Landesanstalt für Bienenkunde

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    Evolutionary genomics of socially polymorphic populations of Pogonomyrmex californicus
    (2024) Errbii, Mohammed; Ernst, Ulrich R.; Lajmi, Aparna; Privman, Eyal; Gadau, Jürgen; Schrader, Lukas; Errbii, Mohammed; Molecular Evolution and Sociobiology Group, Institute for Evolution and Biodiversity, University of Münster, Hüfferstr. 1, DE-48149, Münster, Germany; Ernst, Ulrich R.; Molecular Evolution and Sociobiology Group, Institute for Evolution and Biodiversity, University of Münster, Hüfferstr. 1, DE-48149, Münster, Germany; Lajmi, Aparna; Department of Evolutionary and Environmental Biology, Institute of Evolution, University of Haifa, Haifa, Israel; Privman, Eyal; Department of Evolutionary and Environmental Biology, Institute of Evolution, University of Haifa, Haifa, Israel; Gadau, Jürgen; Molecular Evolution and Sociobiology Group, Institute for Evolution and Biodiversity, University of Münster, Hüfferstr. 1, DE-48149, Münster, Germany; Schrader, Lukas; Molecular Evolution and Sociobiology Group, Institute for Evolution and Biodiversity, University of Münster, Hüfferstr. 1, DE-48149, Münster, Germany
    Background: Social insects vary considerably in their social organization both between and within species. In the California harvester ant, Pogonomyrmex californicus (Buckley 1867), colonies are commonly founded and headed by a single queen (haplometrosis, primary monogyny). However, in some populations in California (USA), unrelated queens cooperate not only during founding (pleometrosis) but also throughout the life of the colony (primary polygyny). The genetic architecture and evolutionary dynamics of this complex social niche polymorphism (haplometrosis vs pleometrosis) have remained unknown. Results: We provide a first analysis of its genomic basis and evolutionary history using population genomics comparing individuals from a haplometrotic population to those from a pleometrotic population. We discovered a recently evolved (< 200 k years), 8-Mb non-recombining region segregating with the observed social niche polymorphism. This region shares several characteristics with supergenes underlying social polymorphisms in other socially polymorphic ant species. However, we also find remarkable differences from previously described social supergenes. Particularly, four additional genomic regions not in linkage with the supergene show signatures of a selective sweep in the pleometrotic population. Within these regions, we find for example genes crucial for epigenetic regulation via histone modification (chameau) and DNA methylation (Dnmt1). Conclusions: Altogether, our results suggest that social morph in this species is a polygenic trait involving a potential young supergene. Further studies targeting haplo- and pleometrotic individuals from a single population are however required to conclusively resolve whether these genetic differences underlie the alternative social phenotypes or have emerged through genetic drift.
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    Same data, different analysts: variation in effect sizes due to analytical decisions in ecology and evolutionary biology
    (2025) Gould, Elliot; Berauer, Bernd J.; Ernst, Ulrich Rainer; Zitomer, Rachel A.
    Although variation in effect sizes and predicted values among studies of similar phenomena is inevitable, such variation far exceeds what might be produced by sampling error alone. One possible explanation for variation among results is differences among researchers in the decisions they make regarding statistical analyses. A growing array of studies has explored this analytical variability in different fields and has found substantial variability among results despite analysts having the same data and research question. Many of these studies have been in the social sciences, but one small “many analyst” study found similar variability in ecology. We expanded the scope of this prior work by implementing a large-scale empirical exploration of the variation in effect sizes and model predictions generated by the analytical decisions of different researchers in ecology and evolutionary biology. We used two unpublished datasets, one from evolutionary ecology (blue tit, Cyanistes caeruleus , to compare sibling number and nestling growth) and one from conservation ecology ( Eucalyptus , to compare grass cover and tree seedling recruitment). The project leaders recruited 174 analyst teams, comprising 246 analysts, to investigate the answers to prespecified research questions. Analyses conducted by these teams yielded 141 usable effects (compatible with our meta-analyses and with all necessary information provided) for the blue tit dataset, and 85 usable effects for the Eucalyptus dataset. We found substantial heterogeneity among results for both datasets, although the patterns of variation differed between them. For the blue tit analyses, the average effect was convincingly negative, with less growth for nestlings living with more siblings, but there was near continuous variation in effect size from large negative effects to effects near zero, and even effects crossing the traditional threshold of statistical significance in the opposite direction. In contrast, the average relationship between grass cover and Eucalyptus seedling number was only slightly negative and not convincingly different from zero, and most effects ranged from weakly negative to weakly positive, with about a third of effects crossing the traditional threshold of significance in one direction or the other. However, there were also several striking outliers in the Eucalyptus dataset, with effects far from zero. For both datasets, we found substantial variation in the variable selection and random effects structures among analyses, as well as in the ratings of the analytical methods by peer reviewers, but we found no strong relationship between any of these and deviation from the meta-analytic mean. In other words, analyses with results that were far from the mean were no more or less likely to have dissimilar variable sets, use random effects in their models, or receive poor peer reviews than those analyses that found results that were close to the mean. The existence of substantial variability among analysis outcomes raises important questions about how ecologists and evolutionary biologists should interpret published results, and how they should conduct analyses in the future.