Evolution; International Journal Of Organic Evolution[JOURNAL]
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200 papers
Allometry, sexual dimorphism, and sexual trait elaboration in the birds-of-paradise.
MacGillavry T, Toyama KS, Fusani L
Evolution · 2026 Mar · PMID 41432283 · Publisher ↗
Rensch's rule (RR) is a widespread macroevolutionary pattern describing a positive association between male-biased dimorphism and species size. Applied to sexual size dimorphism, RR is often associated with sexual select...
Rensch's rule (RR) is a widespread macroevolutionary pattern describing a positive association between male-biased dimorphism and species size. Applied to sexual size dimorphism, RR is often associated with sexual selection, as larger body sizes may benefit males in competition and courtship. Moreover, the presence of RR in sexual traits further indicates that males reap relative performance benefits beyond large body size alone. Here we describe patterns of elaboration, variation, and sexual dimorphism in tail length in the birds-of-paradise (Aves: Paradisaeidae), which exhibit an extreme diversity in tail lengths, ranging from short-tailed species to the longest-tailed passeriform birds. We found that body size followed RR in polygynous, but not monogamous species, in accordance with the sexual selection hypothesis. However, we found no evidence of RR in tail length, indicating similar evolutionary allometries between males and females. Evolutionary allometries of male and female traits were both strongly positive among long-tailed species, suggesting that the lack of RR results from phenotypic correlations between the sexes, rather than constraints on ornament exaggeration. Our study represents the first integrative test of RR in an ornamental morphological trait and evidences how different aspects of dimorphism interact in a group with a hyperdiverse courtship trait.
Mosaic tri-lineage secondary contact shapes diverse genomic outcomes in darters.
Schwarz PF, Krabbenhoft TJ, Near TJ … +1 more , MacGuigan DJ
Evolution · 2026 Mar · PMID 41427908 · Publisher ↗
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...
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.
Digest: Winter is coming: overwintering selection and the cost of insecticide resistance in fruit flies.
Langmüller AM
Evolution · 2026 Mar · PMID 41427907 · Publisher ↗
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 out...
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.
Digest: Reassortment-based evolution of H1N1 subtype swine influenza virus in China.
Casas A
Evolution · 2026 Feb · PMID 41427906 · Publisher ↗
In a new study, Zhao et al. (2025) obtain 959 whole genome sequences of H1N1 subtype swine influenza virus (SIV) isolated from China. Their analysis of the sequences, isolated between 1977 and 2020, reveals how H1N1 line...
In a new study, Zhao et al. (2025) obtain 959 whole genome sequences of H1N1 subtype swine influenza virus (SIV) isolated from China. Their analysis of the sequences, isolated between 1977 and 2020, reveals how H1N1 lineages have co-evolved and contributed to instances of zoonotic transmission within the region. This study's findings characterize the long-term evolutionary effects of frequent viral reassortment in SIV and highlight its potential to drive future pandemics.
Digest: Craniofacial morphology diversification in Malagasy primates and the role of size constraints in adaptive radiation.
Tsige YG
Evolution · 2026 Mar · PMID 41427898 · Publisher ↗
How did size-related evolutionary constraints shape the diversification of craniofacial morphology during the adaptive radiation of Malagasy lemurs? Toyoda (2025) employed geometric morphometrics to investigate craniofac...
How did size-related evolutionary constraints shape the diversification of craniofacial morphology during the adaptive radiation of Malagasy lemurs? Toyoda (2025) employed geometric morphometrics to investigate craniofacial variation across Madagascar primates. The findings suggest that small-bodied lemurs exhibit a conserved craniofacial form-short rostra and large orbits-driven by mechanical and developmental constraints, yet adapt ecological specialization through rostral modifications. Large-bodied lemurs, in contrast, show greater cranial disparity, indicating a relaxation of size-related constraints. These findings underscore that evolutionary constraints do not merely limit diversification but instead channel morphological evolution along distinct, size-dependent trajectories during adaptive radiation.
On the repeated evolution of parthenogenesis in stick insects.
Schwander T, Soldini L, Boisseau RP … +4 more , Mérel V, Massy M, Toubiana W, Lavanchy G
Evolution · 2026 Mar · PMID 41427879 · Publisher ↗
Female-producing parthenogenesis is widespread in stick insects. It ranges from rare in sexual species to facultative or obligate, the latter sometimes in hybrids. This review synthesizes current knowledge on its origins...
Female-producing parthenogenesis is widespread in stick insects. It ranges from rare in sexual species to facultative or obligate, the latter sometimes in hybrids. This review synthesizes current knowledge on its origins, mechanisms, and evolutionary consequences, highlighting the distinction between hybrid and intra-specific origins. Hybrid-derived parthenogens are rare, obligate, frequently polyploid, and produce heterozygous eggs via endoduplication. Intra-specific parthenogens are more frequent, typically diploid, and often homozygous due to gamete duplication. It can be facultative, allowing both reproductive modes. However, natural populations usually exhibit only one strategy, and intermediate sex ratios are rare. The mosaic distribution of mixed-sex and female-only populations without clear ecological differences suggests other factors drive the observed patterns. Sexual conflict has been proposed, but empirical data is not yet conclusive. In the Timema genus, multiple obligate parthenogens evolved independently from rare spontaneous parthenogenesis in sexual species. This suggests repeated selection for increased parthenogenesis frequencies in different genomic backgrounds. However, parthenogenesis is linked to reduced selection efficiency and slower adaptation. Overall, by providing an update on the current understanding of the phylogenetic distribution, mechanistic diversity, and transitions to parthenogenesis in stick insects, this review establishes Phasmatodea as a model to study the evolutionary significance of parthenogenesis.
Insights from the "Women in Evolutionary Biology Workshop" on gender equality in science.
Kyomen S, Ramirez MA, Glynatsi NE … +2 more , Rodríguez-Sánchez GT, de Azevedo-Lopes A
Evolution · 2026 Mar · PMID 41416699 · Publisher ↗
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 cha...
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.
Digest: Modelling autopolyploid establishment in a novel habitat.
Gross K
Evolution · 2026 Mar · PMID 41416693 · Publisher ↗
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 sing...
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.
Digest: The marsupial pouch as a key evolutionary innovation.
Bubadué J
Evolution · 2026 Feb · PMID 41416691 · Publisher ↗
The pouch has been repeatedly gained and lost throughout marsupial evolution. While its presence is linked to K-strategist traits like larger size and smaller litters, the reasoning behind its loss remains unclear. Casa...
The pouch has been repeatedly gained and lost throughout marsupial evolution. While its presence is linked to K-strategist traits like larger size and smaller litters, the reasoning behind its loss remains unclear. Casali et al. (2026) suggest that pouch evolution enabled the ecomorphological diversity among marsupials. Their findings open new research avenues to investigate the costs and benefits of a pouchless state, from life-history and ecology to its genetic and developmental regulators.
Inferring the strength of directional selection on armor plates in Lake Washington stickleback while accounting for migration and drift.
Yamasaki YY, Yamaguchi R, Nagano AJ … +8 more , Chen BJ, Musto N, Archambeault S, Peichel CL, Schulien JA, Code TJ, Beauchamp DA, Kitano J
Evolution · 2026 Mar · PMID 41400213 · Publisher ↗
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,...
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.
Coincident transitions across elevation and origins of functional innovations drove the phenotypic and ecological diversity of lungless salamanders.
Burress ED, Gade MR, Riddell EA … +1 more , Muñoz MM
Evolution · 2026 Mar · PMID 41400207 · Publisher ↗
Ecological opportunity (EO) is an important catalyst for evolution. Whereas theory often centers around a lineage encountering a source of EO in isolation, in practice they experience numerous sources of opportunity, eit...
Ecological opportunity (EO) is an important catalyst for evolution. Whereas theory often centers around a lineage encountering a source of EO in isolation, in practice they experience numerous sources of opportunity, either concurrently or sequentially. Such multiplicity can obscure the macroevolutionary signature of EO. Here, we test the effects of elevation (a proxy of the "mountain effect") and an array of functional innovations on the evolutionary history of plethodontid salamanders, a diverse and charismatic radiation of lungless amphibians. Functional innovations unlock access to novel microhabitats, ultimately enabling sub-lineages to occupy a diverse range of ecological niches, particularly in lowland areas where those niches are more abundant. Consistent with expanded ecological opportunity, such transitions to lower elevation result in rapid phenotypic evolution. At high elevation, by contrast, rates of phenotypic evolution and phenotypic disparity decline, reflecting a loss of phenotypically extreme ecological specialists. Transitions in elevation and the origin of innovations appear largely coincident among lungless salamanders, suggesting myriad sources of EO. The magnitude of the "mountain effect" on evolutionary rates (∼10-fold) is on par or greatly exceeds that of islands, lakes, and coral reefs on other iconic vertebrate radiations. Therefore, we find that elevation acts as a major ecological moderator and, in concert with functional innovations, shapes the ecological and phenotypic diversity of lungless salamanders.
MoleRate: comparing molecular relative evolutionary rates to detect convergent evolution.
Selberg AG, Clark N, Nekrutenko A … +2 more , Chikina M, Kosakovsky Pond SL
Evolution · 2026 Mar · PMID 41384786 · Full text
In comparative evolutionary genomics, faster or slower evolution of a particular gene, site, or branch in a phylogenetic tree, when compared to the appropriate average, has been interpreted as evidence of conservation, f...
In comparative evolutionary genomics, faster or slower evolution of a particular gene, site, or branch in a phylogenetic tree, when compared to the appropriate average, has been interpreted as evidence of conservation, functional importance, or adaptation. With large consortia generating hundreds of genomes, there is an opportunity to interrogate these datasets for evidence of accelerated or reduced evolutionary rates in protein-coding genes associated with the presence or absence of a given phenotype (e.g., marine vs. terrestrial, nocturnal vs. diurnal). Such rate shifts can reflect the molecular basis of convergent phenotypic adaptation when they occur repeatedly across independent lineages. Here, we introduce an explicit phylogenetic rate test, MoleRate, for acceleration or reduction of nucleotide or protein evolutionary rates in focal lineages vs. the rest of the phylogeny. Compared to existing methods, MoleRate offers execution, explicit likelihood-based hypothesis testing, and the ability to detect and filter out potentially aberrant signal from single lineages. We demonstrate MoleRate's performance on simulated and empirical data, and apply it to several mammalian phenotypes. We also highlight its visualization capabilities, which enable exploration and communication of results. These analyses show that MoleRate detects biologically significant enrichments in selective pressure on specific functions related to the given phenotype, and that enrichments in selective pressure related to the given phenotype, absent when random lineages are tested.
The role of ecology in allopatric speciation of darters in the Central Highlands, USA.
Stokes MF, Harrington RC, Kim D … +5 more , Westhoff JT, Berkman LK, Taylor A, Quinn JW, Near TJ
Evolution · 2026 Feb · PMID 41370042 · Publisher ↗
Allopatric speciation is the predominant mode of speciation in riverine fishes. However, the relative importance of genetic drift versus natural selection in the allopatric speciation of these fishes remain uncertain. He...
Allopatric speciation is the predominant mode of speciation in riverine fishes. However, the relative importance of genetic drift versus natural selection in the allopatric speciation of these fishes remain uncertain. Here, we present a case study that demonstrates the role of ecology in the diversification of a group of imperiled freshwater fishes from the central United States. We integrate a phylogenomic dataset with analyses of streamwise distance, environmental variables, meristic and morphological traits, and diet to investigate the ecological context and outcomes of allopatric speciation within a species complex comprising the Slenderhead Darter Percina phoxocephala (Nelson), Ouachita Darter Percina brucethompsoni (Robison, Cashner, and Near), and Longnose Darter Percina nasuta (Bailey). We find that two of the species traditionally delimited based on disparity in snout length, P. phoxocephala and P. nasuta, are polyphyletic, revealing three instances of the parallel evolution of snout length disparity. We propose a revised taxonomy including the delimitation of six new species based on disparity in phenotypic traits and phylogenomic analyses. We find that morphological differences are not correlated with genetic divergence but are congruent with variations in diet and environmental niches, suggesting a role for ecological factors in allopatric speciation of riverine fishes.
Nest weave pattern in weaverbirds: a sexual signal selected through sensory drive?
Harscouet-Commecy E, Penacchio O, Oschadleus HD … +7 more , Colençon P, Pelte M, Dufour P, Andersson S, Covas R, Renoult JP, Doutrelant C
Evolution · 2026 Mar · PMID 41347895 · Publisher ↗
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 pro...
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.
Digest: Direct benefits as a mechanism promoting the evolution of female ornamentation.
López-Idiáquez D
Evolution · 2026 Feb · PMID 41344889 · Publisher ↗
It has been proposed that female ornaments are less likely to evolve because females face a steeper trade-off between offspring production and ornamentation than males. In their study, Pärssinen et al. (2026) show that d...
It has been proposed that female ornaments are less likely to evolve because females face a steeper trade-off between offspring production and ornamentation than males. In their study, Pärssinen et al. (2026) show that direct benefits provided by males during reproduction are associated with the presence of female ornamentation in dance flies, probably because such benefits allow females to offset the costs that may arise from producing these traits.
Interspecific allometry of sexual shape dimorphism in small-bodied and large-bodied geckos.
Glynne E, Adams DC
Evolution · 2026 Mar · PMID 41334821 · Publisher ↗
At macroevolutionary scales across species, sexual dimorphism often covaries with body size, generating allometric trends. Such patterns are most evident for body size dimorphism, while trends in sexual shape dimorphism...
At macroevolutionary scales across species, sexual dimorphism often covaries with body size, generating allometric trends. Such patterns are most evident for body size dimorphism, while trends in sexual shape dimorphism remain underexamined. Additionally, how small body sizes (miniaturization) affects such patterns is largely unknown. We evaluated allometry in sexual shape dimorphism in two families of geckos to determine whether changes in body size associate with changes in shape dimorphism. Using surface scans of head shape from nearly 600 individuals across 99 species, we found considerable variation in levels of sexual shape dimorphism across taxa, with some species displaying little dimorphism and others exhibiting large sexual differentiation. Interspecific trends differed between the two families, with strong negative allometry in Sphaeorodactylidae (a family with many small-bodied species), while Phyllodactylidae (a family containing few small-bodied species) displayed isometry and no discernible trend. Notably, greater sexual shape dimorphism was displayed in small-bodied sphaerodactylid species, and corresponded with females exhibiting more robust heads; consistent with sex-specific foraging strategies and dietary differences observed in this group. Our study reveals that interspecific allometry in traits other than body size can have a pervasive influence on patterns of phenotypic diversity across the tree of life.
Distinct intraspecific diversification dynamics in Neotropical montane versus lowland canopy birds (Thraupidae: Tangara) revealed by whole-genome comparative phylogeography.
Wacker KS, Winger BM
Evolution · 2026 Feb · PMID 41324244 · Publisher ↗
Comparing phylogeographic patterns across different biogeographic regions can illuminate how different types of landscapes promote the formation and persistence of incipient species, providing insights into the evolution...
Comparing phylogeographic patterns across different biogeographic regions can illuminate how different types of landscapes promote the formation and persistence of incipient species, providing insights into the evolutionary mechanisms underlying broadscale biodiversity gradients. The Neotropics are a global biodiversity hotspot, and the megadiverse Andes-Amazonia system exhibits elevational gradients in both species richness and speciation rates. Using whole genomes from a congeneric set of eight habitat-generalist canopy frugivore birds (Tangara tanagers), we compare the phylogeography of tropical Andean versus lowland Amazonian species to characterize intraspecific diversification dynamics associated with these distinct but adjacent biomes. We found that all species exhibited low genetic structure consistent with their dispersive ecology, but Andean species have relatively greater population genetic structuring across their ranges than Amazonian species. Additionally, populations separated by prominent geoclimatic barriers showed lower gene flow and higher differentiation in montane versus lowland Tangara. Lastly, all Andean species have lower genetic diversity, a proxy of effective population size. Together, these results support greater incipient speciation in the mountains owing to stronger allopatry and smaller populations, while the larger, more diverse, and well-connected populations of the lowlands may foster enhanced persistence. We discuss potential implications for the origin and maintenance of regional biodiversity gradients.
The long-term evolutionary potential of four yeast species and their hybrids in extreme temperature conditions.
Pinto J, Stelkens R
Evolution · 2026 Feb · PMID 41313323 · Publisher ↗
Accelerating climate change and extreme temperatures urge us to better understand the potential of populations to tolerate and adapt to thermal challenges. Interspecific hybridization can facilitate adaptation to novel o...
Accelerating climate change and extreme temperatures urge us to better understand the potential of populations to tolerate and adapt to thermal challenges. Interspecific hybridization can facilitate adaptation to novel or extreme environments. However, predicting the long-term fitness effects of hybridization remains a major challenge in evolutionary and conservation biology. Experimental evolution with microbes provides a powerful tool for tracking adaption, across generations and in real time. We investigated the thermal adaptation dynamics of four species of budding yeast (Saccharomyces) and their interspecific F2 hybrids, for 140 generations under cold (5°C) and warm (31°C) conditions. We found significant variation in the evolutionary potential of species and hybrids, strongly determined by their natural temperature tolerance. The largest fitness improvements occurred in hybrids, with some populations nearly quadrupling in fitness in the cold environment, exceeding both parents in thermal adaptive potential. While adaption rates in some hybrid populations were high, their absolute fitness by the end of evolution was comparable to that of their parents. Reciprocal transplanting of evolved populations from the endpoint of evolution into opposite temperatures revealed that hybrids had greater resilience when challenged with sudden temperature shifts. Our results highlight that hybridization alters the fitness outcomes of long-term adaptation to extreme environments and may render populations more resilient to sudden environmental change, presenting both opportunities and challenges for conservation and sustainable agriculture.
Loss of pair formation predates the evolution of male-less society in termites.
Mizumoto N, Yashiro T, Hellemans S
Evolution · 2026 Feb · PMID 41313316 · Publisher ↗
Asexual lineages are rare in social animals with biparental care, where successful reproduction typically requires coordinated behavior between two individuals of opposite sex. Male-less lineages of the termite Glyptoter...
Asexual lineages are rare in social animals with biparental care, where successful reproduction typically requires coordinated behavior between two individuals of opposite sex. Male-less lineages of the termite Glyptotermes nakajimai provide a unique opportunity to unravel how sexual reproduction can be lost in such animals. Here, we show that modification of the mate-pairing process predated the evolution of asexual populations. Termite colonies are typically initiated by a mating pair that searches for a nest site through a tandem courtship behavior. Our comparative analysis of tandem running in Glyptotermes termites revealed that two related species, G. fuscus and G. satsumensis, exhibit both female-leader and male-leader tandem runs. However, tandem running was rare and ephemeral in both sexual and asexual lineages of G. nakajimai. Furthermore, our comparative studies indicated typical monogamous pairing was uniquely lost in G. nakajimai, while pairs initiate nests in G. fuscus and G. satsumensis. Our study evidenced that a clear disruption of termites' classic reproductive behavioral sequence, coupled with an alternative mode of colony foundation, was likely a precondition for the evolution of asexuality in species with biparental care.
On the expression of male harm in Drosophila melanogaster: impacts of density and structural complexity of the mating environment.
Osijo K, Agrawal AF, Rundle HD
Evolution · 2026 Feb · PMID 41313308 · Publisher ↗
Male harm occurs when traits in males that increase their reproductive success incidentally reduce female fitness. In Drosophila melanogaster, many lab studies have revealed the presence of male harm, but recent work has...
Male harm occurs when traits in males that increase their reproductive success incidentally reduce female fitness. In Drosophila melanogaster, many lab studies have revealed the presence of male harm, but recent work has shown that its expression can be dramatically reduced, even eliminated, when sexual interactions and mating occur in an environment that differs from traditional lab rearing vials. Here, we follow up on this to separately test the effect of fly density and structural complexity of the mating environment in mediating the expression of male harm. We performed separate two-way factorial assays that measured the fitness of females while manipulating their exposure to males and the density of flies or the structural complexity of the environment during exposure. Male harm, quantified as the relative reduction in female fitness under increased male exposure, was not affected by density, but was significantly reduced-essentially eliminated-by increased structural complexity. Our results demonstrate that seemingly simple choices, such as the environment used in a laboratory model system, can have profound impacts on the expression of harm and hence views on the prevalence of sexual conflict. This is noteworthy because conflict can shape other fundamental evolutionary processes, including adaptation, purging, and speciation.
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