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Yoder AD, Tiley GP. The challenge and promise of estimating the de novo mutation rate from whole-genome comparisons among closely related individuals. Mol Ecol 2021; 30:6087-6100. [PMID: 34062029 DOI: 10.1111/mec.16007] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/22/2021] [Accepted: 05/26/2021] [Indexed: 12/20/2022]
Abstract
Germline mutations are the raw material for natural selection, driving species evolution and the generation of earth's biodiversity. Without this driver of genetic diversity, life on earth would stagnate. Yet, it is a double-edged sword. An excess of mutations can have devastating effects on fitness and population viability. It is therefore one of the great challenges of molecular ecology to determine the rate and mechanisms by which these mutations accrue across the tree of life. Advances in high-throughput sequencing technologies are providing new opportunities for characterizing the rates and mutational spectra within species and populations thus informing essential evolutionary parameters such as the timing of speciation events, the intricacies of historical demography, and the degree to which lineages are subject to the burdens of mutational load. Here, we will focus on both the challenge and promise of whole-genome comparisons among parents and their offspring from known pedigrees for the detection of germline mutations as they arise in a single generation. The potential of these studies is high, but the field is still in its infancy and much uncertainty remains. Namely, the technical challenges are daunting given that pedigree-based genome comparisons are essentially searching for needles in a haystack given the very low signal to noise ratio. Despite the challenges, we predict that rapidly developing methods for whole-genome comparisons hold great promise for integrating empirically derived estimates of de novo mutation rates and mutation spectra across many molecular ecological applications.
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Affiliation(s)
- Anne D Yoder
- Department of Biology, Duke University, Durham, NC, USA
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Phung TN, Wayne RK, Wilson MA, Lohmueller KE. Complex patterns of sex-biased demography in canines. Proc Biol Sci 2020; 286:20181976. [PMID: 31113325 DOI: 10.1098/rspb.2018.1976] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The demographic history of dogs is complex, involving multiple bottlenecks, admixture events and artificial selection. However, existing genetic studies have not explored variance in the number of reproducing males and females, and whether it has changed across evolutionary time. While male-biased mating practices, such as male-biased migration and multiple paternity, have been observed in wolves, recent breeding practices could have led to female-biased mating patterns in breed dogs. For example, breed dogs are thought to have experienced a popular sire effect, where a small number of males father many offspring with a large number of females. Here we use genetic variation data to test how widespread sex-biased mating practices in canines are during different evolutionary time points. Using whole-genome sequence data from 33 dogs and wolves, we show that patterns of diversity on the X chromosome and autosomes are consistent with a higher number of reproducing males than females over ancient evolutionary history in both dogs and wolves, suggesting that mating practices did not change during early dog domestication. By contrast, since breed formation, we found evidence for a larger number of reproducing females than males in breed dogs, consistent with the popular sire effect. Our results confirm that canine demography has been complex, with opposing sex-biased processes occurring throughout their history. The signatures observed in genetic data are consistent with documented sex-biased mating practices in both the wild and domesticated populations, suggesting that these mating practices are pervasive.
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Affiliation(s)
- Tanya N Phung
- 1 Interdepartmental Program in Bioinformatics, University of California , Los Angeles, CA 90095 , USA
| | - Robert K Wayne
- 2 Department of Ecology and Evolutionary Biology, University of California , Los Angeles, CA 90095 , USA
| | - Melissa A Wilson
- 4 School of Life Sciences and Center for Evolution and Medicine, The Biodesign Institute, Arizona State University , Tempe, AZ 85281 , USA
| | - Kirk E Lohmueller
- 1 Interdepartmental Program in Bioinformatics, University of California , Los Angeles, CA 90095 , USA.,2 Department of Ecology and Evolutionary Biology, University of California , Los Angeles, CA 90095 , USA.,3 Department of Human Genetics, David Geffen School of Medicine, University of California , Los Angeles, CA 90095 , USA
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Chen ZH, Zhang M, Lv FH, Ren X, Li WR, Liu MJ, Nam K, Bruford MW, Li MH. Contrasting Patterns of Genomic Diversity Reveal Accelerated Genetic Drift but Reduced Directional Selection on X-Chromosome in Wild and Domestic Sheep Species. Genome Biol Evol 2018; 10:1282-1297. [PMID: 29790980 PMCID: PMC5963296 DOI: 10.1093/gbe/evy085] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2018] [Indexed: 01/08/2023] Open
Abstract
Analyses of genomic diversity along the X chromosome and of its correlation with autosomal diversity can facilitate understanding of evolutionary forces in shaping sex-linked genomic architecture. Strong selective sweeps and accelerated genetic drift on the X-chromosome have been inferred in primates and other model species, but no such insight has yet been gained in domestic animals compared with their wild relatives. Here, we analyzed X-chromosome variability in a large ovine data set, including a BeadChip array for 943 ewes from the world’s sheep populations and 110 whole genomes of wild and domestic sheep. Analyzing whole-genome sequences, we observed a substantially reduced X-to-autosome diversity ratio (∼0.6) compared with the value expected under a neutral model (0.75). In particular, one large X-linked segment (43.05–79.25 Mb) was found to show extremely low diversity, most likely due to a high density of coding genes, featuring highly conserved regions. In general, we observed higher nucleotide diversity on the autosomes, but a flat diversity gradient in X-linked segments, as a function of increasing distance from the nearest genes, leading to a decreased X: autosome (X/A) diversity ratio and contrasting to the positive correlation detected in primates and other model animals. Our evidence suggests that accelerated genetic drift but reduced directional selection on X chromosome, as well as sex-biased demographic events, explain low X-chromosome diversity in sheep species. The distinct patterns of X-linked and X/A diversity we observed between Middle Eastern and non-Middle Eastern sheep populations can be explained by multiple migrations, selection, and admixture during the domestic sheep’s recent postdomestication demographic expansion, coupled with natural selection for adaptation to new environments. In addition, we identify important novel genes involved in abnormal behavioral phenotypes, metabolism, and immunity, under selection on the sheep X-chromosome.
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Affiliation(s)
- Ze-Hui Chen
- CAS Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing, China.,College of Life Sciences, University of the Academy of Sciences, Beijing 100049, China
| | - Min Zhang
- CAS Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Feng-Hua Lv
- CAS Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing, China
| | - Xue Ren
- CAS Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing, China
| | - Wen-Rong Li
- Animal Biotechnological Research Center, Xinjiang Academy of Animal Science, Urumqi, China
| | - Ming-Jun Liu
- Animal Biotechnological Research Center, Xinjiang Academy of Animal Science, Urumqi, China
| | - Kiwoong Nam
- Diversité, Génomes et Interactions Microorganismes Insectes, Institut National de la Recherche Agronomique, University of Montpellier, Montpellier, France
| | - Michael W Bruford
- Organisms and Environment Division, School of Biosciences and Sustainable Places Research Institute, Cardiff University, Wales, United Kingdom
| | - Meng-Hua Li
- CAS Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing, China
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