Evolution; International Journal Of Organic Evolution[JOURNAL]
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200 papers
Lungless tadpoles breathe fresh air into hypotheses for tetrapod lung loss and trait regain.
Phillips JR, Dias PHDS, Womack MC
Evolution · 2025 Dec · PMID 41143438 · Publisher ↗
The environmental factors associated with adaptive trait loss and the extent to which lost traits can be regained have been subject to much speculation and debate in evolutionary biology. We use tadpole lungs to test if...
The environmental factors associated with adaptive trait loss and the extent to which lost traits can be regained have been subject to much speculation and debate in evolutionary biology. We use tadpole lungs to test if previously proposed environmental factors, such as a stream habitat, are associated with larval lung loss and whether lungs can be regained following loss. We assembled a dataset of lung presence for the larvae of 529 anurans, finding 28 instances of larval lung loss, and develop a methodological framework to test the evolutionary associations between lung loss, general habitat type, terrestriality, and stream specialization, finding strong support for the final 2 factors in adaptive lung loss. The likelihood of regain is thought to depend on whether developmental pathways are preserved over time; accordingly, we predicted larval lung loss to be highly reversible. And yet, we found that larval lungs were never regained, despite lungless tadpoles evolving to live in habitats that favor lung use and all lungless tadpoles developing into lunged frogs. Traditional explanations of irreversibility do not easily explain why stage-specific trait loss would be irreversible, prompting us to examine alternative explanations for natural patterns of irreversibility observed across the tree of life.
Parental care liberates juvenile growth: a common-garden test of the evolutionary benefits of care.
Eggert AK, Prang MA, Capodeanu-Nägler A … +10 more , Takata M, Creighton JC, Hwang W, Sakaluk SK, Sikes DS, Smith AN, Suzuki S, Trumbo ST, Zywucki L, Steiger S
Evolution · 2026 Jan · PMID 41129399 · Publisher ↗
Effects on juvenile growth have long been considered an important benefit of parental care, but they have rarely been tested empirically. Protection and feeding by parents might accelerate offspring growth by allowing of...
Effects on juvenile growth have long been considered an important benefit of parental care, but they have rarely been tested empirically. Protection and feeding by parents might accelerate offspring growth by allowing offspring to allocate more resources to growth (resource-allocation hypothesis). Protected young could shift investment away from defensive adaptations toward growth (defensive reallocation), and parental feeding should increase the total amount of assimilated resources (energy intake). Alternatively, rapid growth can be costly due to damage caused by reactive oxygen species, and parental protection might facilitate slower growth to avoid this (costly acceleration hypothesis). We tested these hypotheses along with the suggestion that egg and adult size are correlated with growth in a common-garden study of 17 species of carrion beetles (Silphinae, a subfamily of the beetle family Staphylinidae). Our results were consistent with the resource-allocation hypothesis but did not support the costly acceleration hypothesis or the idea that egg or adult size constrains growth. Species that are normally protected by parents grew faster, not slower, than those that are not. This was true even when their parents were removed and could not feed, supporting the concept of defensive reallocation. As expected based on greater energy intake, the young of species with parental feeding grew faster when their parents were present than when they were not. When phylogeny was accounted for, neither egg nor adult size was related to early growth rate.
Widespread evolution of poricidal flowers: a striking example of morphological convergence across flowering plants.
Russell AL, Zenil-Ferguson R, Buchmann SL … +3 more , Jolles DD, Kriebel R, Vallejo-Marín M
Evolution · 2026 Jan · PMID 41124058 · Publisher ↗
The evolution of tube-like floral morphologies that control pollen release via small openings (functionally poricidal flowers) represents a taxonomically and geographically widespread instance of repeated and independent...
The evolution of tube-like floral morphologies that control pollen release via small openings (functionally poricidal flowers) represents a taxonomically and geographically widespread instance of repeated and independent evolution of a functionally similar morphology. Poricidal flowers are also often closely associated with buzz pollination by bees. Yet we lack an updated angiosperm-wide survey of their phylogenetic distribution. We identify all known angiosperm genera containing poricidal flowers via a literature survey. We determined their phylogenetic distribution and minimum number of independent gains and losses via a species-level angiosperm-wide phylogeny. We estimated if evolution of poricidal flowers is associated with changes in speciation/extinction via diversification rate analyses. Poricidal flowers occur across 87 angiosperm families and 639 genera containing > 28,000 species. At the species level, an average of 205 independent gains and 215 losses of poricidal flowers occurred. Angiosperm-wide analyses suggest an early burst in poricidal evolution, but no differences in net diversification (origination-extinction) between non-poricidal and poricidal taxa. Analyses for two focal families however indicate strong context-dependent effects of poricidal flowers on diversification. Poricidal evolution thus represents a large-scale example of convergent evolution in floral form, but effects on diversification appear to be strongly contingent on phylogenetic and ecological background.
Revisiting evolutionary rate-time relationships.
De Lisle SP, Svensson EI
Evolution · 2026 Jan · PMID 41124039 · Publisher ↗
Rates of molecular, phenotypic, and lineage diversification typically scale negatively with time interval of measurement, raising longstanding questions about time-dependency of evolutionary processes. These patterns and...
Rates of molecular, phenotypic, and lineage diversification typically scale negatively with time interval of measurement, raising longstanding questions about time-dependency of evolutionary processes. These patterns and their potential meaning have recently re-entered evolutionary discussions. In this Perspective, we revisit the general challenges in interpreting rate-time relationships. Much apparent temporal scaling of evolutionary rate is an inescapable outcome of plotting a ratio against its denominator, either directly or indirectly. Highly unlikely relationships between timescale and accumulated evolutionary change are required to produce anything other than negative rate-time relationships. Simulations reveal that constant-rate evolutionary processes readily generate negative rate-time scaling relationships under many conditions, and that a range of rate-time scaling exponents can be generated by different evolutionary processes. Reanalysis of 6 empirical datasets reveals unscaled magnitudes of evolution that are either unrelated to time and/or vary in their relationship with time. Over 99% of variation in rate-time relationships across 6 datasets is explained by time variation alone. We further evaluated a recent hypothesis that evolutionary rate-time scaling reflects three modes of change, from micro- to macroevolutionary time scales using break-point regression, but we found no strong support for this hypothesis. Taken together, negative rate-time relationships are therefore largely inevitable and challenging to interpret. In contrast, it is more straightforward to assess how evolutionary change accumulates with time.
Genetic diversity and evolution of H1N1 subtype swine influenza virus in China: a comprehensive analysis from 1977 to 2020.
Zhao Y, Han L, Sang H … +3 more , Yang P, Xiao Y, Hou Y
Evolution · 2026 Jan · PMID 41124035 · Publisher ↗
Swine influenza virus (SIV) is a highly contagious respiratory pathogen that causes significant economic losses in the swine industry and poses a potential health risk to humans. This study investigated the genetic diver...
Swine influenza virus (SIV) is a highly contagious respiratory pathogen that causes significant economic losses in the swine industry and poses a potential health risk to humans. This study investigated the genetic diversity and evolution of the H1N1 subtype SIV across different regions of China over the past four decades. Using 959 whole-genome sequences collected between 1977 and 2020 from public databases such as GenBank and the Global Initiative on Sharing Avian Influenza Data (GISAID), we systematically analyzed the epidemiology, phylogenetics, genotypes, and molecular characteristics of the H1N1 subtype SIV. The results revealed marked temporal and geographic heterogeneity in virus distribution, with six major lineages and 25 distinct genotypes identified. The Eurasian avian-like (EA) lineage predominated, reflecting its adaptive advantage in swine populations. Genotypic turnover was evident over time, with certain genotypes (e.g., genotype 2 and genotype 3) exhibiting molecular features associated with adaptation to human hosts, thereby elevating the risk of cross-species transmission and potential pandemics. Amino acid site analysis further identified mutations favoring human-like receptor binding, mammalian adaptation, and antigenic variation. These findings highlight the ongoing evolution of H1N1 subtype SIV in China and underscore the necessity for continuous surveillance and enhanced biosecurity measures in the swine industry to mitigate future pandemic threats.
Genomic divergence, demographic histories, and male territorial response reveal asymmetric reproductive barriers in allopatric eastern versus western Nashville warbler subspecies (Leiothlypis ruficapilla).
Phung LN, Baiz MD, Wood AW … +2 more , Moore M, Toews DPL
Evolution · 2026 Jan · PMID 41124015 · Publisher ↗
In song-learning birds, vocalizations are species recognition signals and may act as premating reproductive barriers; for allopatric taxa, testing how the signals can influence the speciation processes is quite challengi...
In song-learning birds, vocalizations are species recognition signals and may act as premating reproductive barriers; for allopatric taxa, testing how the signals can influence the speciation processes is quite challenging. This study aims to understand genomic divergence and species recognition via songs in 2 allopatric taxa, eastern and western Nashville warblers (Leiothlypis ruficapilla ruficapilla vs. Leiothlypis ruficapilla ridgwayi). We performed playback experiments to assess their reciprocal behavioral responses, which suggests an asymmetric barrier: the eastern L. r. ruficapilla discriminates between the 2 songs, but the western L. r. ridgwayi does not. Using whole-genome sequencing, we also examined the extent of the taxa's genomic divergence and estimated their demographic history. We identified dozens of highly differentiated genomic regions, as well as fluctuations in historical effective population sizes that indicate independent demographic trajectories during the Pleistocene. To contextualize the magnitude of divergence between L. ruficapilla subspecies, we applied the same genomic analyses to 2 additional eastern-western pairs of parulid warblers, Setophaga virens vs. Setophaga townsendi and Setophaga coronata coronata vs. Setophaga coronata auduboni, which have existing behavior studies but are not in strict allopatry. Our findings provide insights into the role of vocalizations in defining within-pair relationship and the important legacy of isolation during the Pleistocene.
The evolution of plasticity and evolvability in a simple gene regulatory network.
Jorritsma A, van den Berg P
Evolution · 2026 Jan · PMID 41124012 · Publisher ↗
Organisms adapt to environmental change by plastic phenotypic responses, genetic adaptation, or a combination of the two. Beyond adapting to the environment, organisms can also evolve the ability to adapt more effectivel...
Organisms adapt to environmental change by plastic phenotypic responses, genetic adaptation, or a combination of the two. Beyond adapting to the environment, organisms can also evolve the ability to adapt more effectively. Evolution can enhance their capacity to respond to environmental cues (increased plasticity), but also their capacity to harness the effects of mutations (increased evolvability). However, it is unclear how these different adaptive capacities co-evolve. Here, we present an evolutionary simulation study in which a simple gene regulatory network must adapt to various regimes of environmental change. We systematically investigate the evolution of plasticity and evolvability in this network, depending on the speed and predictability of environmental changes, and the reliability of environmental cues. We find that plasticity evolves mostly under fast and erratically changing conditions, especially if cues are reliable. In contrast, evolvability evolves under intermediate environmental variability and lower cue reliability. We zoom in on network architecture to investigate what makes these networks more adaptable, showing that different parts of the network become sensitive to mutations depending on the environmental regime. Overall, our results show that both plasticity and evolvability are readily accommodated even in a simple network, depending on the selective pressures exerted by environmental change.
Allometric constraints and the modulation of weapon evolution by mating system in fiddler crabs.
Klunk CL, Florentino JJ, Caetano DS … +2 more , Rosenberg MS, Palaoro AV
Evolution · 2026 Jan · PMID 41092311 · Publisher ↗
Sexual selection potentially drives the evolution of exaggerated traits used in intrasexual contests. However, the extent to which mating systems influence weapon morphology remains unclear. In fiddler crab males, an exa...
Sexual selection potentially drives the evolution of exaggerated traits used in intrasexual contests. However, the extent to which mating systems influence weapon morphology remains unclear. In fiddler crab males, an exaggerated claw functions both as a weapon and a signaling tool, varying according to the species' mating system. We examined claw evolution in male fiddler crabs, differentiating between two main mating strategies: (1) males defend their mating burrows (= "burrow"); (2) males do not mate in their own burrows (= "surface"). We measured claw morphological traits and tested whether the mating system affects their evolutionary rates, expecting "burrow" species to exhibit higher evolutionary rates. In general, claw size scales isometrically with body size across species. Both systems showed no correlation between claw elements and mechanical advantage, indicating the necessity of maintaining a conspicuous signaling tool alongside an efficient lever system for grip strength as body size increases. Contrary to predictions, however, "burrow" males exhibited lower evolutionary rates in claw traits than "surface" males, suggesting stronger stabilizing selection. These findings highlight the nuanced effects of sexual selection on male fiddler crab weapon evolution, suggesting that mating systems can modulate evolutionary trajectories, yet functional demands for dual weapon-signal roles constrain claw morphology.
Genetic offset and vulnerability modeling under climate change scenarios: common misinterpretations and violations of evolutionary principles.
Ahrens CW, Rymer PD, Miller AD
Evolution · 2026 Jan · PMID 41092287 · Publisher ↗
Genetic offset models have become a popular component of the landscape genetics toolbox, with over 600 peer-reviewed publications applying these models. Genetic offset models are most frequently performed following the i...
Genetic offset models have become a popular component of the landscape genetics toolbox, with over 600 peer-reviewed publications applying these models. Genetic offset models are most frequently performed following the identification of putatively adaptive alleles from genotype-environment association analyses in natural populations of nonmodel organisms. These models allow the researcher to make predictions about the vulnerability of species populations to climate change, by estimating the extent of genetic change needed (i.e., genetic offset) to maintain "optimal" allele frequencies and population fitness under future climate change scenarios. However, several review articles have recently drawn attention to fundamental limitations of genetic offset models that compromise their reliability for interpretation. In this commentary, we consolidate and build on preview reviews by describing several key assumptions and violations of basic evolutionary principles that are often overlooked when undertaking these analyses. We use a combination of evolutionary theory and conceptual descriptions to show that current applications fail to account for critical evolutionary processes that shape the selection-fitness landscape and risk producing misleading estimates of population vulnerability. While genetic offset models could have a place in the future, our current interpretations and applications remain problematic and are likely to lead to poor conservation outcomes.
Non-parallel impacts of predators on the evolution of coloration plasticity in Trinidadian killifish.
Lee M, Walsh MR
Evolution · 2026 Jan · PMID 41092284 · Publisher ↗
The ability of organisms to change color in response to a change in environmental conditions is widespread across taxa. Predation represents the longstanding hypothesis for the evolution of such coloration plasticity. Ye...
The ability of organisms to change color in response to a change in environmental conditions is widespread across taxa. Predation represents the longstanding hypothesis for the evolution of such coloration plasticity. Yet, tests of the evolutionary drivers of coloration plasticity remain rare. Here, we examine how predation shapes both baseline coloration and coloration plasticity in the Trinidadian killifish (Anablepsoides hartii). This species inhabits streams that vary in fish predator presence, creating a replicated natural experiment across three rivers. We hypothesized that fish from high-predation sites would exhibit lighter baseline coloration due to associations with open canopy and increased light, and that predators would select for stronger plasticity in background-induced color change. Our results did reveal hypothesized shifts in baseline coloration with high-predation fish generally lighter. Anablepsoides hartii also displayed strong plasticity, darkening on black backgrounds and lightening on white. However, the effect of predation on baseline color and coloration plasticity was inconsistent across rivers, suggesting that additional ecological factors also contribute to these responses. Our study provides empirical evidence that predators are not the sole driver of variation in coloration plasticity and that local ecological factors that covary with predators may also exert selection on body color.
Can the form of sexual selection explain patterns of static weapon allometry expressed by alternative mating morphotypes?
Kelly CD
Evolution · 2026 Jan · PMID 41091895 · Publisher ↗
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 allometrical...
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.
Rapid evolution and cranial morphospace expansion during the terrestrial to marine transition in elapid snakes.
Sherratt E, Crowe-Riddell J, Palci A … +4 more , Ammresh, Hutchinson MN, Lee MSY, Sanders KL
Evolution · 2025 Dec · PMID 41091856 · Publisher ↗
Ecological transitions can trigger rapid phenotypic evolution and novelty, yet the tempo and mode of such changes remain poorly understood in clades that diversify across broad geographic scales, such as continents and o...
Ecological transitions can trigger rapid phenotypic evolution and novelty, yet the tempo and mode of such changes remain poorly understood in clades that diversify across broad geographic scales, such as continents and oceans. We analysed skull shape variation across 91 terrestrial, amphibious, and fully marine species of elapid snakes (Elapidae). We observed a significant increase in rates of skull shape evolution during the land-to-sea transition of viviparous sea snakes. This coincides with a shift into a new region of morphospace, defined by a higher frontoparietal region, more depressed snout, and a wider suspensorium. The acceleration of skull shape evolution in sea snakes was closely followed by a major dichotomy in the evolutionary trajectories of the Hydrophis and Aipysurus clades, which exhibit narrow and wide skulls, respectively. We suggest that narrow skulls in the Hydrophis group provided ecological opportunities that subsequently facilitated the rapid evolution of the axial skeleton (previously documented by Sherratt et al., 2022), with both morphological shifts preceding the increase in speciation rates in core Hydrophis. This study highlights the asynchronous nature of phenotypic and lineage diversification rates during the radiation of geographically widespread clades shaped by major ecological transitions.
Repeated, irreversible evolution of ant-following behavior across Neotropical avian families.
Sweet W, Baldwin J, Gomez JP … +2 more , Pollock H, Martínez AE
Evolution · 2026 Jan · PMID 41091847 · Publisher ↗
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. P...
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.
Distinct evolutionary signatures underlie body shape diversity across deep sea habitats.
Santos EC, Friedman ST, Martinez CM
Evolution · 2026 Jan · PMID 41081766 · Publisher ↗
The deep sea is known for challenging abiotic and biotic conditions; yet, deep-sea fishes have been shown to have higher phenotypic diversity than shallow relatives. An open question is whether different habitats within...
The deep sea is known for challenging abiotic and biotic conditions; yet, deep-sea fishes have been shown to have higher phenotypic diversity than shallow relatives. An open question is whether different habitats within the deep sea differentially contribute to this surprising phenotypic diversity. Here, we explore the joint effects of two major environmental dimensions, the benthic-pelagic axis and ocean depth, on body shape diversification in marine teleost fishes. We found that increasing ocean depth shifted axes of phenotypic evolution and promoted diversification for benthic, demersal, and pelagic fishes alike. However, body shape diversity and rates of body shape evolution did not scale consistently across habitats. For benthic fishes, rate increased more strongly than diversity with increasing ocean depth, while the reverse was true for pelagic fishes. Analyses of habitat transitions suggested that independent invasions may help explain the diversity of deep-pelagic fishes without invoking high evolutionary rates. Relaxed selection may also explain this diversity, as suggested by the wide range of deep-pelagic forms observed along an evolutionary axis of body elongation. Overall, our results reveal a mosaic of pathways through which body plan diversity accumulated across a vertebrate radiation, underscoring the importance of considering finer-scale habitat variation in broad-scale studies.
Body size and litter size as predictors of pouch presence in marsupials.
Casali DM, Yoshikawa MM, Guilhon G … +2 more , Perini FA, Missagia RV
Evolution · 2026 Jan · PMID 41081759 · Publisher ↗
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 compa...
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.
Evolution of female ornamentation in dance flies: valuable gifts are worth dressing up for.
Pärssinen V, Bussière LF, Wiberg RAW … +4 more , Wahlberg E, LeBas NR, Irestedt M, Kvarnemo C
Evolution · 2026 Jan · PMID 41081749 · Publisher ↗
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...
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.
Competitive gametic traits and their coevolution with strong and slight anisogamy.
Lehtonen J, Parker GA
Evolution · 2026 Jan · PMID 41074847 · Publisher ↗
Gamete dynamics (GD) theory for the evolutionary transition from isogamy to anisogamy relies on the biophysics of fertilization, combining the dynamics of gamete limitation and gamete competition with the provisioning re...
Gamete dynamics (GD) theory for the evolutionary transition from isogamy to anisogamy relies on the biophysics of fertilization, combining the dynamics of gamete limitation and gamete competition with the provisioning requirements of gametes and zygotes. A recent development by Siljestam & Martinossi-Allibert, which incorporates competitive gamete traits (motility, target size and chemoattractants) into anisogamy evolution reaches very different conclusions from previous GD predictions, and challenges current views on sexual selection. We develop models incorporating evolution of motility and target size traits under conventional GD theory assumptions showing that (i) unless gamete limitation is strong and the trait is more efficient in the larger gamete, such traits tend to arise in the male gamete, complying with previous analyses predicting that sexually selected expenditures are most likely to arise in males, (ii) gamete trait evolution does not alter the conditions under which anisogamy evolves from isogamy, (iii) the differences between our results and those of Siljestam & Martinossi-Allibert arise from their specific function for zygote survival, which is arguably less plausible than those used in previous GD theory, and (iv) as a novel finding, we show that the coevolution of gamete size with gamete traits (here, motility) can result in the evolution of slight anisogamy.
Tetrapod vocal evolution reveals faster rates and higher-pitched sounds for mammals.
Muñoz MI, Marsot M, Ellers J … +1 more , Halfwerk W
Evolution · 2026 Jan · PMID 41074846 · Publisher ↗
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 with...
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.
Digest: Postzygotic isolation barriers stabilize a hybrid zone between two grosbeak species.
Ottenburghs J
Evolution · 2025 Dec · PMID 41070993 · Publisher ↗
Speciation involves the build-up of reproductive isolation through prezygotic or postzygotic barriers. Research on avian speciation has emphasized the role of prezygotic barriers, whereas postzygotic barriers have remain...
Speciation involves the build-up of reproductive isolation through prezygotic or postzygotic barriers. Research on avian speciation has emphasized the role of prezygotic barriers, whereas postzygotic barriers have remained underappreciated. Revisiting the hybrid zone between two grosbeak species with genomic data, DeRaad et al. (2025) detected ongoing hybridization but strong selection against later-generation hybrids, consistent with mitonuclear incompatibilities. These results demonstrate that postzygotic isolation, whether intrinsic or extrinsic, can be essential in maintaining a hybrid zone.
Rate-time scaling in phenotypic evolution: Limitations of current models in capturing temporal dynamics.
Kinneberg VB, Lysne Voje K
Evolution · 2026 Jan · PMID 41070992 · Publisher ↗
Evolutionary rates correlate negatively with time, which makes it complicated to compare rates across lineages that have diversified on different time intervals. The causes of this correlation are debated. Using simulati...
Evolutionary rates correlate negatively with time, which makes it complicated to compare rates across lineages that have diversified on different time intervals. The causes of this correlation are debated. Using simulations, we first show that rates of evolution estimated as a parameter in the unbiased random walk model lack a rate-time scaling when data has been generated using this model, even when time series are made incomplete and biased. This indicates that it is theoretically possible to estimate rates that are not time correlated from empirical data. We then analyze 643 empirical time series to assess whether accounting for model misspecification, sampling error, and model identifiability reduces the negative scaling, but none appear to have a significant impact. This suggests that the rate-time correlation requires an explanation grounded in evolutionary biology and that common models used in phylogenetic comparative studies and phenotypic time series analyses often fail to accurately describe trait evolution in empirical data. Making meaningful comparisons of estimated rates between clades and lineages covering different time intervals remains a challenge.
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