Evolution最新文献

Do winter conditions drive rapid adaptation in insects, and does prior selection for insecticide resistance constrain it? To test these questions, Prileson et al. (2026) exposed replicate Drosophila populations to an outdoor overwintering period and tracked traits before and after in common gardens. Control populations that had not been previously exposed to insecticides showed consistent shifts in body size and fecundity, indicating rapid adaptation. Resistant populations suffered higher winter mortality, and both control and resistant populations were more susceptible to insecticides after overwintering, indicating a trade-off between resistance and overwintering performance.

A recently published genome sequence of a YY guppy male supports long-standing suggestions about the Y-linked region of this fish-that it includes both the male-determining locus and also male coloration factors that have sexually antagonistic effects. Selection against effects of these factors in females is expected to maintain associations with the male-determining locus, and to select for closer linkage in the region, and might lead to suppressed recombination and "evolutionary strata". The new finding that two sequenced Y chromosomes differ specifically in this region suggests that these represent two different Y haplotypes carrying different coloration factors that have been maintained for long enough that their sequences have become differentiated. As theory predicts, such a genome region will show complex peaks and troughs of sequence diversity, and it may be very difficult to locate the individual male-determining and male coloration loci, even when both types of factors have been maintained long-term by frequency-dependent balancing selection.

Nests are primarily shaped by natural selection, but are also subject to sexual selection. Here, we investigated the potential role of sexual selection in shaping nest visual patterns, focusing on scale-invariance, a property describing how patterns remain similar across spatial scales. In humans, it has been documented that visual patterns are more attractive when their scale-invariance resembles natural habitats, likely because they are more efficiently processed. The underlying mechanism, called processing bias, extends the sensory drive hypothesis from colors to patterns. Applied to birds, processing bias predicts that nests whose scale-invariance matches natural habitats could be sexually selected. We tested this using a comparative analysis of weaverbirds. We quantified the deviation of nest scale-invariance from a range of putative selection optima, and then evaluated whether interspecific variation in this deviation is explained by mating system and sexual size dimorphism, two proxies for sexual selection. For both proxies, effect sizes were largest for the same putative optimum, aligning with scale-invariance values in natural habitats. Sexual selection may thus favor nest designs that are efficiently processed, such as those with habitat-like features. Our findings also highlight the challenge of designing a specific test for this hypothesis and call for further research linking pattern perception and sexual selection.

Contemporary evolution allows us to investigate how natural selection drives phenotypic and genotypic evolution in nature. Recent advances in molecular genetics have identified causative genes underlying adaptive traits, enabling estimation of selection coefficients at these loci. However, estimating selection is challenging when populations receive migrants from genetically and phenotypically distinct populations. With genome-wide data now allowing estimation of migration rates and effective population sizes, these demographic parameters can be integrated into models for measuring selection. In Lake Washington, USA, the frequency of the completely plated morph of the threespine stickleback (Gasterosteus aculeatus) increased from 1957 to 2005, plausibly due to increased trout predation pressure caused by enhanced water clarity. Here, we estimated the selection coefficient at a major locus responsible for the plate morph using historical data, taking migration and genetic drift into consideration. Model-based predictions of present allele frequencies were tested with samples collected in 2022. Consistent with directional selection, the completely plated morphs and the underlying allele have increased since 2005, but to higher frequencies than predicted, suggesting a recent increase in selection. Thus, integrating molecular genetics, population genomics, and simulations enables the estimation of selection strength while considering migration and drift, to reveal directional selection in nature.

Speciation does not always lead to complete reproductive isolation, which can result in hybrid zones with gene flow. In freshwater fishes, secondary contact and hybridization can arise when river courses shift. Shifting river courses can create physical and ecological dispersal barriers, producing fragmented species distributions within the same stream system. Here, we investigate a secondary contact zone in western New York (USA) between the Tessellated Darter (Etheostoma olmstedi) and the Johnny Darter (Etheostoma nigrum), integrating double digest restriction site associated DNA sequencing (ddRADseq), low-coverage whole genome sequencing (lcWGS), and mtDNA datasets. Our analyses reveal a complex tri-lineage hybrid zone of E. olmstedi and two divergent E. nigrum lineages. lcWGS and ddRADseq approaches yield similar overall results for population genetic structure; however, the two approaches differ in estimates of the magnitude of population differentiation. Several sites with ongoing admixture are proximate to stream confluences and form a temporally stable mosaic of hybridization across the contact zone. We observe active and apparently stable states of hybridization, supporting the hypothesis that niche partitioning by stream size maintains species identity. The species and populations in the contact zone maintain high levels of genome-wide differentiation across streams. Our study provides insight into the dynamic process of secondary contact and highlights the array of possible genomic outcomes of hybridization.

What is the probability that autopolyploids establish in a novel, unoccupied habitat, and how is this affected by selfing and assortative mating? Using a modelling approach, Zwaenepoel (2025) found that, following a single migration event, autopolyploids are more likely than diploids to establish under a wide range of circumstances. The author also found that, under continuous migration, the rate of migration, along with factors such as selfing and assortative mating, affects the time to autopolyploid establishment. These findings help to explain how polyploids may colonize more extreme peripheral habitats.

Phenotypic plasticity is widespread and evolutionarily important, but genomic consequences of new plastic traits remain unclear. Here, we explore patterns of molecular evolution linked to the repeated evolution of Cephalotes turtle ant worker plasticity, in which smaller minor workers and distinct larger soldiers are produced from a single genomic blueprint through developmentally plastic mechanisms. We integrate developmental transcriptomics with comparative genomic approaches to test the relative relationships of selection on genes, selection on regulatory sequences, and the emergence of lineage-specific genes with the repeated evolution of the soldier morph. We find that phenotypic plasticity shields protein-coding genes from selection, whereas it imposes a strong selective constraint on the evolution of gene regulatory loci. The development of a soldier morph disproportionately involves the activity of evolutionarily ancient genes. Moreover, our data link 3 pathways-nutrition via insulin signaling, imaginal disc development, and for the first time Hippo signaling-which allow for the differential development of soldiers and workers from a single genomic background in turtle ants. Taken together, our results provide evidence that plasticity leads to relaxed selection on genes, but imposes selective constraint on regulatory elements, during the repeated evolution of the turtle ant soldier morph.

Phenotypic plasticity can alter evolutionary dynamics, but its genomic consequences remain contested. Barkdull & Moreau (2026) combine comparative genomics and developmental transcriptomics in Cephalotes turtle ants to show that the repeated evolution of a soldier morph produces an asymmetric genomic signature: protein-coding genes experience genome-wide relaxed selection and reduced positive selection, whereas conserved noncoding regulatory elements show increased purifying constraint. Worker morph plasticity is driven mainly by co-option of ancient genes and by integration of insulin, imaginal-disc, and Hippo signaling.

In May 2024, the Women in Evolutionary Biology Workshop was held at the Max Planck Institute for Evolutionary Biology. The event served as a platform for researchers to present their scientific work and to reflect on challenges that can arise for women in academic environments. The program featured scientific talks and poster sessions, alongside discussion forums focused on advancing equity and improving working conditions in academia. In this manuscript, we provide an overview of the workshop and highlight key themes that emerged from the discussions. These included under-representation in leadership roles, implicit bias, structural inequality, intersectionality, workplace culture, and the impact of parenthood on academic careers. By situating these insights within the broader scholarly literature, we identify recurring structural patterns across institutions and disciplines. We also offer actionable strategies to inform efforts toward a more supportive academic culture. The workshop discussions emphasized how power imbalances and distorted assumptions about meritocracy can contribute to unequal access to opportunities, with intersectional factors-such as race, class, and cultural background-further shaping these dynamics. This manuscript highlights the value of events like this one and contributes to ongoing conversations around equity and inclusion in science by capturing and contextualizing the experiences and reflections shared during the workshop.