Mabel D Giménez

Publications (7)17.52 Total impact

• Article: Understanding the basis of diminished gene flow between hybridizing chromosome races of the house mouse.

  Mabel D Giménez, Thomas A White, Heidi C Hauffe, Thadsin Panithanarak, Jeremy B Searle
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  ABSTRACT: Speciation may be promoted in hybrid zones if there is an interruption to gene flow between the hybridizing forms. For hybridizing chromosome races of the house mouse in Valtellina (Italy), distinguished by whole-arm chromosomal rearrangements, previous studies have shown that there is greater interruption to gene flow at the centromeres of chromosomes that differ between the races than at distal regions of the same chromosome or at the centromeres of other chromosomes. Here, by increasing the number of markers along race-specific chromosomes, we reveal a decay in between-race genetic differentiation from the centromere to the distal telomere. For the first time, we use simulation models to investigate the possible role of recombination suppression and hybrid breakdown in generating this pattern. We also consider epistasis and selective sweeps as explanations for isolated chromosomal regions away from the centromere showing differentiation between the races. Hybrid breakdown alone is the simplest explanation for the decay in genetic differentiation with distance from the centromere. Robertsonian fusions/whole-arm reciprocal translocations are common chromosomal rearrangements characterizing both closely related species and races within species, and this fine-scale empirical analysis suggests that the unfitness associated with these rearrangements in the heterozygous state may contribute to the speciation process.
  Evolution 05/2013; 67(5):1446-62. · 5.15 Impact Factor
• Article: Heterogeneity of heterochromatin in six species ofCtenomys (Rodentia: Octodontoidea: Ctenomyidae) from Argentina revealed by a combined analysis of C- and RE-banding

  María C. Ipucha, Mabel D. Giménez, Claudio J. Bidau
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  ABSTRACT: Exceptional chromosomal variability makesCtenomys an excellent model for evolutionary cytogenetic analysis. Six species belonging to three evolutionary lineages were studied by means of restriction endonuclease and C-chromosome banding. The resulting banding patterns were used for comparative analysis of heterochromatin distribution on chromosomes. This combined analysis allowed intra- and inter-specific heterochromatin variability to be detected, groups of species belonging to different lineages to be characterized, and phylogenetic relationships hypothesized from other data to be supported. The “ancestral group”,Ctenomys pundti andC. talarum, share three types of heterochromatin, the most abundant of which was also found in C. aff.C. opimus, suggesting that the latter species also belongs to the “ancestral group”. Additionally, within the subspeciesC. t. talarum, putative chromosomal rearrangements distinguishing two of the three chromosomal races were identified. Two species belong to an “eastern lineage”,C. osvaldoreigi andC. rosendopascuali, and share only one type of heterochromatin homogeneously distributed across their karyotypes.C. latro, the only analyzed species from the “chacoan” lineage, showed three types of heterochromatin, one of them being that which characterizes the “eastern lineage”.C. aff.C. opimus, because of its low heterochromatin content, is the most primitive karyotype of the genus yet described. The heterochromatin variability showed by these species, reflecting the evolutionary divergence toward different heterochromatin types, may have diverged since the origin of the genus. Heterochromatin amplification is proposed as a trend withinCtenomys, occurring independently of chromosomal change in diploid numbers. Key words Ctenomys -lineages-heterochromatin evolution-restriction endonucleases-tuco-tucos
  Acta theriologica 04/2012; 53(1):57-71. · 0.89 Impact Factor
• Article: First wild XXY house mice.

  Heidi C Hauffe, Mabel D Giménez, Silvia Garagna, Jeremy B Searle
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  ABSTRACT: Laboratory house mice (Mus musculus) with the XXY condition can be generated with ease and have been used as a biomedical model. However, although the XXY constitution has been described in humans and many domestic and wild mammal species, and a very large number of wild house mice have been karyotyped previously, no wild individuals of M. musculus with an XXY karyotype have ever been reported. Therefore, it is rather extraordinary that two wild XXY house mice were caught by us on two different farms in northern Italy in 2008. Except for the extra X chromosome, one male had a standard karyotype (2n = 40) and the other, the karyotype of the Cremona metacentric population (2n = 22). In this paper, the phenotype of these two individuals is described. Observations for both of these wild males agree with those of laboratory XXY mice, i.e., they had a normal body mass and appearance, but significantly smaller testes than normal, and no visible germ cells. The incidence of the XXY chromosome anomaly in wild mice (two among 5,123 wild mice surveyed by us and our colleagues, i.e., approximately 0.08% among wild-caught males) is intermediate between that found in male laboratory mice (approximately 0.04%) and that found in male humans (0.2%).
  Chromosome Research 07/2010; 18(5):599-604. · 3.09 Impact Factor
• Article: Population and species boundaries in the South American subterranean rodent Ctenomys in a dynamic environment

  PATRICIA MIROL, MABEL D. GIMÉNEZ, JEREMY B. SEARLE, CLAUDIO J. BIDAU, CHRIS G. FAULKES
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  ABSTRACT: Subterranean rodents of the genus Ctenomys are an interesting system to assess the effects of habitat instability on the genetic structure of populations. The perrensi group is a complex of three species (C. roigi, C. perrensi and C. dorbignyi) and several forms of uncertain taxonomic status, distributed in the vicinity of the Iberá wetland in Argentina. Because of limited availability of suitable dry habitat, Ctenomys populations are distributed patchily around a vast mosaic of marshes, swamps and lagoons and become connected or isolated over time, depending particularly on the precipitation regime. Genetic variation at 16 microsatellite loci in 169 individuals collected in the area revealed eight clusters of populations which are thought to be evolutionary units, but which do not fit previous species limits. We interpret this lack of congruence between taxonomy and genetic structure as the result of a dynamic population structure. Where populations become connected, hybridization is possible. Where populations become isolated, rapid genetic divergence may occur. In the perrensi group, it appears that both of these factors disrupt the association between different genetic and morphological characters. The study of multiple characters is crucial to the understanding of the recent evolutionary history for dynamic systems such as this. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 368–383.
  Biological Journal of the Linnean Society 05/2010; 100(2):368 - 383. · 2.19 Impact Factor
• Source

  Available from: María José López-Fuster

  Article: Staggered Chromosomal Hybrid Zones in the House Mouse: Relevance to Reticulate Evolution and Speciation

  Gündüz İslam, Christianne L. Pollock, Mabel D Giménez, Daniel W. Förster, Thomas A White, Maria A. Sans-Fuentes, Heidi C Hauffe, Ventura Jacint, María José López-Fuster, Jeremy B Searle
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  ABSTRACT: In the house mouse there are numerous chromosomal races distinguished by different combinations of metacentric chromosomes. These may come into contact with each other and with the ancestral all-acrocentric race, and form hybrid zones. The chromosomal clines that make up these hybrid zones may be coincident or separated from each other (staggered). Such staggered hybrid zones are interesting because they may include populations of individuals homozygous for a mix of features of the hybridising races. We review the characteristics of four staggered hybrid zones in the house mouse and discuss whether they are examples of primary or secondary contact and whether they represent reticulate evolution or not. However, the most important aspect of staggered hybrid zones is that the homozygous populations within the zones have the potential to expand their distributions and become new races (a process termed ‘zonal raciation’). In this way they can add to the total ‘stock’ of chromosomal races in the species concerned. Speciation is an infrequent phenomenon that may involve an unusual set of circumstances. Each one of the products of zonal raciation has the potential to become a new species and by having more races increases the chance of a speciation event.
  Genes. 01/2010;
• Source

  Available from: Frida Johannesdottir

  Article: Of mice and (Viking?) men: phylogeography of British and Irish house mice.

  Jeremy B Searle, Catherine S Jones, Islam Gündüz, Moira Scascitelli, Eleanor P Jones, Jeremy S Herman, R Victor Rambau, Leslie R Noble, R J Berry, Mabel D Giménez, Fríoa Jóhannesdóttir
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  ABSTRACT: The west European subspecies of house mouse (Mus musculus domesticus) has gained much of its current widespread distribution through commensalism with humans. This means that the phylogeography of M. m. domesticus should reflect patterns of human movements. We studied restriction fragment length polymorphism (RFLP) and DNA sequence variations in mouse mitochondrial (mt) DNA throughout the British Isles (328 mice from 105 localities, including previously published data). There is a major mtDNA lineage revealed by both RFLP and sequence analyses, which is restricted to the northern and western peripheries of the British Isles, and also occurs in Norway. This distribution of the 'Orkney' lineage fits well with the sphere of influence of the Norwegian Vikings and was probably generated through inadvertent transport by them. To form viable populations, house mice would have required large human settlements such as the Norwegian Vikings founded. The other parts of the British Isles (essentially most of mainland Britain) are characterized by house mice with different mtDNA sequences, some of which are also found in Germany, and which probably reflect both Iron Age movements of people and mice and earlier development of large human settlements. MtDNA studies on house mice have the potential to reveal novel aspects of human history.
  Proceedings of the Royal Society B: Biological Sciences 10/2008; 276(1655):201-7. · 5.41 Impact Factor
• Article: A First Report of HSRs in Chromosome 1 of Mus Musculus Domesticus from South America

  Mabel D. Giménez, Claudio J. Bidau
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  ABSTRACT: Despite its ubiquitous geographic distribution, the domestic mouse has not received attention from the cytogenetic point of view in South America, possibly because of its apparently conservative karyotype. In this paper we report, for the first time outside the Old World, a polymorphism for a Homogeneously Staining Region (HSR) between G-bands C5 and D of chromosome 1 in commensal populations of house mice from Misiones and Corrientes provinces (Argentina). The HSR is of the Mus musculus domesticus type as has been previously described for European populations. The comparison at the cytogenetic and molecular levels of chromosome polymorphisms such as the one described in this paper, between Old and New World house mice can help clarify the origin and antiquity of New World populations.
  Hereditas 06/2004; 121(3):291 - 294. · 0.79 Impact Factor