Male common shrews (&lt;i&gt;Sorex araneus&lt;/i&gt;) with long meiotic chain configurations can be fertile: implications for chromosomal models of speciation

Mercer, Simon; Wallace, B. M. N.; Searle, Jeremy B.

doi:10.1159/000133298

Cited by 53 publications

(52 citation statements)

References 16 publications

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“…At meiosis I, hybrids should produce chains of 10 chromosomes: o/ok/ki/ih/hn/np/pm/mg/gr/r. Hybrids with large meiotic complexes have been obtained in S. araneus in breeding conditions (Searle, 1 984a;Mercer et at., 1992) and they also occur under natural conditions (Aniskin & Lukianova, 1989). Studies of heterozygous mice suggest that the probability of producing chromosomally balanced gametes is inversely proportional to the number of chromosomes within a meiotic complex (Capanna, 1975;Capanna eta!., 1977;Gropp & Winking, 1981;Gropp et al, 1982).…”

Section: Discussionmentioning

confidence: 99%

Study of a contact between two chromosomally monomorphic races of Sorex araneus L. (common shrew)

1993

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One hundred and twelve specimens of the common shrew from 21 populations in NE Poland were studied from an area of contact between chromosomal race II (metacentric chromosomes: hi, ko, gm, np) and race VII (ki, hn, gr, mp). No direct contact was found between the races in the study area; there were no mixed or hybrid populations. The shortest distance between populations of the two races was 1.2-1.6 km. Possible explanations for this pattern of the races' disjunction are discussed.

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Section: Discussionmentioning

confidence: 99%

Study of a contact between two chromosomally monomorphic races of Sorex araneus L. (common shrew)

1993

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“…In the latter case, multivalents are formed during the meiotic process in the hybrids, which can lead to aneuploid gametes and thus to a more or less strong reduction in fertility. Recent work suggests that male heterozygotes for metacentrics with monobrachial homologies can be almost fully fertile (Mercer et al 1992). Nevertheless, incompatibility problems probably occur in nature, as shown by the very well-documented examples given by the hybrid zones between Oxford and Hermitage race in England (Searle 1986b(Searle , 1988 and between races II and IV in northeastern Poland .…”

Section: Samniticus (3-507)mentioning

confidence: 99%

CHROMOSOMAL VERSUS MITOCHONDRIAL DNA EVOLUTION: TRACKING THE EVOLUTIONARY HISTORY OF THE SOUTHWESTERN EUROPEAN POPULATIONS OF THESOREX ARANEUSGROUP (MAMMALIA, INSECTIVORA)

1994

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Abstract. -The shrews of the Sorex araneus group have undergone a spectacular chromosome evolution. The karyotype of Sorex granarius is generally considered ancestral to those of Sorex coronatus and S. araneus. However, a sequenceof 777 base pairs of the cytochrome b gene of the mitochondrial DNA (mtDNA) produces a quite differentpicture: S. granarius is closelyrelated to the populations of S. araneus from the Pyrenees and from the northwestern Alps, whereas S. coronatus and S. araneus from Italy and the southern Alps represent two well-separated lineages. It is suggested that mtDNA and chromosomal evolution are in this case largely independant processes. Whereas mtDNA haplotypes are closelylinked to the geographical history of the populations, chromosomal mutations were probably transmitted from one population to another. Available data suggest that the impressive chromosome polymorphism of this group is quite a recent phenomenon. The shrews of the Sorex araneus group show one of the most spectacular chromosomal evolutions ever recorded in mammals. Eight karyologically well-differentiated species are recognized in this group. They are characterized by the presence in males ofaXY,Y2 sex chromosome complex, and most species additionally show intraspecific chromosomal polymorphism. Numerous studies on this chromosomal variation both at interspecific and at intraspecific levels have been published (recent reviews in Hausser 1994; Ivanitskaya 1994; Volobouev and Dutrillaux 199 I). This paper is concerned with the southwestern European forms of the group, for which karyotypic relationships are quite easy to decipher. The three species, S. granarius, S. coronatus, and S. araneus, differ mainly by Robertsonian changes. Extensive studies ofthe polymorphism ofS. araneus strongly argue that Robertsonian (centric) fusions rather than fissions played the major role in this karyotypic differentiation (but for a different point of view see Halkka et aI. 1987). Phylogenies of the chromosomal races ofS. araneus and reconstructions of the postglacial recolonization of Europe have been suggested on the basis of such fusion pre-. cedence (Searle 1984; Hausser et aI. 1986 Hausser et aI. , 1991Searle and Wilkinson 1987).Sorex granarius is generally considered to have a karyotype closely similar to the common ancestor of the restricted group considered here (W 6jcik and Searle 1988;Volobouev and Catzeflis 1989; Volobouev and Dutriliaux 1991). Ifwe follow the nomenclature for the chromosomes of S. araneus proposed by Searle et aI. (1991), where the individual arms are labeled by letters according to their size and their G-band pattern, S. granarius has every autosomal arm (a to r) in an acrocentric form, whereas S. corona/us and S. araneus bear both a common fusion (af) and specific fusions of autosomal arms. It is thus tempting to suggest that S. granarius, which is now confined to central and northwestern Spain and Portugal, was isolated early from the mainstream of the group. This mainstream then acquired the fusion af, and event...

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“…It is not known, whether these observations are relevant to the course of spermatogenesis in the complex heterozygotes of common shrews. To date, except few cases, spermatogenesis was only investigated in Robertsonian heterozygotes of the common shrews (Searle 1986b, Garagna et al 1989, Mercer et al 1991, Mercer et al 1992. However, the analysis of genetic structure of a few well studied contact zones suggests that some of the meiotic configurations are direct targets of natural selection.…”

Section: Discussionmentioning

confidence: 99%

Maximatization of the frequency of recombinants in the hybrid zones of Sorex araneus in northern Poland

Szałaj¹,

Fedyk²,

Banaszek³

et al. 1995

Acta Theriol.

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. 1995. Maximization of the frequency of recombinants in the hybrid zones of Sorex araneus in northern Poland. Acta Theriologica 40: 225-236.We studied populations of Sorex araneus Linnaeus, 1758 in the upper Drwęca River valley and in the vicinity of Lake Szeląg Wielki. We found that the cline of frequency of metacentric np decays in the Drwęca River valley, which results in a smooth transition between the Stobnica race (karyotype hi, ko, gm, np) and the Laska race (hi, ko, gm). However, on the west shore of Lake Szeląg Wielki the cline of frequency of metacentric gm disappears. Reduction of frequencies of autosomes np and gm makes possible broadening of the clines of metacentrics gr and mn, originating from the Łęgucki Młyn race. This results in a reduction of the number of hybrids and maximization of frequency of recombinants (hi, ko, gr, mn), which reaches the value of 1.0 in the populations located on the west shore of the lake. We compared studied populations with those in the Pasłęka River valley, and those between the Pasłęka and Drwęca Rivers valleys. We also discussed the maximization of the frequency of recombinants as a mechanism enhancing fertility of hybrid populations.

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Male common shrews (<i>Sorex araneus</i>) with long meiotic chain configurations can be fertile: implications for chromosomal models of speciation

Cited by 53 publications

References 16 publications

Study of a contact between two chromosomally monomorphic races of Sorex araneus L. (common shrew)

Study of a contact between two chromosomally monomorphic races of Sorex araneus L. (common shrew)

CHROMOSOMAL VERSUS MITOCHONDRIAL DNA EVOLUTION: TRACKING THE EVOLUTIONARY HISTORY OF THE SOUTHWESTERN EUROPEAN POPULATIONS OF THESOREX ARANEUSGROUP (MAMMALIA, INSECTIVORA)

Maximatization of the frequency of recombinants in the hybrid zones of Sorex araneus in northern Poland

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