Evolution最新文献

Allopatric speciation in riverine fishes is often assumed to be ecologically neutral, with divergence driven primarily by geographic isolation and genetic drift. However, recent work on darters from the Central Highlands of the United States reveals that ecological divergence during allopatry is highly variable and context dependent. By integrating phylogenomics, morphology, diet, and environmental data, Stokes et al. (2026) demonstrate that phenotypic divergence can arise in allopatrically distributed riverine fish species. However, the degree of phenotypic disparity is not predicted by divergence time, genomic isolation, or geographic distance, highlighting a contingent role for ecology in shaping evolutionary outcomes under allopatry.

Net selection on a trait reflects the association of phenotype to fitness across an entire life cycle. This longitudinal selection estimate can be viewed as the summation of selection episodes across time, each characterized by a cross-sectional estimate. Selection may be consistent in direction and strength across episodes for some traits, fluctuating in others, and for some, concentrated in a single intense event. While selection on plant reproductive traits is predicted to be stronger through male fitness than female fitness, male fitness remains less studied. We investigated how selection on flowering traits in Brassica rapa varies across a season by measuring male reproductive fitness in four experimental populations. To estimate longitudinal and cross-sectional selection, we introduced plants at successive intervals within a single reproductive season. We genotyped over 3000 plants and calculated selection on flowering time, duration, and total flowers. Cross-sectional analyses revealed directional selection was common, but patterns were masked by longitudinal estimates. Manipulation of spatial arrangement within populations further revealed to significantly impact pollen movement. Our experiment demonstrates that breeding timing and spatial aggregation interact to create complex evolutionary dynamics.

Global temperatures are rising and inbreeding is increasingly common in wild animals as populations decline. There is extensive research on inbreeding and temperature stress, but little is known about how they interact to affect sexually selected traits. We therefore investigated how developmental temperature (26°C or 30°C) and inbreeding affect male guppies (Poecilia reticulata). We reciprocally cross-bred full-siblings to create inbred and outbred fish, then measured traits under either pre-copulatory (i.e., coloration, gonopodium length, sexual attractiveness, mating behavior) or post-copulatory (i.e., sperm number, velocity) sexual selection for ∼120 adult males. There was no evidence that temperature and inbreeding interact to affect trait expression; instead, their effects were additive. Males reared at 30°C were significantly less attractive to females, and made fewer sigmoid mating displays, than males reared at 26 °C. Inbred males were also less attractive, but their mating behavior did not differ from that of outbred males. Sperm number and velocity were unaffected by inbreeding or developmental temperature. Unexpectedly, males reared at 30 °C and inbred males both had significantly more orange coloration. Our results show that inbreeding and developmental temperature independently influence some sexually selected male traits, suggesting that climate change and habitat fragmentation might alter evolution under sexual selection.

Phylogenetic eigenvector regression (PVR) is widely used in ecology and evolution by representing phylogenetic structure through separable eigenvectors. Despite this flexibility, its implementation faces three key challenges: (1) the selection of eigenvectors, (2) the reduced robustness of ordinary least-squares (OLS) regression under shift-like evolutionary heterogeneity, and (3) the applicability of conventional model complexity rules such as the "samples-per-variable (SPV) ≥ 10" guideline. Here, we propose an optimized PVR framework that addresses these limitations. First, we show that trait-specific selections of eigenvectors often diverge, sometimes producing inconsistent results, and that using their union offers stronger control of phylogenetic non-independence. Second, we evaluate robust regression estimators within PVR, demonstrating that PVR-MM-and in most cases PVR-L2, the standard OLS estimator-maintains high accuracy under non-stationary evolutionary shifts where other non-robust methods fail. Third, through simulation, we reassess the SPV ≥ 10 rule, showing that PVR tolerates eigenvector counts well beyond this threshold, offering greater flexibility while requiring attention to potential overfitting. Extensive simulations across diverse trees and evolutionary scenarios confirm that the optimized framework improves accuracy and robustness. By addressing key aspects of eigenvector selection, regression, and model complexity, our findings strengthen the reliability and applicability of PVR.

Biodiversity is structured in nested Retrospective Reproductive Communities (RRCs) reflecting different levels of information about evolutionary processes. Ranking species involves deciding which level to emphasize, based on a trade-off in information gain and loss. Modeling the selective processes that maintain RRCs along distinct evolutionary paths can inform these trade-offs in species delimitation. We illustrate this approach using the Brazilian wandering spiders (Phoneutria). Integrating genetic markers, geometric morphometrics, color patterns, and environmental data, we applied both established and novel approaches to test divergence through historical natural and sexual selection. We found evidence that selection on ecological niche and ventral abdominal coloration contributed to the formation of four distinct RRCs. Two of these RRCs also showed evidence of a Lock-and-Key mechanism influencing genital morphology evolution. Despite the distinct cohesive forces, gene flow modeling revealed incomplete reproductive isolation, with potential hybrid individuals. We evaluate the implications of lumping versus splitting these lineages and argue that recognizing all four RRCs as distinct species would better preserve evolutionary information and minimize downstream impacts on other research fields such as pharmacology, public health and conservation. Our approach provides a quantitative basis to ponder the implications of choosing between different species hypotheses.

Divergent selection on coloration and patterning can drive diversification among closely related species. In a recent study, Schroth-Sanchez et al. (2026) used Darter fish to identify specific habitat variables that influence color evolution. They found that smaller, rocky streams with fewer predators and high light environments contribute to greater rates of diversification and brighter, bolder patterns. This work suggests that certain habitats may foster greater diversification and speciation through an interplay of ecological and sexual selection.

Principal Component Analysis (PCA) is one of the most widely used approaches for multivariate datasets. Biologists use PCA to visualize data, identify patterns in large datasets, determine independent axes of variation, and reduce dimensionality for further statistical analyses. Phylogenetic PCA is an extension of regular PCA that seeks to identify the major axes of variation independent of the phylogeny. We extend these methods by estimating PCA parameters using an explicit probability modeling framework. We implement multiple models of trait evolution (Brownian motion, Ornstein-Uhlenbeck, Early Burst, and Pagel's λ) and use the Akaike Information Criterion (AIC) for model selection. We also introduce a probabilistic approach to select the number of principal components to retain from a PCA. We demonstrate the advantages of probabilistic PCA, such as incorporating the error, or noise, arising from dimensionality reduction, which is ignored in regular PCA. We use extensive simulations and an empirical dataset with 35 traits to show the method's performance. We implemented the new approach in the R package "do3PCA" available from the RCran repository.

Eusociality, the highest level of social organization, is rare among vertebrates and is best exemplified by two African mole-rat species (Bathyergidae). The lifetime monogamy hypothesis suggests that monogamy enhances genetic relatedness within colonies, favoring the evolution of cooperative behaviors and eusociality. While strongly supported in eusocial insects, its role in vertebrates remains unclear. We evaluated this hypothesis in the Bathyergidae to determine the role of monogamy in the evolution of eusociality in vertebrates. We evaluated two predictions: (1) eusociality should be restricted to monogamous lineages, i.e., monogamy is a pre-condition of eusociality; and (2) factors additional to monogamy are required for eusociality to evolve. To test these predictions, we inferred a time-calibrated phylogeny for most species of Bathyergidae and combined it with mating system and sociality data to estimate ancestral states and assess evolutionary correlations. We inferred an ancestral monogamous state for social and eusocial African mole-rats. One of the evolutionary transitions with the highest rate of change was from monogamy + solitary to monogamy + social. Our results are consistent with monogamy representing a necessary prerequisite for the evolution of obligate eusociality, while also indicating that additional ecological and life-history factors are required for eusociality to evolve and intensify.

Recent studies have revealed bacterial genome-wide evolution to be complex and dynamic even in a constant environment, characterized by the emergence of new clades competing or temporarily coexisting as each clade undergoes evolutionary change. Previous studies on predator-prey dynamics tracking simple ecological and phenotypic metrics have shown predation to fundamentally alter prey evolution, facilitating defense evolution followed by coevolution and frequency dependent selection between defended and undefended prey genotypes. Here we sought to consolidate these fields by examining genome-wide evolution in five bacterial prey species separately subjected to long-term evolution under ciliate predation. We hypothesized that the presence of predation could change the pattern of clonal dynamics, for example, by more frequently producing selective sweeps if predation-defense-related mutations are under strong selection. For all species, we found mutational signals of prey adaptation, with phenotypic data and genomic mutation targets demonstrating changes in composition between the experimental treatments. Intriguingly, despite higher variant counts, overall temporal clade dynamics across the coevolved prey species were strikingly similar to those of bacteria evolving alone, with constant emergence, competition and quasi-stable coexistence of clades. This study shows that long-term molecular evolution in bacterial prey under predation is more interesting and less predictable than we might expect based on existing coevolutionary theories.

Evolutionary theory predicts that variation in longevity persists due to trade-offs between early-life fitness traits (e.g., growth or fecundity) and long-term somatic maintenance. However, such trade-offs can be difficult to detect and may often become apparent only under certain conditions. For instance, developing in novel or atypical environments may alter the genetic architecture of traits, revealing trade-offs that are otherwise hidden under normal conditions. To test this, we compared full-sibling families of the Mexican spadefoot (Spea multiplicata) reared across two larval diets: a typical detritus diet and an atypical live shrimp diet, which they are competitively excluded from in nature. The shrimp diet significantly increased broad-sense genetic variance and heritability for larval growth rate, whereas heritability for post-metamorphic telomere length - a known longevity correlate - remained similar across diets. Moreover, only on the shrimp diet did families with faster growth exhibit shorter telomeres, consistent with a diet-dependent trade-off between growth and somatic maintenance. Overall, our study shows that developing under atypical dietary conditions exposes previously cryptic genetic variation in growth, thereby revealing a trade-off with somatic maintenance. These findings have implications for understanding how environmental change, such as rapid dietary shifts, can shape aging processes and vulnerability to age-related disease.