Evolution最新文献

Parental age at conception can have both short- and long-term consequences on the health, survival, and reproduction of their offspring. To date, most of our knowledge comes from laboratory studies, and considers the effects of maternal age and a "snapshot" of the life history trajectory of the offspring. Here, we use a multigenerational demographic dataset in a free-living, long-lived (median lifespan is 7 years old) bird, the Alpine swift (Tachymarptis melba), to investigate the effects of maternal and paternal age on offspring traits, from nestling to adulthood, and considering all major life history traits, from growth and age at first reproduction to reproductive success and lifespan. Parental age affected offspring phenotype before fledging and lifespan, but differently so for sons and daughters. Offspring from old-age mothers (≥11 years old) and fathers (≥9 years old) were bigger and less infested by ectoparasites before fledging, except sons from old-age fathers that show no reduction in ectoparasite load. We also report evidence of negative effects of paternal age on the lifespan of their offspring (i.e., Lansing effect), with sons (but not daughters) from old-age fathers having shorter lifespans. Our findings highlight the importance of the transgenerational effects of parental age at conception on the reproductive performance, survival, and phenotype of their offspring.

The search for the genetic basis of phenotypes has primarily focused on single nucleotide polymorphisms, often overlooking structural variants (SVs). SVs can significantly affect gene function, but detecting and characterizing them is challenging, even with long-read sequencing. Moreover, traditional single-reference methods can fail to capture many genetic variants. Using long reads, we generated a Capuchino Seedeater (Sporophila) pangenome, including 16 individuals from 7 species, to investigate how SVs contribute to species and coloration differences. Leveraging this pangenome, we mapped short-read data from 127 individuals, genotyped variants identified in the pangenome graph, and subsequently performed FST scans and genome-wide association studies. Species divergence primarily arises from SNPs and indels (< 50 bp) in non-coding regions of melanin-related genes, as larger SVs rarely overlap with divergence peaks. One exception was a 55 bp deletion near the OCA2 and HERC2 genes, associated with feather pheomelanin content. These findings support the hypothesis that the reshuffling of small regulatory alleles, rather than larger species-specific mutations, accelerated plumage evolution leading to prezygotic isolation in Capuchinos.

The persistence of a declining population under environmental change may depend on how fast natural selection restores fitness, a process called "evolutionary rescue". In turn, evolutionary rescue depends on a population's adaptive capacity, which can be defined as the ratio between additive genetic variance for fitness [VA(W)] and mean fitness ($bar W$), or represented by ${Delta _{textit{evol}}}bar W$. However, little is known about how both VA(W) and $bar W$ change in wild populations during environmental change, including changes in dominance variance for fitness [VD(W)]. We assessed the change in ${Delta _{textit{evol}}}bar W$ and VD(W) for a Québec population of wild mustard (Brassica rapa) under climate warming. We also assessed adaptive constraints that could arise from negative genetic correlations for fitness across environments. We grew a pedigreed population of 7,000 plants under ambient and heated (+4 °C) temperatures and estimated the change in mean survival and fecundity ($bar W$), VA(W), and VD(W), plus cross-environment genetic correlations (rA). VA for fecundity non-significantly increased under heated conditions, mean fecundity ($bar W$) increased significantly, and ${Delta _{textit{evol}}}bar W$ was unchanged. We also detected no significant rA for survival and fecundity, suggesting little antagonistic constraint to adaptation. Overall, while this B. rapa population may feature some adaptive plasticity via fecundity, its adaptive capacity to warming seems limited.

Animals often reproduce in complex environments, which should generate selection for both enhanced detectability in signaling traits and improved cognitive processing abilities. However, the extent to which signaling and cognitive traits have evolved to overcome the challenges of interacting in complex habitats remains understudied. We examined whether habitat complexity influences sexual selection in the pygmy halfbeak, Dermogenys collettei, a small livebearing freshwater fish. Using free-swimming arenas, we created low- and high-complexity environments and observed mating behaviors in mixed-sex groups. While the opportunity for sexual selection did not differ significantly between environments for either sex, we observed positive selection gradients for female brain size in open arenas, but not in complex habitats. Selection on morphological traits associated with visual signaling was also primarily detected in open environments, particularly in females. These results suggest that habitat complexity may reduce selection pressures on both cognitive traits, such as brain size, and signaling traits relevant to mate choice. Together, our findings highlight the importance of integrating cognitive traits into sexual selection theory and considering sex-specific selection across ecologically relevant contexts.

Sexual selection is a key driver of reproductive strategy evolution; however, its molecular mechanisms remain poorly understood. In the mouthbrooding Tanganyikan cichlid (Ophthalmotilapia ventralis), fertilization occurs in the female mouth cavity, where sperm competition and post-mating female choice arise because females collect sperm from multiple territorial males. Seminal plasma glycoprotein 120 (SPP120) is involved in sperm immobilization and aggregation, which may contribute to prolonged storage and use of sperm in the female buccal cavity. In this study, we examined how factors related to pre- and post-mating sexual selection affect sperm traits and SPP120 expression in O. ventralis. Field observations and physiological and molecular analyses showed positive correlations between sperm longevity of territorial males and encounter rate with floating males (ERFM) as a measure of sperm competition or bower (spawning site) density related to sperm competition and between SPP120 expression of territorial males and ERFM or courtship success as a measure of pre- and post-mating female mate choice. Furthermore, males with higher SPP120 expression levels achieved greater mating success. These findings highlight the complex interplay between sexual selection and molecular adaptation, providing new insights into the evolution of animal reproductive strategies.

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.

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, 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 favour 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.

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. (2025) 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.

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.