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Ritchot Y, Festa‐Bianchet M, Coltman D, Pelletier F. Determinants and long-term costs of early reproduction in males of a long-lived polygynous mammal. Ecol Evol 2021; 11:6829-6845. [PMID: 34141259 PMCID: PMC8207375 DOI: 10.1002/ece3.7530] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 03/17/2021] [Indexed: 01/17/2023] Open
Abstract
In long-lived polygynous species, male reproductive success is often monopolized by a few mature dominant individuals. Young males are generally too small to be dominant and may employ alternative tactics; however, little is known about the determinants of reproductive success for young males. Understanding the causes and consequences of variability in early reproductive success may be crucial to assess the strength of sexual selection and possible long-term trade-offs among life-history traits. Selective pressures driven by fluctuating environmental conditions may depend on age class. We evaluated the determinants of reproduction in male bighorn sheep (Ovis canadensis) aged 2-4 years using 30 years of individual-level data. These young males cannot defend estrous ewes and use alternative mating tactics. We also investigated how the age of first detected reproduction was correlated to lifetime reproductive success and longevity. We found that reproductive success of males aged 3 years was positively correlated to body mass, to the proportion of males aged 2-4 years in the competitor pool, and to the number of females available per adult male. These results suggest that reproductive success depends on both competitive ability and population age-sex structure. None of these variables, however, had significant effects on the reproductive success of males aged 2 or 4 years. Known reproduction before the age of five increased lifetime reproductive success but decreased longevity, suggesting a long-term survival cost of early reproduction. Our analyses reveal that both individual-level phenotypic and population-level demographic variables influence reproductive success by young males and provide a rare assessment of fitness trade-offs in wild polygynous males.
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Affiliation(s)
- Yanny Ritchot
- Département de biologieUniversité de SherbrookeSherbrookeQCCanada
| | | | - David Coltman
- Department of Biological SciencesUniversity of AlbertaEdmontonABCanada
| | - Fanie Pelletier
- Département de biologieUniversité de SherbrookeSherbrookeQCCanada
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Chain FJJ, Flynn JM, Bull JK, Cristescu ME. Accelerated rates of large-scale mutations in the presence of copper and nickel. Genome Res 2019; 29:64-73. [PMID: 30487211 PMCID: PMC6314161 DOI: 10.1101/gr.234724.118] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 11/22/2018] [Indexed: 12/13/2022]
Abstract
Mutation rate variation has been under intense investigation for decades. Despite these efforts, little is known about the extent to which environmental stressors accelerate mutation rates and influence the genetic load of populations. Moreover, most studies on stressors have focused on unicellular organisms and point mutations rather than large-scale deletions and duplications (copy number variations [CNVs]). We estimated mutation rates in Daphnia pulex exposed to low levels of environmental stressors as well as the effect of selection on de novo mutations. We conducted a mutation accumulation (MA) experiment in which selection was minimized, coupled with an experiment in which a population was propagated under competitive conditions in a benign environment. After an average of 103 generations of MA propagation, we sequenced 60 genomes and found significantly accelerated rates of deletions and duplications in MA lines exposed to ecologically relevant concentrations of metals. Whereas control lines had gene deletion and duplication rates comparable to other multicellular eukaryotes (1.8 × 10-6 per gene per generation), the presence of nickel and copper increased these rates fourfold. The realized mutation rate under selection was reduced to 0.4× that of control MA lines, providing evidence that CNVs contribute to mutational load. Our CNV breakpoint analysis revealed that nonhomologous recombination associated with regions of DNA fragility is the primary source of CNVs, plausibly linking metal-induced DNA strand breaks with higher CNV rates. Our findings suggest that environmental stress, in particular multiple stressors, can have profound effects on large-scale mutation rates and mutational load of multicellular organisms.
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Affiliation(s)
- Frédéric J J Chain
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Jullien M Flynn
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada
| | - James K Bull
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada
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Reimer KA, Stark MR, Aguilar LC, Stark SR, Burke RD, Moore J, Fahlman RP, Yip CK, Kuroiwa H, Oeffinger M, Rader SD. The sole LSm complex in Cyanidioschyzon merolae associates with pre-mRNA splicing and mRNA degradation factors. RNA 2017; 23:952-967. [PMID: 28325844 PMCID: PMC5435867 DOI: 10.1261/rna.058487.116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 03/15/2017] [Indexed: 05/22/2023]
Abstract
Proteins of the Sm and Sm-like (LSm) families, referred to collectively as (L)Sm proteins, are found in all three domains of life and are known to promote a variety of RNA processes such as base-pair formation, unwinding, RNA degradation, and RNA stabilization. In eukaryotes, (L)Sm proteins have been studied, inter alia, for their role in pre-mRNA splicing. In many organisms, the LSm proteins form two distinct complexes, one consisting of LSm1-7 that is involved in mRNA degradation in the cytoplasm, and the other consisting of LSm2-8 that binds spliceosomal U6 snRNA in the nucleus. We recently characterized the splicing proteins from the red alga Cyanidioschyzon merolae and found that it has only seven LSm proteins. The identities of CmLSm2-CmLSm7 were unambiguous, but the seventh protein was similar to LSm1 and LSm8. Here, we use in vitro binding measurements, microscopy, and affinity purification-mass spectrometry to demonstrate a canonical splicing function for the C. merolae LSm complex and experimentally validate our bioinformatic predictions of a reduced spliceosome in this organism. Copurification of Pat1 and its associated mRNA degradation proteins with the LSm proteins, along with evidence of a cytoplasmic fraction of CmLSm complexes, argues that this complex is involved in both splicing and cytoplasmic mRNA degradation. Intriguingly, the Pat1 complex also copurifies with all four snRNAs, suggesting the possibility of a spliceosome-associated pre-mRNA degradation complex in the nucleus.
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Affiliation(s)
- Kirsten A Reimer
- Department of Chemistry, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
| | - Martha R Stark
- Department of Chemistry, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
| | - Lisbeth-Carolina Aguilar
- Laboratory of RNP Biochemistry, Institut de Recherches Cliniques de Montréal (IRCM), Faculty of Medicine, McGill University, Montreal, QC H3A 0G4, Canada
| | - Sierra R Stark
- Department of Chemistry, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
| | - Robert D Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, V8W 3P6, Canada
| | - Jack Moore
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Richard P Fahlman
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
- Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Calvin K Yip
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Haruko Kuroiwa
- Kuroiwa Initiative Research Unit, College of Science, Rikkyo University, Toshima, Tokyo 171-8501, Japan
| | - Marlene Oeffinger
- Laboratory of RNP Biochemistry, Institut de Recherches Cliniques de Montréal (IRCM), Faculty of Medicine, McGill University, Montreal, QC H3A 0G4, Canada
- Département de Biochimie, Université de Montréal, Montréal, QC H2W 1R7, Canada
| | - Stephen D Rader
- Department of Chemistry, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
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