Latest recommendations
Id | Title * | Authors * | Abstract * | Picture * ▲ | Thematic fields * | Recommender | Reviewers | Submission date | |
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23 Apr 2020
![]() How do invasion syndromes evolve? An experimental evolution approach using the ladybird Harmonia axyridisJulien Foucaud, Ruth A. Hufbauer, Virginie Ravigné, Laure Olazcuaga, Anne Loiseau, Aurelien Ausset, Su Wang, Lian-Sheng Zang, Nicolas Lemenager, Ashraf Tayeh, Arthur Weyna, Pauline Gneux, Elise Bonnet, Vincent Dreuilhe, Bastien Poutout, Arnaud Estoup, Benoit Facon https://doi.org/10.1101/849968Selection on a single trait does not recapitulate the evolution of life-history traits seen during an invasionRecommended by Inês Fragata and Ben Phillips based on reviews by 2 anonymous reviewersBiological invasions are natural experiments, and often show that evolution can affect dynamics in important ways [1-3]. While we often think of invasions as a conservation problem stemming from anthropogenic introductions [4,5], biological invasions are much more commonplace than this, including phenomena as diverse as natural range shifts, the spread of novel pathogens, and the growth of tumors. A major question across all these settings is which set of traits determine the ability of a population to invade new space [6,7]. Traits such as: increased growth or reproductive rate, dispersal ability and ability to defend from predation often show large evolutionary shifts across invasion history [1,6,8]. Are such multi-trait shifts driven by selection on multiple traits, or a correlated response by multiple traits to selection on one? Resolving this question is important for both theoretical and practical reasons [9,10]. But despite the importance of this issue, it is not easy to perform the necessary manipulative experiments [9]. References [1] Sakai, A.K., Allendorf, F.W., Holt, J.S. et al. (2001). The population biology of invasive species. Annual review of ecology and systematics, 32(1), 305-332. doi: 10.1146/annurev.ecolsys.32.081501.114037 | How do invasion syndromes evolve? An experimental evolution approach using the ladybird Harmonia axyridis | Julien Foucaud, Ruth A. Hufbauer, Virginie Ravigné, Laure Olazcuaga, Anne Loiseau, Aurelien Ausset, Su Wang, Lian-Sheng Zang, Nicolas Lemenager, Ashraf Tayeh, Arthur Weyna, Pauline Gneux, Elise Bonnet, Vincent Dreuilhe, Bastien Poutout, Arnaud Est... | <p>Experiments comparing native to introduced populations or distinct introduced populations to each other show that phenotypic evolution is common and often involves a suit of interacting phenotypic traits. We define such sets of traits that evol... | ![]() | Adaptation, Evolutionary Applications, Experimental Evolution, Life History, Quantitative Genetics | Inês Fragata | 2019-11-29 07:07:00 | View | |
13 Sep 2019
![]() Deceptive combined effects of short allele dominance and stuttering: an example with Ixodes scapularis, the main vector of Lyme disease in the U.S.A.Thierry De Meeûs, Cynthia T. Chan, John M. Ludwig, Jean I. Tsao, Jaymin Patel, Jigar Bhagatwala, and Lorenza Beati https://doi.org/10.1101/622373New curation method for microsatellite markers improves population genetics analysesRecommended by Aurelien TellierGenetic markers are used for in modern population genetics/genomics to uncover the past neutral and selective history of population and species. Besides Single Nucleotide Polymorphisms (SNPs) obtained from whole genome data, microsatellites (or Short Tandem Repeats, SSR) have been common markers of choice in numerous population genetics studies of non-model species with large sample sizes [1]. Microsatellites can be used to uncover and draw inference of the past population demography (e.g. expansion, decline, bottlenecks…), population split, population structure and gene flow, but also life history traits and modes of reproduction (e.g. [2,3]). These markers are widely used in conservation genetics [4] or to study parasites or disease vectors [5]. Microsatellites do show higher mutation rate than SNPs increasing, on the one hand, the statistical power to infer recent events (for example crop domestication, [2,3]), while, on the other hand, decreasing their statistical power over longer time scales due to homoplasy [6]. References [1] Jarne, P., and Lagoda, P. J. (1996). Microsatellites, from molecules to populations and back. Trends in ecology & evolution, 11(10), 424-429. doi: 10.1016/0169-5347(96)10049-5 | Deceptive combined effects of short allele dominance and stuttering: an example with Ixodes scapularis, the main vector of Lyme disease in the U.S.A. | Thierry De Meeûs, Cynthia T. Chan, John M. Ludwig, Jean I. Tsao, Jaymin Patel, Jigar Bhagatwala, and Lorenza Beati | <p>Null alleles, short allele dominance (SAD), and stuttering increase the perceived relative inbreeding of individuals and subpopulations as measured by Wright’s FIS and FST. Ascertainment bias, due to such amplifying problems are usually caused ... | ![]() | Evolutionary Ecology, Other, Population Genetics / Genomics | Aurelien Tellier | 2019-05-02 20:52:08 | View | |
06 Oct 2017
![]() Evolutionary analysis of candidate non-coding elements regulating neurodevelopmental genes in vertebratesFrancisco J. Novo https://doi.org/10.1101/150482Combining molecular information on chromatin organisation with eQTLs and evolutionary conservation provides strong candidates for the evolution of gene regulation in mammalian brainsRecommended by Marc Robinson-Rechavi based on reviews by Marc Robinson-Rechavi and Charles DankoIn this manuscript [1], Francisco J. Novo proposes candidate non-coding genomic elements regulating neurodevelopmental genes. What is very nice about this study is the way in which public molecular data, including physical interaction data, is used to leverage recent advances in our understanding to molecular mechanisms of gene regulation in an evolutionary context. More specifically, evolutionarily conserved non coding sequences are combined with enhancers from the FANTOM5 project, DNAse hypersensitive sites, chromatin segmentation, ChIP-seq of transcription factors and of p300, gene expression and eQTLs from GTEx, and physical interactions from several Hi-C datasets. The candidate regulatory regions thus identified are linked to candidate regulated genes, and the author shows their potential implication in brain development. While the results are focused on a small number of genes, this allows to verify features of these candidates in great detail. This study shows how functional genomics is increasingly allowing us to fulfill the promises of Evo-Devo: understanding the molecular mechanisms of conservation and differences in morphology. References [1] Novo, FJ. 2017. Evolutionary analysis of candidate non-coding elements regulating neurodevelopmental genes in vertebrates. bioRxiv, 150482, ver. 4 of Sept 29th, 2017. doi: 10.1101/150482 | Evolutionary analysis of candidate non-coding elements regulating neurodevelopmental genes in vertebrates | Francisco J. Novo | <p>Many non-coding regulatory elements conserved in vertebrates regulate the expression of genes involved in development and play an important role in the evolution of morphology through the rewiring of developmental gene networks. Available biolo... | ![]() | Genome Evolution | Marc Robinson-Rechavi | Marc Robinson-Rechavi, Charles Danko | 2017-06-29 08:55:41 | View |
06 Feb 2024
![]() Can mechanistic constraints on recombination reestablishment explain the long-term maintenance of degenerate sex chromosomes?Thomas Lenormand, Denis Roze https://doi.org/10.1101/2023.02.17.528909New modelling results help understanding the evolution and maintenance of recombination suppression involving sex chromosomesRecommended by Jos Käfer based on reviews by 3 anonymous reviewersDespite advances in genomic research, many views of genome evolution are still based on what we know from a handful of species, such as humans. This also applies to our knowledge of sex chromosomes. We've apparently been too much used to the situation in which a highly degenerate Y chromosome coexists with an almost normal X chromosome to be able to fully grasp all the questions implied by this situation. Lately, many more sex chromosomes have been studied in other organisms, such as in plants, and the view is changing radically: there is a large diversity of situations, ranging from young highly divergent sex chromosomes to old ones that are so similar that they're hard to detect. Undoubtedly inspired by these recent findings, a few theoretical studies have been published around 2 years ago that put an entirely new light on the evolution of sex chromosomes. The differences between these models have however remained somewhat difficult to appreciate by non-specialists. In particular, the models by Lenormand & Roze (2022) and by Jay et al. (2022) seemed quite similar. Indeed, both rely on the same mechanism for initial recombination suppression: a ``lucky'' inversion, i.e. one with less deleterious mutations than the population average, encompassing the sex-determination locus, is initially selected. However, as it doesn't recombine, it will quickly accumulate deleterious mutations lowering its fitness. And it's at this point the models diverge: according to Lenormand & Roze (2022), nascent dosage compensation not only limits the deleterious effects on fitness by the ongoing degeneration, but it actually opposes recombination restoration as this would lead gene expression away from the optimum that has been reached. On the other hand, in the model by Jay et al. (2022), no additional ingredient is required: they argue that once an inversion had been fixed, reversions that restore recombination are extremely unlikely. This is what Lenormand & Roze (2024) now call a ``constraint'': in Jay et al.'s model, recombination restoration is impossible for mechanistic reasons. Lenormand & Roze (2024) argue such constraints cannot explain long-term recombination suppression. Instead, a mechanism should evolve to limit the negative fitness effects of recombination arrest, otherwise recombination is either restored, or the population goes extinct due to a dramatic drop in the fitness of the heterogametic sex. These two arguments work together: given the huge fitness cost of the lack of ongoing degeneration of the non-recombining Y, in the absence of compensatory mechanisms, there is a very strong selection for the restoration of recombination, so that even when restoration a priori is orders of magnitude less likely than inversion (leading to recombination suppression), it will eventually happen. One way the negative fitness effects of recombination suppression can be limited, is the way the authors propose in their own model: dosage compensation evolves through regulatory evolution right at the start of recombination suppression. This changes our classical, simplistic view that dosage compensation evolves in response to degeneration: rather, Lenormand & Roze (2024) argue, that degeneration can only happen when dosage compensation is effective. The reasoning is convincing and exposes the difference between the models to readers without a firm background in mathematical modelling. Although Lenormand & Roze (2024) target the "constraint theory", it seems likely that other theories for the maintenance of recombination suppression that don't imply the compensation of early degeneration are subject to the same criticism. Indeed, they mention the widely-cited "sexual antagonism" theory, in which mutations with a positive effect in males but a negative in females will select for recombination suppression that will link them to the sex-determining gene on the Y. However, once degeneration starts, the sexually-antagonistic benefits should be huge to overcome the negative effects of degeneration, and it's unlikely they'll be large enough. A convincing argument by Lenormand & Roze (2024) is that there are many ways recombination could be restored, allowing to circumvent the possible constraints that might be associated with reverting an inversion. First, reversions don't have to be exact to restore recombination. Second, the sex-determining locus can be transposed to another chromosome pair, or an entirely new sex-determining locus might evolve, leading to sex-chromosome turnover which has effectively been observed in several groups. These modelling studies raise important questions that need to be addressed with both theoretical and empirical work. First, is the regulatory hypothesis proposed by Lenormand & Roze (2022) the only plausible mechanism for the maintenance of long-term recombination suppression? The female- and male-specific trans regulators of gene expression that are required for this model, are they readily available or do they need to evolve first? Both theoretical work and empirical studies of nascent sex chromosomes will help to answer these questions. However, nascent sex chromosomes are difficult to detect and dosage compensation is difficult to reveal. Second, how many species today actually have "stable" recombination suppression? Maybe many species are in a transient phase, with different populations having different inversions that are either on their way to being fixed or starting to get counterselected. The models have now shown us some possibilities qualitatively but can they actually be quantified to be able to fit the data and to predict whether an observed case of recombination suppression is transient or stable? The debate will continue, and we need the active contribution of theoretical biologists to help clarify the underlying hypotheses of the proposed mechanisms. Conflict of interest statement: I did co-author a manuscript with D. Roze in 2023, but do not consider this a conflict of interest. The manuscript is the product of discussions that have taken place in a large consortium mainly in 2019. It furthermore deals with an entirely different topic of evolutionary biology. References Jay P, Tezenas E, Véber A, and Giraud T. (2022) Sheltering of deleterious mutations explains the stepwise extension of recombination suppression on sex chromosomes and other supergenes. PLoS Biol.;20:e3001698. https://doi.org/10.1371/journal.pbio.3001698 | Can mechanistic constraints on recombination reestablishment explain the long-term maintenance of degenerate sex chromosomes? | Thomas Lenormand, Denis Roze | <p style="text-align: justify;">Y and W chromosomes often stop recombining and degenerate. Most work on recombination suppression has focused on the mechanisms favoring recombination arrest in the short term. Yet, the long-term maintenance of reco... | ![]() | Evolutionary Theory, Genome Evolution, Population Genetics / Genomics, Reproduction and Sex | Jos Käfer | 2023-10-27 21:52:06 | View | |
20 Jan 2020
![]() A young age of subspecific divergence in the desert locust Schistocerca gregaria, inferred by ABC Random ForestMarie-Pierre Chapuis, Louis Raynal, Christophe Plantamp, Christine N. Meynard, Laurence Blondin, Jean-Michel Marin, Arnaud Estoup https://doi.org/10.1101/671867Estimating recent divergence history: making the most of microsatellite data and Approximate Bayesian Computation approachesRecommended by Takeshi Kawakami and Concetta Burgarella based on reviews by Michael D Greenfield and 2 anonymous reviewersThe present-day distribution of extant species is the result of the interplay between their past population demography (e.g., expansion, contraction, isolation, and migration) and adaptation to the environment. Shedding light on the timing and magnitude of key demographic events helps identify potential drivers of such events and interaction of those drivers, such as life history traits and past episodes of environmental shifts. The understanding of the key factors driving species evolution gives important insights into how the species may respond to changing conditions, which can be particularly relevant for the management of harmful species, such as agricultural pests (e.g. [1]). Meaningful demographic inferences present major challenges. These include formulating evolutionary scenarios fitting species biology and the eco-geographical context and choosing informative molecular markers and accurate quantitative approaches to statistically compare multiple demographic scenarios and estimate the parameters of interest. A further issue comes with result interpretation. Accurately dating the inferred events is far from straightforward since reliable calibration points are necessary to translate the molecular estimates of the evolutionary time into absolute time units (i.e. years). This can be attempted in different ways, such as by using fossil and archaeological records, heterochronous samples (e.g. ancient DNA), and/or mutation rate estimated from independent data (e.g. [2], [3] for review). Nonetheless, most experimental systems rarely meet these conditions, hindering the comprehensive interpretation of results. The contribution of Chapuis et al. [4] addresses these issues to investigate the recent history of the African insect pest Schistocerca gregaria (desert locust). They apply Approximate Bayesian Computation-Random Forest (ABC-RF) approaches to microsatellite markers. Owing to their fast mutation rate microsatellite markers offer at least two advantages: i) suitability for analyzing recently diverged populations, and ii) direct estimate of the germline mutation rate in pedigree samples. The work of Chapuis et al. [4] benefits of both these advantages, since they have estimates of mutation rate and allele size constraints derived from germline mutations in the species [5]. The main aim of the study is to infer the history of divergence of the two subspecies of the desert locust, which have spatially disjoint distribution corresponding to the dry regions of North and West-South Africa. They first use paleo-vegetation maps to formulate hypotheses about changes in species range since the last glacial maximum. Based on them, they generate 12 divergence models. For the selection of the demographic model and parameter estimation, they apply the recently developed ABC-RF approach, a powerful inferential tool that allows optimizing the use of summary statistics information content, among other advantages [6]. Some methodological novelties are also introduced in this work, such as the computation of the error associated with the posterior parameter estimates under the best scenario. The accuracy of timing estimate is assured in two ways: i) by the use of microsatellite markers with known evolutionary dynamics, as underlined above, and ii) by assessing the divergence time threshold above which posterior estimates are likely to be biased by size homoplasy and limits in allele size range [7]. The best-supported model suggests a recent divergence event of the subspecies of S. gregaria (around 2.6 kya) and a reduction of populations size in one of the subspecies (S. g. flaviventris) that colonized the southern distribution area. As such, results did not support the hypothesis that the southward colonization was driven by the expansion of African dry environments associated with the last glacial maximum, as it has been postulated for other arid-adapted species with similar African disjoint distributions [8]. The estimated time of divergence points at a much more recent origin for the two subspecies, during the late Holocene, in a period corresponding to fairly stable arid conditions similar to current ones [9,10]. Although the authors cannot exclude that their microsatellite data bear limited information on older colonization events than the last one, they bring arguments in favour of alternative explanations. The hypothesis privileged does not involve climatic drivers, but the particularly efficient dispersal behaviour of the species, whose individuals are able to fly over long distances (up to thousands of kilometers) under favourable windy conditions. A single long-distance dispersal event by a few individuals would explain the genetic signature of the bottleneck. There is a growing number of studies in phylogeography in arid regions in the Southern hemisphere, but the impact of past climate changes on the species distribution in this region remains understudied relative to the Northern hemisphere [11,12]. The study presented by Chapuis et al. [4] offers several important insights into demographic changes and the evolutionary history of an agriculturally important pest species in Africa, which could also mirror the history of other organisms in the continent. As the authors point out, there are necessarily some uncertainties associated with the models of past ecosystems and climate, especially for Africa. Interestingly, the authors argue that the information on paleo-vegetation turnover was more informative than climatic niche modeling for the purpose of their study since it made them consider a wider range of bio-geographical changes and in turn a wider range of evolutionary scenarios (see discussion in Supplementary Material). Microsatellite markers have been offering a useful tool in population genetics and phylogeography for decades, but their popularity is perhaps being taken over by single nucleotide polymorphism (SNP) genotyping and whole-genome sequencing (WGS) (the peak year of the number of the publication with “microsatellite” is in 2012 according to PubMed). This study reaffirms the usefulness of these classic molecular markers to estimate past demographic events, especially when species- and locus-specific microsatellite mutation features are available and a powerful inferential approach is adopted. Nonetheless, there are still hurdles to overcome, such as the limitations in scenario choice associated with the simulation software used (e.g. not allowing for continuous gene flow in this particular case), which calls for further improvement of simulation tools allowing for more flexible modeling of demographic events and mutation patterns. In sum, this work not only contributes to our understanding of the makeup of the African biodiversity but also offers a useful statistical framework, which can be applied to a wide array of species and molecular markers (microsatellites, SNPs, and WGS). References [1] Lehmann, P. et al. (2018). Complex responses of global insect pests to climate change. bioRxiv, 425488. doi: https://dx.doi.org/10.1101/425488 [2] Donoghue, P. C., & Benton, M. J. (2007). Rocks and clocks: calibrating the Tree of Life using fossils and molecules. Trends in Ecology & Evolution, 22(8), 424-431. doi: https://dx.doi.org/10.1016/j.tree.2007.05.005 [3] Ho, S. Y., Lanfear, R., Bromham, L., Phillips, M. J., Soubrier, J., Rodrigo, A. G., & Cooper, A. (2011). Time‐dependent rates of molecular evolution. Molecular ecology, 20(15), 3087-3101. doi: https://dx.doi.org/10.1111/j.1365-294X.2011.05178.x [4] Chapuis, M.-P., Raynal, L., Plantamp, C., Meynard, C. N., Blondin, L., Marin, J.-M. and Estoup, A. (2020). A young age of subspecific divergence in the desert locust Schistocerca gregaria, inferred by ABC Random Forest. bioRxiv, 671867, ver. 4 peer-reviewed and recommended by PCI Evolutionary Biology. doi: https://dx.doi.org/10.1101/671867 5] Chapuis, M.-P., Plantamp, C., Streiff, R., Blondin, L., & Piou, C. (2015). Microsatellite evolutionary rate and pattern in Schistocerca gregaria inferred from direct observation of germline mutations. Molecular ecology, 24(24), 6107-6119. doi: https://dx.doi.org/10.1111/mec.13465 [6] Raynal, L., Marin, J. M., Pudlo, P., Ribatet, M., Robert, C. P., & Estoup, A. (2018). ABC random forests for Bayesian parameter inference. Bioinformatics, 35(10), 1720-1728. doi: https://dx.doi.org/10.1093/bioinformatics/bty867 [7] Estoup, A., Jarne, P., & Cornuet, J. M. (2002). Homoplasy and mutation model at microsatellite loci and their consequences for population genetics analysis. Molecular ecology, 11(9), 1591-1604. doi: https://dx.doi.org/10.1046/j.1365-294X.2002.01576.x [8] Moodley, Y. et al. (2018). Contrasting evolutionary history, anthropogenic declines and genetic contact in the northern and southern white rhinoceros (Ceratotherium simum). Proceedings of the Royal Society B, 285(1890), 20181567. doi: https://dx.doi.org/10.1098/rspb.2018.1567 [9] Kröpelin, S. et al. (2008). Climate-driven ecosystem succession in the Sahara: the past 6000 years. science, 320(5877), 765-768. doi: https://dx.doi.org/10.1126/science.1154913 [10] Maley, J. et al. (2018). Late Holocene forest contraction and fragmentation in central Africa. Quaternary Research, 89(1), 43-59. doi: https://dx.doi.org/10.1017/qua.2017.97 [11] Beheregaray, L. B. (2008). Twenty years of phylogeography: the state of the field and the challenges for the Southern Hemisphere. Molecular Ecology, 17(17), 3754-3774. doi: https://dx.doi.org/10.1111/j.1365-294X.2008.03857.x [12] Dubey, S., & Shine, R. (2012). Are reptile and amphibian species younger in the Northern Hemisphere than in the Southern Hemisphere?. Journal of evolutionary biology, 25(1), 220-226. doi: https://dx.doi.org/10.1111/j.1420-9101.2011.02417.x ***** A video about this preprint is available here: | A young age of subspecific divergence in the desert locust Schistocerca gregaria, inferred by ABC Random Forest | Marie-Pierre Chapuis, Louis Raynal, Christophe Plantamp, Christine N. Meynard, Laurence Blondin, Jean-Michel Marin, Arnaud Estoup | <p>Dating population divergence within species from molecular data and relating such dating to climatic and biogeographic changes is not trivial. Yet it can help formulating evolutionary hypotheses regarding local adaptation and future responses t... | ![]() | Bioinformatics & Computational Biology, Evolutionary Applications, Phylogeography & Biogeography, Population Genetics / Genomics | Takeshi Kawakami | 2019-06-20 10:31:15 | View | |
18 Nov 2020
![]() A demogenetic agent based model for the evolution of traits and genome architecture under sexual selectionLouise Chevalier, François de Coligny, Jacques Labonne https://doi.org/10.1101/2020.04.01.014514Sexual selection goes dynamicRecommended by Michael D Greenfield based on reviews by Frédéric Guillaume and 1 anonymous reviewer150 years after Darwin published ‘Descent of man and selection in relation to sex’ (Darwin, 1871), the evolutionary mechanism that he laid out in his treatise continues to fascinate us. Sexual selection is responsible for some of the most spectacular traits among animals, and plants, and it appeals to our interest in all things reproductive and sexual (Bell, 1982). In addition, sexual selection poses some of the more intractable problems in evolutionary biology: Its realm encompasses traits that are subject to markedly different selection pressures, particularly when distinct, yet associated, traits tend to be associated with males, e.g. courtship signals, and with females, e.g. preferences (cf. Ah-King & Ahnesjo, 2013). While separate, such traits cannot evolve independently of each other (Arnqvist & Rowe, 2005), and complex feedback loops and correlations between them are predicted (Greenfield et al., 2014). Traditionally, sexual selection has been modelled under simplifying assumptions, and quantitative genetic approaches that avoided evolutionary dynamics have prevailed. New computing methods may be able to free the field from these constraints, and a trio of theoreticians (Chevalier, De Coligny & Labonne 2020) describe here a novel application of a ‘demo-genetic agent (or individual) based model’, a mouthful hereafter termed DG-ABM, for arriving at a holistic picture of the sexual selection trajectory. The application is built on the premise that traits, e.g. courtship, preference, gamete investment, competitiveness for mates, can influence the genetic architecture, e.g. correlations, of those traits. In turn, the genetic architecture can influence the expression and evolvability of the traits. Much of this influence occurs via demographic features, i.e. social environment, generated by behavioral interactions during sexual advertisement, courtship, mate guarding, parental care, post-mating dispersal, etc. References Ah-King, M. and Ahnesjo, I. 2013. The ‘sex role’ concept: An overview and evaluation Evolutionary Biology, 40, 461-470. doi: https://doi.org/10.1007/s11692-013-9226-7 | A demogenetic agent based model for the evolution of traits and genome architecture under sexual selection | Louise Chevalier, François de Coligny, Jacques Labonne | <p>Sexual selection has long been known to favor the evolution of mating behaviors such as mate preference and competitiveness, and to affect their genetic architecture, for instance by favoring genetic correlation between some traits. Reciprocall... | ![]() | Adaptation, Behavior & Social Evolution, Evolutionary Dynamics, Evolutionary Theory, Life History, Population Genetics / Genomics, Sexual Selection | Michael D Greenfield | 2020-04-02 14:44:25 | View | |
16 Mar 2017
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Correlated paternity measures mate monopolization and scales with the magnitude of sexual selectionDorken, ME and Perry LE https://doi.org/10.1111/jeb.13013Measurement of sexual selection in plants made easierRecommended by Emmanuelle Porcher and Mathilde DufaySexual selection occurs in flowering plants too. However it tends to be understudied in comparison to animal sexual selection, in part because the minuscule size and long dispersal distances of the individuals producing male gametes (pollen grains) seriously complicate the estimation of male siring success and thereby the measurement of sexual selection. Dorken and Perry [1] introduce a novel and clever approach to estimate sexual selection in plants, which bypasses the need for a direct quantification of absolute male mating success. This approach builds on the fact that the strength of sexual selection is directly related to the ability of individuals to monopolize mates [2]. In plants, mate monopolization can be assessed by examining the proportion of seeds produced by a given plant that are full-sibs, i.e. that share the same father. A nice feature of this proportion of full-sib seeds per maternal parent is it equals the coefficient of correlated paternity of Ritland [3], which can be readily obtained from the hundreds of plant mating system studies using genetic markers. A less desirable feature of the proportion of full sibs per maternal plant is that it is inversely related to population size, an effect that should be corrected for. The resulting index of mate monopolization is a simple product: (coefficient of correlated paternity)x(population size – 1). The authors test whether their index of mate monopolization is a good correlate of sexual selection, measured more traditionally as the selection differential on a trait influencing mating success, using a combination of theoretical and experimental approaches. Both approaches confirm that the two quantities are positively correlated, which suggests that the index of mate monopolization could be a convenient way to estimate the relative strength of sexual selection in flowering plants. These results call for further investigation, e.g. to verify that the effect of population size is well controlled for, or to assess the effects of non-random mating and inbreeding depression; however, this work paves the way for an expansion of sexual selection studies in flowering plants. References [1] Dorken ME and Perry LE. 2017. Correlated paternity measures mate monopolization and scales with the magnitude of sexual selection. Journal of Evolutionary Biology 30: 377-387 doi: 10.1111/jeb.13013 [2] Klug H, Heuschele J, Jennions M and Kokko H. 2010. The mismeasurement of sexual selection. Journal of Evolutionary Biology 23:447-462. doi: 10.1111/j.1420-9101.2009.01921.x [3] Ritland K. 1989. Correlated matings in the partial selfer Mimulus guttatus. Evolution 43:848-859. doi: 10.2307/2409312 | Correlated paternity measures mate monopolization and scales with the magnitude of sexual selection | Dorken, ME and Perry LE | <p>Indirect measures of sexual selection have been criticized because they can overestimate the magnitude of selection. In particular, they do not account for the degree to which mating opportunities can be monopolized by individuals of the sex th... | ![]() | Sexual Selection | Emmanuelle Porcher | 2017-03-13 23:22:26 | View | |
01 Sep 2021
Connectivity and selfing drives population genetic structure in a patchy landscape: a comparative approach of four co-occurring freshwater snail speciesJarne P., Lozano del Campo A., Lamy T., Chapuis E., Dubart M., Segard A., Canard E., Pointier J.-P., David P. https://hal.archives-ouvertes.fr/hal-03295242Determinants of population genetic structure in co-occurring freshwater snailsRecommended by Trine BildeGenetic diversity is a key aspect of biodiversity and has important implications for evolutionary potential and thereby the persistence of species. Improving our understanding of the factors that drive genetic structure within and between populations is, therefore, a long-standing goal in evolutionary biology. However, this is a major challenge, because of the complex interplay between genetic drift, migration, and extinction/colonization dynamics on the one hand, and the biology and ecology of species on the other hand (Romiguier et al. 2014, Ellegren and Galtier 2016, Charlesworth 2003). Jarne et al. (2021) studied whether environmental and demographic factors affect the population genetic structure of four species of hermaphroditic freshwater snails in a similar way, using comparative analyses of neutral genetic microsatellite markers. Specifically, they investigated microsatellite variability of Hygrophila in almost 280 sites in Guadeloupe, Lesser Antilles, as part of a long-term survey experiment (Lamy et al. 2013). They then modelled the influence of the mating system, local environmental characteristics and demographic factors on population genetic diversity. Consistent with theoretical predictions (Charlesworth 2003), they detected higher genetic variation in two outcrossing species than in two selfing species, emphasizing the importance of the mating system in maintaining genetic diversity. The study further identified an important role of site connectivity, through its influences on effective population size and extinction/colonisation events. Finally, the study detects an influence of interspecific interactions caused by an ongoing invasion by one of the studied species on genetic structure, highlighting the indirect effect of changes in community composition and demography on population genetics. Jarne et al. (2021) could address the extent to which genetic structure is determined by demographic and environmental factors in multiple species given the remarkable sampling available. Additionally, the study system is extremely suitable to address this hypothesis as species’ habitats are defined and delineated. Whilst the authors did attempt to test for across-species correlations, further investigations on this matter are required. Moreover, the effect of interactions between factors should be appropriately considered in any modelling between genetic structure and local environmental or demographic features. The findings in this study contribute to improving our understanding of factors influencing population genetic diversity, and highlights the complexity of interacting factors, therefore also emphasizing the challenges of drawing general implications, additionally hampered by the relatively limited number of species studied. Jarne et al. (2021) provide an excellent showcase of an empirical framework to test determinants of genetic structure in natural populations. As such, this study can be an example for further attempts of comparative analysis of genetic diversity. References Charlesworth, D. (2003) Effects of inbreeding on the genetic diversity of populations. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 358, 1051-1070. doi: https://doi.org/10.1098/rstb.2003.1296 Ellegren, H. and Galtier, N. (2016) Determinants of genetic diversity. Nature Reviews Genetics, 17, 422-433. doi: https://doi.org/10.1038/nrg.2016.58 Jarne, P., Lozano del Campo, A., Lamy, T., Chapuis, E., Dubart, M., Segard, A., Canard, E., Pointier, J.-P. and David, P. (2021) Connectivity and selfing drives population genetic structure in a patchy landscape: a comparative approach of four co-occurring freshwater snail species. HAL, hal-03295242, ver. 2 peer-reviewed and recommended by Peer Community in Evolutionary Biology. https://hal.archives-ouvertes.fr/hal-03295242 Lamy, T., Gimenez, O., Pointier, J. P., Jarne, P. and David, P. (2013). Metapopulation dynamics of species with cryptic life stages. The American Naturalist, 181, 479-491. doi: https://doi.org/10.1086/669676 Romiguier, J., Gayral, P., Ballenghien, M. et al. (2014) Comparative population genomics in animals uncovers the determinants of genetic diversity. Nature, 515, 261-263. doi: https://doi.org/10.1038/nature13685 | Connectivity and selfing drives population genetic structure in a patchy landscape: a comparative approach of four co-occurring freshwater snail species | Jarne P., Lozano del Campo A., Lamy T., Chapuis E., Dubart M., Segard A., Canard E., Pointier J.-P., David P. | <p style="text-align: justify;">The distribution of neutral genetic variation in subdivided populations is driven by the interplay between genetic drift, migration, local extinction and colonization. The influence of environmental and demographic ... | Adaptation, Evolutionary Dynamics, Population Genetics / Genomics, Reproduction and Sex, Species interactions | Trine Bilde | 2021-02-11 19:57:51 | View | ||
17 Dec 2016
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Evolution of HIV virulence in response to widespread scale up of antiretroviral therapy: a modeling studyHerbeck JT, Mittler JE, Gottlieb GS, Goodreau SM, Murphy JT, Cori A, Pickles M, Fraser C https://doi.org/10.1093/ve/vew028Predicting HIV virulence evolution in response to widespread treatmentRecommended by Samuel AlizonIt is a classical result in the virulence evolution literature that treatments decreasing parasite replication within the host should select for higher replication rates, thus driving increased levels of virulence if the two are correlated. There is some evidence for this in vitro but very little in the field. HIV infections in humans offer a unique opportunity to go beyond the simple predictions that treatments should favour more virulent strains because many details of this host-parasite system are known, especially the link between set-point virus load, transmission rate and virulence. To tackle this question, Herbeck et al. [1] used a detailed individual-based model. This is original because it allows them to integrate existing knowledge from the epidemiology and evolution of HIV (e.g. recent estimates of the ‘heritability’ of set-point virus load from one infection to the next). This detailed model allows them to formulate predictions regarding the effect of different treatment policies; especially regarding the current policy switch away from treatment initiation based on CD4 counts towards universal treatment. The results show that, perhaps as expected from the theory, treatments based on the level of remaining host target cells (CD4 T cells) do not affect virulence evolution because they do not strongly affect the virulence level that maximizes HIV’s transmission potential. However, early treatments can lead to moderate increase in virulence within several years if coverage is high enough. These results seem quite robust to variation of all the parameters in realistic ranges. The great step forward in this model is the ability to obtain quantitative prediction regarding how a virus may evolve in response to public health policies. Here the main conclusion is that given our current knowledge in HIV biology, the risk of virulence evolution is perhaps more limited than expected from a direct application of virulence evolution model. Interestingly, the authors also conclude that recently observed increased in HIV virulence [2-3] cannot be explained by the impact of antiretroviral therapy alone; which raises the question about the main mechanism behind this increase. Finally, the authors make the interesting suggestion that “changing virulence is amenable to being monitored alongside transmitted drug resistance in sentinel surveillance”. References [1] Herbeck JT, Mittler JE, Gottlieb GS, Goodreau SM, Murphy JT, Cori A, Pickles M, Fraser C. 2016. Evolution of HIV virulence in response to widespread scale up of antiretroviral therapy: a modeling study. Virus Evolution 2:vew028. doi: 10.1093/ve/vew028 [2] Herbeck JT, Müller V, Maust BS, Ledergerber B, Torti C, et al. 2012. Is the virulence of HIV changing? A meta-analysis of trends in prognostic markers of HIV disease progression and transmission. AIDS 26:193-205. doi: 10.1097/QAD.0b013e32834db418 [3] Pantazis N, Porter K, Costagliola D, De Luca A, Ghosn J, et al. 2014. Temporal trends in prognostic markers of HIV-1 virulence and transmissibility: an observational cohort study. Lancet HIV 1:e119-26. doi: 10.1016/s2352-3018(14)00002-2 | Evolution of HIV virulence in response to widespread scale up of antiretroviral therapy: a modeling study | Herbeck JT, Mittler JE, Gottlieb GS, Goodreau SM, Murphy JT, Cori A, Pickles M, Fraser C | <p>There are global increases in the use of HIV antiretroviral therapy (ART), guided by clinical benefits of early ART initiation and the efficacy of treatment as prevention of transmission. Separately, it has been shown theoretically and empirica... | ![]() | Bioinformatics & Computational Biology, Evolutionary Applications, Evolutionary Epidemiology | Samuel Alizon | 2016-12-16 20:54:08 | View | |
15 Dec 2016
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Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodesShapiro-Ilan D. and B. Raymond https://doi.org/10.1111/eva.12348Application of kin theory to long-standing problem in nematode production for biocontrolRecommended by Thomas Sappington and Ruth Arabelle HufbauerMuch research effort has been extended toward developing systems for managing soil inhabiting insect pests of crops with entomopathogenic nematodes as biocontrol agents. Although small plot or laboratory experiments may suggest a particular insect pest is vulnerable to management in this way, it is often difficult to scale-up nematode production for application at the field- and farm scale to make such a tactic viable. Part of the problem is that entomopathogenic nematode strains must be propagated by serial passage in vivo, because storage by freezing decreases fitness. At the same time, serial propagation results in loss of virulence (ability to infect) over generations in the laboratory, a phenomenon called attenuation. To probe the underlying reasons for development of attenuation, as a prerequisite to designing strategies to mitigate it, Shapiro-Ilan and Raymond [1] turned to evolutionary theory of social conflict as a possible explanatory framework. Virulence of entomopathogenic nematodes depends on a combination of virulence factors, like various proteases, secreted by both the nematode and symbiotic bacteria to overcome host defenses. Attenuation is characterized in part by a reduced production of these factors. Invasion of a host involves simultaneous attack by a group of nematodes ("cooperators"), which together neutralize host defenses enough to allow individuals to successfully invade. "Cheaters" in the invading population can avoid the metabolic costs of producing virulence factors while reaping the benefits of infecting the host made vulnerable by the cooperators in the population. The authors hypothesize that an increase in frequency of cheaters may contribute to attenuation of virulence during serial propagation in the laboratory. The evolutionary dynamics of cheater frequency in a population have been explored in many contexts as part of kin selection theory. Cheaters can increase in a population by outcompeting cooperators in a host if overall relatedness within the invading population is low. Conversely, frequency of altruism, or costly cooperation, increases in a population if relatedness is high, which is enhanced by low effective dispersal. However, a population that is too isolated can suffer from inbreeding effects, and competition will occur mainly among relatives, which decreases the fitness benefits of altruism. Shapiro-Ilan and Raymond [1] tested changes in virulence and reproductive output in a serially propagated entomopathogenic nematode, Heterorhabditis floridensis. They compared lines of high or low relatedness, manipulated via multiplicity of infection (MOI) rates (where a low dose of nematodes gives high relatedness and a high dose gives low relatedness); and under global or local competition, manipulated by pooling populations emerging from all or only two host cadavers per generation, respectively. As predicted, treatments of high relatedness (low MOI) and global competition had the greatest level of reproduction, while all lines of low relatedness (high MOI) evolved decreased reproduction and decreased virulence, which led to extinction. The key finding was that lines in the high relatedness (low MOI) and low (local) competition treatment exhibited the most stable virulence through the 12 generations tested. Thus, to minimize attenuation of virulence while maintaining fitness of recently isolated entomopathogenic nematodes, the authors recommend insect hosts be inoculated with low doses of nematodes from inocula pools from as few cadavers as possible. The application of evolutionary theory, with a clever experimental design, to an important problem in pest management makes this paper particularly noteworthy. Reference [1] Shapiro-Ilan D, Raymond B. 2016. Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes. Evolutionary Applications 9:462-470. doi: 10.1111/eva.12348 | Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes | Shapiro-Ilan D. and B. Raymond | <p>Cooperative secretion of virulence factors by pathogens can lead to social conflict when cheating mutants exploit collective secretion, but do not contribute to it. If cheats outcompete cooperators within hosts, this can cause loss of virulence... | ![]() | Adaptation, Behavior & Social Evolution, Evolutionary Applications, Evolutionary Dynamics, Evolutionary Ecology, Evolutionary Epidemiology, Evolutionary Theory, Experimental Evolution, Population Genetics / Genomics, Reproduction and Sex | Thomas Sappington | 2016-12-15 18:33:39 | View |
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