Ecology and Evolution最新文献

Hatching synchronisation is widespread in oviparous taxa. It has been demonstrated that many species use sounds to coordinate synchronous hatching, being widespread among archosaurs (birds and crocodilians). Recent studies have shown that some turtle species produce vocalisations from within the egg, but the role of this behaviour in synchronising hatch is untested. The small amount of information about sound production by turtle embryos, limited to a handful of closely related species, precludes any inferences based on differences in their ecology, reproductive behaviour and phylogenetic context. With the goal to investigate if coordinated synchronous behaviour is mediated by within-egg vocalisations in turtles, we recorded clutches from six different turtle species. The selected animals present different ecological and reproductive niches and belong to distinct phylogenetic lineages at the family level. We aimed to understand: (1) what is the phylogenetic distribution of within-egg vocal behaviour among turtles; (2) if asynchronous turtle species vocalise from within the egg; (3) if clutch size influences synchronous behaviour and (4) if within-egg turtle calls follow any phylogenetic signal. The new evidence provides light to the current knowledge about synchronous behaviour and within-egg calls, challenging previous hypothesis that within-egg sounds are accidentally produced as side-effects of other behaviours.

The introduction of alien species poses a serious threat to native biodiversity, and mountain lake systems in the southwest of China are particularly vulnerable to the introduction of non-native fish. The prey naivety hypothesis states that native species may not be able to recognize novel introduced species due to a lack of common evolutionary background and therefore become easy targets, so the impacts of non-native fish on mountain endemic amphibians need to be urgently assessed. In an ex-situ experiment, we exposed the tadpoles of the Chaochiao Brown Frog (Rana chaochiaoensis), endemic to western China, to kairomones of both native and translocated fish species, and their phenotypic and genetic response patterns were compared. The results revealed significant phenotypic plasticity responses in total length (TOL), tail length (TL), and tail muscle width (TW) of tadpoles induced by native fish kairomone, while tadpoles exposed to translocated fish kairomone exhibited weaker phenotypic changes. At the transcriptional level, the number of differently expressed genes (DEGs) in the native fish treatment was 3.1-fold (liver) and 52.6-fold (tail muscle) higher than in the translocated fish treatment, respectively. There were more unique DEGs in the native fish treatment, primarily enriched in terms and pathways related to stress response, energy metabolism, and muscle development. The study revealed a lack of risk perception by native tadpoles toward novel non-native fish, providing new evidence for the prey naivety hypothesis from both phenotypic and molecular perspectives. Future conservation efforts should prioritize assessing the impacts of non-native fish on alpine and subalpine threatened and narrowly distributed amphibians. Additionally, prevention, early warning, monitoring, and removal of non-native fish should be carried out as soon as possible.

The number of wild bees and cavity-nesting wasps is abundant in agricultural areas and they contribute significantly to ecosystem services. Due to their specialization in nesting sites and food sources, these groups are sensitive to habitat condition changes and they are therefore important indicators for environmental impact assessments. As semi-natural habitats are steadily declining and often understudied, their significance for research is increasingly recognized. During this research, the role of wild bee species and cavity-nesting Hymenopteran taxa as indicators was examined, along the unique combination of high nature value and traditional land use habitats in Eastern Europe, Transylvania. Transects and trap nests were used to test the diversity and abundance of wild bees and cavity-nesting Hymenopterans to identify possible differences between highly protected and less protected areas. The differences in taxonomic groups between the sites and the potential effects of landscape structure on wild bees and cavity-nesting Hymenopterans were also assessed. We detected a high diversity of wild bee species and a significant species replacement from one study year to another. Among the nest-building Hymenopteran taxa, the majority of nests was built by Trypoxylon sp. during both study years, with a stronger dominance in the second year. The different taxonomic groups of wild bees and cavity-nesting Hymenopterans showed differences in their habitat affinities. The majority of the sampled bumblebee species as well as Trypoxylon sp. had an affinity towards the study sites located within the highly protected study area. Altogether, we found different habitat preferences for different Hymenopteran groups (both wild bees and wasps) and conclude that these groups definitely have the potential to serve as indicators for differences in the intensity of land use.

Spatially divergent natural selection can drive adaptation to contrasting environments and thus the evolution of ecotypes. In perennial plants, selection shapes life history traits by acting on subsequent life stages, each contributing to fitness. While evidence of adaptation in perennial plants is common, the expression of life history traits is rarely characterized, limiting our understanding of their role in adaptive evolution. We conducted a multi-year reciprocal transplant experiment with seedlings from low and high elevation populations of the alpine carnation Dianthus carthusianorum to test for adaptation linked to contrasting climates and inferred specific contributions of early life stages to fitness. We assessed genotype by environment interactions in single fitness components, applied matrix population models to achieve an integrated estimate of fitness through population growth rates, and performed trade-off analyses to investigate the advantage of alternate life history traits across environments. We found evidence of genotype by environment interactions consistent with elevational adaptation at multiple stages of the early life cycle. Estimates of population growth rates corroborated a strong advantage of the local genotype. Early reproduction and survival are alternate major contributors to adaptation at low and high elevation, respectively, and are linked by trade-offs that underlie the evolution of divergent life history traits across environments. While these traits have a strong genetic basis, foreign populations express co-gradient plasticity, reflecting the adaptive strategy of the local populations. Our study reveals that selection associated to climate has driven the evolution of divergent life histories and the formation of elevational ecotypes. While the high energy environment and strong competition favor investment in early reproduction at low elevation, limiting resources favor a more conservative strategy relying on self-maintenance at high elevation. The co-gradient plasticity expressed by high-elevation populations may facilitate their persistence under warming climatic conditions.

It is 100 years since the first paper described the multiannual cycles in Arctic rodents and lagomorphs. The mechanisms driving population cycles in animals like lemmings and voles are complex, often attributed to extrinsic factors, such as food availability and quality, pathogens, parasites and/or predators. While extrinsic factors provide insights into population cycles, none fully explain the phenomenon. We propose an underlying innate, intrinsic mechanism, based on epigenetic regulation, that drives population cycles under harsh arctic conditions. We propose that epigenetically driven phenotypic changes associated with sexual development, growth and behaviour accumulate over time in offspring, eventually producing a phase change from rising population density to eventual population collapse. Under this hypothesis, and unlike previous hypotheses, extrinsic factors modify population cycles but would not be primary drivers. The interaction between our intrinsic cycle and extrinsic factors explains established phenomena like delayed-density dependence, whereby population growth is controlled by time-dependent negative feedback. We advocate integrating a century of field research with the latest epigenetic analysis to better understand the drivers of population cycles.

As the threat of climate change and associated heatwaves grows, we need to understand how natural populations will respond. Inter-generational non-genetic inheritance may play a key role in rapid adaptation, but whether such mechanisms are truly adaptive and sufficient to protect wild populations is unclear. The contribution of paternal effects in particular is not fully understood, even though the male reproductive system may be highly sensitive to heatwaves. We used the zebrafish Danio rerio to investigate the effects of heatwaves on male fertility and assess potential adaptive benefits to their offspring in a number of large-scale heatwave experiments. Heatwave conditions had negative effects on male fertility by reducing gamete quality and fertilisation success, and we found indications of an adaptive effect on hatching in offspring produced by heatwave-exposed males. Our findings highlight the importance of including male and female fertility when determining species ability to cope with extreme conditions and suggest that parental effects provide limited adaptive benefits.

The decline of biodiversity, particularly among amphibians, is strongly associated with habitat loss and fragmentation. Vernal pools are a critical ecosystem for many pool-breeding amphibians, but they are often overlooked in wetland protection guidelines. Mitigation efforts include vernal pool creation and restoration, but these efforts have varying success in replacing lost functions. This study investigates the success of created vernal pools through long-term environmental monitoring of wood frogs and spotted salamanders (2014–2023) and integrates population genetics to assess the local population health of the wood frog. First, we monitored and compared environmental parameters and reproductive success of indicator species between natural and created pools in a Pennsylvania state park. We then used microsatellite loci to assess within- and between-pool measures of genetic diversity, population structuring, and gene flow for wood frogs. We found two carefully designed created pools positively contributed to local amphibian population persistence by maintaining similar measures of genetic diversity as compared to natural pools. On the other hand, one poorly created pool was genetically distinct and acted as a population sink. Although our findings offer valuable insights, they are based on a limited sample and may not fully represent the broader landscape. However, by integrating genetic information into long-term monitoring datasets, our interdisciplinary approach enhances our understanding of amphibian population dynamics in vernal pool ecosystems. Our findings imply that the most important factors for restoration practitioners to consider when creating or restoring vernal pools are hydroperiod (12–35 weeks), volume (> 50 m³), depth (≥ 30 cm), and surrounding forest land cover (> 60%). These variables are better predictors of indicator species success than pool type (i.e., natural or created). Ultimately, this study emphasizes the need to accompany restoration efforts with long-term monitoring programs that can be used to make adaptive management decisions in an era of extreme environmental change.

Quercus chungii, a rare and endangered endemic tree species, is found exclusively in subtropical regions of China. Understanding the population structure and temporal dynamics of Q. chungii is pivotal for effective conservation and restoration of its populations and associated ecosystems. However, large knowledge gaps remain about its population structure and temporal change and its key demographic rates across size classes. In this study, we investigated the population structures of Q. chungii in 2013 and 2023 in a nature reserve specifically established to better conserve this species and its associated ecosystems. We found that Q. chungii increased in its overall abundance and tree size in the past decade, suggesting active regeneration and a rapid growth rate for this species and the effectiveness of past conservation efforts. The age structure in 2023 showed a pyramid shape, with a sharp decline in the numbers of individuals from germinated seeds to seedlings and from seedlings to saplings. These led to the low numbers of seedlings and saplings and high age-specific death probabilities at the early developmental stages. These results indicated potential risks of future population decline. These risks may have already manifested over the past decade, as a high mortality rate during the seedling-to-sapling transition could be one of the primary reasons contributing to the decreased proportion of saplings in 2023 compared to 2013. We propose that future studies may benefit from in-depth studies on the regeneration processes of Q. chungii by considering seed predation and germination under changing climate. This study improves the prediction of population development of Q. chungii, thereby offering theoretical guidance essential for its conservation.

Prey depletion threatens many carnivore species across the world and can especially threaten low-density subordinate competitors, particularly if subordinates are limited to low densities by their dominant competitors. Understanding the mechanisms that drive responses of carnivore density to prey depletion is not only crucial for conservation but also elucidates the balance between top-down and bottom-up limitations within the large carnivore guild. To avoid predation, competitively subordinate African wild dogs typically avoid their dominant competitors (lions) and the prey rich areas they are associated with, but no prior research has tested whether this pattern persists in ecosystems with anthropogenically-reduced prey density, and reduced lion density as a result. We used spatial data from wild dogs and lions in the prey-depleted Greater Kafue Ecosystem to test if wild dogs continue to avoid lions (despite their low density), and consequently avoid habitats with higher densities of their dominant prey species. We found that although lion density is 3X lower than comparable ecosystems, wild dogs continue to strongly avoid lions, and consequently avoid habitats associated with their two most important prey species. Although the density of lions in the GKE is low due to prey depletion, their competitive effects on wild dogs remain strong. These effects are likely compounded by prey-base homogenization, as lions in the GKE now rely heavily on the same prey preferred by wild dogs. These results suggest that a reduction in lion density does not necessarily reduce competition, and helps explain why wild dogs decline in parallel with their dominant competitors in ecosystems suffering from anthropogenic prey depletion. Protecting prey populations within the few remaining strongholds for wild dogs is vitally important to avoid substantial population declines. Globally, understanding the impacts of prey depletion on carnivore guild dynamics should be an increasingly important area of focus for conservation.

Underwater light is a key factor that affects the growth of submerged macrophytes. However, the responses of different growth forms of submerged macrophytes to light quality remain unclear. The morphological, physiological, photosynthetic, and stoichiometric responses of erect Potamogeton crispus (P. crispus) and low-canopy Elodea nuttallii (E. nuttallii) to six different light qualities (white light, R/B = 1:8, 1: 4, 1:1, 4:1, 8:1) were studied by a control experiment. (1) No significant differences were observed in the germination number, leaf length, and leaf width of P. crispus under different light qualities (p > 0.05). Both P. crispus and E. nuttallii produced greater plant heights, more leaves and branches under more red light (4:1, 8:1), which was beneficial for the extension of leaves. Under white light, the germination number of P. crispus, adventitious roots of E. nuttallii, and branch number of P. crispus and E. nuttallii were the lowest. (2) Compared to red light, more blue light (1:4, 1:8) was more conducive to the synthesis of photosynthetic pigments. However, excessive blue and red light was not conducive to the accumulation of pigments. The result of malondialdehyde showed that the physiological stress induced by blue light in P. crispus and E. nuttallii was stronger. (3) The N:P, C:N, and C:P ratios of P. crispus and E. nuttallii were higher under more red light, which was beneficial for the synthesis of nutrients in two submerged macrophy; however, the contents of TN and TP in E. nuttallii were higher under more blue light. Two different growth forms of submerged macrophytes grew better under red light, and better adapted to the eutrophic water dominated by red light. However, for aquatic restoration, other submerged macrophytes need to be supplemented after the water quality is improved.