Chromosome evolution in Australian Rattus ? G-banding and hybrid meiosis

Baverstock, P. R.; Gelder, Marion E. Meijer–van; Jahnke, A.

doi:10.1007/bf00127495

Cited by 39 publications

(46 citation statements)

References 26 publications

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“…Although direct evidence is lacking in many instances, fertility of a simple heterozygote is theoretically reduced by 50 %, making tandem translocations one of the most deleterious chromosomal rearrangements from a reproductive standpoint (King, 1993). Despite this strong negative heterotic effect, this kind of rearrangement has been documented in numerous mammals, including Insectivora, Soricidae (Volobouev, 1989), Chiroptera, Phyllostomatidae (Baker and Bickham, 1980), Artiodactyla, Cervidae (e.g., Neitzel, 1987;Yang et al, 1997), Rodentia, Arvicolinae (Modi, 1987), Murinae (Baverstock et al, 1983), and Sigmodontinae (e.g., Sigmodon spp. : Elder and Hsu, 1988; Akodon spp.…”

Section: Discussionmentioning

confidence: 99%

Explosive chromosome evolution and speciation in the gerbil genus Taterillus (Rodentia, Gerbillinae): a case of two new cryptic species

Dobigny

Анискин

Volobouev

2002

Cytogenet Genome Res

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The five morphologically sibling gerbil species of the genus Taterillus in West Africa were first identified from karyotypes. These species possess an XX/XY₁Y₂ sex-chromosome system and are characterized by significant karyotypic reorganization, thus making them a suitable model for studying the role of chromosomal rearrangements in the speciation process. We present here a description of two new cytotypes, Taterillus sp. 1 and Taterillus sp. 2, from the Lake Chad area, the former having a 2n = 22/23, NFa = 40, and the latter 2n = 24/25, NFa = 44. Comparison of their G- and C- banding patterns with those of T. pygargus (2n = 22/23, NFa = 38/40), examined in an earlier paper, revealed that all three species differ from each other by 7 to 11 chromosomal rearrangements, comprising tandem translocations, pericentric inversions, and Robertsonian metacentrics displaying monobrachial homology. Meiotic configurations formed in potential hybrids among any of these three forms would consist of complex rings and chains, alone or in combination, resulting, as expected, in a significant disruption of gametogenesis. These results provide support for assigning Taterillus sp. 1 and Taterillus sp. 2 to two different biological species, which, as demonstrated by our preliminary molecular studies, would have emerged recently. Possible factors responsible for the rapid karyotypic evolution and speciation in this West African gerbil complex are discussed.

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Section: Discussionmentioning

confidence: 99%

Explosive chromosome evolution and speciation in the gerbil genus Taterillus (Rodentia, Gerbillinae): a case of two new cryptic species

Dobigny

Анискин

Volobouev

2002

Cytogenet Genome Res

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“…lb) (21,32,(36)(37)(38)(39)(40)(41) and the breadth of biological parameters (demography, litter size, longevity, etc.) (21,(36)(37)(38)(39)(40)(41) that are characteristic of these taxa imply that speciation by monobrachial centric fusions can be expected to be phylogenetically widespread within the class Mammalia.…”

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confidence: 99%

Speciation by monobrachial centric fusions

Baker

Bickham

1986

Proc. Natl. Acad. Sci. U.S.A.

253

210

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Fixation of centric fusions in natural populations often encounters minimal meiotic problems due to the ability of trivalents to segregate normally; therefore, little sterility barrier is achieved between a founder population and the parental stock. However, a strong sterility barrier can develop between different founder populations fixed for centric fusions that are monobrachially homologous in the resulting biarmed chromosomes (one arm is homologous but the other is nonhomologous). Hybridization through secondary contact then results in complex multivalents, which encounter problems in segregation and produce unbalanced gametes. Speciation mediated by centric fusions is a peripatric speciation model that does not postulate populational phenomena atypical of those characteristic of most mammals. The model appears applicable to a diversity of mammalian taxa such as bats of the Rhogeessa tumida-parvula complex, shrews of the Sorex araneus complex, and rodents of the Mus musculus and Rattus rattus complexes.The role of chromosomes in speciation has been controversial. On the one hand, there have been advocates of the view that a restructuring of the karyotype is a sine qua non of speciation, but this clearly was refuted by the demonstration of homosequential species (1). Yet the fact that so many closely related and obviously very similar species differ in their karyotype is rather strong evidence that at least in some and perhaps the majority of speciation events, a restructuring of the chromosomes is involved.Two primary areas of controversy are (i) the role of geography in chromosomal changes associated with speciation (2-11) and (ii) the dilemma of how any chromosomal mutation that causes sufficient loss of fitness in a heterozygote to be an effective isolating mechanism can become established in a population. The solution to this dilemma is addressed below in detail relative to the proposed model. Geographic aspects need to be established at this point as a foundation for the remainder of the model. Two major models of the geographic situation of chromosomally mediated speciation have been considered in the past (below we propose a third one). White (2) (3) and Key (11) have shown, the situations ascribed to the sympatric models do not conform to the postulated sequence of events observed in natural populations.The second geographic alternative postulates chromosomal speciation to occur only in small-sized founder populations in the course of a peripatric speciation event. The logic for such a conclusion comes from the fact that such models of chromosomal speciation rely on a measure of selection against the heterozygote as a direct indication ofthe effectiveness of a rearrangement in producing reproductive isolation. Thus, chromosomal rearrangements responsible for speciation infer a high level of sterility (negative heterosis) upon the heterozygote. A problem with such an assumption is that the probability of a rearrangement being established in a population is inversely related to its effectiven...

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“…(1983) and Koop et al (1984) used the largest 14 autosomal pairs shared with Peromyscus in a cladistic analysis of some muroid rodents. Many other studies used only chromosomal arms identified by G-banding in two or more of the taxa examined (e.g.. Baverstock et al, 1982Baverstock et al, . 1983Hood et al, 1984;Baker et al, 1987b).…”

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confidence: 99%

Problems in using Robertsonian rearrangements in determining monophyly: examples from the genera Tatera and Gerbillurus

Qumsiyeh¹,

Hamilton²,

Schlitter³

1987

Cytogenet Genome Res

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Chromosomal banding data on three species of Tatera from Kenya significantly alter the previous hypothesis of relationships between and within the genera Tatera and Gerbillurus based on cladistic analyses and the rule of parsimony (Qumsiyeh, 1986b). Of the many possible hypothetical relationships, the most parsimonious tree showed three homoplasies and allowed the genus Gerbillurus to be paraphyletic. The alternative trees, depicting larger number of homoplasies but with homoplasies restricted to fusion or fission events, were compatible with the morphological data in supporting the monophyly of Gerbillurus. To choose between the hypothesis based on the most parsimonious chromosomal tree and those supported by both morphology and slightly less parsimonious chromosomal trees, we performed an electrophoretic study on this group of gerbils. The conclusions are that the genus Gerbillurus is monophyletic and represents a branch that is closely related to the T. robusta group of Taterillini. The study documents that fissions and fusions must have occurred frequently and that in some cases the same fusions were acquired in two independent lineages in numbers exceeding those that are predicted by strict parsimony. The results raise questions about the validity of systematic conclusions based solely on fusion/fission data and utilizing the parsimony criterion.

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Chromosome evolution in Australian Rattus ? G-banding and hybrid meiosis

Cited by 39 publications

References 26 publications

Explosive chromosome evolution and speciation in the gerbil genus <i>Taterillus</i> (Rodentia, Gerbillinae): a case of two new cryptic species

Explosive chromosome evolution and speciation in the gerbil genus <i>Taterillus</i> (Rodentia, Gerbillinae): a case of two new cryptic species

Speciation by monobrachial centric fusions

Problems in using Robertsonian rearrangements in determining monophyly: examples from the genera <i>Tatera </i>and <i>Gerbilluru</i><i>s</i>

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