Fertility in the male common shrews, Sorex araneus, from the extremely narrow hybrid zone between chromosome races

Jadwiszczak, Katarzyna A.; Banaszek, Agata

doi:10.1016/j.mambio.2006.02.004

Cited by 28 publications

(26 citation statements)

References 24 publications

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“…Indeed, F-statistics on multilocus microsatellite markers suggests that genetic differences between populations within races are higher than the differences between races [29]. Some studies have even found that fertility may be relatively high for some types of complex heterozygotes and that metapopulation dynamics can overwhelm the weak barrier effects of reduced hybrid fitness [15], [16], [30]. The lack of genetic differentiation between races contrasts with the high level of differentiation between sister species [31], [32].…”

Section: Introductionmentioning

confidence: 99%

Phenotypic Variation across Chromosomal Hybrid Zones of the Common Shrew (Sorex araneus) Indicates Reduced Gene Flow

et al. 2013

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Sorex araneus, the Common shrew, is a species with more than 70 karyotypic races, many of which form parapatric hybrid zones, making it a model for studying chromosomal speciation. Hybrids between races have reduced fitness, but microsatellite markers have demonstrated considerable gene flow between them, calling into question whether the chromosomal barriers actually do contribute to genetic divergence. We studied phenotypic clines across two hybrid zones with especially complex heterozygotes. Hybrids between the Novosibirsk and Tomsk races produce chains of nine and three chromosomes at meiosis, and hybrids between the Moscow and Seliger races produce chains of eleven. Our goal was to determine whether phenotypes show evidence of reduced gene flow at hybrid zones. We used maximum likelihood to fit tanh cline models to geometric shape data and found that phenotypic clines in skulls and mandibles across these zones had similar centers and widths as chromosomal clines. The amount of phenotypic differentiation across the zones is greater than expected if it were dissipating due to unrestricted gene flow given the amount of time since contact, but it is less than expected to have accumulated from drift during allopatric separation in glacial refugia. Only if heritability is very low, Ne very high, and the time spent in allopatry very short, will the differences we observe be large enough to match the expectation of drift. Our results therefore suggest that phenotypic differentiation has been lost through gene flow since post-glacial secondary contact, but not as quickly as would be expected if there was free gene flow across the hybrid zones. The chromosomal tension zones are confirmed to be partial barriers that prevent differentiated races from becoming phenotypically homogenous.

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Section: Introductionmentioning

confidence: 99%

Phenotypic Variation across Chromosomal Hybrid Zones of the Common Shrew (Sorex araneus) Indicates Reduced Gene Flow

et al. 2013

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“…Analysis of meiosis in hybrids of the Oxford/Aber deen [8], Drnholec/Bia owie a [19], and Novosi birsk/Tomsk [20] chromosomal races showed that the frequency of univalent formation in diakinesis, as well as the frequency of nondisjunction in metaphase I increased with the configuration complication in mei osis, from trivalents (CIII) and tetravalents (CIV) to multivalents CIX and CX. Disturbance of ring config urations in pachytene of meiosis are frequent in males with multivalents of the Hällefors and Upsala chromo somal races.…”

Section: Hybrid Adaptationmentioning

confidence: 99%

“…In the meiosis I of the hybrids, RIV, CIV, CV complex heterozygotes, in two hybrid zones of chromosome races in Poland, an increased level of germ cell death at different stages of meiosis, which did not affect male fertility, was observed [22]. The formation of uni valents and other synaptic aberrations was described in Drnholec/Bia owie a [19] and Novosibirsk/Tomsk [20] hybrids. However, in all cases of complex het erozygotes examined, non disturbed multivalent con figurations were similarly frequent.…”

Section: Hybrid Adaptationmentioning

confidence: 99%

“…For instance, in the meiosis I spreads of l z · l z · the hybrids between Drnholec and Bia owie a chro mosomal races 10 mer chains (CX) along with differ ent multivalent variants, from CIV to CX, were observed, which increased the probability of correct disjunction of the homologues [19]. It is noteworthy that male shrews with normally developed testes were found in all cases of complex heterozygote hybrids examined [14,[21][22][23].…”

Section: Hybrid Adaptationmentioning

confidence: 99%

“…The decrease of the hybrid proportion may be asso ciated with the increase of the number of univalents and nondisjunctions resulting from the increase of multivalent complexity in meiosis I of the hybrids [18][19][20]. However, in none of the cases a decrease of the F 1 hybrids fertility was observed.…”

Section: Hybrid Proportionmentioning

confidence: 99%

See 2 more Smart Citations

Narrow hybrid zone between Moscow and Western Dvina chromosomal races and specific features of population isolation in common shrew Sorex araneus (Mammalia)

et al. 2012

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The contact zone between Moscow and Western Dvina chromosomal races of common shrew Sorex araneus L. at the south of the Valdai Hights was traced over a distance of 20 km. Within this, close to parapatric, contact zone of chromosomal races the width of sympatry zone was about 500 m (the narrowest among currently known hybrid zones), and the proportion of hybrids was 24.3%. It was shown that in bimodal hybrid zones between chromosomal races of common shrew the width of sympatry zones varied from 0.5 to 13 km. This width does not correlate with the cytogenetic features of the hybrids, and seems to be determined by competitive relations between the races. The hybrid proportion is determined by the type of hybrid het erozygosity, and decreased in the race sympatry zone from 33-40 to 21.5-25.2%. The decrease of the hybrid proportion can be associated with the abnormal fertility of either the first generation, or the backcross hybrids.

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Natural male hybrid common shrews with a very long chromosomal multivalent at meiosis appear not to be completely sterile

Matveevsky,

Kolomiets,

Shchipanov

et al. 2023

J Exp Zool Pt B

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Among 36 known chromosomal hybrid zones of the common shrew Sorex araneus, the Moscow–Seliger hybrid zone is of special interest because inter‐racial complex heterozygotes (F1 hybrids) produce the longest meiotic configuration, consisting of 11 chromosomes with monobrachial homology (undecavalent or chain‐of‐eleven: CXI). Different studies suggest that such a multivalent may negatively affect meiotic progression and in general should significantly reduce fertility of hybrids. In this work, by immunocytochemical and electron microscopy methods, we investigated for the first time chromosome synapsis, recombination and meiotic silencing in pachytene spermatocytes of natural inter‐racial heterozygous shrew males carrying CXI configurations. Despite some abnormalities detected in spermatocytes, such as associations of chromosomes, stretched centromeres, and the absence of recombination nodules in some arms of the multivalent, a large number of morphologically normal spermatozoa were observed. Possible low stringency of pachytene checkpoints may mean that even very long meiotic configurations do not cause complete sterility of such complex inter‐racial heterozygotes.

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Fertility in the male common shrews, Sorex araneus, from the extremely narrow hybrid zone between chromosome races

Cited by 28 publications

References 24 publications

Phenotypic Variation across Chromosomal Hybrid Zones of the Common Shrew (Sorex araneus) Indicates Reduced Gene Flow

Phenotypic Variation across Chromosomal Hybrid Zones of the Common Shrew (Sorex araneus) Indicates Reduced Gene Flow

Narrow hybrid zone between Moscow and Western Dvina chromosomal races and specific features of population isolation in common shrew Sorex araneus (Mammalia)

Natural male hybrid common shrews with a very long chromosomal multivalent at meiosis appear not to be completely sterile

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