Constraints and normalized measures for cytonuclear disequilibria

Asmussen, Marjorie A.; Basten, Christopher J.

doi:10.1038/hdy.1996.33

Cited by 44 publications

(26 citation statements)

References 14 publications

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“…To estimate within‐species cohesion over the whole genome, departure from random cytonuclear associations was tested per locus using the CNDM program (Basten & Asmussen 1997) after encoding genotypes using synthetic alleles. The normalized cytonuclear disequilibrium (CND) was calculated following Asmussen & Basten (1996) for genotype–chlorotype combinations and tested using Fisher’s exact test. Cytonuclear associations were tested separately in Q. suber , Q. ilex and the hybrids, as well as over all individuals in the same region.…”

Section: Methodsmentioning

confidence: 99%

Contrasting nuclear and cytoplasmic exchanges between phylogenetically distant oak species (Quercus suberL. andQ. ilexL.) in Southern France: inferring crosses and dynamics

et al. 2009

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Gene flow is particularly frequent in the genus Quercus (oaks), especially between closely related species. We focus here on Quercus ilex and the cork-producing Quercus suber, which occasionally hybridize although they are phylogenetically markedly separated. Morphological observations were combined with both allozymic and chloroplastic diagnostic markers to characterize hybridization and introgression and to infer their dynamics in two French regions (French Catalonia and Provence), which are separated by several hundred kilometres. Some hybrids were found in both regions, indicating recent hybridization events. As expected from previous studies, most hybrids resulted from female symbol Q. ilex x male symbol Q. suber crosses, but our data showed that the reciprocal cross is also possible. Partial independence between nuclear and chloroplastic introgression was observed in the two species. Nuclear introgression was limited in both species and both regions, with no preferred direction. In Provence, chloroplastic introgression was very rare in both species. Conversely, all Q. suber individuals from French Catalonia were introgressed by Q. ilex chlorotypes. This might be explained by introgression in the Iberian Peninsula antedating the first occurrence of the two species in French Catalonia. We also observed a new chlorotype that was created locally, and was exchanged between the two species. However, the two species still remain genetically differentiated. The dynamics and complexity of exchanges and the factors determining them (including human management of Q. suber) are discussed.

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Section: Methodsmentioning

confidence: 99%

Contrasting nuclear and cytoplasmic exchanges between phylogenetically distant oak species (Quercus suberL. andQ. ilexL.) in Southern France: inferring crosses and dynamics

et al. 2009

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“…Let 3sD/2 = ˙− ˙⑀ = ␥ Ј ⑀ . Since ͉D͉ Յ 1/4 according to Asmussen and Basten (1996), then ͉3sD/2͉ = ͉␥ Ј ⑀ ͉ Յ 3s/8, which limits arbitrary choice of the value ␥. An integral that is invariant during cline shift due to perturbation can be configured, I = ͐ +ϱ −ϱ g Ј ⑀ ␥dx.…”

Section: General Casementioning

confidence: 99%

Seed and pollen flow and cline discordance among genes with different modes of inheritance

2002

Heredity

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The relationships between seed and pollen flow and cline discordance/concordance between cytoplasmic and nuclear genes, with the incorporation of the effects of natural selection, are formulated for one locus with two alleles, under assumptions of random mating, no drift and no mutation. Results show that under certain conditions, the relative roles of seed and pollen flow in shaping cline discordance/ concordance are very similar to their roles in influencing population differentiation for selectively neutral markers with different modes of inheritance. Where the disequilibria

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“…Table 3 summarizes the cytonuclear disequilibrium estimates and statistical tests for their significance levels, first for the entire sample of lizards, and then for the four subsets taken from different parts of the zone. Also included are the normalized disequilibrium values (D'), which express each estimate as a proportion of the maximum possible disequilibrium of that sign for a population with the observed marginal frequencies (Asmussen & Basten 1995 Recall that A and B denote F5 and FM2 chromosomes, respectively, and that M is the F5 mtDNA haplotype.…”

Section: Distribution Of Chromosomal and Mitochondria1 Genotypes In Tmentioning

confidence: 99%

Cytonuclear genetic structure of a hybrid zone in lizards of the Sceloporus grammicus complex (Sauria, Phrynosomatidae)

Sites¹,

Basten²,

Asmussen³

1996

Mol Ecol

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Lizards of the Sceloporus grammicus complex are comprised of multiple chromosome races that form several zones of parapatric hybridization in central Mexico. We scored diagnostic mitochondrial DNA (mtDNA) haplotypes and autosomal chromosome markers in a sample of 342 lizards from one well-defined zone between 2n = 34 and 2n = 46 races. A two-part analysis was performed on this data set in an attempt to infer the predominant evolutionary forces shaping the cytonuclear structure of this zone. The complications posed by its spatial structure were addressed by analysing a hierarchical series of smaller subsamples chosen to approximate single mating units. Two critical conclusions were drawn from this first-stage analysis. First and foremost, the three chromosomes have largely concordant cytonuclear disequilibrium patterns within each subsample with adequate numbers of individuals for detecting nonrandom cytonuclear associations. This suggests that the cytonuclear structure of this zone is predominantly a result of deterministic genome-wide forces rather than genetic drift of deterministic forces specific to individual chromosomes or loci. Second, the fit of a series of migration models to the data shows that the cytonuclear structure of the subsamples is well accounted for by continued gene flow from the two parental races alone, with random mating with respect to cytonuclear genotype and no other evolutionary forces. These results motivate several further empirical and theoretical investigations to refine our understanding of the relative roles of migration and other potentially important forces such as natural selection and genetic drift, in this and other hybrid zones.

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Constraints and normalized measures for cytonuclear disequilibria

Cited by 44 publications

References 14 publications

Contrasting nuclear and cytoplasmic exchanges between phylogenetically distant oak species (Quercus suberL. andQ. ilexL.) in Southern France: inferring crosses and dynamics

Contrasting nuclear and cytoplasmic exchanges between phylogenetically distant oak species (Quercus suberL. andQ. ilexL.) in Southern France: inferring crosses and dynamics

Seed and pollen flow and cline discordance among genes with different modes of inheritance

Cytonuclear genetic structure of a hybrid zone in lizards of the Sceloporus grammicus complex (Sauria, Phrynosomatidae)

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