Scaling, Selection, and Evolutionary Dynamics of the Mitotic Spindle

Farhadifar, Reza; Baer, Charles F.; Valfort, Aurore; Andersen, Erik C.; Müller‐Reichert, Thomas; Delattre, Marie; Needleman, Daniel

doi:10.1016/j.cub.2014.12.060

Cited by 76 publications

(99 citation statements)

References 43 publications

(62 reference statements)

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“…Of the 19 traits, 9 changed in the same direction in both sets of lines and 10 changed in opposite directions, exactly as predicted if the direction of change was random. Moreover, these results are consistent with the traits being under some degree of stabilizing selection [perhaps collectively (Farhadifar et al 2015)], because deleterious mutations do not have consistently directional effects. For a trait with a consistent mutational bias, at equilibrium selection must exactly counteract the mutational bias.…”

Section: Evolution Of Trait Means In Ma Lines (Dm)supporting

confidence: 74%

“…1100). Embryo size has been previously inferred to be under long-term stabilizing selection (Farhadifar et al 2015) and the reduced t P is consistent with stronger selection on that trait than on the other traits. We have no intuition about why centrosome size is a high outlier.…”

mentioning

confidence: 53%

“…Significant correlations exist between at least some of these traits (Farhadifar et al 2015), so the possibility exists that the 19 traits are essentially only 1 or a few traits. To address that Figure 1 for descriptions of traits; Mean (G 0 ), mean trait value of the ancestral G 0 control; Mean (MA250), mean of the MA lines; DM, percentage of per-generation change in the trait mean.…”

Section: Multivariate Trait Architecturementioning

confidence: 99%

“…The details of maintenance, microscopy, and image processing of the first mitotic spindle in C. elegans embryos are reported in Farhadifar and Needleman (2014) and Farhadifar et al (2015). Briefly, all lines were cultured at 24°on nematode growth media and fed the OP50 strain of Escherichia coli.…”

Section: Mitotic Cell Division Phenotype Assaysmentioning

confidence: 99%

“…There are too few degrees of freedom to calculate the full set of quadratic selection gradients for these traits (Lande and Arnold 1983). However, a previous analysis of a subset of 6 of these traits (traits 1, 2, 3, 15, 17, and 19) revealed that stabilizing selection on embryo size (trait 15) of strength V S = VM/(VG) 2 is sufficient to explain the observed standing genetic covariance matrix G for those traits, with no need to invoke selection on the other traits (Farhadifar et al 2015). In that study, embryo size was chosen a priori as the likely target of stabilizing selection, for three reasons.…”

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confidence: 98%

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Mutation Is a Sufficient and Robust Predictor of Genetic Variation for Mitotic Spindle Traits in Caenorhabditis elegans

et al. 2016

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Different types of phenotypic traits consistently exhibit different levels of genetic variation in natural populations. There are two potential explanations: Either mutation produces genetic variation at different rates or natural selection removes or promotes genetic variation at different rates. Whether mutation or selection is of greater general importance is a longstanding unresolved question in evolutionary genetics. We report mutational variances (VM) for 19 traits related to the first mitotic cell division in Caenorhabditis elegans and compare them to the standing genetic variances (VG) for the same suite of traits in a worldwide collection C. elegans. Two robust conclusions emerge. First, the mutational process is highly repeatable: The correlation between VM in two independent sets of mutation accumulation lines is 0.9. Second, VM for a trait is a good predictor of VG for that trait: The correlation between VM and VG is 0.9. This result is predicted for a population at mutation-selection balance; it is not predicted if balancing selection plays a primary role in maintaining genetic variation.KEYWORDS mutation accumulation; mutational robustness; mutation-selection balance; mutational variance; persistence time T HE question "What are the factors that govern genetic variation in natural populations?" has been central to the field of evolutionary genetics ever since its inception (Dobzhansky 1937;Lewontin 1974Lewontin , 1997. Within a group of organisms, seemingly similar or related phenotypic traits can vary considerably, and consistently, in the extent of genetic variation in the trait. For example, in many organisms, resistance to acute heat stress is much less heritable and evolvable than resistance to acute cold stress (Hoffmann et al. 2013). If different traits in the same set of organisms have consistently different levels of genetic variation, there are two potential underlying evolutionary causes: mutation and/or selection. Traits may differ in the mutational target they present, i.e., the number and/or types of loci that potentially affect the trait, or in the rate at which those loci mutate. Traits may also differ in the average effect that mutations have on the trait; i.e., they may be differently robust to the effects of mutation. Alternatively, traits may be subject to differing strengths and/or kinds of selection.In quantitative genetics, a few empirical conclusions seem fairly certain. First, traits that are direct components of fitness-life history traits-are typically more genetically variable than other classes of traits (Houle 1992;Lynch et al. 1999). Second, when scaled relative to the trait mean, life history traits experience greater input of genetic variation from mutation than other classes of traits (Houle et al. 1996;Halligan and Keightley 2009). Third, life history traits appear to be under stronger purifying selection than other classes of traits (Houle et al. 1996;Lynch et al. 1999;McGuigan et al. 2015).A longstanding related, but unanswered, question is the relative...

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Section: Evolution Of Trait Means In Ma Lines (Dm)supporting

confidence: 74%

mentioning

confidence: 53%

Section: Multivariate Trait Architecturementioning

confidence: 99%

Section: Mitotic Cell Division Phenotype Assaysmentioning

confidence: 99%

mentioning

confidence: 98%

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Mutation Is a Sufficient and Robust Predictor of Genetic Variation for Mitotic Spindle Traits in Caenorhabditis elegans

et al. 2016

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Caenorhabditis evolution in the wild

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2015

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Recent research has filled many gaps about Caenorhabditis natural history, simultaneously exposing how much remains to be discovered. This awareness now provides means of connecting ecological and evolutionary theory with diverse biological patterns within and among species in terms of adaptation, sexual selection, breeding systems, speciation, and other phenomena. Moreover, the heralded laboratory tractability of C. elegans, and Caenorhabditis species generally, provides a powerful case study for experimental hypothesis testing about evolutionary and ecological processes to levels of detail unparalleled by most study systems. Here, I synthesize pertinent theory with what we know and suspect about Caenorhabditis natural history for salient features of biodiversity, phenotypes, population dynamics, and interactions within and between species. I identify topics of pressing concern to advance Caenorhabditis biology and to study general evolutionary processes, including the key opportunities to tackle problems in dispersal dynamics, competition, and the dimensionality of niche space.

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Molecular evolution across developmental time reveals rapid divergence in early embryogenesis

et al. 2019

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Ontogenetic development hinges on the changes in gene expression in time and space within an organism, suggesting that the demands of ontogenetic growth can impose or reveal predictable pattern in the molecular evolution of genes expressed dynamically across development. Here, we characterize coexpression modules of the Caenorhabditis elegans transcriptome, using a time series of 30 points from early embryo to adult. By capturing the functional form of expression profiles with quantitative metrics, we find fastest evolution in the distinctive set of genes with transcript abundance that declines through development from a peak in young embryos. These genes are highly enriched for oogenic function and transient early zygotic expression, are nonrandomly distributed in the genome, and correspond to a life stage especially prone to inviability in interspecies hybrids. These observations conflict with the “early conservation model” for the evolution of development, although expression‐weighted sequence divergence analysis provides some support for the “hourglass model.” Genes in coexpression modules that peak toward adulthood also evolve fast, being hyper‐enriched for roles in spermatogenesis, implicating a history of sexual selection and relaxation of selection on sperm as key factors driving rapid change to ontogenetically distinguishable coexpression modules of genes. We propose that these predictable trends of molecular evolution for dynamically expressed genes across ontogeny predispose particular life stages, early embryogenesis in particular, to hybrid dysfunction in the speciation process.

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Scaling, Selection, and Evolutionary Dynamics of the Mitotic Spindle

Cited by 76 publications

References 43 publications

Mutation Is a Sufficient and Robust Predictor of Genetic Variation for Mitotic Spindle Traits in Caenorhabditis elegans

Mutation Is a Sufficient and Robust Predictor of Genetic Variation for Mitotic Spindle Traits in Caenorhabditis elegans

Caenorhabditis evolution in the wild

Molecular evolution across developmental time reveals rapid divergence in early embryogenesis

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