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492 ecological experiment Preprints

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Please note: These are preprints and have not been peer reviewed. Data may be preliminary.
Predator-induced shape plasticity in D. pulex
Sam Paplauskas
Oscar Morton

Sam Paplauskas

and 8 more

August 11, 2023
All animals and plants respond to changes in the environment during their life cycle. This flexibility is known as phenotypic plasticity and allows organisms to cope with variable environments. A common source of environmental variation is predation risk, which describes the likelihood of being attacked and killed by a predator. Some species can respond to the level of predation risk by producing morphological defences against predation. A classic example is the production of pedestals and head spikes in the water flea, Daphnia pulex, which defend against predation from Chaoborus midge larvae. Previous studies of these defences have focussed on changes in pedestal size and the number of spikes along a gradient of predation risk. Although these studies have provided a model for continuous plasticity, they do not capture the whole-organism shape response to predation risk. In contrast, studies in fish and amphibians focus on shape as a complex, multi-faceted trait made up of different variables. In this study, we analyse how multiple aspects of shape change in D. pulex along a gradient of predation risk from C. flavicans. These changes are dominated by the inducible morphological defence, but there are also changes in the size and shape of the head and the body. We detected change in specific modules of the body plan and a level of integration among modules. These results are indicative of a complex, multi-faceted response to predation and provide insight into how predation risk drives variation in shape and size at the level of the whole organism.
Heatwave-induced functional shifts in zooplankton communities result in weaker top-do...
Thu-Huong Huynh-Ngoc
Zsófia Horváth

Thu-Huong Huynh-Ngoc

and 6 more

August 11, 2023
Freshwater ecosystems are increasingly affected by rising annual mean temperatures and extreme heatwaves. While heatwaves are expected to have more immediate effects than mean temperature increases on local communities, comparative experimental studies are largely lacking. We conducted a one-month mesocosm experiment to test the effect of different warming scenarios, constantly raised temperatures (+3°C), and recurring heatwaves (+6°C) on plankton communities. We specifically tested how shifts in zooplankton trait composition and functional groups are reflected in ecosystem functioning (top-down control on primary producers). We found that heatwaves had a stronger and more immediate effect on trait and functional group compositions. Heatwaves were associated with larger body sizes, and the decrease in micrograzers resulted in weaker top-down control, leading to elevated algal biomass. Altogether, our results highlight the importance of the indirect effects of heatwaves via inducing shifts in zooplankton functional groups and trait composition which may foster periodic algal blooms.
Application of environmental DNA metabarcoding to identify fish community characteris...
Sai Wang
Dong-Hai Wu

Sai Wang

and 12 more

August 04, 2023
Fish play vital roles in river ecosystems; however, traditional investigations of fish usually cause certain ecological damage. Extracting DNA from aquatic environments and identifying DNA sequences offers an alternative, non-invasive approach for detecting fish species. In this study, environmental DNA (eDNA), coupled with PCR and next-generation sequencing, and electrofishing were used to compare their effects in identifying fish community characteristics. In three subtropical rivers of southern China, fish specimens and eDNA in water were collected from headwaters to estuaries. Both eDNA OTU richness and individual abundance (including number and biomass) could group 38 sampling sites into eight spatial zones with significant differences in local fish community composition. Compared with the order-/family-level grouping, the genus-/species-level grouping could more accurately recognize the differences between upstream zones I − III, midstream zones IV − V, and downstream zones VI – VIII. From headwaters to estuary, two environmental gradients significantly influenced the longitudinal distribution of fish species, including the first gradient composed of habitat and physical water parameters and the second gradient composed of chemical water parameters. The high regression coefficient of alpha diversity between eDNA and electrofishing methods as well as the accurate recognition of dominant, alien, and biomarker species at each spatial zone indicated that eDNA could characterize fish community attributes at a similar level of traditional approach. Generally, our results demonstrated that eDNA metabarcoding can be used as an effective tool in revealing fish composition and diversity, which is important for using the eDNA technique in aquatic field monitoring.
Phylogenetic signals, biomass allocation, and variation patterns collectively reflect...
Taotao Wang
Bangyan Liu

Taotao Wang

and 4 more

August 03, 2023
Root system architecture is limited by phylogenetic relationships and ultimately affect the biomass allocation of resource acquisition organs. However, many studies have only focused on the impact of environmental driven trait variation and biomass allocation on root system architecture, neglecting the impact of phylogenetic relationships. Therefore, biomass allocation and phylogenetic relationship affect the root system architecture and its variation patterns were investigated in annual ephemerals. We found that the interspecific variation of root tissue density (RTD) was the highest (51.63%), and the topological index (TI) was the lowest (5.92%). Moreover, the range of intraspecific variation for specific root length (SRL) and specific surface area (SRA) is high, and the TI is low. This convergence and divergence of root traits reflect the Phenotypic plasticity of roots and their adaptation to environmental filtering and interspecific competition. Maximum root depth (MRD) was detected significantly and weakly phylogenetic signal (0
Morphometry, Growth, and Condition of Hatchery-Reared Cisco ( Coregonus artedi ) and...
Marc Chalupnicki
Gregg E. Mackey

Marc Chalupnicki

and 4 more

August 01, 2023
The re-introduction of native species that have been extirpated or in low abundance in the Great Lakes has been a binational initiative between the United States and Canadian governments. Recently, new management programs have been unway that use current hatchery facilities for the restoration of native forage fishes in Lake Ontario. These species include Bloater ( Coregonus hoyi), which has been extirpated from Lake Ontario for approximately four decades, and Cisco ( C. artedi), which exists at a fraction of its former abundance. We assessed morphometrics, length-weight relationships, and condition factors during early life development for eight cohorts of Cisco and Bloater reared during 2012-2019. Weekly samples for Cisco and Bloater were measured from hatch until release (29-45 weeks, 133-1,002 samples annually). Head width, gape, mandible length, and mouth height metrics were all larger for Cisco than Bloater at any given size but increased at similar rates for both species. Average condition factors for Cisco and Bloater were 0.54317 and 0.55892, respectively. his information may also improve field identification of these species, helping managers evaluate the relative success of different release strategies for rehabilitation of populations of these native species.
By stimulating soil microbes, grazing threatens the ecosystem function of alpine mead...
Lin Wei
yalin wang

Lin Wei

and 6 more

July 31, 2023
The geographical environment of the Qinghai-Tibet Plateau is complex, and there are a large number of poor environmental conditions of pastures, such pastures are limited by the terrain, and the change of grassland function after grazing may be different from that of well-grown pastures. Grazing causes changes in soil physical and chemical properties and soil microbial characteristics and increases soil carbon release in grazed grasslands, which could trigger a positive feedback and threaten the soil carbon function of grazed grasslands. It is therefore necessary to investigate the grazing response of such pastures. Early observations focused on grazing, and observations of different types of grazing and grazing management concluded that insufficient attention had been paid to the effects of environmental constraints on vegetation growth and grazing response. Based on the systematic observation of the response of soil characteristics and soil microbial biomass to grazing gradient in a natural alpine meadow on the Qinghai-Tibet Plateau, the changes in soil ecosystem response to grazing and their correlations are discussed in this paper. The results showed that: 1) environmental conditions, especially the soil environment, significantly influence the response of alpine meadow ecosystems to grazing; 2) SOM is the main controlling factor in the soil material cycle, controlling both aboveground vegetation growth and belowground microbial biomass; 3) grazing increases the activity of soil microorganisms by initiating the microbial stimulation effect, thereby accelerating the consumption of soil nutrients and increasing CO2 release, while creating nutrient competition with aboveground vegetation, which is an important factor causing vegetation degradation, and the continuous increase of the microbial stimulation effect will also weaken the soil carbon sequestration function; 4) in actual production, light grazing is the best choice for alpine meadows in areas with poor growing environment.
Experimental evidence for adaptive divergence in response to a warmed habitat reveals...
Bethany Smith
Ana Costa

Bethany Smith

and 3 more

July 31, 2023
Ectotherms are expected to be particularly vulnerable to climate change driven increases in temperature. Understanding how populations adapt to novel thermal environments will be key for informing mitigation plans. We took advantage of threespine stickleback (Gasterosteus aculeatus) populations inhabiting adjacent geothermal (warm) and ambient (cold) habitats to test whether their evolutionary divergence was adaptive using field reciprocal transplant experiment. We found evidence for adaptive morphological divergence, as growth (length change) in the non-native habitat was found to relate to head, posterior and total body shape. Higher growth in fish transplanted to a non-native habitat was found to be associated with shape profiles closer to that of the native fish. The consequences of transplantation were asymmetric with cold sourced fish transplanted to the warm habitat suffering from lower survival rates and greater parasite prevalence than warm sourced fish transplanted to the cold habitat. We also found evidence for divergent shape allometries that related to growth. Our findings suggest that wild populations can adapt quickly to thermal conditions. However, immediate transitions to warmer conditions may be particularly difficult.
Fake news? The impact of cue mismatch in mating behaviour
Leonor Rodrigues
Sara Magalhães

Leonor Rodrigues

and 1 more

July 26, 2023
Although the role of multiple cues in mate choice have been widely studied, the consequences thereof for receivers remain poorly understood, especially when there is a mismatch between cues. We address this using the spider mite Tetranychus urticae, in which virgin females are highly valuable mates compared to mated females, given first male sperm precedence. We tested how the presence of females of different mating status, and of cues they left in the substrate affected mating behaviour as well as male costs. Male mating attempts were solely affected by substrate cues, being more frequent on patches with cues of virgins, while female acceptance and number of mating events were independently affected by both female identity and substrate cues, being higher when cues stemmed from virgins. Once copulation started, its duration depended mainly on the mating status of the female being fertilized, with the overall amount of time spent mating being higher in matings with virgins than in those with mated females. Male survival costs mirrored their investment in mating, with patches with a mismatch between cues showing intermediate survival costs. The substrate cues left by females are thus instrumental for males to find their mates, but they can also lead to males paying a high survival cost while not reaping the benefit of mating effectively, which suggest they are less reliable but more efficient than cues on females. The benefit of using redundant cues will then hinge upon the frequency of mismatch between cues, which itself should vary with the dynamics of populations.
A pantropical analysis of fire impacts and post-fire recovery on tropical plant diver...
Dharma Sapkota
David Edwards

Dharma Sapkota

and 3 more

July 21, 2023
Fire is increasingly driving loss and degradation of tropical habitats, but factors influencing biodiversity responses to fire are inadequately understood. We conduct a pan-tropical analysis of systematically collated data – 5257 observations of 1705 plant species (trees and shrubs, forbs, graminoids and climbers) in burnt and unburnt plots from 28 studies. We use model averaging of mixed effect models assessing how plant species richness and turnover (comparing burnt and unburnt communities) vary with time since fire, fire type, protected area status and biome type. More long-term studies are needed, but our analyses highlight three key findings. First, prescribed and non-prescribed burns have contrasting impacts on plant communities, the direction of which depends on focal life form and biome. Forb richness, for example, increases following non-prescribed (but not prescribed) burns in savannahs and flooded grasslands, but in moist broadleaved forest forb richness increases strongly following prescribed (but not non-prescribed) burns. Second, protected areas mitigate fire impacts on plant communities. Species richness of trees/shrubs increased (by ~50%) following fires in non-protected sites but tended to remain similar in protected sites. Similarly, ten years after a fire event graminoid community composition had recovered fully to resemble non-burnt communities in protected areas, but remained highly divergent in unprotected sites. Finally, this persistence in divergence of community composition following fire events occurs across a number of life forms. Composition of tree/shrub communities remained divergent from unburnt communities ten years after a fire, and composition of forb communities only returned to those of unburnt sites after ten years. Fire intervals are already less than ten years in some tropical locations, and future climate and land use change are predicted to further shorten these intervals. Plant communities across much of the tropics are thus likely to change substantially in response increased exposure to fire.
Habitat geometry rather than visual acuity limits the visibility of a ground-nesting...
George Hancock
Lizzie Grayshon

George Hancock

and 5 more

July 19, 2023
The nests of ground-nesting birds rely heavily on camouflage for their survival, and predation pressures, often linked to human activity, are a major source of mortality. Numerous ground-nesting bird populations are in decline, so understanding the effects of camouflage on their nesting behaviour is of relevance to their conservation concern. Habitat three-dimensional (3D) geometry together with predator visual abilities, viewing distance, and viewing angle determine whether a nest is either visible, occluded or too far away to detect. While this link is intuitive, few studies have investigated how fine-scale geometry is likely to help defend nests from different predator guilds. We quantified nest visibility based on 3D occlusion, camouflage, and predator visual modelling in northern lapwing, Vanellus Vanellus, on different land management regimes. Lapwings selected local backgrounds that had a higher 3D complexity at a spatial scale greater than their entire clutches compared to nearby control sites. Importantly, our findings show that habitat geometry – rather than predator visual acuity restricts nest visibility to terrestrial predators, and that an open field would actually be perceived as a closed habitat to a terrestrial predator searching for nests on the ground. Taken together with lapwings’ careful nest site selection, our findings highlight the importance of considering habitat geometry for understanding the evolutionary ecology and management of conservation sites for ground-nesting birds.
Season-specific impacts of climate change on canopy-forming seaweed communities.
Anthony Truong
Matthew Edwards

Anthony Truong

and 2 more

July 17, 2023
Understory assemblages associated with canopy-forming species such as trees, kelps, and rockweeds should respond strongly to climate stressors due to strong interaction strengths. Climate change can directly and indirectly modify these assemblages, particularly during more stressful seasons and climate scenarios. However, fully understanding the seasonal impacts of different climate conditions on canopy-reliant assemblages is difficult due to a continued emphasis on studying single species responses to a single future climate scenario during a single season. To examine these more complex interactions, we used mesocosm experiments to expose intertidal assemblages associated with the canopy-forming golden rockweed, Silvetia compressa, to elevated temperature and pCO2 conditions reflecting two projected greenhouse emission scenarios [RCP 2.6 (low) & RCP 4.5 (moderate)]. Assemblages were grown in the presence and absence of Silvetia, and in two seasons. Relative to ambient conditions, predicted climate scenarios generally suppressed Silvetia biomass and photosynthetic efficiency. However, these effects varied seasonally - both future scenarios reduced Silvetia biomass in summer, but only the moderate scenario did so in winter. These reductions shifted the assemblage, with more extreme shifts occurring in summer. Contrarily, future scenarios did not shift assemblages within Silvetia Absent treatments, suggesting that climate primarily affected assemblages indirectly through changes in Silvetia. Mesocosm experiments were coupled with a field Silvetia-removal experiment to simulate the effects of climate-mediated Silvetia loss on natural assemblages. Consistent with the mesocosm experiment, Silvetia loss resulted in season-specific assemblage shifts, with weaker effects observed in winter. Together, our study supports the hypotheses that climate-mediated changes to canopy-forming species can indirectly affect the associated assemblage, and that these effects vary seasonally. Such seasonality is important to consider as it may provide periods of recovery when conditions are less stressful, especially if we can reduce the severity of future climate scenarios.
Indiscriminate aggression and threat-level insensitive egg rejection maintain host su...
Jennifer York

Jennifer York

July 17, 2023
The existence of adult sexual dimorphism is typically explained as a consequence of sexual selection, yet coevolutionary drivers of sexual dimorphism frequently remain untested. Here, I investigate the role of sexual dimorphism in host-parasite interactions of the brood parasitic diederik cuckoo, Chrysococcyx caprius. Female diederik cuckoos are more cryptic in appearance and pose a threat to the clutch, while male diederik cuckoos are conspicuous and not a direct threat. Specifically, I examine whether sexual dimorphism in diederik cuckoos provokes threat-level sensitive responses in Southern red bishop, Euplectes orix, hosts. I use experimentally simulated nest intrusions to test whether hosts have the capacity to differentially (i) detect, and/or (ii) discriminate between, male and female diederik cuckoos, relative to controls. Overall, I found no evidence that diederik cuckoos differ in detectability, since both sexes are comparable to controls in the probability and speed of host detection. Furthermore, neither male nor female hosts discriminate between sexually dimorphic diederik cuckoos when engaging in frontline nest defences. However, hosts that witnessed a male diederik cuckoo during the trial were more than twice as likely to reject odd eggs compared to those that saw a control. Moreover, hosts were more likely to reject experimental eggs when exposed to a male compared to a female diederik cuckoo: the reverse of a beneficial threat-level sensitive response. While the cryptic appearance of female diederik cuckoos does not differentially avoid detection by hosts, it does appear to provide the benefit of anonymity given the egg rejection costs of male-like appearance in the nest vicinity. These findings have implications for the evolution and maintenance of sexual dimorphism across the Cuculidae, and highlight the value of testing assumptions about the ecological drivers of sexual dimorphism.
From current to potential distribution: the case of Taxus baccata L. (Taxaceae, Pinal...
Giacomo Calvia
Pablo Hidalgo

Giacomo Calvia

and 5 more

July 14, 2023
Taxus baccata is a relic declining species, especially at the southern margins of its natural distribution, such as the Mediterranean and Irano-Turanian biogeographic regions. On the Island of Sardinia, it is still present in many mountain sites. This study identified 232 locations where yews grow. The species is indifferent to substrates, but prefers moist sites with northern aspects, and has elevation range is 695-1225 m a.s.l. To predict yew’s potential distribution in Sardinia, we collected data from the literature and field observations and applied the Maximum Entropy algorithm (MaxEnt). We used 202 field-based sites and 19 bioclimatic variables to model the potential distribution area under current climatic conditions. Annual precipitation, mean temperature of the warmest month and isothermality were the key drivers for the distribution of T. baccata in Sardinia. In terms of permutation importance, mean diurnal range and precipitation of the warmest quarter were the main environmental variables. The response curves showed that T. baccata prefers annual mean temperatures ranging from 8.65 to 12.55°C and annual mean precipitation from 770 to 1085 mm. Most potential suitable conditions were found in northern and central Sardinia. Using the Global Circulation Model, we also modelled future habitat suitability for T. baccata under two different scenarios, highlighting a substantial reduction of the habitat suitability for the species by the end of this century. This reduction is associated with climate change and poses an increasing concern about the future of the species and the priority habitat described in many parts of Sardinia.
Arboreal or terrestrial: Oviposition site of frogs affects the thermal function of fo...
Yukio Ichioka
Hisashi Kajimura

Yukio Ichioka

and 1 more

July 13, 2023
1. Temperature is essential for the survival and development of eggs. Some anurans have evolved and developed foam nesting traits, with thermal insulation considered to be among their functions. Foam nesting frogs tend to exhibit reproductive plasticity. For example, they oviposit on both trees and the ground. How such plasticity affects foam nest function is of major relevance and is likely related to the adaptation of foam nesting frogs. However, this has not been well studied. 2. In this study, we studied the interaction between foam nest site, foam nest function, and egg fate using the Japanese green tree frog, Zhangixalus arboreus, and analysed how nest site differences (arboreal or terrestrial) affect the thermal function of foam nests. 3. We compared the thermal functions of foam nests between arboreal and terrestrial oviposition sites of Z. arboreus. We artificially replaced half of the arboreal nests to terrestrial environments and recorded temperature in and outside of the experimental terrestrial nest and original arboreal nests. We also examined egg survival and hatching rate for all the nests. 4. The results indicated superior heat insulation in terrestrial nests, with warmer temperatures inside than outside the nests, especially at night, which led to a high egg survival rate. Therefore, terrestrial ovipositing should be valid under cold weather conditions. This may be related to the evolutionary history of oviposition site plasticity of this genus, which originally had an arboreal oviposition trait but evolved into terrestrial site use owing to global cooling. 5. Our novel insights into the evolution and adaptivity of foam nesting and oviposition site use in Z. arboreus make a significant contribution to animal ecology.
Assessing Genetic Diversity in Critically Endangered Chieniodendron hainanense Popula...
Haili Zhang

Haili Zhang

July 13, 2023
Habitat fragmentation engenders a reduction in the geographic distribution of species, thereby rendering diminutive populations susceptible to extinction due to environmental, demographic, and genetic factors. Chieniodendron hainanense (henceforth C. hainanense) exemplifies a wild plant with extremely small populations (WPESP) and faces endangerment, necessitating urgent national conservation efforts. Elucidating the genetic diversity of C. hainanense is crucial for uncovering underlying mechanisms and devising protective strategies. In the present study, 35 specimens from six distinct cohort groups were genotyped utilizing genotyping-by-sequencing (GBS) and single nucleotide polymorphism (SNP) methodologies. The results indicated that C. hainanense exhibits limited genetic diversity. Observed heterozygosity within C. hainanense populations spanned from 10.79% to 14.55%, with an average value of 13.15%. The six C. hainanense populations can be categorized into two distinct groups: (1) Diaoluoshan and Baishaling, and (2) Wuzhishan, Huishan, Bawangling, and Jianfengling. The degree of genetic differentiation among C. hainanense populations is relatively weak. The observed loss of diversity can be attributed to the effects of natural selection.
Super-scavengers: Vertebrates outperform invertebrates and microbes at removing carri...
Bhavya Iyer
Sutirtha Dutta

Bhavya Iyer

and 3 more

July 10, 2023
Scavenging by vertebrates is an important ecosystem service as they are known to remove carrion more efficiently than other taxa. How long would carrion persist bereft of vertebrate scavengers? Our study addresses this question in a forested landscape, by comparing carrion utilization by vertebrate scavengers, invertebrates, and microbes (decomposers). To understand carrion removal, we used experimental placement of chicken carcasses in a dry deciduous forest near Panna Tiger Reserve, Madhya Pradesh, India. Carcasses were placed under different treatment conditions (vertebrate scavenging, invertebrate scavenging, microbial decomposition and control to account for moisture loss), by experimentally excluding other scavengers. The daily rate of carcass utilization and proportion of carrion biomass remaining differed between treatments. Vertebrates consumed carcasses at the highest rates, removing 83% of carcass biomass in one day (CI 95%), followed by invertebrates (7.3%) and microbes (3.9%). Additionally, desiccation accounted for another 3.6% weight loss per day. The study showed drastic differences in carrion removal rates between taxa, indicating the irreplaceable role of vertebrates in the scavenging community of tropical forests, without whom carcasses would persist over prolonged periods. Our results support earlier studies that found overwhelming influence of vertebrate scavengers on carrion removal compared to other scavenging guilds.
Variations in C, N and P stoichiometry of leaf-litter-soil associated with Mongolian...
Guanglei  Gao
Guodong Ding

Guanglei Gao

and 4 more

July 10, 2023
Ecological stoichiometry is an important approach to understand the nutrient cycling and balance through the leaf-litter-soil system of Mongolian pine among different stand origins in desert regions. To reveal the variations in Mongolian pine carbon (C), nitrogen (N), and phosphorus (P) stoichiometry and stoichiometric homeostasis among different stand origins, we measured C, N, and P concentrations of leaves, litter, and soil, and analyzed the nutrient resorption efficiencies of leaves in differently aged plantations and natural forests from semi-arid and dry sub-humid regions. The results showed that (a) the stand origin had a significant effect on the C-N-P stoichiometry, and also significantly affected leaf N and P reabsorption efficiencies. Leaf N/P ratios indicated that Mongolian pine was co-limited by N and P in the NF, HB and HQ, and was mainly limited by P in MU. (2) With increasing stand age, C concentrations in the leaf-litter-soil system initially increased and then decreased, the N and P concentrations and reabsorption efficiencies in the leaf-litter-soil system were gradually increased. Overall, stand age had a significant effect on N concentrations, C/N and C/P ratios in the leaf-litter-soil system. (3) The C and N elements between the leaf-litter-soil system had a strong coupling relationship, and the P element between litter-soil had a strong coupling relationship. In addition, plantations exhibited greater N/P homeostasis than natural forests, and N/P exhibited greater homeostasis than N and P alone, which may be a nutrient utilization strategy for forests to alleviate N or P limitation. (4) Environmental factors have a significant influence on C-N-P stoichiometry in the leaf-litter-soil system, the most important soil properties and meteorological factors being soil water content and precipitation, respectively. These results will be essential to provide guidance for plantation restoration and management in desert regions.
Mating strategies of Vitex negundo L. var. heterophylla (Franch.) Rehder (Lamiaceae):...
Zhang Qing
Jilin Zhang

Zhang Qing

and 6 more

February 10, 2023
Plant reproductive ecology is one of the research hotspots in ecology. With the increasing attention paid to the conservation of plant diversity, the research on reproductive characteristics and flowering biological characteristics of more species has attracted more attention. However, plant reproduction is affected by multiple interacting factors such as pollen limitation and resource availability. Vitex negundo var. heterophylla (Franch.) Rehder (Lamiaceae) is a significant species for water and soil conservation. Previous studies have revealed its mating system by the biological characteristics of flowering and SSR markers, but its reproductive strategies remain to be further studied. We evaluated reproductive success through artificial pollination to explore the reproductive characteristics of V. negundo var. heterophylla for the first time. From the results of fruit set, there is a mixed mating system dominated by outcrossing in V. negundo var. heterophylla accompanied by self-compatibility, and it cannot carry out autonomous selfing. Our data shows the pollinator-mediated interaction in the success of reproduction, whereas the effect of anemophily is very weak. And the seed germination rate of inbred line progenies was lower than that of hybrid progenies, which is suspected to be caused by inbreeding depression. The research will provide scientific information for the protection and conservation of V. negundo var. heterophylla from the point of view of reproduction. In sum, the results are necessary to protect animal vectors in the background of insect decline.
The synergistic effects of a leaf mixture on decomposition change with a period of te...
Manuela Abelho
Enrique Descals

Manuela Abelho

and 1 more

June 30, 2023
The effect of mixing litter on decomposition has received considerable attention in terrestrial and aquatic (but rarely in both) ecosystems, with a striking lack of consensus in the obtained results. We studied the decomposition of a mixture of poplar and alder in three terrestrial:aquatic exposures to determine (1) if the effect of mixing litter on mass loss, associated decomposers and detritivores differs between the stream (fully aquatic exposure) and when litter is exposed to a period of terrestrial exposure prior to immersion and (2) the global effect of the mixture across exposure scenarios. The effect of the mixture was additive on mass loss and synergistic on decomposers and detritivores across exposure scenarios. Within scenarios, mass loss and decomposers showed synergistic effects only in the fully aquatic exposure, detritivores showed synergistic effects only when the period of terrestrial was shorter than the period of aquatic exposure, and when the period of terrestrial was equal to the period of aquatic exposure the effect of the mixture was additive on mass loss, decomposers, and detritivores. The species-specific effects also differed among exposure scenarios. Alder affected poplar only when there was a period of terrestrial exposure, with increased sporulation rates and fungal richness in exposure 25:75, and increased mass loss in exposure 50:50. Poplar affected alder only under fully aquatic exposure, with increased mass loss. In conclusion, the synergistic effects of the mixture changed with a period of terrestrial exposure prior to immersion. These results provide a cross-boundary perspective on the effect of mixing litter, showing a legacy effect of exposure to terrestrial decomposition on the fate of plant litter in aquatic ecosystems and highlighting the importance of assessing the effect of mixing litter on the associated biota and not only on mass loss.
Continuous artificial activity has threatened wetland ecological environment changes...
Wenrui Yuan
Lingkang Chen

Wenrui Yuan

and 5 more

June 28, 2023
Poyang Lake is an essential natural wetland in the Yangtze River basin and plays a vital role in maintaining the ecosystem function and ecological security in the middle and lower reaches of the Yangtze River. However, the relative importance and spatial heterogeneity of the impacts of human activities and land use changes on ecological security needs to be further explored. Here, we analyzed the habitat quality level around Poyang Lake in 2022 and explored the factors of habitat quality change from a geographical perspective. The land use structure changes around the Poyang Lake basin from 2000 to 2022 were quantitatively analyzed, and then the relative importance and spatial heterogeneity of each factor on ecological security changes were investigated using geographic probes. The results show that (1) The worst quality habitat (0–0.1) consists mainly of construction land (1624.9 km2) with an area of 1634.64 km2; (2) Construction land continues to increase with the most significant change, and the dynamic land use attitude is 0.47. Grassland and mudflats have the greatest decrease. The increase in cultivated land in different periods is mainly due to the shift of water surface and forest land; (3) Wetland land use change drivers are more influenced by the interaction of socioeconomic factors. The explanatory degrees of the interaction between population density and total year-end population and population density and administrative area are greater than 0.84. The data are greater than the explanatory degrees of every single factor, indicating that the land use change is mainly coupled with population density, total year-end population, and administrative area. These results reveal that human activities influence the degradation of wetlands around the Poyang Lake area. This study has significant reference value for coordinating human–land relationships in Poyang Lake, optimizing land management policy, and improving the sustainable development of cities
Differential effects of early life adversity on male and female rhesus macaque lifesp...
Stephanie Gonzalez
Anthony Sherer

Stephanie Gonzalez

and 2 more

June 20, 2023
Early life adversity predicts shorter adult lifespan in several animal taxa. Yet, work on long-lived primate populations suggests the evolution of mechanisms that contribute to resiliency and long lives despite early life insults. Here, we tested associations between individual and cumulative early life adversity and lifespan on rhesus macaques at the Cayo Santiago Biological Field Station using 50 years of demographic data. We performed sex-specific survival analyses at different life stages to contrast short-term effects of adversity (i.e., infant survival) with long-term effects (i.e., adult survival). Rhesus macaques exposed to adversity at birth suffered a significant increase in mortality risk during infancy with both individual and cumulative adversities having the highest impact among affected females. However, when considering adult lifespan, affected males showed higher vulnerability to both individual and cumulative adversities early in life. Our study shows profound immediate effects of insults at birth on female infant cohorts and suggests that affected female adults are more robust (i.e., viability selection). In contrast, adult males who experienced harsh conditions early in life showed an increased mortality risk at older ages as expected from hypotheses of long-term effects of individual, as well as cumulative, adversity early in life. Our study reveals that mortality risk during infancy is mainly driven by the type of adversity, rather than their accumulation at birth. However, cumulative adversity seems to play a major role in adult survival. Our analysis suggests sex-specific selection pressures on life histories and highlights the need for studies addressing the effects of early life adversity across multiple life stages. This information is critical for planning life stage-specific strategies of conservation interventions.
Does the number or size of plant patches contribute to vegetation restoration of rest...
Haishan Niu
Min Liu

Haishan Niu

and 8 more

June 16, 2023
Arid and semi-arid vegetation is characterized by plant patches of different sizes, and plant cover is determined by patch size (PS) and number of patches (NP). However, it is still unclear how PS and NP contribute to the restoration of degraded grasslands through grazing exclusion (GE). Transect lines were sampled in six alpine steppe communities in Tibet in 2017 and 2018. Both PS and NP were assessed and compared between inside and outside grazing exclosures. Our results showed that grazing exclosures increased the mean size but decreased the total number of plant patches. This pattern of change was common to other species and could not be attributed to a shift in community composition. The results suggest that the recovery of the degraded alpine steppe is being driven by PS at the expense of NP. By promoting the expansion of the larger patches while excluding the smaller ones, GE led to an aggregating pattern with a higher proportion of bare ground, potentially reducing primary productivity.
A New Mechanistic Model for Individual Growth Applied to Insects under Ad Libitum Con...
Karl Mauritsson
Tomas Jonsson

Karl Mauritsson

and 1 more

June 16, 2023
Metabolic theories in ecology interpret ecological patterns at different levels through the lens of metabolism, typically applying allometric power scaling laws to describe rates of energy use. This requires a sound theory for metabolism at the individual level. Commonly used mechanistic growth models, such as von Bertalanffy, DEB and the ontogenetic growth model lack a number of potentially important aspects and fail to accurately capture a growth pattern often observed in insects. Recently, a new model (MGM – the Maintenance-Growth Model) was developed for ontogenetic and post-mature growth, based on an energy balance that expresses growth as the net result of assimilation and metabolic costs for maintenance and feeding. The most important contributions of MGM are: 1) the division of maintenance costs into a non-negotiable and a negotiable part, potentially resulting in non-linear allometric scaling of maintenance and lowered maintenance under food restriction; 2) differentiated energy allocation strategies between sexes and 3) inclusion of costs for finding and processing food. MGM may also account for effects of body composition and type of growth at the cellular level. The model was here calibrated and evaluated using empirical data from an experiment on house crickets growing under ad libitum conditions. The procedure involved parameter estimations from the literature and collected data, using statistical models to account for individual variation in parameter values. It was found that ingestion rates cannot be generally described by simple allometries, here requiring more complex descriptions after maturation. By the unusual assumption of super-linear scaling of maintenance with body mass, MGM could well capture the differentiated growth patterns of male and female crickets. Other mechanistic growth models have also been able to provide good predictions of insect growth during early ontogeny, but MGM seems to be unique in its ability to accurately describe the trajectory until terminated growth.
Assessing the impacts of recreation on habitat use by mammals in an isolated alpine p...
Mitchell Fennell
Adam Ford

Mitchell Fennell

and 3 more

June 14, 2023
The management objectives of many protected areas must meet the dual mandates of protecting biodiversity while providing recreational opportunities. Balancing these mandates is made difficult by constraints on monitoring trends in the status of biodiversity and impacts of recreation. Using detections from 45 camera traps deployed between July 2019 and September 2021, we assessed the potential impacts of recreation on spatial and temporal habitat use for 8 medium- and large-bodied terrestrial mammals in an isolated alpine protected area: Cathedral Provincial Park, Canada. We hypothesized that some wildlife perceive a level of threat from people, such that they avoid ‘risky times’ or ‘risky places’ associated with human activity. Other species may benefit from associating with people, be it through access to anthropogenic resource subsidies or filtering of competitors/predators that are more human-averse (i.e., human shield hypothesis). Specifically, we predicted that large carnivores would show the greatest segregation from people while mesocarnivores and ungulates would associate spatially with people. We found spatial co-occurrence between ungulates and recreation, consistent with the human shield hypothesis, but did not see the predicted negative relationship between larger carnivores and humans, except for coyotes (Canis latrans). Temporally, all species other than cougars (Puma concolor) had activity patterns significantly different from that of recreationists, suggesting potential displacement in the temporal niche. Wolves (Canis lupus) and mountain goats (Oreamnos americanus) showed shifts in temporal activity away from people on recreation trails relative to off-trail areas, providing further evidence of potential displacement. Our results highlight the importance of monitoring spatial and temporal interactions between recreation activities and wildlife communities, in order to ensure the effectiveness of protected areas in an era of increasing human impacts.
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