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Touzet P.,CNRS Evolution, Ecology, and Paleonthology Laboratory | Meyer E.H.,Max Planck Institute of Molecular Plant Physiology
Mitochondrion | Year: 2014

Cytoplasmic male sterility (CMS) is a common feature encountered in plant species. It is the result of a genomic conflict between the mitochondrial and the nuclear genomes. CMS is caused by mitochondrial encoded factors which can be counteracted by nuclear encoded factors restoring male fertility. Despite extensive work, the molecular mechanism of male sterility still remains unknown. Several studies have suggested the involvement of respiration on the disruption of pollen production through an energy deficiency. By comparing recent works on CMS and respiratory mutants, we suggest that the "ATP hypothesis" might not be as obvious as previously suggested. © 2014 Elsevier B.V. and Mitochondria Research Society. Source

Santure A.W.,University of Sheffield | De Cauwer I.,University of Sheffield | De Cauwer I.,CNRS Evolution, Ecology, and Paleonthology Laboratory | Robinson M.R.,University of Sheffield | And 3 more authors.
Molecular Ecology | Year: 2013

Clutch size and egg mass are life history traits that have been extensively studied in wild bird populations, as life history theory predicts a negative trade-off between them, either at the phenotypic or at the genetic level. Here, we analyse the genomic architecture of these heritable traits in a wild great tit (Parus major) population, using three marker-based approaches - chromosome partitioning, quantitative trait locus (QTL) mapping and a genome-wide association study (GWAS). The variance explained by each great tit chromosome scales with predicted chromosome size, no location in the genome contains genome-wide significant QTL, and no individual SNPs are associated with a large proportion of phenotypic variation, all of which may suggest that variation in both traits is due to many loci of small effect, located across the genome. There is no evidence that any regions of the genome contribute significantly to both traits, which combined with a small, nonsignificant negative genetic covariance between the traits, suggests the absence of genetic constraints on the independent evolution of these traits. Our findings support the hypothesis that variation in life history traits in natural populations is likely to be determined by many loci of small effect spread throughout the genome, which are subject to continued input of variation by mutation and migration, although we cannot exclude the possibility of an additional input of major effect genes influencing either trait. © 2013 John Wiley & Sons Ltd. Source

Touzet P.,CNRS Evolution, Ecology, and Paleonthology Laboratory
Advances in Botanical Research | Year: 2012

Gynodioecy is a breeding system frequently encountered in flowering plants. It consists of the co-occurrence of hermaphrodites and females in populations. Gynodioecy is generally under nuclear-cytoplasmic control, which involves mitochondrial sterilizing genes and nuclear genes that restore male fertility. Sterilizing mitochondrial genomes have been described in crops in which cytoplasmic male sterility (CMS) is cryptic, i.e. not maintained in populations of wild relative species. However, the isolation of sterilizing genes has led to the definition of a profile that can help to find candidate genes in CMSs found in gynodioecious species. We discuss the expected effect of two alternative evolutionary dynamics of gynodioecy on mitochondrial diversity and describe the pattern of diversity observed at the gene and genome levels. On the basis of whole sequence analyses of mitochondrial genomes in beet and maize, we suggest that CMS mitochondrial genomes might exhibit a faster evolution rate, and a clue to its cause might be found in male sterility itself. © 2012 Elsevier Ltd. Source

Cramer B.D.,University of Iowa | Vandenbroucke T.R.A.,CNRS Evolution, Ecology, and Paleonthology Laboratory | Vandenbroucke T.R.A.,Ghent University | Ludvigson G.A.,University of Kansas
Earth-Science Reviews | Year: 2015

The ability to resolve the stratigraphic record of Earth history is critical to understanding past global change events and the range of natural variability within the global paleoclimate. The geosphere-hydrosphere-atmosphere-biosphere system operates on geologically very short time scales and we must be able to resolve the stratigraphic record of past events on similar time scales if we are to understand the cause-and-effect relationships operating within the system. Global resolution ≤. 100. kyr is commonly available when evaluating events from the Cenozoic Era, but such resolution is less common for older portions of Earth history. The introduction of High-Resolution Event Stratigraphy (HiRES) more than two decades ago revolutionized the ability to resolve the Mesozoic and Cenozoic stratigraphic records of global change, and a similar revolution is currently underway for the Paleozoic as well. Here, we review the application of the principles of HiRES to the Paleozoic stratigraphic record with examples from the Silurian System, discuss the quantification of chronostratigraphic uncertainty, and highlight the current deep-time Earth history revolution that has the potential to open the entire Phanerozoic record to the evaluation of short time scale global climate dynamics. © 2014 Elsevier B.V. Source

Roux C.,CNRS Evolution, Ecology, and Paleonthology Laboratory | Pauwels M.,CNRS Evolution, Ecology, and Paleonthology Laboratory | Ruggiero M.-V.,Stazione Zoologica Anton Dohrn | Charlesworth D.,University of Edinburgh | And 2 more authors.
Molecular Biology and Evolution | Year: 2013

Balancing selection can maintain different alleles over long evolutionary times. Beyond this direct effect on the molecular targets of selection, balancing selection is also expected to increase neutral polymorphism in linked genome regions, in inverse proportion to their genetic map distances from the selected sites. The genes controlling plant self-incompatibility are subject to one of the strongest forms of balancing selection, and they show clear signatures of balancing selection. The genome region containing those genes (the S-locus) is generally described as nonrecombining, and the physical size of the region with low recombination has recently been established in a few species. However, the size of the region showing the indirect footprints of selection due to linkage to the S-locus is only roughly known. Here, we improved estimates of this region by surveying synonymous polymorphism and estimating recombination rates at 12 flanking region loci at known physical distances from the S-locus region boundary, in two closely related self-incompatible plants Arabidopsis halleri and A. lyrata. In addition to studying more loci than previous studies and using known physical distances, we simulated an explicit demographic scenario for the divergence between the two species, to evaluate the extent of the genomic region whose diversity departs significantly from neutral expectations. At the closest flanking loci, we detected signatures of both recent and ancient indirect effects of selection on the S-locus flanking genes, finding ancestral polymorphisms shared by both species, as well as an excess of derived mutations private to either species. However, these effects are detected only in a physically small region, suggesting that recombination in the flanking regions is sufficient to quickly break up linkage disequilibrium with the S-locus. Our approach may be useful for distinguishing cases of ancient versus recently evolved balancing selection in other systems. © The Author(s) 2012. Source

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