1. Resource polymorphism is common across taxa and can result in alternate ecotypes with specific morphologies, feeding modes, and behaviours that increase performance in a specific habitat. This can result in high intraspecific variation in the expression of specific traits and the extent to which these traits are correlated within a single population. Although metabolic rate influences resource aquisition and the overall pace of life of individuals it is not clear how metabolic rate interact with the larger suite of traits to ultimately determine individual fitness. 2. We examined the relationship between metabolic rates and the major differences (habitat use, morphology, and resource use) between littoral and pelagic ecotypes of European perch (Perca fluviatilis) from a single lake in Central Sweden. 3. Standard metabolic rate (SMR) was significantly higher in pelagic perch but did not correlate with resource use or morphology. Maximum metabolic rate (MMR) was not correlated with any of our explanatory variables or with SMR. Aerobic scope (AS) showed the same pattern as SMR, differing across habitats, but contrary to expectations, was lower in pelagic perch. 4. This study helps to establish a framework for future experiments further exploring the drivers of intraspecific differences in metabolism. In addition, since metabolic rates scale with temperature and determine predator energy requirements, our observed differences in SMR across habitats will help determine ecotype-specific vulnerabilities to climate change and differences in top-down predation pressure across habitats.
Sexual selection frequently promotes the evolution of aggressive behaviours that help males compete against their rivals, but which may harm females and hamper their fitness. Kin selection theory predicts that optimal male-male competition levels can be reduced when competitors are more genetically related to each other than to the population average, contributing to resolve this sexual conflict. Work in Drosophila melanogaster has spearheaded empirical tests of this idea, but studies so far have been conducted in lab-adapted populations in homogeneous rearing environments that may hamper kin recognition, and used highly skewed sex ratios that may fail to reflect average natural conditions. Here, we performed a fully factorial design with the aim of exploring how rearing environment (i.e. familiarity) and relatedness affect male-male aggression, male harassment, and overall male harm levels in a natural population of Drosophila melanogaster, under more natural conditions. Namely, we: a) manipulated relatedness and familiarity so that larvae reared apart were raised in different environments, as is common in the wild, and b) studied the effects of relatedness and familiarity under average levels of male-male competition in the field. We show that, contrary to previous findings, groups of unrelated-unfamiliar males were as likely to fight with each other and harass females than related-familiar males, and that overall levels of male harm to females were similar across treatments. Our results suggest that the role of kin selection in modulating sexual conflict is yet unclear in Drosophila melanogaster, and call for further studies that focus on natural populations and realistic socio-sexual and ecological environments.
In recent decades, warming temperatures and changes in land use are supposed to have enabled several tick species to expand their distribution limit northwards. The progression of ticks to new areas may introduce new and emerging tick-borne pathogens as well as increase existing diseases. Aside from climatic conditions, ticks are dependent on hosts for survival, and rodents often act as important hosts for ticks and as pathogen reservoirs. At northern latitudes, rodents often undergo multi-annual population cycles, and the periodic absence of hosts may inhibit the further progression of ticks. We investigated the potential role of common shrews (Sorex araneus) to serve as a stable host source to immature life stages of a generalist tick Ixodes ricinus and a specialist tick I. trianguliceps, during decreasing abundances of bank voles (Myodes glareolus). We tested whether ticks would have a propensity to parasitize a certain host type dependent on host population size and composition in two high latitude locations in southern Norway, by comparing tick burdens on trapped animals. We found that I. ricinus larvae showed an equal propensity to parasitize both host types as the host population composition changed, but voles had a higher level of parasitism by nymphs (p< 0.004). An overall larger host population size favored the parasitism of voles by larvae (p= 0.027), but not by nymphs (p= 0.074). I. trianguliceps larvae showed a higher propensity to parasitize shrews, regardless of host population size or composition (p= 0.004), while nymphs parasitized shrews more as vole abundance increased (p= 0.002). The results indicate that common shrews may have the potential to act as a replacement host during periods of low rodent availability, but long-term observations encompassing complete rodent cycles may determine whether shrews are able to maintain tick range expansion despite low rodent availability.
1. Dietary studies in birds of prey involve direct observation and examination of food remains at resting and nesting sites. Although these methods accurately identify diet in raptors, they are time-consuming, resource-intensive, and associated with biases from the feeding ecology of raptors like Gyps vultures. Our study set out to estimate diet composition in Gyps vultures informed by stable isotopes that provide a good representation of assimilated diet from local systems. 2. We hypothesized that differences in Gyps vulture diet composition is a function of sampling location, and that these vultures move between Serengeti National Park and Selous Game Reserve protected areas to forage. We also, theorised that grazing ungulates are the principal items in Gyps vulture diet. 3. Through combined linear and Bayesian modelling, diet-derived from 13C in Gyps vultures consisted of grazing herbivores across sites, with those in Serengeti National Park consuming higher proportions of grazing herbivores (> 87%). 13C differences in vulture feather subsets did not indicate shifts in vulture diet and combined with blood 13C, vultures fed largely on grazers for ~159 days before they were sampled. Similarly, 15N values indicated Gyps vultures fed largely on herbivores. 34S ratios separated where vultures fed when the two sites were compared. 34S variation in vultures across sites resulted from baseline differences in plant 34S values, though it is not possible to match 34S to specific locations. 4. Our findings highlight the relevance of repeated sampling that considers tissues with varying isotopic turnover and emerging Bayesian techniques for dietary studies using stable isotopes. Findings also suggested limited vulture movement between the two local systems. However, more sampling coupled with telemetry is required to fully comprehend this observation and its implications to Gyps vulture ecology and conservation.
Animals with dependent and vulnerable young need to decide where to raise their offspring to minimize ill effects of weather, competition, parasitism, and predation. These decisions have critical fitness consequences through impacting the survival of both adults and juveniles. Birds routinely place their nest in specific sites, allowing species to be broadly classified based on nest location (e.g., ground- or tree-nesting). However, from 2018–2020 we observed 24 American robin (Turdus migratorius) nests placed not on their species-typical arboreal substrates or human-made structures but on the ground at a predator-rich commercial arbor in Illinois, U.S.A. This behavior does not appear to be in response to competition and did not affect nest daily survival rate but was restricted to the early half of the breeding season. We hypothesize that ground-nesting may be an adaptive response to avoid exposure and colder temperatures at sites above the ground early in the breeding season or a non-adaptive consequence of latent robin nest-placement flexibility.
Land-use intensification is the main factor for the catastrophic decline of insect pollinators. However, land-use intensification includes multiple processes that act across various scales and should affect pollinator guilds differently depending on their ecology. We aimed to reveal how two main pollinator guilds, wild bees (specialists) and hoverflies (generalists), respond to different land-use intensification measures, i.e. arable field cover (AFC), landscape heterogeneity (LH) and functional flower composition of local plant communities as a measure of habitat quality. We sampled wild bees and hoverflies on 22 dry grassland sites within a highly intensified landscape (NE Germany) within three campaigns using pan traps. We estimated AFC and LH on consecutive radii (60-3000m) around the dry grassland sites and estimated the local functional flower composition. Wild bee species richness and abundance was positively affected by LH and negatively by AFC at small scales (140-400m). In contrast, hoverflies were positively affected by AFC and negatively by LH at larger scales (500-3000m), where both landscape parameters were negatively correlated to each other. At small spatial scales, though, LH had a positive effect on hoverflies abundance. Functional flower diversity had no positive effect on pollinators, but conspicuous flowers seem to attract abundance of both guilds. In conclusion, landscape parameters contrarily affect two pollinator guilds at different scales. The correlation of landscape parameters may influence the observed relationships between landscape parameters and pollinators. Hence, effects of land-use intensification seems to be highly landscape-specific.
Reproductive isolation between geographically separated populations is generally considered the most common form of speciation. However, speciation may also occur in the absence of geographic barriers due phenotypic and genotypic factors such as chemical cue divergence, mating signal divergence and mitonuclear conflict. Here we performed an integrative study based on two genome-wide techniques, 3RAD and ultraconserved elements, coupled with cuticular hydrocarbon and mtDNA sequence data, to assess the species limits within the E. ruidum species-complex, a widespread and conspicuous group of Neotropical ants for which heteroplasmy has been recently discovered in some populations from southeast Mexico. Our analyses indicate the existence of at least five distinct species in this complex, two widely distributed along the Neotropics and three that are restricted to southeast Mexico and that apparently have high levels of heteroplasmy. We found that species boundaries in the complex did not coincide with geographic barriers. We therefore consider possible roles of alternative drivers that may have promoted the observed patterns of speciation, including mitonuclear incompatibility, cuticular hydrocarbon differentiation, and colony structure. Our study highlights the importance of simultaneously assessing different sources of evidence to disentangle the species limits of taxa with complicated evolutionary histories.
Digital point-occurrence records from the Global Biodiversity Information Facility (GBIF) and other data providers enable a wide range of research in macroecology and biogeography. However, data errors may hamper immediate use. Manual data cleaning is time-consuming and often unfeasible, given that the databases may contain thousands or millions of records. Automated data cleaning pipelines are therefore of high importance. Taking North American Ephedra as a model, we examined how different data cleaning pipelines (using, e.g., the GBIF web application, and four different R packages) affect downstream species distribution models (SDMs). We also assessed how data differed from expert data. From 13,889 North American Ephedra observations in GBIF, the pipelines removed 31.7% to 62.7% false positives, invalid coordinates, and duplicates, leading to datasets between 9,484 (GBIF application) and 5,196 records (manual-guided filtering). The expert data consisted of 704 records, comparable to data from field studies. Although differences in the absolute numbers of records were relatively large, species richness models based on stacked SDMs (S-SDM) from pipeline and expert data were strongly correlated (mean Pearson's r across the pipelines: 0.9986, versus the expert data: 0.9173). Our results suggest that all R package-based pipelines reliably identified invalid coordinates. In contrast, the GBIF-filtered data still contained both spatial and taxonomic errors. Major drawbacks emerge from the fact that no pipeline fully discovered misidentified specimens without the assistance of taxonomic expert knowledge. We conclude that application-filtered GBIF data will still need additional review to achieve higher spatial data quality. Achieving high-quality taxonomic data will require extra effort, probably by thoroughly analyzing the data for misidentified taxa, supported by experts.
The intestinal microbiota play an important role in the life of amphibians. The composition of the intestinal microbial community may vary by developmental stage. In this study, 16S rRNA high-throughput sequencing was used to study the intestinal microbiota of Hynobius maoershanensis tadpoles and adults that exclusively inhabit the Maoer Mountain swamp at an altitude of approximately 2000 m. The results indicated that there was no significant difference in intestinal microbiota between tadpoles and adults. Nevertheless, the abundance of intestinal microbiota in adults was much higher than that in tadpoles. Specifically, at the phylum level, Bacteroidetes was more abundant in adults than in tadpoles. At the genus level, Proteobacteria, Actinobacteria, Cyanobacteria, and Planctomycetes were more abundant in tadpoles, whereas Burkholderiaceae, Caedibacter, Bacteroides, and Serratia were more abundant in adults. A functional prediction analysis revealed that there was no significant difference between tadpoles and adults; however, the function of the intestinal microbiota in H. maoershanensis includes amino acid transport and metabolism, general function prediction only, transcription, energy production and conversion, liquid transport, and metabolism. The aquatic and terrestrial living environment of tadpoles and adults may be the main reason for the difference in intestinal microbiota between tadpoles and adults. Our study provides evidence of variations in the intestinal microbiota of tadpoles and adult amphibians, highlighting the influence of historical developments on the intestinal microbiota and the need for increased understanding of the importance of physiological characteristics in shaping intestinal microbiota of amphibians, which consequently help us to understand the adaptative mechanism of amphibians from an aquatic to a terrestrial environment.
Prey evolve anti-predator strategies against multiple enemies in nature. We examined how a prey species adopts different predation avoidance tactics against pursuit or sit-and-wait predators. As prey, we used two strains of Tribolium beetles artificially selected for short or long duration of death feigning. The results showed that, as prey, the short strains displayed the same behavior, escaping, against the two types of predators. On the other hand, death feigning is known to be effective for evading a jumping spider in the case of the long strains, while the present study showed that the long strain beetles used freezing behavior against a sit-and-wait type predator A. venator in this study. The short strain beetles were more easily orientated by predators and suffered a higher rate of predation than the long strains. The time to predation was also shorter in the short strains compared to the long strains. When the predator was starved, even the long strains were preyed upon when the predator was orientated toward the prey, suggesting the starvation period, i.e., prey density, is an important factor for antipredator behavior. Traditionally, death feigning has been thought to be the last resort in a series of anti-predator avoidance behaviors. However, our results showed that freezing and death feigning were not parts of a series of behavior, but independent behaviors against different predators, at least for these beetles. The results also suggest that the differences in feeding rates between the strains could be explained by differences in activity among the strains.
To provide the most comprehensive picture of species phylogeny and phylogeography of European roe deer (Capreolus capreolus), we analysed mtDNA control region (610 bp) of 1469 samples of roe deer from Central and Eastern Europe and included into the analyses additional 1541 mtDNA sequences from GenBank from other regions of the continent. We detected two mtDNA lineages of the species: European and Siberian one (an introgression of C. pygargus mtDNA into C. capreolus). The Siberian lineage was most frequent in eastern part of the continent and declined towards Central Europe. The European lineage contained three clades (Central, Eastern and Western) composed of 2 to 8 subclades, many of which were separated in space. The Western clade appeared to have a discontinuous range from Portugal to Russia. Most of the subclades in the Central and the Eastern clades were under expansion during the Weichselian glacial period before the Last Glacial Maximum (LGM), while the expansion time of the Western clade overlapped with the Eemian interglacial. High genetic diversity of extant roe deer is the result of their survival during the LGM in a large, contiguous range spanning from the Iberian Peninsula to the Caucasus Mts. and in two northern refugia.
Acute exposure to warming temperatures increases minimum energetic requirements in ectotherms. However, over and within multiple generations, increased temperatures may cause plastic and evolved changes that modify the temperature sensitivity of energy demand and alter individual behaviours. Here, we aimed to test whether populations recently exposed to geothermally elevated temperatures express an altered temperature sensitivity of metabolism and behaviour. We expected that long-term exposure to warming would moderate metabolic rate, reducing the temperature sensitivity of metabolism, with concomitant reductions in boldness and activity. We compared the temperature sensitivity of metabolic rate (acclimation at 20 versus 30°C) and allometric slopes of routine, standard, and maximum metabolic rates, in addition to boldness and activity behaviours, across eight recently divergent populations of a widespread fish species (Gambusia affinis). Our data reveal that warm-source populations express a reduced temperature sensitivity of metabolism, with relatively high metabolic rates at cool acclimation temperatures and relatively low metabolic rates at warm acclimation temperatures. Allometric scaling of metabolism did not differ with thermal history. Across individuals from all populations combined, higher metabolic rates were associated with higher boldness and activity. However, warm-source populations displayed relatively more bold behaviour at both acclimation temperatures, despite their relatively low metabolic rates at warm acclimation temperatures. Overall, our data suggest that in response to warming, multigenerational processes may not direct trait change along a simple “pace-of-life syndrome” axis, instead causing relative decreases in metabolism and increases in boldness. Ultimately, our data suggest that multigenerational warming may produce a novel combination of physiological and behavioural traits, with consequences for animal performance in a warming world.
Oxford Nanopore Technologies (ONT) is a third-generation sequencing technology that is gaining popularity in ecological research for its portable and low-cost sequencing possibilities. Although the technology is primarily developed for long-read sequencing, it can also be applied to sequence amplicons. The downside of ONT is the low quality of the raw reads. Hence, generating a high-quality consensus sequence is still a challenge. We present Amplicon_sorter, a tool for reference-free sorting of ONT sequenced amplicons based on their similarity in sequence and length and for building solid consensus sequences.
High elevation grasslands provide critical services in agriculture and ecosystem stabilization. However, these ecosystems face elevated risks of disturbance due to predicted soil and climate changes. We experimentally exposed model grassland communities, comprised of three species grown on either local or reference soil, to varied climatic environments along an elevational gradient in the European Alps, measuring the effects on species and community traits. Although species-specific biomass varied across soil and climate, species’ proportional contributions to community-level biomass production remained consistent. Where species experienced low survivorship, species-specific biomass production was maintained through increased production of surviving individuals. Species responded directionally to climatic variation, segregating differentially by plant traits (including height, reproduction, biomass, survival, leaf dry weight, and leaf area) across all sites. Local soil variation drove stochastic trait responses across all species. This soil variability obscured climate-driven responses: we recorded no directional trait responses driven by climate. Our species-based approach contributes to our understanding of grassland community stabilization and suggests that these communities show some stability under climatic variation.
1. Context and need for work The effects and extent of the impacts of agricultural insect pests in and around cropping systems is a rich field of study. However, little research exists on the presence and consequence of pest insects in undisturbed landscapes distant from crop hosts. Research in such areas may yield novel or key insights on pest behavior or ecology that is not evident from agroecosystem-based studies. 2. Approach and methods Using the invasive fruit pest Drosophila suzukii (Matsumura) as a case study, we investigated the presence and resource use patterns of this agricultural pest in wild blackberries growing within the southern Appalachian Mountain range of North Carolina over two years. 3. Main results We found D. suzukii throughout the sampled range with higher levels of infestation (D. suzukii eggs/g fruit) in all ripeness stages in natural areas as compared to cultivated blackberry samples, but especially in under-ripe fruit. 4. Main results We also explored a direct comparison of oviposition preference between wild and cultivated fruit and found higher oviposition in wild berries when equal weights of fruit were offered, but oviposition was higher in cultivated berries when fruit number was equal. 5. Synthesis and applications D. suzukii were wide-spread in previously unsampled remote, forest habitats. Forest populations laid more eggs in unripe wild-grown blackberries throughout the year than populations infesting cultivated berries. This suggests D. suzukii may change its oviposition and foraging behavior in relation to fruit type. Additionally, as D. suzukii exploits a common forest fruit prior to ripeness, further research is needed to explore how this affects wild food web dynamics and spillover to regional agroecosystems.
Once widespread throughout the tropical forests of the Indian Subcontinent, the sloth bears have suffered a rapid range collapse and local extirpations in the recent decades. A significant portion of their current distribution range is situated outside of the protected areas (PAs). These unprotected sloth bear populations are under tremendous human pressures, but little is known about the patterns and determinants of their occurrence in most of these regions. The situation is more prevalent in Nepal where virtually no systematic information is available for sloth bears living outside of the PAs. We undertook a sign survey-based single-season occupancy study intending to overcome this information gap for the sloth bear populations residing in the Trijuga forest of southeast Nepal. Sloth bear sign detection/non-detection data and field-based covariates data were collected at the 74 randomly chosen 4-km2 grid cells using a varying number of 400m long transects in each grid cell. From our results, the model-averaged estimate of site use probability (ψ ± SE) was estimated to be 0.432 ± 0.039, which is a 13% increase from the naïve estimate (0.297) not accounting for imperfect detections of sloth bear signs. The presence of termite mounds and the distance to the nearest water source were the most important variables affecting the habitat use probability of sloth bears. The average site-level detectability (p ± SE) of sloth bear signs was estimated to be 0.195 ± 0.003 and was significantly determined by the index of human disturbances. We recommend considering the importance of fine-scale ecological and anthropogenic factors in predicting the sloth bear-habitat relationships across their range in the Churia habitat of Nepal.
Insect pollinators are important means for a stable ecosystem. The habitat types play a crucial role in the community composition, abundance, diversity, and species richness of the pollinators. The present study in Shivapuri–Nagarjun National Park explored the species richness and abundances of insect pollinators in four different habitats and different environmental variables in determining the community composition of the pollinators. Data were collected from 1500 m–2700 m using pan traps and hand sweeping methods. Non–metric multidimensional scaling (NMDS) and redundancy analysis (RDA) were conducted to show the association between insect pollinators and environmental variables. The results firmly demonstrated that species richness and abundances were higher in open trails compared to other habitats. The distribution of the pollinator species was more uniform in the open trail followed by the grassland. Similarly, a strong positive correlation between flower resources and pollinator’s abundance was found. In conclusion, the open trail harbor rich insect pollinators in lower elevation. The community structure of the pollinators was strongly influenced by the presence of flowers in the trails.
The timing of different life history events are often correlated, and selection might only rarely be exerted independently on the timing of a single event. In plants, phenotypic selection has often been shown to favour earlier flowering. However, little is known about to what extent this selection acts directly vs. indirectly via vegetative phenology, and if selection on the two traits is correlational. We estimated direct, indirect and correlational phenotypic selection on vegetative and reproductive phenology over three years for the perennial herb Lathyrus vernus. Direct selection favoured earlier flowering and shorter timespans between leaf-out and flowering in all years. However, early flowering was associated with early leaf-out, and the direction of selection on leaf-out day varied among years. As a result, selection on leaf-out weakened selection for early flowering in one of the study years. We found no evidence of correlational selection. Our results highlight the importance of including temporally correlated traits when exploring selection on the phenology of seasonal events.