A document by Ellen Yasumiishi. Click on the document to view its contents.

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.

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.

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 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.

Insect herbivores, such as lepidopteran larvae, often have close evolutionary relationships with their host plants, with which they may be locked in an evolutionary arms race. Larval grouping behaviour may be one behavioural adaptation that improves host plant feeding, but aggregation also comes with costs, such as higher competition and limited resource access. Here, we use the Heliconiini butterfly tribe to explore the impact of host plant traits on the evolution of larval gregariousness. Heliconiini almost exclusively utilise species from the Passifloraceae as larval host plants. Passifloraceae display incredible diversity of form, leaf shape and a range of anti-herbivore defences, suggesting they are locked in an arms race with Heliconiini larvae. By analysing larval social behaviour as both a binary (solitary or gregarious) and categorical (increasing larval group size) trait, we revisit the multiple origins of larval gregariousness across Heliconiini. We investigate whether host habitat, leaf defences and leaf size are important drivers of, or constraints on, larval gregariousness. Whereas our data do not reveal links between larval gregariousness and the host plant traits included in this study, we do find an interaction between larval host specialisation and behaviour, revealing gregarious larvae to be more likely to feed on a narrower range of host plant species than solitary larvae. We also find evidence that this increased specialisation typically precedes the evolutionary transition to gregarious behaviour. The comparatively greater host specialisation of gregarious larvae suggests that there are specific morphological and/or ecological features of their host plants that favour this behaviour.

1. Cyanobacterial blooms in freshwater sources are a global concern, and gaining insight into their causes is crucial for effective resource management and control. 2. In this study, we present a computational framework for the causal analysis of cyanobacterial harmful algal blooms (cyanoHABs) in Lake Kinneret. Our framework integrates Convergence Cross Mapping (CCM) and Extended CCM (ECCM) causal networks with Bayesian Network (BN) models. 3. The constructed CCM - ECCM causal networks and BN models unveil significant interactions among factors influencing cyanoHAB formation. These interactions have been validated by domain experts and supported by evidence from peer-reviewed publications. Our findings suggest that M. flos-aquae levels are influenced not only by community structure but also by nitrate, nitrite, ammonium, phosphate, oxygen, and temperature levels in the weeks preceding bloom occurrences. 4. We have demonstrated a non-parametric computational framework for the causal analysis of a multivariate ecosystem. Our framework offers a more comprehensive understanding of the underlying mechanisms driving M. flos-aquae in Lake Kinneret. It captures complex interactions and provides an explainable prediction model. By considering causal relationships, temporal dynamics, and joint probabilities of environmental factors, the proposed framework enhances our understanding of cyanoHABs in Lake Kinneret.

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.

Landscape structure plays a key role in mediating a variety of ecological processes affecting biodiversity patterns, however its precise effects and the mechanisms underpinning them remain unclear. While the effects of landscape structure have been extensively investigated both empirically, and theoretically from a metapopulation perspective, the effects of spatial structure at the landscape scale remain poorly explored from a metacommunity perspective. Here, we attempt to address this gap using a spatially explicit, individual-based metacommunity model to explore the effects of landscape compositional heterogeneity and per se spatial configuration on diversity at the landscape and patch level via their influence on long term community assembly processes. Our model simulates communities composed of lineages of annual, asexual organisms living, reproducing, dispersing, and competing within grid-based, fractal landscapes which vary in their magnitude of spatial environmental heterogeneity and in their degree of spatial environmental autocorrelation. Communities are additionally subject to temporal environmental fluctuation and external immigration, allowing for turnover in community composition. We found that compositional heterogeneity and spatial autocorrelation had differing effects on richness and diversity and the landscape and patch scales. We also note a slight negative effect of compositional heterogeneity on median total landscape population size. Landscape level diversity was driven by community dissimilarity at the patch level and increased with greater heterogeneity, while landscape richness was largely the result of short-term accumulation of immigrants and decreased with greater compositional heterogeneity. Both richness and diversity decreased in variance with greater compositional heterogeneity, indicating a reduction in community turnover over time. Patch-level richness and diversity patterns appeared to be driven by overall landscape richness and local mass effects, resulting in maximum patch level richness and diversity at moderate levels of compositional heterogeneity and high spatial autocorrelation.

Understanding how ecological and environmental changes, anthropogenic activities, and climate have driven and will direct animals’ development and predicting their prospective distribution profiles in the Quaternary are essential to making a tangible conservation strategy. Macaques (Macaca) distributed in mainland East Asia provide an ideal research model for such an effort. We reconstruct macaques’ geographic distribution profiles during the Quaternary, from the last inter-glaciation (LIG, 120,000 - 140,000 years BP), the Last Glacial Maximum (LGM, 22,000 years BP), and the present (1970-2000) – based on which we deduce their perspective distribution in the 2050s. The results show their suitable habitats during LIG and LGM were mainly in Southwest, Central, and Coastal China. A noticeable distribution reduction started in LIG and persisted until the current (1970-2000). Their distribution centroid would shift northward to mountainous regions, mainly in Southwest China, where more migration corridors would be reserved for their future development. Also, the results indicate that China’s Protected Area currently does not cover more than 87% of macaques’ habitats, a dismal situation for their conservation. Finally, this study proclaims that the conservation priority of the macaques in the years to come should focus on Southwest China – their future refuge region in Quaternary.

Aim High alpine regions are threatened but understudied ecosystems that harbor diverse endemic species, making them an important biome for testing the role of environmental factors in driving functional trait-mediated community assembly processes. We tested the hypothesis that plant-soil feedbacks along a climatic and elevation gradient influence plant community assembly through shifts in habitat suitability, which drive plant functional, phylogenetic, and spectral diversity. Location In a high mountain system (2400-3500 m) of Región Metropolitana in the Chilean Andes (33°S, 70°W). Methods We surveyed vegetation and spectroscopic reflectance (400-2400 nm) to quantify taxonomic, phylogenetic, functional, and spectral diversity at five sites from 2400 m to 3500 m elevation. We characterized soil attributes and processes by measuring water content, carbon and nitrogen, and net nitrogen mineralization rates. Results At high elevation, colder temperatures reduced available soil nitrogen, while at warmer, lower elevations, soil moisture was lower. Metrics of taxonomic, functional, and spectral alpha diversity peaked at mid-elevations, while phylogenetic species richness was highest at low elevation. Leaf nitrogen increased with elevation at the community level and within individual species, consistent with global patterns of increasing leaf nitrogen with colder temperatures. Main conclusions The increase in leaf nitrogen, coupled with shifts in taxonomic and functional diversity associated with turnover in lineages, indicate that the ability to acquire and retain nitrogen in colder temperatures may be important in plant community assembly in this range. Such environmental filters have important implications for forecasting shifts in alpine plant communities under a warming climate.

1. Fine root distribution influences the potential for resource acquisition in soil profiles, which defines how plants interact with local soil environments; however, a deep understanding of how fine root vertical distribution varies with soil structural variations and across plant ages is lacking. 2. We subjected four xerophytic species native to an arid valley of China, Artemisia vestita, Bauhinia brachycarpa, Sophora davidii, and Cotinus szechuanensis, to increasing rock fragment content (RFC) treatments (0%, 25%, 50%, and 75%, v v-1) in an arid environment and measured fine root vertical profiles over four years of growth. 3. Fine root depth and biomass of woody species increased with increasing RFC, but the extent of increase declined with plant age. Increasing RFC also increased the degree of interannual decreases in fine root diameter. The limited supply of soil resources in coarse soils explained the increases in rooting depth and variations in the pattern of fine root profiles across RFC. Fine root depth and biomass of the subshrub species (A. vestita) in soil profiles decreased with the increase in RFC and plant age, showing an opposite pattern from the other three woody species. 4. Within species, the annual increase in fine root biomass varied with RFC, which led to large interannual differences in the patterns of fine root profiles. Capacity of younger or subshrub plants to cope with soil environmental changes were greater than the older or shrub plants. These results provide insights into the limitations of soil resources in dry and rocky environments, and have management implications for degraded agroforest ecosystem.

In the Central Himalayas, where environmental conditions vary greatly, understanding the biophysical limitations on forest carbon is crucial for accurately determining the region’s forest carbon stocks. This study investigates the role of climate and disturbance on the spatial variation of two key forest carbon pools: aboveground carbon (AGC) and soil organic carbon (SOC). Using field-observed plot-level carbon pool estimates from Nepal’s national forest inventory and structural equation modeling, we explore the relationship between forest carbon stocks and proxies of environmental constraints. The forest AGC and SOC models explained 25 % and 59 % of the observed spatial variation in forest AGC and SOC, respectively. The climatic availability of water and energy in broad-scale gradients combined with the fine-scale gradients of terrain and disturbance intensity were found to influence forest carbon stocks, but the sign and strength of the statistical relationships differ for forest AGC and SOC. While AGC showed a negative relationship to disturbance, SOC was impacted by the availability of climatic energy. Disturbances such as selective logging and firewood collection result in immediate forest carbon loss, while soil carbon changes take longer to respond. The lower decomposition rates in the high-elevation region, due to lower temperatures, preserve organic matter and contribute to the high SOC stocks observed there. These results have important implications for forest carbon management and conservation in the Central Himalayas.

The consequences of biological invasions and habitat degradation for native biodiversity depend on how species cope with the individual and synergetic challenges these processes present. To assess the impact of anthropogenic land-use on the food web architecture of an invaded community, we examine the diets of nine native and two highly invasive mammal species at different trophic levels, inhabiting different land-uses across six biogeographic regions in Tasmania, Australia. We use two complementary methods, environmental DNA metabarcoding analysis (eDNA) of faeces and stable isotope analysis (SIA) of nitrogen (N) and carbon (C) in whole blood, to account for the high inter-individual and temporal variability in animal diets. eDNA showed regionalisation in the diet of smaller species, with land-use further defining dietary taxa within each region. SIA revealed that bioregion and land-use influence the δ13C values of all carnivore species and omnivores, whereas the δ15N values of these species are influenced only by land-use and not bioregion. Including multiple species showed that native rats are changing their diet in response to the presence of invasive rats, an impact that would have been otherwise attributed to land-use. Our findings demonstrate that human activities and invasive species are molding the diets of invaded communities raising questions about the potential impacts that dietary modifications will have on the life-history traits and the evolutionary consequences these modifications might have on the survival of native species. This highlights the urgency to include human activities in ecological studies and the importance of targeting multispecies assemblages to gain a better understanding of synergetic impacts on native biodiversity.

Evidence for spatially varying selection and adaptive variation can provide insight into a species’ ability to adapt to different environments. However, despite recent advances in genomics, it remains difficult to detect footprints of spatially varying selection in natural populations. Here we analysed ddRAD sequencing data (21,892 SNPs) in conjunction with geographic climate variation to search for signatures of adaptive differentiation in twelve populations of the bank vole (Myodes/Clethrionomys glareolus) distributed across Europe. To identify the loci subject to spatially varying selection and associated with climate variation, we applied multiple genotype-environment association (GEA) methods, two univariate and one multivariate, and controlled for the effect of population structure. In total, we identified 213 candidate adaptive loci, 74 of which were located within genes. In particular, we identified signatures of selection in candidate genes with functions related to lipid metabolism and the immune system. Using the results of redundancy analysis (RDA), we demonstrated that population history and climate have joint effects on the genetic variation in the pan-European metapopulation. Furthermore, by examining only candidate loci, we found that annual mean temperature is an important factor shaping adaptive genetic variation in the bank vole. By combining landscape genomic approaches, our study sheds light on genome-wide adaptive differentiation and the spatial distribution of variants underlying adaptive variation in bank voles that are influenced by local climate.

Increasing studies have shown the importance of intraspecific trait variation (ITV) on the ecological process. However, the patterns and sources of ITV are still unclear, especially in the propagule of coastal vegetation. Here, we measured fresh weight (FW), fresh length (FL), maximum transverse diameter (TDmax), minimum transverse diameter (TDmin) and the ratio of TDmax to TDmin (RTD) of the hypocotyl (propagule) of Kandelia obovata for 66 genealogies across 26 sites. By combining multiple factors of climate, ocean and maternal tree to analyze their effects on the intraspecific trait variation of mangrove hypocotyl. The results showed that value of establishment traits (FW, FL, TDmax and TDmin which are related to mass) decreased along increasing latitudinal gradients and they were directly positively regulated by temperature. ITV of dispersal trait (RTD) was unstructured along latitudinal gradients, which was constrained by fitness tradeoff. Our findings indicate that establishment traits mainly varied between populations, whereas dispersal traits mainly varied between individuals. This study provides insights into the ITV of propagule in different functional dimensions on a broad scale and that may help integrate ITV into future analyses of mangrove protection.

1. Ice coverage duration on lakes and ponds is decreasing due to climate change, but experimentally testing the effects of decreased ice coverage on aquatic communities is challenging in field settings. 2. To assess whether we could simulate changes predicted to occur in aquatic habitats as climate change progresses including shorter ice duration, warmer temperatures, and thinner ice and associated water chemistry changes, we designed and constructed greenhouses to place over a set of ten experimental ponds, roughly 3x3m in area which slope to a maximum depth of 1m, dug into the ground at the Koffler Scientific Reserve (Ontario, Canada). Half of the wedge-shaped greenhouses were enclosed on all sides (n=5) while the other the other half were open on three sides, with only the top fitted with plastic sheeting (n=5). The open greenhouses provided a less-warmed treatment while controlling for precipitation reduction and light filtering caused by the sheeting. In November 2019 greenhouses were placed over the ponds. Snow was cleared from the greenhouses and water chemistry measures were taken once weekly through the 2019-2020 winter. 3. Ice was thinner across the winter and melted on average 10.6 days earlier in closed greenhouses compared to open greenhouses. Average winter water temperatures were also significantly higher in closed versus open greenhouses although these differences were not significant in all months. Similarly, maximum and minimum water temperatures were also higher in ponds with closed compared with open greenhouses. We successfully demonstrate a method for simulating expected changes in ice conditions as climate change progresses including decreasing ice coverage duration at levels similar to those observed in north temperate ecosystems (per century) and alpine ecosystems (per 36 years) and raising temperatures in a highly manipulatable experimental system.

Tidal flats can be found on most of the world's coastlines and are particularly vulnerable to anthropogenic disturbances. They are important transient ecosystems between terrestrial and marine ecosystems and their biodiversity provides important ecosystem services. Owed to their unique position between the terrestrial and the marine realm, strong environmental gradients of elevation, sediment composition but also food availability are prevailing. Here we investigate which environmental factors drive the spatial and temporal patterns in macrozoobenthos abundance, biomass, richness, diversity and species composition on back barrier tidal flats in the East-Frisian Wadden Sea. We found that with increasing mud content the total abundance of organisms in the sediment significantly increased, while biodiversity and biomass were not changing significantly with increasing mud content. Biomass of macrozoobenthos decreased with higher elevation towards the salt marsh. In contrast to expectations, increasing Chl a availability as a measure of primary productivity did not enhance biomass or abundance, but was associated with significantly reduced species richness. Species composition varied significantly among and within islands due to variation in sediment composition, resource availability and human-induced disturbance. In conclusion, macrozoobenthos biomass, abundance and biodiversity is interrelated in a complex way with the physical, abiotic and biotic processes in and above the sediment. Negative impacts of primary production on macrozoobenthos species richness demonstrate possible negative effects of nutrient inputs in tidal flat areas and the need for cross-boundary protection.