Ecology and Evolution最新文献

Facilitation between species in diverse communities can enhance ecosystem services like pollination, a crucial service for southern highbush blueberry (SHB). SHB growers rely heavily on managed honey bees, but often experience insufficient pollination, possibly because blueberries require buzz pollination for optimal pollen release, which honey bees are incapable of providing. Buzz-pollinating bumble bees could help to facilitate pollination services provided by honey bees through increasing pollen release, though this has never been explicitly tested. To test whether bumble bees facilitate pollination by honey bees, we caged SHB bushes with only honey bees (HB only) and with honey bees plus bumble bees (HB + BB). Across treatments, we assessed foraging honey bee pollen loads on their bodies to see if this increased when buzz-pollinating bumble bees were present; as well as bee visitation rates, direct interactions between bees that could enhance cross pollination, and berry weight. We found no evidence that pollen loads (incidental or corbiculate) on honey bees were higher when bumble bees were present. Instead, we found that honey bees could release and collect blueberry pollen under the constraint of a caged environment with no alternative forage, even when buzz pollinators were absent. We did find evidence for other forms of facilitation and complementarity such as three-fold more direct interactions in the HB + BB treatment and differential foraging across temperatures by honey bees and bumble bees. Finally, berry weight did not vary between treatments likely due to the high pollinator density in both treatments. Our experiment provides clear evidence that honey bees can collect blueberry pollen despite the inability to buzz pollinate; alternatively, it did not support our hypothesis that bumble bees would facilitate pollen release and transfer by honey bees. However, we found evidence that bumble bees and honey bees complement and facilitate each other in additional ways, suggesting that using both could improve pollination.

The pace-of-life syndrome (POLS) hypothesis posits that consistent individual differences in behaviour are integrated with physiology and life-history traits such that behaviour mediates how individuals resolve life-history trade-offs. For instance, individuals exhibiting higher exploration tendencies may accelerate reproduction by gaining access to resources more quickly, but this same behaviour could reduce survival through increased risks of predation and competition. While empirical support for POLS remains mixed, recent theory emphasises the role of environmental context in resolving some inconsistencies. Resource quality, in particular, may strongly mediate context-dependent effects, yet its functional role has received little empirical attention. To address this, we monitored the complete life-histories of 344 female house mice (Mus musculus domesticus) across four semi-natural enclosures running in parallel, provisioned with either high or standard-quality food. We first assessed how resource quality influenced life-history traits and then repeatedly measured behaviour to investigate the among-individual correlations between behaviour and life-history within each food quality treatment. Two axes captured most of the variation in life-history in both food quality treatments, with the primary axis reflecting a fast-slow continuum. The relationship between behaviour and life-history was context-dependent at the among-individual level: under a lower quality treatment, more exploratory females exhibited a faster pace-of-life, consistent with a risk-mortality trade-off. By contrast, in higher quality food conditions, individuals that covered more distance in an open-field, that is, more active stress-copers, delayed reproduction and followed a slower pace-of-life, suggesting a POLS that incorporates aspects of asset protection. Our results indicate that pace-of-life syndromes are context-dependent, emerging most clearly when behavioural variation interacts with environmental factors that affect some aspect of fitness. More broadly, we provide evidence that POLS vary profoundly in different ecological conditions, highlighting the importance of considering environmental context when testing fundamental links between behaviour and life-history.

Floral orientation as a key floral trait for understanding how plants integrate biotic and abiotic selective pressures. Polygonatum cyrtonema is an economically significant medicinal species. The adaptive significance of its downward floral orientation remains poorly understood. We conducted manipulation experiments to explore the visiting time per flower, visitation rate and the pollination efficiency of bumble bees and honey bees between downward flowers and artificially reoriented upward flowers. We also assessed pollen viability and stigma receptivity under both sunlight and rainwater exposure in the two orientations. Furthermore, we quantified reproductive fitness components to compare the fruit set, seed set, and the qualities of fruit/seed between two orientation flowers. Our results showed that the downward orientation enhances reproductive success through integrated biotic and abiotic factors. Downward flowers attracted more effective bumble bee pollinators, resulting in higher visitation rates, longer visiting time, and higher pollen transfer efficiency compared to upward flowers. While the upward floral orientation increased the visitation of ineffective visitors, such as honey bees and other syrphid flies. Simultaneously, the downward orientation flowers provided protection from solar radiation and rainwater, maintaining higher pollen viability, and stigma receptivity while reducing pollen loss. Although the fruit set per plant showed no significant difference between orientations, downward flowers developed significantly larger fruits with greater fresh mass and fruit size. Both the seed number and the seed set per fruit were significantly higher in downward flowers than upward ones. These results collectively support the pollinator attraction, pollinator filtering and abiotic protection hypothesis, demonstrating that the downward orientation in P. cyrtonema is shaped by both biotic and abiotic selection.

Batrachochytrium dendrobatidis (Bd) is the most catastrophic wildlife pathogen, associated with severe amphibian population declines or the extinction of over 500 species. Bd has the potential to influence the structure and dynamics of amphibian populations in multiple and compounding ways, yet few studies have investigated how Bd effects vary in communities with differential susceptibility. Here, we used temporal data from amphibian communities in temperate Tasmania, Australia, comprising four co-occurring species: the brown treefrog (Litoria ewingii), Tasmanian treefrog (L. burrowsae), common froglet (Crinia signifera), and Tasmanian froglet (C. tasmaniensis). Previous laboratory trials indicated L. burrowsae and C. tasmaniensis are susceptible to Bd, whereas L. ewingii and C. signifera act as reservoirs. Using Bayesian Markov chain Monte Carlo models, we tested whether Bd presence, the presence of reservoirs, or same-genus species influenced susceptible species across sites and years. Contrary to expectations-that Bd and reservoir hosts destabilise amphibian communities-we found no evidence of population declines in L. burrowsae or C. tasmaniensis. Instead, species appeared to coexist in a relatively stable community structure, despite Bd presence. Our findings suggest that susceptibility identified by laboratory trials might not reliably predict field disease outcomes in this system, owing to an absence of relevant extrinsic environmental variables. We postulate that pond conditions in which amphibian communities in our study occur, characterised by low temperature and pH, limit Bd growth and survival, creating a refuge from its effects. These results highlight the importance of ecological and environmental context when assessing disease impacts in wild multi-host communities, and also that climate change may threaten community resilience.

Prolonged larval development in marine gastropods is less frequent in high latitudes, with non-pelagic larval development much more common in these regions. This pattern has been historically referred to in biogeography as the Thorson's rule. The most invoked theoretical explanation for this pattern is that pelagic larval duration becomes too long as temperatures decrease, thus increasing exposure to predators and transport towards habitats not suitable for recruitment. However, more factors rather than only water temperature could influence pelagic duration and overall larval performance, like initial embryo and juvenile sizes, currents and phytoplankton fluctuations. On the other hand, phylogeny and environmental conditions affecting the adults, like the stability of benthic habitats in time, could also play an important role in the evolution of developmental modes. Besides, Thorson's latitudinal pattern could be an artefact arising from insufficient, incomplete and uneven sampling. In this work, we gathered an up-to-date dataset for 94 species of European gastropods from the literature, including developmental mode and other life history traits together with variables related to bottom habitat, water column and primary productivity. Thorson's rule was not recovered when the proportion of species with non-pelagic development was analysed with fine spatial resolution at regions with at least 20 gastropod species present. Moreover, temperature and phylogeny played a negligible role in determining developmental mode, while greater depths and marked chlorophyll-a seasonality significantly favoured non-pelagic development. Thus, we infer that the increased temporal shifts in bottom habitats at shallow waters in regions with a non-seasonal and more constant phytoplankton availability drive the evolution of pelagic larval forms in gastropods.

Semi-arid mallee landscapes are shaped by wildfires. Due to climate change, wildfires are expected to become more frequent and intense, making their management a conservation priority. Ants are often used as bioindicators in land management studies, as their composition, richness, and abundance respond to disturbances, including wildfires, both directly and indirectly through habitat modification. In the semi-arid zone of western New South Wales, Australia, we examined how time-since-fire influences ant species richness, abundance, and community composition and assessed whether fire-induced changes in vegetation composition explain the observed patterns in ant community structure. We sampled ants at five sites that last burned 3, 5, 9, 26, and 34 years ago, respectively. We identified 59 ant species from 20 genera in a total of 16,360 sampled ants. We found that post-fire ant communities exhibited higher abundance immediately after fire, while species richness increased with time-since-fire. Early successional stages with greater shrub density favored dominant and opportunistic ant species, whereas later stages with increased tree and grass cover supported more diverse ant communities. These results demonstrate that fire drives successional specialization in ant communities through niche filtering. Maintaining heterogeneous fire-age vegetation mosaics is therefore critical for conserving landscape-level biodiversity in fire-regulated mallee ecosystems.

Mosquito-borne diseases are on the rise globally due to the shifting distribution of key disease vector species. Due to increased global trade and travel and increasing temperatures and changing precipitation patterns, the spread of mosquitoes and the increasing burden of their accompanying diseases like malaria, yellow fever, and dengue persist. Seeking sustainable control measures, there's growing interest in natural control, particularly through predators like amphibians, a globally threatened vertebrate group. However, the effectiveness of different natural predators and their role in an ecological context remains poorly understood. This study compares the predator efficiency of common European amphibian species to common aquatic insect mosquito predators. Focusing on the cosmopolitan mosquito Culex pipiens s.l., known for transmitting pathogens like West Nile virus, we assessed predator rates, sex-specific efficiency in amphibians, and the impact of predator presence on mosquito oviposition behavior. Amphibians proved to be more effective mosquito predators than aquatic insects, consuming up to 4-8 times as many larvae per individual compared to the aquatic insects. No difference was detected between the two amphibian species, nor their sexes or the levels of eutrophication. Predator cues deterred oviposition behavior across the entire experimental setup, thus suggesting the ability of mosquitoes to react to a (purported) landscape of fear. The combined effect of deterring egg laying and lowering mosquito survival highlights the potential of natural predation, and particularly that of amphibian species as natural larval control agents, thus emphasizing the importance of conserving these threatened species and facilitating them in urban and rural environments.

The gastrointestinal microbiota of marine fishes plays important roles in host physiology and ecosystem processes yet remains poorly characterized. Here, we used 16S rRNA metabarcoding to examine the gastrointestinal microbiota of pompano dolphinfish (Coryphaena equiselis) collected from a neritic site (< 200 m) and a deep-sea site (> 3800 m) in the South China Sea. Across sites, the microbial community was unexpectedly simplified and strongly dominated by Spirochaetes, particularly the genus Brachyspira. Because Brachyspira includes well-documented pathogens of terrestrial animals, its high prevalence raises concern that pompano dolphinfish may act as reservoirs of potentially pathogenic bacteria with the capacity for trophic transfer. Coastal exposure may represent a critical source: Brachyspira was also detected at low levels in seawater eDNA from nearshore habitats, suggesting that dolphinfish could acquire these microbes during neritic stages and subsequently transport them into deep-sea ecosystems. Functional predictions further revealed that gastrointestinal microbiota from both sites were closely associated with pathogenic processes, while neritic individuals additionally exhibited enrichment of functions linked to adaptation to anthropogenic stressors. Our findings underscore the ecological importance of dolphinfish microbiota as both a reservoir of potentially pathogenic lineages and a sensitive indicator of environmental stress in marine ecosystems.

Ecological and genetic interactions among conspecific populations play an important role in population viability, but these interactions are not always fully considered in strategies to recover endangered taxa. Southern Resident killer whales are a high-profile population listed as endangered by both the United States and Canada. Risks to the population are well known, and include insufficient prey, inbreeding depression, disturbance, and environmental contaminants. Here, we argue that a fifth factor-interactions with other sympatric killer whale populations-plays an underappreciated role in the population's current and potential status. Based on studies conducted over the past two decades, we illustrate that consumption of shared prey, behavioral interactions in shared habitat, and shared DNA through potential interbreeding with other populations will strongly influence the future trajectory of the Southern Resident killer whales.

Predicting how species will respond to global change requires understanding how environmental drivers shape both neutral and adaptive genetic variation across space. The kelp Eisenia arborea is a thermally tolerant foundation species spanning more than 3000 km of coastline and a broad latitudinal temperature gradient in the Northeast Pacific, yet how environmental and demographic processes influence genomic and population structure remain unclear. We used genome-wide ddRAD sequencing to investigate patterns of genetic diversity, connectivity and local adaptation in E. arborea across two depths and ~2700 km of coastline. We detected strong genetic differentiation between northern (British Columbia, Canada) and southern (Baja California, Mexico) populations, indicating limited gene flow across the species' broad range. Southern populations also had the lowest genetic diversity and highest inbreeding, broadly consistent with expectations for populations occupying environmentally marginal portions of a species' range. However, the two southernmost populations (~200 km apart) were highly similar and well connected, whereas mid-range sites were more differentiated, indicating that the geographic range edge population was not genetically isolated as is often hypothesised. Environmental association analyses identified SNPs correlated with both sea surface temperature and depth, revealing signals of local adaptation to broad climatic gradients and fine-scale habitat variation. The combination of high inbreeding, restricted connectivity and local adaptation highlights both the vulnerability and potential conservation value of distinct genetic units, especially warm-adapted southern populations, for maintaining the resilience of these Eisenia forests under ocean warming.