Evolution最新文献

Coevolutionary cycling in allele frequencies due to negative frequency-dependent selection-sometimes referred to as Red Queen Dynamics-is a key potential outcome of host-parasite coevolution. While many theoretical studies have focused on understanding the consequences of coevolutionary cycling for the evolution of sex and recombination, little is known about the impact of coevolutionary cycling on the evolution of other life history traits. It is therefore currently unknown how coevolutionary cycling in allele frequencies affects the evolution of key disease characteristics, such as virulence. Here, we combine population genetic and quantitative genetic approaches to theoretically determine the impacts of coevolutionary cycling in allele frequencies on the evolution of virulence in a free-living parasite. By varying the level of genetic specificity required for infection while controlling for the average infection rate, we induce coevolutionary cycles and examine their effects on virulence evolution. We show that coevolutionary cycling does indeed have a strong impact on virulence evolution, with more specific infection genetics and higher allelic diversity generally driving larger and more rapid cycles in allele frequencies, leading to selection for higher virulence. Our research provides new fundamental insights into the relationship between coevolutionary cycling and the evolution of virulence.

Historically, phylogenetic datasets had relatively few loci but were over-represented for cytoplasmic sequences (mitochondria and chloroplast) because of their ease of amplification and large numbers of informative sites. Under those circumstances, it made sense to contrast individual gene tree topologies obtained from cytoplasmic loci and nuclear loci, with the goal of detecting differences between them-so-called cytonuclear discordance. In the current age of phylogenomics and ubiquitous gene tree discordance among thousands of loci, it is important to distinguish between simply observing discordance between cytoplasmic trees and a species tree inferred from many nuclear loci and identifying the cause of discordance. Here, we examine what inferences one can make from trees representing different genomic compartments. While topological discordance can be caused by multiple factors, the end goal of many studies is to determine whether the compartments have different evolutionary histories: what we refer to as "cytonuclear dissonance." Answering this question is more complex than simply asking whether there is discordance, requiring additional analyses to determine whether genetic exchange has affected only (or mostly) one compartment. Furthermore, even when these histories differ, expectations about why they differ are not always clear. We conclude by pointing to current research and future opportunities that may help to shed light on topological variation across the multiple genomes contained within a single eukaryotic cell.

Omnivory has been hypothesized to be a macroevolutionary sink. A new study by Ochoa-Sanz et al. (2025) tests this hypothesis in Phyllostomidae, a highly ecologically and species-diverse bat family comprising species with different feeding habits, including omnivores and plant specialists. Plant specialists have higher speciation rates than omnivorous bat species, while balanced omnivores have higher speciation rates than plant-predominant ones. Part of the explanation for these differences might be related to the evolution of omnivory during periods of resource scarcity.

The regime of selection acting on a trait is expected to shape its static allometry. Few studies, however, have quantified the form of sexual selection acting on a trait in the wild to test whether the trait allometrically scales as predicted. Even fewer studies have tested these predictions using males expressing weapon polymorphism as part of their alternative mating strategies. Here, I use field data to test how sexual selection shapes scaling allometries of male weaponry in the Wellington tree wētā (H. crassidens), a male-trimorphic and harem-polygynous insect endemic to New Zealand. Contrary to the prediction that 10th instar males' large weaponry would scale hyperallometrically because it is under direct sexual selection, I found that 10th instar weaponry is not subject to direct sexual selection and scales hypoallometrically. Similarly, neither 8th nor 9th instar male weaponry experiences direct sexual selection, and their weaponry scales hyperallometrically and hypoallometrically, respectively. My study suggests that disentangling competing hypotheses for the evolution of scaling patterns of sexually selected traits must go beyond a simple viability-sexual selection dichotomy by also considering weapon function and the ecological context within which the weapon is used.

Winter is a formidable challenge for ectotherms that inhabit temperate climates. The extent to which winter conditions drive rapid adaptation, and separately, how selection from novel stressors affects adaptation to winter, remain poorly understood. Here, we use replicate populations of Drosophila melanogaster in a field experiment to test (i) whether winter conditions drive rapid adaptation and (ii) for trade-offs between insecticide resistance and overwintering survival. Following a longitudinal field experiment investigating the evolution of insecticide resistance, we tracked subsequent evolution during an overwintering period. In unexposed control populations, we detected parallel evolutionary shifts indicative of adaptation to winter conditions in multiple traits, including body size and fecundity. Additionally, populations that had evolved insecticide resistance during the growing season were more likely to go extinct than control populations. Further, both control and resistant populations showed patterns of lower resistance following the winter period, suggestive of a trade-off between overwintering success and insecticide resistance. Rapid evolutionary responses to winter conditions, and potential costs of resistance, provide important context for understanding overwintering performance in temperate insects with implications for pest management and ecosystem services.

Using the voice to produce sound is a widespread form of communication and plays an important role across diverse species and contexts. Variation in the rate and mode of sound production has been extensively studied within orders or classes, but understanding vocal signal evolution ultimately requires comparison across all major lineages involved. Here, we used phylogenetic comparative methods to investigate the evolution of dominant frequency and its association with body mass across a set of 873 species of mammals, birds, and frogs. Our results show that all vocal systems share the same general feature of the negative allometric relationship between body mass and dominant frequency, but that mammals clearly deviate compared to frogs and birds. We found mammals to vocalize at much higher frequencies and their signals evolved four- to sixfold faster compared to other tetrapod clades. Although all three groups strongly rely on vocal communication, our findings show that only mammals have extensively explored the spectral acoustic space. We argue that such high vocal diversity of mammals is made possible by their unique hearing system, and discuss the functional drivers that allowed their shared ancestors to evolve a richer array of frequencies than other tetrapods.

Ecological specialization is a result of the interplay between ecological and evolutionary processes. One iconic ecological specialization of the Neotropics involves birds that follow army ant swarms in feeding groups. Prior work has focused on a single avian family, the Neotropical antbirds (Thamnophilidae), but over a century of fieldwork has now revealed that ant-following occurs in hundreds of distantly related birds. To understand the relative contributions of shared ancestry and ecological specialization in the evolution of ant-following, we compiled a database of all Neotropical ant-following birds (n = 472 species) and their degree of specialization on army ants, and tested if (1) ant-following becomes increasingly specialized through evolutionary time and (2) ecomorphological functional traits predict ant-following behavior. Ancestral state reconstruction revealed that specialized ant-following evolved independently in 8 clades and 4 families of Neotropical birds (Antbirds: Thamnophilidae, Ovenbirds: Furnariidae, Tanagers: Thraupidae, and Cuckoos: Cuculidae). Ant-following behavior was highly conserved phylogenetically (Pagel's λ = 0.97), and specialized clades evolved from less specialized ancestors, with few evolutionary reversals. In contrast, ecomorphological traits poorly predicted the level of ant-following specialization across species. Our results suggest increasing specialization on army ants is governed by niche conservatism, not ecological specialization.

Buzz pollination, where some species of bees vibrate flowers to release pollen, is easily disrupted by rain. Sperotto et al. (2025) show that in the Neotropical clade Miconieae, small flowers often evolve acuminate "drip-tip" petals in humid regions and wet seasons. These petals, resembling leaf drip-tips, repeatedly arose across the phylogeny and are strongly associated with wetter habitats. By draining water away from reproductive organs, drip-tip petals may promote effective pollination, highlighting how floral evolution is shaped by both pollinator interactions and environmental pressures.

The marsupial pouch is a key adaptation for offspring protection and development, yet its evolutionary drivers remain unclear. While body size matters, the role of litter size is less understood. Using phylogenetic comparative methods, we investigated the evolutionary relationship between pouch presence, body mass, and litter size across 195 marsupial species. Our results reveal that pouch presence is strongly phylogenetically conserved and positively correlated with body size, with all large-bodied species possessing a pouch. By contrast, pouch presence is negatively associated with litter size, with species with larger litters typically lacking a pouch, while those with smaller litters retain one. We found that body mass evolves faster in pouched lineages. Ancestral state reconstructions suggest multiple independent origins of the pouch, although the ancestral marsupial condition remains uncertain, but most likely corresponding to pouch absence. These findings support the hypothesis that the pouch evolves in response to trade-offs between offspring quantity and maternal investment, aligning with broader patterns of parental care strategies. Our work provides a new vision for the evolutionary trajectory of one of the most conspicuous marsupial features.

Elaborate female ornaments are rare in nature. One explanation for this is that female investment in ornamentation may take away crucial resources from other costly life history traits, such as fecundity, for which there is likely to be a higher fitness return. However, this trade-off between ornaments and fecundity may be less severe in species where the males offer the female an edible nuptial gift during mating. The nutrition gained from mating may make attracting males with elaborate ornaments more cost-effective for the female. We investigated this link in dance flies in which there is large variation in nuptial gifts, as well as female ornaments. Our phylogenetic analysis showed that nuptial gift value is positively associated with the evolution of female ornaments. We found that species that lack nuptial gifts have no ornaments, and high levels of female ornamentation have evolved most frequently in species with reliable access to an edible nuptial gift with each mating. Our results also suggest that female ornaments have most likely evolved following the evolution of nuptial gifts. We argue that the added benefits from each mating have helped the females to overcome the costs associated with the development and maintenance of ornaments.