish ( Coregonus clupeaformis ). We examined chromosomes in pure embryos, and healthy and malformed backcross embryos. While pure individuals displayed chromosome numbers corresponding to the expected diploid number (2 n = 80), healthy backcrosses showed evidence of mitotic instability through an increased variance of chromosome numbers within an individual. In malformed backcrosses, extensive aneuploidy corresponding to multiples of the haploid number (1 n = 40, 2 n = 80, 3 n = 120) was found, suggesting meiotic breakdown in their F 1 parent. However, no detectable chromosome rearrangements between parental forms were identified. Genomic instability through aneuploidy thus appears to contribute to reproductive isolation between dwarf and normal lake whitefish, despite their very recent divergence (approx. 15–20 000 generations). Our data suggest that genetic incompatibilities may accumulate early during speciation and limit hybridization between nascent species.

scholarly journals Limited intrinsic postzygotic reproductive isolation despite chromosomal rearrangements between closely related sympatric species of small ermine moths (Lepidoptera: Yponomeutidae)

2019 ◽  
Vol 128 (1) ◽  
pp. 44-58 ◽  
Author(s):  
Katerina H Hora ◽  
František Marec ◽  
Peter Roessingh ◽  
Steph B J Menken
Keyword(s):  
Reproductive Isolation ◽  
Parental Species ◽  
Meiotic Chromosome ◽  
Chromosomal Rearrangements ◽  
Sympatric Species ◽  
Hybrid Fitness ◽  
New Host ◽  
Closely Related Species ◽  
Postzygotic Reproductive Isolation

Abstract In evolutionarily young species and sympatric host races of phytophagous insects, postzygotic incompatibility is often not yet fully developed, but reduced fitness of hybrids is thought to facilitate further divergence. However, empirical evidence supporting this hypothesis is limited. To assess the role of reduced hybrid fitness, we studied meiosis and fertility in hybrids of two closely related small ermine moths, Yponomeuta padella and Yponomeuta cagnagella, and determined the extent of intrinsic postzygotic reproductive isolation. We found extensive rearrangements between the karyotypes of the two species and irregularities in meiotic chromosome pairing in their hybrids. The fertility of reciprocal F1 and, surprisingly, also of backcrosses with both parental species was not significantly decreased compared with intraspecific offspring. The results indicate that intrinsic postzygotic reproductive isolation between these closely related species is limited. We conclude that the observed chromosomal rearrangements are probably not the result of an accumulation of postzygotic incompatibilities preventing hybridization. Alternative explanations, such as adaptation to new host plants, are discussed.

scholarly journals Karyotype description and comparative analysis in Ringed Kingfisher and Green Kingfisher (Coraciiformes, Alcedinidae)

2018 ◽  
Vol 12 (2) ◽  
pp. 163-170
Author(s):  
Tiago Marafiga Degrandi ◽  
Jean Carlo Pedroso de Oliveira ◽  
Amanda de Araújo Soares ◽  
Mario Angel Ledesma ◽  
Iris Hass ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Chromosome Number ◽  
Chromosome Numbers ◽  
Diploid Number ◽  
Chromosomal Rearrangements ◽  
The Family ◽  
Cytogenetic Studies ◽  
Karyotype Structure ◽  
Chromosome Fusions ◽  
Size And Morphology

Kingfishers comprise about 115 species of the family Alcedinidae, and are an interesting group for cytogenetic studies, for they are among birds with most heterogeneous karyotypes. However, cytogenetics knowledge in Kingfishers is extremely limited. Thus, the aim of this study was to describe the karyotype structure of the Ringed Kingfisher (Megaceryletorquata Linnaeus, 1766) and Green Kingfisher (Chloroceryleamericana Gmelin, 1788) and also compare them with related species in order to identify chromosomal rearrangements. The Ringed Kingfisher presented 2n = 84 and the Green Kingfisher had 2n = 94. The increase of the chromosome number in the Green Kingfisher possibly originated by centric fissions in macrochromosomes. In addition, karyotype comparisons in Alcedinidae show a heterogeneity in the size and morphology of macrochromosomes, and chromosome numbers ranging from 2n = 76 to 132. Thus, it is possible chromosomal fissions in macrochromosomes resulted in the increase of the diploid number, whereas chromosome fusions have originated the karyotypes with low diploid number.

scholarly journals Using Telomeric Length Measurements and Methylation to Understand The Karyotype Diversification of Ctenomys Minutus (A Small Fossorial Mammals)

2021 ◽  
Author(s):  
Cristina A. Matzenbacher ◽  
Juliana Silva ◽  
Ana Leticia H. Garcia ◽  
Rafael Kretschmer ◽  
Mónica Cappetta ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Genomic Instability ◽  
Chromosomal Instability ◽  
Diploid Number ◽  
Karyotype Evolution ◽  
Chromosomal Rearrangements ◽  
Global Dna Methylation ◽  
Methylated Dna ◽  
Significant Difference ◽  
Length Measurements

Abstract The genus Ctenomys has been widely used in karyotype evolution studies due to the variation in their diploid numbers (2n), which range from 2n = 10 to 2n = 70. Ctenomys minutus is characterized by intraspecific variation in diploid number (2n = 42, 46, 48, and 50), which makes it an interesting model to investigate the genomic instability mechanisms that have led to different cytotypes in this species. We aimed to contribute to the knowledge about telomeres’ role in chromosomal instability and global DNA methylation in the genome evolution of C. minutus. This study found that telomere length differs between cytotypes, but only for females (50a<46a,48a,42), although methylation was also higher, no significant difference was shown. It was also shown that young individuals, regardless of cytotype, had the longest telomere and the most methylated DNA, although only the last was statistically significant. Despite this, there is still much to be answered, although new cytotypes seem to have emerged within the distribution of parental cytotypes by the accumulation of different chromosomal rearrangements.

scholarly journals The strength and genetic basis of reproductive isolating barriers in flowering plants

2008 ◽  
Vol 363 (1506) ◽  
pp. 3009-3021 ◽  
Author(s):  
David B Lowry ◽  
Jennifer L Modliszewski ◽  
Kevin M Wright ◽  
Carrie A Wu ◽  
John H Willis
Keyword(s):  
Reproductive Isolation ◽  
Chromosomal Rearrangements ◽  
Variable Number ◽  
Future Research ◽  
Relative Role ◽  
Postzygotic Isolation ◽  
Direct Role ◽  
Evolutionary Forces ◽  
Geographical Scale

Speciation is characterized by the evolution of reproductive isolation between two groups of organisms. Understanding the process of speciation requires the quantification of barriers to reproductive isolation, dissection of the genetic mechanisms that contribute to those barriers and determination of the forces driving the evolution of those barriers. Through a comprehensive analysis involving 19 pairs of plant taxa, we assessed the strength and patterns of asymmetry of multiple prezygotic and postzygotic reproductive isolating barriers. We then reviewed contemporary knowledge of the genetic architecture of reproductive isolation and the relative role of chromosomal and genic factors in intrinsic postzygotic isolation. On average, we found that prezygotic isolation is approximately twice as strong as postzygotic isolation, and that postmating barriers are approximately three times more asymmetrical in their action than premating barriers. Barriers involve a variable number of loci, and chromosomal rearrangements may have a limited direct role in reproductive isolation in plants. Future research should aim to understand the relationship between particular genetic loci and the magnitude of their effect on reproductive isolation in nature, the geographical scale at which plant speciation occurs, and the role of different evolutionary forces in the speciation process.

scholarly journals Involvement of Very Short DNA Tandem Repeats and the Influence of the RAD52 Gene on the Occurrence of Deletions in Saccharomyces cerevisiae

Genetics ◽  
2000 ◽  
Vol 156 (2) ◽  
pp. 549-557 ◽  
Author(s):  
Anne J Welcker ◽  
Jacky de Montigny ◽  
Serge Potier ◽  
Jean-Luc Souciet
Keyword(s):  
Fusion Proteins ◽  
Tandem Repeats ◽  
Chromosomal Rearrangements ◽  
Reversion Rate ◽  
Wild Type ◽  
Recombination Mechanism ◽  
Nonhomologous Recombination ◽  
Deletion Rate ◽  
Dna Tandem Repeats

Abstract Chromosomal rearrangements, such as deletions, duplications, or Ty transposition, are rare events. We devised a method to select for such events as Ura+ revertants of a particular ura2 mutant. Among 133 Ura+ revertants, 14 were identified as the result of a deletion in URA2. Of seven classes of deletions, six had very short regions of identity at their junctions (from 7 to 13 bp long). This strongly suggests a nonhomologous recombination mechanism for the formation of these deletions. The total Ura+ reversion rate was increased 4.2-fold in a rad52Δ strain compared to the wild type, and the deletion rate was significantly increased. All the deletions selected in the rad52Δ context had microhomologies at their junctions. We propose two mechanisms to explain the occurrence of these deletions and discuss the role of microhomology stretches in the formation of fusion proteins.

scholarly journals Analysis of multiple chromosomal rearrangements in the genome of Willisornis vidua using BAC-FISH and chromosome painting on a supposed conserved karyotype

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Talita Fernanda Augusto Ribas ◽  
Julio Cesar Pieczarka ◽  
Darren K. Griffin ◽  
Lucas G. Kiazim ◽  
Cleusa Yoshiko Nagamachi ◽  
...  
Keyword(s):  
Chromosome Painting ◽  
Diploid Number ◽  
Chromosomal Rearrangements ◽  
Large Degree ◽  
Artificial Chromosome ◽  
Gallus Gallus ◽  
Phylogeographic Structure ◽  
Molecular Cytogenetic ◽  
Burhinus Oedicnemus ◽  
Intrachromosomal Rearrangements

Abstract Background Thamnophilidae birds are the result of a monophyletic radiation of insectivorous Passeriformes. They are a diverse group of 225 species and 45 genera and occur in lowlands and lower montane forests of Neotropics. Despite the large degree of diversity seen in this family, just four species of Thamnophilidae have been karyotyped with a diploid number ranging from 76 to 82 chromosomes. The karyotypic relationships within and between Thamnophilidae and another Passeriformes therefore remain poorly understood. Recent studies have identified the occurrence of intrachromosomal rearrangements in Passeriformes using in silico data and molecular cytogenetic tools. These results demonstrate that intrachromosomal rearrangements are more common in birds than previously thought and are likely to contribute to speciation events. With this in mind, we investigate the apparently conserved karyotype of Willisornis vidua, the Xingu Scale-backed Antbird, using a combination of molecular cytogenetic techniques including chromosome painting with probes derived from Gallus gallus (chicken) and Burhinus oedicnemus (stone curlew), combined with Bacterial Artificial Chromosome (BAC) probes derived from the same species. The goal was to investigate the occurrence of rearrangements in an apparently conserved karyotype in order to understand the evolutionary history and taxonomy of this species. In total, 78 BAC probes from the Gallus gallus and Taeniopygia guttata (the Zebra Finch) BAC libraries were tested, of which 40 were derived from Gallus gallus macrochromosomes 1–8, and 38 from microchromosomes 9–28. Results The karyotype is similar to typical Passeriformes karyotypes, with a diploid number of 2n = 80. Our chromosome painting results show that most of the Gallus gallus chromosomes are conserved, except GGA-1, 2 and 4, with some rearrangements identified among macro- and microchromosomes. BAC mapping revealed many intrachromosomal rearrangements, mainly inversions, when comparing Willisornis vidua karyotype with Gallus gallus, and corroborates the fissions revealed by chromosome painting. Conclusions Willisornis vidua presents multiple chromosomal rearrangements despite having a supposed conservative karyotype, demonstrating that our approach using a combination of FISH tools provides a higher resolution than previously obtained by chromosome painting alone. We also show that populations of Willisornis vidua appear conserved from a cytogenetic perspective, despite significant phylogeographic structure.

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