| 1. |
- Arnqvist, Göran, et al.
(författare)
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Genetic architecture of metabolic rate : environment specific epistasis between mitochondrial and nuclear genes in an insect
- 2010
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 64:12, s. 3354-3363
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Tidskriftsartikel (refereegranskat)abstract
- The extent to which mitochondrial DNA (mtDNA) variation is involved in adaptive evolutionary change is currently being reevaluated. In particular, emerging evidence suggests that mtDNA genes coevolve with the nuclear genes with which they interact to form the energy producing enzyme complexes in the mitochondria. This suggests that intergenomic epistasis between mitochondrial and nuclear genes may affect whole-organism metabolic phenotypes. Here, we use crossed combinations of mitochondrial and nuclear lineages of the seed beetle Callosobruchus maculatus and assay metabolic rate under two different temperature regimes. Metabolic rate was affected by an interaction between the mitochondrial and nuclear lineages and the temperature regime. Sequence data suggests that mitochondrial genetic variation has a role in determining the outcome of this interaction. Our genetic dissection of metabolic rate reveals a high level of complexity, encompassing genetic interactions over two genomes, and genotype x genotype x environment interactions. The evolutionary implications of these results are twofold. First, because metabolic rate is at the root of life histories, our results provide insights into the complexity of life-history evolution in general, and thermal adaptation in particular. Second, our results suggest a mechanism that could contribute to the maintenance of nonneutral mtDNA polymorphism.
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| 2. |
- Dowling, Damian K., et al.
(författare)
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Cytonuclear Interactions and the Economics of Mating in Seed Beetles
- 2010
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Ingår i: American Naturalist. - : University of Chicago Press. - 0003-0147 .- 1537-5323. ; 176:2, s. 131-140
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies have uncovered an abundance of non-neutral cytoplasmic genetic variation within species, which suggests that we should no longer consider the cytoplasm an idle intermediary of evolutionary change. Nonneutrality of cytoplasmic genomes is particularly intriguing, given that these genomes are maternally transmitted. This means that the fate of any given cytoplasmic genetic mutation is directly tied to its performance when expressed in females. For this reason, it has been hypothesized that cytoplasmic genes will coevolve via a sexually antagonistic arms race with the biparentally transmitted nuclear genes with which they interact. We assess this prediction, examining the intergenomic contributions to the costs and benefits of mating in Callosobruchus maculatus females subjected to a mating treatment with three classes (kept virgin, mated once, or forced to cohabit with a male). We find no evidence that the economics of mating are determined by interactions between cytoplasmic genes expressed in females and nuclear genes expressed in males and, therefore, no support for a sexually antagonistic intergenomic arms race. The cost of mating to females was, however, shaped by an interaction between the cytoplasmic and nuclear genes expressed within females. Thus, cytonuclear interactions are embroiled in the economics of mating.
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| 3. |
- Innocenti, Paolo, et al.
(författare)
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Experimental Evidence Supports a Sex-Specific Selective Sieve in Mitochondrial Genome Evolution
- 2011
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 332:6031, s. 845-848
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondria are maternally transmitted; hence, their genome can only make a direct and adaptive response to selection through females, whereas males represent an evolutionary dead end. In theory, this creates a sex-specific selective sieve, enabling deleterious mutations to accumulate in mitochondrial genomes if they exert male-specific effects. We tested this hypothesis, expressing five mitochondrial variants alongside a standard nuclear genome in Drosophila melanogaster, and found striking sexual asymmetry in patterns of nuclear gene expression. Mitochondrial polymorphism had few effects on nuclear gene expression in females but major effects in males, modifying nearly 10% of transcripts. These were mostly male-biased in expression, with enrichment hotspots in the testes and accessory glands. Our results suggest an evolutionary mechanism that results in mitochondrial genomes harboring male-specific mutation loads.
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