Latest recommendations
| Id | Title * | Authors * | Abstract * | Picture * | Thematic fields * | Recommender | Reviewers | Submission date▼ | |
|---|---|---|---|---|---|---|---|---|---|
31 May 2024
Cross-tolerance evolution is driven by selection of heat tolerance in Drosophila subobscuraEvolution of cross-tolerance: a mechanism to cope with climate change?Recommended by Pedro Simões based on reviews by Marina Stamenkovic-Radak and 1 anonymous reviewer
Understanding how populations evolve under thermal stress and how this process shapes the response of other stress responses is an important research topic in the context of thermal adaptation and climate change. In a thermal experimental evolution study in Drosophila subobscura, Castañeda (2024) addressed the correlated responses to selection for increasing knockdown temperature in different resistance traits, either directly related to thermal stress (e.g. knockdown time at different temperatures and CTmax) or not (e.g. desiccation and starvation resistance). The author found that the evolution of higher knockdown temperature did in fact lead to correlated responses in other stress traits. While such correlations might be expected for the thermal stress traits measured (knockdown time and CTmax), it was perhaps less expectable for desiccation and starvation resistance. However, the general occurrence of correlated evolutionary responses between stressors has been previously described, namely in Drosophila (e.g. see Bubliy and Loeschcke 2005), pointing to a possible genetic link between distinct (thermal) stress traits. There are however some features that make the findings of this study rather appealing. First, the evidence that the correlated stress responses depend on the intensity of thermal selection (i.e. the warming rate) and on the sex of the organisms. Second, correlated patterns of both desiccation and starvation resistance highlight the possibility of the evolution of a cross-tolerance response, which might positively impact on population ability to evolve under sustained stressful environments (Rodgers and Gomez Izasa 2023). However, it is important to point out that the correlated patterns between these two resistance traits (desiccation and starvation) were not exactly consistent. In fact, the negative correlated response observed for female starvation resistance is thought provoking and argues again a general scenario of cross-tolerance. While these findings are a step forward for a more multifaceted understanding of thermal adaptation in the context of stressful environments, they also highlight the need for further studies of thermal adaptation namely 1) addressing the underlying physiological and genomic mechanisms that link male and female heat tolerance and the response to other stress resistance traits (namely starvation resistance); 2) testing the extent to which cross-resistance patterns can be generalized to different thermal selection contexts and populations. In addition, this study also opens new questions considering the scope of correlated evolution to other stress traits, that might be relevant in diverse ecological scenarios. For instance, does selection towards higher heat resistance lead to correlated evolution of cold resistance? And under which circumstances (e.g. different heat selection intensities)? In fact, the occurrence of a positive (or negative) correlation cold and heat stress responses is a topic of high interest, with relevant ecological implications particularly considering the increased thermal fluctuations in natural environments because of climate warming. Cross-tolerance between cold and heat stress responses has been described (Singh 2022, Rodgers and Gomez Izasa 2023). On the other hand, negative correlations (i.e. trade-offs) between these stress traits (Stazione et al. 2020; Schou et al 2022) can impact negatively on populations’ ability to withstand thermal variability. As climatic changes proceed leading to increasing environmental variability, empirical studies such as that of Castañeda (2024) are critical in the pursue for a multivariate perspective on trait evolution in scenarios of climate change adaptation. Understanding how tolerance to different environmental stressors may evolve and which factors can act as drivers of that variation will ultimately enable better forecasts of climate change effects on biodiversity in nature. References Castañeda, LE. Cross-tolerance evolution is driven by selection on heat tolerance in Drosophila subobscura. Biorxiv, ver. 4 peer-reviewed and recommended by Peer Community in Evolutionary Biology (2024). https://www.doi.org/10.1101/2023.09.05.556367 Bubliy, OA, Loeschcke, V. Correlated responses to selection for stress resistance and longevity in a laboratory population of Drosophila melanogaster. J Evol Biol. 18(4):789-803 (2005). https://www.doi.org/10.1111/j.1420-9101.2005.00928.x. Rodgers, EM, Gomez Isaza, DF. The mechanistic basis and adaptive significance of cross-tolerance: a 'pre-adaptation' to a changing world? J Exp Biol. 226(11):jeb245644 (2023). https://www.doi.org/10.1242/jeb.245644. Schou, MF, Engelbrecht, A, Brand, Z, Svensson, EI, Cloete, S, Cornwallis, CK. Evolutionary trade-offs between heat and cold tolerance limit responses to fluctuating climates. Sci Adv. 8(21):eabn9580 (2022). https://www.doi.org/10.1126/sciadv.abn9580. Singh, K, Arun Samant, M, Prasad, NG. Evolution of cross-tolerance in Drosophila melanogaster as a result of increased resistance to cold stress. Sci Rep. 12(1):19536 (2022). https://www.doi.org/10.1038/s41598-022-23674-z. Stazione, L, Norry, FM, Gomez, FH, Sambucetti, P. Heat knockdown resistance and chill-coma recovery as correlated responses to selection on mating success at high temperature in Drosophila buzzatii. Ecol Evol. 10(4):1998-2006 (2020). https://www.doi.org/10.1002/ece3.6032. | Cross-tolerance evolution is driven by selection of heat tolerance in *Drosophila subobscura* | Luis E. Castañeda | <p>The evolution of heat tolerance is a crucial mechanism for the adaptive response to global warming, but it depends on the genetic variance carried by populations and on the intensity of thermal stress in nature. Experimental selection studies h... | | Adaptation, Experimental Evolution | Pedro Simões | 2023-10-02 14:13:02 | ||
14 Jan 2025
Partitioning the phenotypic and genetic variances of reaction normsPhenotypic plasticity across traits, organisms and environments: decomposing the components of phenotypic varianceRecommended by Staffan Jacob based on reviews by Jarrod Hadfield and Thibaut Morel JournelPhenotypic plasticity can lead to rapid and important changes of trait distributions depending on environmental conditions, with important consequences for population dynamics, species interactions and adaptation. To better understand the evolution and importance of plasticity, we need to improve our ability to quantify and compare phenotypic plasticity among organisms, and estimate the evolutionary potential of plastic capacity. Plasticity is classically quantified through regression slopes, with units of traits per environment that by definition vary across organisms, traits and studies, and makes complex the comparison of how does plasticity vary across biological units, especially when linear versus quadratic reaction norms are considered. A clear methodology to quantify phenotypic plasticity in a way that allow for comparison across traits, organisms and environments is lacking. In this contribution, Pierre de Villemereuil and Luis-Miguel Chevin clarify key concepts about variability and evolutionary potential of plasticity, and propose an efficient method to partition phenotypic variance between genotype and environment. Expanding from the classical (too) simple regression slope approach, and directly integrating the genetic variability of plasticity, they provide a clear framework to quantify the part of phenotypic variance resulting from phenotypic plasticity, integrate the role of the shape of reaction norms, and estimate the heritable variation of trait plasticity. They integrate this method in a R package named Reacnorm, with step by step decision tree, that should greatly help the applicability of this framework. The authors here propose a contribution that simultaneously clarify key concepts and challenges about plasticity and reaction norms, being very interesting on the theoretical side, and is directly and quite simply applicable to any trait and organism. This should help and stimulate comparative studies of how does plasticity vary across traits, organisms and environmental contexts, both using already published datasets and through new experiments. References Pierre de Villemereuil, Luis-Miguel Chevin (2025) Partitioning the phenotypic and genetic variances of reaction norms. EcoEvorxiv, ver.4 peer-reviewed and recommended by PCI Evol Biol https://doi.org/10.32942/X2NC8B | Partitioning the phenotypic and genetic variances of reaction norms | Pierre de Villemereuil, Luis-Miguel Chevin | <p>Many traits show plastic phenotypic variation across environments, captured by their norms of reaction. These reaction norms may be discrete or continuous, and can substantially vary in shape across organisms and traits, making it difficult to ... | | Evolutionary Ecology, Phenotypic Plasticity, Quantitative Genetics | Staffan Jacob | 2023-09-01 16:42:45 | ||
28 Mar 2024
Gene expression is the main driver of purifying selection in large penguin populationsPurifying selection on highly expressed genes in PenguinsRecommended by Bruce Rannala based on reviews by Tanja Pyhäjärvi and 1 anonymous reviewer
Given the general importance of protein expression levels, in cells it is widely accepted that gene expression levels are often a target of natural selection and that most mutations affecting gene expression levels are therefore likely to be deleterious [1]. However, it is perhaps less obvious that the strength of selection on the regulated genes themselves may be influenced by their expression levels. This might be due to harmful effects of misfolded proteins, for example, when higher protein concentrations exist in cells [2]. Recent studies have suggested that highly expressed genes accumulate fewer deleterious mutations; thus a positive relationship appears to exist between gene expression levels and the relative strength of purifying selection [3]. The recommended paper by Trucchi et al. [4] examines the relationship between gene expression, purifying selection and a third variable -- effective population size -- in populations of two species of penguin with different population sizes, the Emperor penguin (Aptenodytes forsteri) and the King penguin (A. patagonicus). Using transcriptomic data and computer simulations modeling selection, they examine patterns of nonsynonymous and synonymous segregating polymorphisms (p) across genes in the two populations, concluding that even in relatively small populations purifying selection has an important effect in eliminating deleterious mutations. References 1] Gilad Y, Oshlack A, and Rifkin SA. 2006. Natural selection on gene expression. Trends in Genetics 22: 456-461. https://doi.org/10.1016/j.tig.2006.06.002 [4] Trucchi E, Massa P, Giannelli F, Latrille T, Fernandes FAN, Ancona L, Stenseth NC, Obiol JF, Paris J, Bertorelle G, and Le Bohec, C. 2023. Gene expression is the main driver of purifying selection in large penguin populations. bioRxiv 2023.08.08.552445, ver. 2 peer-reviewed and recommended by Peer Community in Evolutionary Biology. https://doi.org/10.1101/2023.08.08.552445
| Gene expression is the main driver of purifying selection in large penguin populations | Emiliano Trucchi, Piergiorgio Massa, Francesco Giannelli, Thibault Latrille, Flavia A.N. Fernandes, Lorena Ancona, Nils Chr Stenseth, Joan Ferrer Obiol, Josephine Paris, Giorgio Bertorelle, Celine Le Bohec | <p style="text-align: justify;">Purifying selection is the most pervasive type of selection, as it constantly removes deleterious mutations arising in populations, directly scaling with population size. Highly expressed genes appear to accumulate ... | | Bioinformatics & Computational Biology, Evolutionary Dynamics, Evolutionary Theory, Population Genetics / Genomics | Bruce Rannala | 2023-08-09 17:53:03 | ||
12 Feb 2024
How do plant RNA viruses overcome the negative effect of Muller s ratchet despite strong transmission bottlenecks?How to survive the mutational meltdown: lessons from plant RNA virusesRecommended by Kavita Jain based on reviews by Brent Allman, Ana Morales-Arce and 1 anonymous reviewerAlthough most mutations are deleterious, the strongly deleterious ones do not spread in a very large population as their chance of fixation is very small. Another mechanism via which the deleterious mutations can be eliminated is via recombination or sexual reproduction. However, in a finite asexual population, the subpopulation without any deleterious mutation will eventually acquire a deleterious mutation resulting in the reduction of the population size or in other words, an increase in the genetic drift. This, in turn, will lead the population to acquire deleterious mutations at a faster rate eventually leading to a mutational meltdown. This irreversible (or, at least over some long time scales) accumulation of deleterious mutations is especially relevant to RNA viruses due to their high mutation rate, and while the prior work has dealt with bacteriophages and RNA viruses, the study by Lafforgue et al. [1] makes an interesting contribution to the existing literature by focusing on plants. In this study, the authors enquire how despite the repeated increase in the strength of genetic drift, how the RNA viruses manage to survive in plants. Following a series of experiments and some numerical simulations, the authors find that as expected, after severe bottlenecks, the fitness of the population decreases significantly. But if the bottlenecks are followed by population expansion, the Muller’s ratchet can be halted due to the genetic diversity generated during population growth. They hypothesize this mechanism as a potential way by which the RNA viruses can survive the mutational meltdown. As a theoretician, I find this investigation quite interesting and would like to see more studies addressing, e.g., the minimum population growth rate required to counter the potential extinction for a given bottleneck size and deleterious mutation rate. Of course, it would be interesting to see in future work if the hypothesis in this article can be tested in natural populations. References [1] Guillaume Lafforgue, Marie Lefebvre, Thierry Michon, Santiago F. Elena (2024) How do plant RNA viruses overcome the negative effect of Muller s ratchet despite strong transmission bottlenecks? bioRxiv, ver. 3 peer-reviewed and recommended by Peer Community In Evolutionary Biology | How do plant RNA viruses overcome the negative effect of Muller s ratchet despite strong transmission bottlenecks? | Guillaume Lafforgue, Marie Lefebvre, Thierry Michon, Santiago F. Elena | <p>Muller's ratchet refers to the irreversible accumulation of deleterious mutations in small populations, resulting in a decline in overall fitness. This phenomenon has been extensively observed in experiments involving microorganisms, including ... | | Experimental Evolution, Genome Evolution | Kavita Jain | 2023-08-04 09:37:08 | ||
02 Feb 2024
Community structure of heritable viruses in a Drosophila-parasitoids complexThe virome of a Drosophilidae-parasitoid communityRecommended by Ben Longdon based on reviews by 3 anonymous reviewers
Understanding the factors that shape the virome of a host is key to understanding virus ecology and evolution (Obbard, 2018; French & Holmes, 2020). There is still much to learn about the diversity and distribution of viruses in a host community (Wille et al., 2019; Chen et al., 2023). The viruses of parasitoid wasps are well studied, and their viruses, or integrated viral genes, are known to suppress their insect host’s immune response to enhance parasitoid survival (Herniou et al., 2013; Coffman et al., 2022). Likewise, the insect virome is being increasingly well studied (Shi et al., 2016), with the virome of Drosophila species being particularly well characterised over the best part of the last century (L'Heritier & Teissier, 1937; L'Heritier, 1970; Brun & Plus, 1980; Longdon et al., 2010; Longdon et al., 2011; Longdon et al., 2012; Webster et al., 2015; Webster et al., 2016; Medd et al., 2018; Wallace et al., 2021). However, the viromes of parasitoids and their insect host communities have been less well studied (Leigh et al., 2018; Caldas-Garcia et al., 2023), and the inherent connectivity between parasitoids and their hosts provides an interesting system to study virus host range and cross-species transmission. Here, Varaldi et al (Varaldi et al., 2024) have examined the viruses associated with a community of nine Drosophilidae hosts and six parasitoids. Using both RNA and DNA sequencing of insects reared for two generations, they selected viruses that are maintained in the lab either via vertical transmission or contamination of rearing medium. From 55 pools of insects they found 53 virus-like sequences, 37 of which were novel. Parasitoids were host to nearly twice as many viruses as their Drosophila hosts, although they note this could be due to differences in the rearing temperatures of the hosts. They next quantified if species, year, season, or location played a role in structuring the virome, finding only a significant effect of host species, which explained just over 50% of the variation in virus distribution. No evidence was found of related species sharing more similar virus communities. Although looking at a limited number of species, this suggests that these viruses are not co-speciating or preferentially host switching between closely related species. Finally, they carried out crosses between lines of the parasitoid Leptopilina heterotoma that were infected and uninfected for a novel Iflavirus found in their sequencing data. They found evidence of high levels of maternal transmission and lower level horizontal transmission between wasp larvae parasitising the same host. No evidence of changes in parasitoid-induced mortality, developmental success or the sex ratio was found in iflavirus-infected parasitoids. Interestingly individuals infected with this RNA virus also contained viral DNA, but this did not appear to be integrated into the wasp genome. Overall, this work has taken the first steps in examining the community structure of the virome of parasitoids together with their Drosophilidae hosts. This work will not doubt stimulate follow-up studies to explore the evolution and ecology of these novel virus communities. References Brun G, Plus N (1980) The viruses of Drosophila. In: The genetics and biology of Drosophila eds Ashburner M & Wright TRF), pp. 625-702. Academic Press, New York. | Community structure of heritable viruses in a *Drosophila*-parasitoids complex | Julien Varaldi, David Lepetit, Nelly Burlet, Camille Faber, Bérénice Baretje, Roland Allemand | <p style="text-align: justify;">The diversity and phenotypic impacts related to the presence of heritable bacteria in insects have been extensively studied in the last decades. On the contrary, heritable viruses have been overlooked for several re... | | Evolutionary Ecology, Species interactions | Ben Longdon | 2023-08-03 01:07:43 | ||
04 Mar 2024
Simultaneous Inference of Past Demography and Selection from the Ancestral Recombination Graph under the Beta CoalescentBeyond the standard coalescent: demographic inference with complete genomes and graph neural networks under the beta coalescentRecommended by Julien Yann Dutheil based on reviews by 2 anonymous reviewers
Modelling the evolution of complete genome sequences in populations requires accounting for the recombination process, as a single tree can no longer describe the underlying genealogy. The sequentially Markov coalescent (SMC, McVean and Cardin 2005; Marjoram and Wall 2006) approximates the standard coalescent with recombination process and permits estimating population genetic parameters (e.g., population sizes, recombination rates) using population genomic datasets. As such datasets become available for an increasing number of species, more fine-tuned models are needed to encompass the diversity of life cycles of organisms beyond the model species on which most methods have been benchmarked. The work by Korfmann et al. (Korfmann et al. 2024) represents a significant step forward as it accounts for multiple mergers in SMC models. Multiple merger models account for simultaneous coalescence events so that more than two lineages find a common ancestor in a given generation. This feature is not allowed in standard coalescent models and may result from selection or skewed offspring distributions, conditions likely met by a broad range of species, particularly microbial. Yet, this work goes beyond extending the SMC, as it introduces several methodological innovations. The "classical" SMC-based inference approaches rely on hidden Markov models to compute the likelihood of the data while efficiently integrating over the possible ancestral recombination graphs (ARG). Following other recent works (e.g. Gattepaille et al. 2016), Korfmann et al. propose to separate the ARG inference from model parameter estimation under maximum likelihood (ML). They introduce a procedure where the ARG is first reconstructed from the data and then taken as input in the model fitting step. While this approach does not permit accounting for the uncertainty in the ARG reconstruction (which is typically large), it potentially allows for the extraction of more information from the ARG, such as the occurrence of multiple merging events. Going away from maximum likelihood inference, the authors trained a graph neural network (GNN) on simulated ARGs, introducing a new, flexible way to estimate population genomic parameters. The authors used simulations under a beta-coalescent model with diverse demographic scenarios and showed that the ML and GNN approaches introduced can reliably recover the simulated parameter values. They further show that when the true ARG is given as input, the GNN outperforms the ML approach, demonstrating its promising power as ARG reconstruction methods improve. In particular, they showed that trained GNNs can disentangle the effects of selective sweeps and skewed offspring distributions while inferring past population size changes. This work paves the way for new, exciting applications, though many questions must be answered. How frequent are multiple mergers? As the authors showed that these events "erase" the record of past demographic events, how many genomes are needed to conduct reliable inference, and can the methods computationally cope with the resulting (potentially large) amounts of required data? This is particularly intriguing as micro-organisms, prone to strong selection and skewed offspring distributions, also tend to carry smaller genomes. References Gattepaille L, Günther T, Jakobsson M. 2016. Inferring Past Effective Population Size from Distributions of Coalescent Times. Genetics 204:1191-1206. | Simultaneous Inference of Past Demography and Selection from the Ancestral Recombination Graph under the Beta Coalescent | Kevin Korfmann, Thibaut Sellinger, Fabian Freund, Matteo Fumagalli, Aurélien Tellier | <p style="text-align: justify;">The reproductive mechanism of a species is a key driver of genome evolution. The standard Wright-Fisher model for the reproduction of individuals in a population assumes that each individual produces a number of off... | | Adaptation, Bioinformatics & Computational Biology, Evolutionary Applications, Evolutionary Theory, Life History, Population Genetics / Genomics | Julien Yann Dutheil | 2023-07-31 13:11:22 | ||
24 Sep 2024
Spatial autocorrelation and host anemone species drive variation in local components of fitness in a wild clownfish populationIs our best measure of fitness correlated with environment? A study in an orange clownfish population.Recommended by Pierre de Villemereuil based on reviews by Stefan Vriend and 2 anonymous reviewers
Getting a clear definition of fitness for a particular evolutionary biology question is a complex challenge, fraught with pitfalls and misconceptions (Orr, 2009; Walsh & Lynch, 2018). In longitudinal surveys of wild populations, lifetime reproductive success (LRS) is generally considered the best measure of individual fitness (Bonnet, 2022). However, it is important to bear in mind that LRS is only a (noisy) measure of the realised success, relying on a substantial amount of assumptions (e.g. with regard to generation overlap, Walsh & Lynch, 2018), not a direct measure of fitness. In a study on the clownfish, Marrot et al. (2024) studied the spatial and ecological drivers of lifetime reproductive success. To do so, they analysed a 10-year long survey on over 300 anemones harbouring clownfishes, and used a genetics-based pedigree to infer the LRS of each individual. Using a characterisation of the micro-habitat provided by each anemone, they used the anemone species, density and depth as ecological drivers and spatial-autocorrelated models to study more general (and undefined) spatial drivers. The authors found that LRS was influenced by a significant amount by the spatial structure of the population, and, to some extent, by the anemone species harbouring the clownfish individuals. Together, they explain a substantial proportion of the individual variation in LRS. While the actual determinants of spatial variation of LRS in this (and other) species remain understood, this study highlights an important aspect of measuring fitness in wild populations using LRS: it is particularly noisy and subject to environmental variation. This certainly does not mean that LRS is a bad proxy for fitness, it is still among the best measure of it we can have access to. However, it highlights how carefully we should thread when analysing it. Especially, spatial auto-correlation of LRS, combined with population structure within a population, would lead to genotype-environment correlation for fitness, which is likely to bias predictions of response to natural selection and would be extremely difficult to estimate (Falconer & Mackay, 1996). References Pascal Marrot, Cécile Fauvelot, Michael L. Berumen, Maya Srinivasan, Geoffrey P. Jones, Serge Planes, and Benoit Pujol (2024) Spatial autocorrelation and host anemone species drive variation in local components of fitness in a wild clownfish population. Zenodo, ver.3 peer-reviewed and recommended by PCI Evol Biol https://doi.org/10.5281/zenodo.13806778 Bonnet, T., Morrissey, M. B., de Villemereuil, P., Alberts, S. C., Arcese, P., Bailey, L. D., Boutin, S., Brekke, P., Brent, L. J. N., Camenisch, G., Charmantier, A., Clutton-Brock, T. H., Cockburn, A., Coltman, D. W., Courtiol, A., Davidian, E., Evans, S. R., Ewen, J. G., Festa-Bianchet, M., … Kruuk, L. E. B. (2022). Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals. Science, 376(6596), 1012–1016. https://doi.org/10.1126/science.abk0853 Falconer, D. S. and Mackay, T. F. C. (1996). Introduction to quantitative genetics (4th ed.). Benjamin Cummings. Orr, H. A. (2009). Fitness and its role in evolutionary genetics. Nature Reviews Genetics, 10(8), 531–539. https://doi.org/10.1038/nrg2603 Walsh, B. and Lynch, M. (2018). Evolution and selection of quantitative traits. Oxford University Press. | Spatial autocorrelation and host anemone species drive variation in local components of fitness in a wild clownfish population | Pascal Marrot, Cécile Fauvelot, Michael L. Berumen, Maya Srinivasan, Geoffrey P. Jones, Serge Planes, and Benoit Pujol | <p style="text-align: justify;">The susceptibility of species to habitat changes depends on which ecological drivers shape individual fitness components. To date, only a few studies have quantified fitness components such as the Lifetime Reproduct... | | Adaptation, Evolutionary Ecology, Quantitative Genetics | Pierre de Villemereuil | 2023-07-31 11:42:58 | ||
05 Apr 2024
Does the seed fall far from the tree? Weak fine scale genetic structure in a continuous Scots pine populationWeak spatial genetic structure in a large continuous Scots pine population – implications for conservation and breedingRecommended by Myriam Heuertz based on reviews by Joachim Mergeay, Jean-Baptiste Ledoux and Roberta Loh
Spatial genetic structure, i.e. the non-random spatial distribution of genotypes, arises in populations because of different processes including spatially limited dispersal and selection. Knowledge on the spatial genetic structure of plant populations is important to assess biological parameters such as gene dispersal distances and the potential for local adaptations, as well as for applications in conservation management and breeding. In their work, Niskanen and colleagues demonstrate a multifaceted approach to characterise the spatial genetic structure in two replicate sites of a continuously distributed Scots pine population in South-Eastern Finland. They mapped and assessed the ages of 469 naturally regenerated adults and genotyped them using a SNP array which resulted in 157 325 filtered polymorphic SNPs. Their dataset is remarkably powerful because of the large numbers of both individuals and SNPs genotyped. This made it possible to characterise precisely the decay of genetic relatedness between individuals with spatial distance despite the extensive dispersal capacity of Scots pine through pollen, and ensuing expectations of an almost panmictic population. The authors’ data analysis was particularly thorough. They demonstrated that two metrics of pairwise relatedness, the genomic relationship matrix (GRM, Yang et al. 2011) and the kinship coefficient (Loiselle et al. 1995) were strongly correlated and produced very similar inference of family relationships: >99% of pairs of individuals were unrelated, and the remainder exhibited 2nd (e.g., half-siblings) to 4th degree relatedness. Pairwise relatedness decayed with spatial distance which resulted in extremely weak but statistically significant spatial genetic structure in both sites, quantified as Sp=0.0005 and Sp=0.0008. These estimates are at least an order of magnitude lower than estimates in the literature obtained in more fragmented populations of the same species or in other conifers. Estimates of the neighbourhood size, the effective number of potentially mating individuals belonging to a within-population neighbourhood (Wright 1946), were relatively large with Nb=1680-3210 despite relatively short gene dispersal distances, σg = 36.5–71.3m, which illustrates the high effective density of the population. The authors showed the implications of their findings for selection. The capacity for local adaptation depends on dispersal distances and the strength of the selection coefficient. In the study population, the authors inferred that local adaptation can only occur if environmental heterogeneity occurs over a distance larger than approximately one kilometre (or larger, if considering long-distance dispersal). Interestingly, in Scots pine, no local adaptation has been described on similar geographic scales, in contrast to some other European or Mediterranean conifers (Scotti et al. 2023). The authors’ results are relevant for the management of conservation and breeding. They showed that related individuals occurred within sites only and that they shared a higher number of rare alleles than unrelated ones. Since rare alleles are enriched in new and recessive deleterious variants, selecting related individuals could have negative consequences in breeding programmes. The authors also showed, in their response to reviewers, that their powerful dataset was not suitable to obtain a robust estimate of effective population size, Ne, based on the linkage disequilibrium method (Do et al. 2014). This illustrated that the estimation of Ne used for genetic indicators supported in international conservation policy (Hoban et al. 2020, CBD 2022) remains challenging in large and continuous populations (see also Santo-del-Blanco et al. 2023, Gargiulo et al. 2024). ReferencesCBD (2022) Kunming-Montreal Global Biodiversity Framework. https://www.cbd.int/doc/decisions/cop-15/cop-15-dec-04-en.pdf Do C, Waples RS, Peel D, Macbeth GM, Tillett BJ, Ovenden JR (2014). NeEstimator v2: re-implementation of software for the estimation of contemporary effective population size (Ne ) from genetic data. Molecular Ecology Resources 14: 209–214. https://doi.org/10.1111/1755-0998.12157 Gargiulo R, Decroocq V, González-Martínez SC, Paz-Vinas I, Aury JM, Kupin IL, Plomion C, Schmitt S, Scotti I, Heuertz M (2024) Estimation of contemporary effective population size in plant populations: limitations of genomic datasets. Evolutionary Applications, in press, https://doi.org/10.1101/2023.07.18.549323 Hoban S, Bruford M, D’Urban Jackson J, Lopes-Fernandes M, Heuertz M, Hohenlohe PA, Paz-Vinas I, et al. (2020) Genetic diversity targets and indicators in the CBD post-2020 Global Biodiversity Framework must be improved. Biological Conservation 248: 108654. https://doi.org/10.1016/j.biocon.2020.108654 Loiselle BA, Sork VL, Nason J & Graham C (1995) Spatial genetic structure of a tropical understorey shrub, Psychotria officinalis (Rubiaceae). American Journal of Botany 82: 1420–1425. https://doi.org/10.1002/j.1537-2197.1995.tb12679.x Santos-del-Blanco L, Olsson S, Budde KB, Grivet D, González-Martínez SC, Alía R, Robledo-Arnuncio JJ (2022). On the feasibility of estimating contemporary effective population size (Ne) for genetic conservation and monitoring of forest trees. Biological Conservation 273: 109704. https://doi.org/10.1016/j.biocon.2022.109704 Scotti I, Lalagüe H, Oddou-Muratorio S, Scotti-Saintagne C, Ruiz Daniels R, Grivet D, et al. (2023) Common microgeographical selection patterns revealed in four European conifers. Molecular Ecology 32: 393-411. https://doi.org/10.1111/mec.16750 Wright S (1946) Isolation by distance under diverse systems of mating. Genetics 31: 39–59. https://doi.org/10.1093/genetics/31.1.39 Yang J, Lee SH, Goddard ME & Visscher PM (2011) GCTA: a tool for genome-wide complex trait analysis. The American Journal of Human Genetics 88: 76–82. https://www.cell.com/ajhg/pdf/S0002-9297(10)00598-7.pdf | Does the seed fall far from the tree? Weak fine scale genetic structure in a continuous Scots pine population | Alina K. Niskanen, Sonja T. Kujala, Katri Kärkkäinen, Outi Savolainen, Tanja Pyhäjärvi | <p>Knowledge of fine-scale spatial genetic structure, i.e., the distribution of genetic diversity at short distances, is important in evolutionary research and in practical applications such as conservation and breeding programs. In trees, related... | | Adaptation, Evolutionary Applications, Population Genetics / Genomics | Myriam Heuertz | Joachim Mergeay | 2023-06-27 21:57:28 | |
25 Jan 2024
Sperm production and allocation in response to risk of sperm competition in the black soldier fly Hermetia illucensElevated sperm production and faster transfer: plastic responses to the risk of sperm competition in males of the black sodier fly Hermetia illuceRecommended by Trine Bilde based on reviews by Rebecca Boulton, Isabel Smallegange and 1 anonymous reviewer
In this paper (Manas et al., 2023), the authors investigate male responses to risk of sperm competition in the black soldier fly Hermetia illuce, a widespread insect that has gained recent attention for its potential to be farmed for sustainable food production (Tomberlin & van Huis, 2020). Using an experimental approach that simulated low-risk (males were kept individually) and high-risk (males were kept in groups of 10) of sperm competition, they found that males reared in groups showed a significant increase in sperm production compared with males reared individually. This shows a response to the rearing environment in sperm production that is consistent with an increase in the perceived risk of sperm competition. These males were then used in mating experiments to determine whether sperm allocation to females during mating was influenced by the perceived risk of sperm competition. Mating experiments were initiated in groups, since mating only occurs when more than one male and one female are present, indicating strong sexual selection in the wild. Once a copulation began, the pair was moved to a new environment with no competition, with male competitors, or with other females, to test how social environment and potentially the sex of surrounding individuals influenced sperm allocation during mating. Copulation duration and the number of sperm transferred were subsequently counted. In these mating experiments, the number of sperm stored in the female spermathecae increased under immediate risk of sperm competition. Interestingly, this was not because males copulated for longer depending on the risk of sperm competition, indicating that males respond plastically to the risk of competition by elevating their investment in sperm production and speed of sperm transfer. There was no difference between competitive environments consisting of males or females respectively, suggesting that it is the presence of other flies per se that influence sperm allocation. The study provides an interesting new example of how males alter reproductive investment in response to social context and sexual competition in their environment. In addition, it provides new insights into the reproductive biology of the black soldier fly Hermetia illucens, which may be relevant for optimizing farming conditions. References Manas F, Labrousse C, Bressac C (2023) Sperm production and allocation in response to risks of sperm competition in the black soldier fly Hermetia illucens. bioRxiv, 2023.06.20.544772, ver. 5 peer-reviewed and recommended by Peer Community in Evolutionary Biology. https://doi.org/10.1101/2023.06.20.544772 Tomberlin JK, Van Huis A (2020) Black soldier fly from pest to ‘crown jewel’ of the insects as feed industry: an historical perspective. Journal of Insects as Food and Feed, 6, 1–4. https://doi.org/10.3920/JIFF2020.0003 | Sperm production and allocation in response to risk of sperm competition in the black soldier fly Hermetia illucens | Frédéric Manas, Carole Labrousse, Christophe Bressac | <p style="text-align: justify;">In polyandrous species, competition between males for offspring paternity goes on after copulation through the competition of their ejaculates for the fertilisation of female's oocytes. Given that males allocating m... | | Reproduction and Sex, Sexual Selection | Trine Bilde | 2023-06-26 09:41:07 | ||
04 Mar 2024
Interplay between fecundity, sexual and growth selection on the spring phenology of European beech (Fagus sylvatica L.).Interplay between fecundity, sexual and growth selection on the spring phenology of European beech (Fagus sylvatica L.)Recommended by Santiago C. Gonzalez-Martinez based on reviews by 2 anonymous reviewers
Starting with the seminar paper by Lande & Arnold (1983), several studies have addressed phenotypic selection in natural populations of a wide variety of organisms, with a recent renewed interest in forest trees (e.g., Oddou-Muratorio et al. 2018; Alexandre et al. 2020; Westergren et al. 2023). Because of their long generation times, long-lived organisms such as forest trees may suffer the most from maladaptation due to climate change, and whether they will be able to adapt to new environmental conditions in just one or a few generations is hotly debated. In this study, Oddou-Muratorio and colleagues (2024) extend the current framework to add two additional selection components that may alter patterns of fecundity selection and the estimation of standard selection gradients, namely sexual selection (evaluated as differences in flowering phenology conducting to assortative mating) and growth (viability) selection. Notably, the study is conducted in two contrasted environments (low vs high altitude populations) providing information on how the environment may modulate selection patterns in spring phenology. Spring phenology is a key adaptive trait that has been shown to be already affected by climate change in forest trees (Alberto et al. 2013). While fecundity selection for early phenology has been extensively reported before (see Munguía-Rosas et al. 2011), the authors found that this kind of selection can be strongly modulated by sexual selection, depending on the environment. Moreover, they found a significant correlation between early phenology and seedling growth in a common garden, highlighting the importance of this trait for early survival in European beech. As a conclusion, this original research puts in evidence the need for more integrative approaches for the study of natural selection in the field, as well as the importance of testing multiple environments and the relevance of common gardens to further evaluate phenotypic changes due to real-time selection. PS: The recommender and the first author of the preprint have shared authorship in a recent paper in a similar topic (Westergren et al. 2023). Nevertheless, the recommender has not contributed in any way or was aware of the content of the current preprint before acting as recommender, and steps have been taken for a fair and unpartial evaluation. References Alberto, F. J., Aitken, S. N., Alía, R., González‐Martínez, S. C., Hänninen, H., Kremer, A., Lefèvre, F., Lenormand, T., Yeaman, S., Whetten, R., & Savolainen, O. (2013). Potential for evolutionary responses to climate change - evidence from tree populations. Global Change Biology, 19(6), 1645‑1661. Oddou-Muratorio S, Bontemps A, Gauzere J, Klein E (2024) Interplay between fecundity, sexual and growth selection on the spring phenology of European beech (Fagus sylvatica L.). bioRxiv, 2023.04.27.538521, ver. 2 peer-reviewed and recommended by Peer Community In Evolutionary Biology https://doi.org/10.1101/2023.04.27.538521 Oddou-Muratorio, S., Gauzere, J., Bontemps, A., Rey, J.-F., & Klein, E. K. (2018). Tree, sex and size: Ecological determinants of male vs. female fecundity in three Fagus sylvatica stands. Molecular Ecology, 27(15), 3131‑3145. | Interplay between fecundity, sexual and growth selection on the spring phenology of European beech (*Fagus sylvatica* L.). | Sylvie Oddou-Muratorio, Aurore Bontemps, Julie Gauzere, Etienne Klein | <p>Background: Plant phenological traits such as the timing of budburst or flowering can evolve on ecological timescales through response to fecundity and viability selection. However, interference with sexual selection may arise from assortative ... | | Adaptation, Evolutionary Ecology, Quantitative Genetics, Reproduction and Sex, Sexual Selection | Santiago C. Gonzalez-Martinez | 2023-05-02 11:57:23 |
