Evolution最新文献

Choosiness, or how picky an individual is in mate choice, is key to both sexual selection and speciation. Yet the amount of phenotypic variation in choosiness and how that variation is partitioned among individuals remain largely unexplored. Here, using the Pacific field cricket Teleogryllus oceanicus, we dissect preference for two song traits, proportion of long chirp and interpulse interval. We subsequently quantify phenotypic variation in choosiness and investigate whether there is consistent individual variation in choosiness and whether choosiness for different song traits covary. Strikingly, we found that the overall shape and peak preference for proportion of long chirp remained similar to those reported in an earlier study from the same population more than a decade ago, providing evidence that directional sexual selection can be relatively stable over long time frames in wild populations. Further, we found moderate levels of within-individual repeatability in choosiness for both song traits, suggesting a substantial level of individual variation in choosiness. Interestingly, choosiness for the two song traits positively covaries, indicating that there may exist overall choosier and more permissive females in song preference.

Genetic diversity is a fundamental population genetic parameter, and predicts adaptive capacity. Neutral theory predicts a positive correlation between population (or range) size and genetic diversity, but this can be confounded by other demographic processes. To investigate the role of range size, population fluctuation and introgression in determining genetic diversity, we generate and analyse population-level, genomic-scale SNP data from 21 species of Australian Gehyra geckos (769 samples) that vary in range size over three orders of magnitude. Using a best-practice approach to estimate heterozygosity, we found a significantly positive overall correlation between range size and heterozygosity (R2 = 0.30, p < 0.01), although with a shallow slope, consistent with Lewontin's Paradox. At a clade level, we show a stronger relationship between range size and heterozygosity in the australis group (R2 = 0.74, p < 0.01) than the nana group (R2 = 0.15, n.s.). A significantly negative correlation between genome-wide Tajima's D and range size in both groups, indicating population expansion, and evidence for introgression in the nana group, suggest a role for both population fluctuation and introgression in driving deviations from theoretical expectations. Our results provide insight into the biological and demographic processes that influence genetic diversity, in addition to neutral expectations.

Trichomes are diverse and functionally important plant structures that vary in response to selection pressures across ecological gradients and evolutionary timescales. Classic hypotheses predict higher investment in trichomes in arid environments, at lower latitudes, and in long-lived species, as well as shifts in trichome production to reduce conflict between defense traits and mutualisms. However, tests of these hypotheses often rely on aggregate trichome metrics and neglect the rich diversity of trichome phenotypes. Here, we collected data on fine-scale patterns of trichome length, density, and type in 52 species of blazingstars (Mentzelia: Loasaceae) and tested whether individual trichome traits were consistent with existing adaptive hypotheses. Contrary to longstanding hypotheses, we found that Mentzelia species tend to display greater trichome investment in less arid environments and at higher latitudes. Barbed trichomes are significantly less common on the upper surface of the leaf, possibly reducing defense-pollination conflict. Species with larger petals (a proxy for reliance on insect pollinators) also shift investment away from insect-trapping hairs on the underside of the leaf. Examining trichome types separately revealed that different morphologies show distinct responses to abiotic and biotic factors, demonstrating the need to consider multiple axes of diversity when testing adaptive hypotheses for complex traits.

Conspicuous juvenile phenotypes are puzzling to evolutionary biologists. Why should organisms vulnerable to predation boldly broadcast their presence? We reconstructed the evolutionary history of juvenile phenotypes across the estrildid finches (family Estrildidae) a radiation exhibiting unparalleled diversity in nestling ornamentation. Many are parasitised by Vidua finches whose offspring mimic host nestling phenotypes. We examined the role of brood parasitism, predation, sibling competition and signalling environment in the diversification of nestling ornamentation. We found that parasitised lineages exhibit elevated rates of nestling ornamentation evolution compared to unparasitised lineages. Despite this, the extent to which nestlings were ornamented did not differ between parasitised and unparasitised lineages, contrasting with systems where coevolution proceeds at the egg stage and generates increased complexity in host traits. Species occupying denser habitats had increased ornamentation, suggesting a role for light environment in the evolution of begging displays. Nestling appearance showed strong phylogenetic signal, helping to explain why successfully colonised hosts are often closely related to ancestral ones. Neither nest height nor clutch size (proxies for predation and sibling competition) predicted nestling ornamentation levels, and parasitism did not predict estrildid finch diversification rates. Overall, our results support a model of trait diversification in which hosts lead and parasites follow in the coevolutionary arms race.

Phenotypic expression is often constrained by functional conflicts between traits, and the resulting trade-offs impose limits on phenotypic and taxonomic diversity. However, the underlying mechanisms that maintain trade-offs or allow organisms to resolve them via phenotypic plasticity are often challenging to detect. The trade-off between gas exchange and water loss across respiratory surfaces represents a fundamental trade-off that constrains phenotypic diversity in terrestrial life. Here, we investigate plastic mechanisms that mitigate this trade-off in lungless salamanders that breathe exclusively across their skin. Our field and laboratory experiments identified plastic responses to environmental variation in water loss and oxygen uptake, and gene expression analyses identified putative pathways that regulate this trade-off. Although the trade-off was generally strong, its strength covaried with environmental conditions. At the molecular level, antagonistic pleiotropy in multiple biological pathways (e.g., vasoconstriction and upregulation of aerobic respiration) putatively produce the trade-off, while other pathways mitigate the trade-off by affecting a single trait (e.g., oxygen binding affinity, melanin synthesis). However, organisms are likely to encounter novel trade-offs in the process of bypassing another. Our study provides evidence that alternative pathways allow organisms to mitigate pleiotropic conflicts, which ultimately may allow greater phenotypic diversity and persistence in novel environments.

Do weakly deleterious mutations contribute to the reproductive and health challenges of bottlenecked species? Peers et al. (2025) investigated the role of prolonged low effective population size in cheetahs (Acinonyx jubatus) and its implications in the accumulation of pseudogenes. They identified 65 cheetah-specific premature termination codons, four of which (DEFB116, ARL13A, CFAP119, and NT5DC4) were linked to male fertility and immune deficiencies. These findings reveal how pseudogenization may contribute to fertility challenges and reproductive health decline.

Organismal body weight correlates with morphology, life history, physiology, and behavior, making it perhaps the most telling single indicator of an organism's evolutionary and ecological profile. Island populations provide an exceptional opportunity to study body weight evolution. In accord with the "island rule," insular small-bodied vertebrates often evolve larger sizes, whereas insular large-bodied vertebrates evolve smaller sizes. To understand how island populations evolve extreme sizes, we adopted a developmental perspective and compared a suite of traits with established connections to body size in the world's largest wild house mice from Gough Island and mice from a smaller-bodied mainland strain. We pinpoint 24-hour periods during the third and fifth week of age in which Gough mice gain exceptionally more weight than mainland mice. We show that Gough mice accumulate more visceral fat beginning early in postnatal development. During a burst of weight gain, Gough mice shift toward carbohydrates and away from fat as fuel, despite being more active than and consuming equivalent amounts of food as mainland mice. Our findings showcase the value of developmental phenotypic characterization for discovering how body weight evolves in the context of broader patterns of trait evolution.

The Arctic and the Qinghai-Tibet Plateau (QTP) are two northern regions with the most extensive cold habitats on Earth and have undergone dramatic warming in recent decades. However, we know little about the historical connection of the Arctic and QTP biotas and their respective diversification processes. Here, we used Meconopsis and Oreomecon, an Arctic-QTP disjunct angiosperm genus pair with poor seed dispersal abilities, to shed light on the evolutionary connection of the Arctic and QTP floras and their respective diversification patterns. Our results show that the Meconopsis-Oreomecon clade colonized the Arctic from the QTP in the Late Eocene, suggesting the hitherto earliest known dispersal event between the two regions. The Arctic Oreomecon split from the QTP Meconopsis at ~34 Ma, associated with their climatic niche differentiation and aridification of the Asian interior. Although both Oreomecon and Meconopsis pre-adapted to open and low-temperature environments and had similar diversification patterns, they diversified asynchronously in respondence to different Cenozoic climate cooling events. The Arctic is approaching its carrying capacity, whereas the QTP is still far from saturation. These findings improve knowledge of evolutionary connection and difference between Arctic and QTP floras, and have important conservation implications given enhanced warming in both regions.

Local adaptation is the biological process by which native populations become more fit. Intraspecific patterns of local adaptation occur through shifts in allele frequency within or near genes and may occur similarly across species. Identifying repeated adaptation across species increases statistical power to determine causal genes driving adaptation and reveals insights into the nature of evolution. These types of insights could have theoretical and applied applications, particularly as the climate continues to change. We interrogate repeated molecular adaptation across 13 eucalypt species. In total, we found 38 candidate genes with shared putatively adaptive signals in as many as 12 species. This suite of genes contains important functions, including MYB proteins, acyl-CoA dehydrogenases and Leucine-rich kinases. Species with restricted and widespread geographical distributions shared putative patterns of adaptation, and phylogenetic closeness did not increase patterns of repeated adaptation compared to geographic overlap. This work provides further evidence that repeated adaptation can occur among orthologs, which may play a consistent role in local adaptation.

Understanding organismal responses to environmental change is a central goal of biology with profound implications for the conservation of biodiversity. Widespread evidence of epigenetic modifications in response to environmental stress, including those inherited across generations, has led to considerable speculation about their role in organismal responses to environmental change. Yet, the magnitude and fitness consequences of epigenetic marks carried beyond maternal inheritance are largely unknown. Here, we tested how transgenerational epigenetic inheritance (TEI) shapes the phenotypic response of Daphnia clones to the environmental stressor Microcystis. We split individuals from each of eight genotypes into exposure and control treatments (P0 generation) and tracked the fitness of their descendants to the F3 generation. We found transgenerational epigenetic exposure to Microcystis led to reduced survival and growth rates and no consistent effect on offspring production. TEI was associated with increases in trait variance, suggesting the potential for heritable bet hedging driven by TEI. Taken together, our results demonstrate that TEI causes substantial-but not adaptive-trait shifts, suggesting transgenerational adaptive plasticity may be rare.