Many insects possess the plastic ability to either develop directly to adulthood, or enter diapause and postpone reproduction until the next year, depending on environmental cues (primarily photoperiod) that signal the amount of time remaining until the end of the growth season. These two developmental pathways often differ in co-adapted life history traits, e.g. with slower development and larger size in individuals headed for diapause. The developmental timing of these differences may be of adaptive importance: if pathways diverge late, the scope for phenotypic differences is smaller, whereas if pathways diverge early, the risk is higher of expressing a maladaptive phenotype if the selective environment changes. Here we explore the effects of changes in photoperiodic information during life on pupal diapause and associated life history traits in the butterfly Pararge aegeria. We find that both pupal diapause and larval development rate are asymmetrically regulated: while exposure to long days late in life (regardless of earlier experiences) was sufficient to produce nondiapause development and accelerate larval development accordingly, more prolonged exposure to short days was required to induce diapause and slow down pre-diapause larval development. While the two developmental pathways diverged early in development, development rates could be partially reversed by altered environmental cues. Meanwhile, pathway differences in body size were more inflexible, despite emerging late in development. Hence, in P. aegeria several traits are regulated by photoperiod, along subtly different ontogenies, into an integrated phenotype that strikes a balance between flexibility and phenotype-environment matching.
Kauri dieback, caused by Phytophthora agathidicida, is an ecosystem disturbance that poses a recent threat to the survival of kauri (Agathis australis) forests in New Zealand. Throughfall and stemflow play an important role in meeting the nutrient requirements of kauri forests. However, the effects of kauri dieback on canopy nutrient deposition remain unknown. Here we measured throughfall, stemflow and forest floor water yield and nutrient concentrations and fluxes (potassium, calcium, magnesium, manganese, silicon, sulphur, sodium, iron) of ten kauri trees differing in soil P. agathidicida DNA concentration and health status. We did not observe an effect of soil P. agathidicida DNA concentration on throughfall and stemflow water yield. Throughfall and forest floor nutrient concentrations and fluxes tended to decrease (up to 50%) with increasing soil P. agathidicida DNA concentration. Significant effects were found for potassium and manganese fluxes in throughfall, and calcium and silicon fluxes in forest floor leachate. The decline in nutrient input will have implications on plant nutrition, tree health and susceptibility to future pathogen infection in these ecologically unique kauri forests. Given our findings and the increasing spread of Phytophthora species worldwide, research on the underlying physiological mechanisms linking dieback and plant-soil nutrient fluxes is critical.
Understanding what variables affect ungulate neonate survival is imperative to successful conservation and management of the species. Predation is commonly cited as a cause-specific source of mortality and ecological covariates often influence neonate survival. However, variation in survival estimates related to capture methodology has been documented with opportunistically captured neonates generally displaying greater survival than those captured via aid of vaginal implant transmitters (VITs), likely because of increased left truncation observed in the opportunistically captured datasets. Our goal was to assess if 3- and 6-month survival estimates varied by capture method while simultaneously assessing if capture method affected model selection and interpretation of ecological covariates for white-tailed deer neonates captured from three study sites in North Dakota and South Dakota, USA. We found survival varied by capture method for 3-month neonate survival with opportunistically captured neonates displaying up to 26% greater survival than their counterparts captured via VITs; however, this relationship was not present for 6-month survival. We also found model selection and subsequent interpretation of ecological covariates varied when analyzing datasets comprised of neonates captured via VITs, neonates captured opportunistically, and all neonates combined regardless of capture method. When interpreting results from our VIT only analysis for 3-month survival, we found survival varied by three time intervals and was lowest in the first two weeks of life. Capture method did not affect 6-month survival which was most influenced by total precipitation occurring during 3 – 8 weeks of a neonate’s life and percent canopy cover found at a neonate’s capture site. Our results support previous research that capture method must be accounted for when deriving survival estimates for ungulate neonates as it can impact derived estimates and subsequent interpretation of results.
Seed recruitment is a major driver of mangrove restoration globally. It is hypothesized that soil condition and channel hydrology can accelerate seedling recruitment and regeneration after a major disturbance. Species abundance, diversity indices, microbial and chemical concentrations in sand-filled mangrove forest was studied. Eight plots (area = 3902.16 m2) were established with ten transects in each plot in a random block design to investigate the effect of soil conditions on seedling growth. A total of 1, 886 seedlings were physically counted. Seedling abundance was significantly different between red (Rizophora racemosa), white (Laguncularia racemosa) and black (Avicennia germinans) mangroves and nypa palm (nypa fruticans). The most dominant species was black mangroves and the least dominant species was nypa palm. Muddy soils had the most abundant species while sandy soils had the least abundant species. Furthermore, semi-muddy soils had the highest species diversity (H = 0.948) whereas muddy soils had the least species diversity (H = 0.022). The soil metal concentration has no correlation with seed abundance and occur in the order Iron>Nitrate>Copper>Cadmium. Soil with high species diversity had high soil microbial population; however, seedling abundance was correlated with soil nutrients and not heavy metals. Small seeds are easily recruited while good soil condition plus existing hydrological connection facilitated natural seedling regeneration in the disturbed mangrove forest.
Cooperative breeding, which is commonly characterized by non-breeding individuals that assist others with reproduction, is common in avian species. However, few accounts have been reported in Charadriiformes, particularly island-nesting species. We present observations of cooperative breeding behaviors in Hawaiian Stilts during the 2012-2020 nesting seasons on the Hawaiian islands of O‘ahu and Moloka‘i. We describe three different behaviors that indicate cooperative breeding: (1) nest sharing; (2) helper at the nest; (3) cooperative chick rearing. Our observations suggest an ideal opportunity to examine the evolution of cooperative breeding behaviors in the order Charadriiformes.
Capture-mark-recapture (CMR) studies have been used extensively in ecology and evolution. While it is feasible to apply CMR in some animals, it is considerably more challenging in small fast-moving species such as insects. In these groups, low recapture rates can bias estimates of demographic parameters, thereby, handicapping effective management of wild populations. Here we use high-speed videos (HSV) of the adults of two large dragonfly species that rarely land and, thus, are particularly challenging for CMR studies. We specifically test whether HSV, compared to conventional eye observations, increases the “resighting” rates and improves the certainty of the estimates of survival rate, and the effects of demographic covariates on survival rates. We show that the use of HSV increases the number of resights substantially. HSV improved our estimates of resighting and survival probability which were either under- or overestimated with the conventional observations. HSV increased the accuracy of the estimates of effect sizes of important covariates (age and body size). Integrating HSV in CMR of highly mobile animals is valuable because it is easy, non-invasive, and has the potential to improve demographic estimates. Hence, it opens the door for a wide range of research possibilities on species that are traditionally difficult to monitor, including within insects, birds, and mammals.
The main strategy for animal diversity conservation is to increase the territory size but little consideration is given to habitat characteristics requirement, which lead to a decrease in effectiveness for protected areas. Marginal of protected areas are considered to have higher species richness due to the edge effect. Strategy in these sites are still adopts to increase territory size or pay no attention to needs of specific habitat characteristics that is an important topic for the planner and manager. In this study, camera traps was used to estimate composition, diversity and habitat characteristics of mammals in a non-protected area near Huangshan Mountains in Anhui Province, China. We ran 49 liner models with the relative abundance index and 13 habitat characteristic factors of 11 mammals. To answer the question of habitat characteristics or territory size: which is more important to composition and diversity of mammals in non-protect area? We hypothesized that: (1) Non-protected areas have more mammal species than protected areas with the edge effect. (2) Non-protected areas have more species associated with habitat characteristics. We predicted that the habitat characteristics should be firstly considered, territory size secondly in non-protected areas, would provide a last refuge for mammals. Cameras were operated from June 2017 to October 2019, for a total of 29 months, 2,212 independent photos, 9,485 trap-days, recorded 18 species of mammals more than any other protected areas confirmed first hypothesis 1. The model analysis results showed that, habitat characteristics of mammals were different and showed a significant correlation, supported hypothesis 2. In addition, most species are related to vegetation characteristics except to primates (Macaca. thibetana) and rodent (Leopoldamys edwardsi) confirmed our prediction. We suggested conservation policies in non-protected areas: Habitat characteristics should be concerned at first and then increasing protected areas to provide the last refuge for species conservation.
1. Behavior and organization of social groups is thought to be vital to the functioning of societies, yet the contributions of various roles within social groups towards population growth and dynamics have been difficult to quantify. A common approach to quantifying these role-based contributions is evaluating the number of individuals conducting certain roles, which ignores how behavior might scale up to effects at the population-level. Manipulative experiments are another common approach to determine population-level effects, but they often ignore potential feedbacks associated with these various roles. 2. Here, we evaluate the effects of worker size distribution in bumblebee colonies on worker production in 24 observational colonies across three environments, using functional linear models. Functional linear models are an underused correlative technique that has been used to assess lag effects of environmental drivers on plant performance. We demonstrate potential applications of this technique for exploring high-dimensional ecological systems, such as the contributions of individuals with different traits to colony dynamics. 3. We found that more larger workers had mostly positive effects and more smaller workers had negative effects on worker production. Most of these effects were only detected under low or fluctuating resource environments suggesting that the advantage of colonies with larger-bodied workers becomes more apparent under stressful conditions. 4. We also demonstrate the wider ecological application of functional linear models. We highlight the advantages and limitations when considering these models, and how they are a valuable complement to many of these performance-based and manipulative experiments.
Elevation is involved in determining plant diversity in montane ecosystems. This study examined whether the species distribution of plants in the Yatsugatake Mountains, central Japan, substantiated hypotheses associated with an elevational diversity gradient. Species richness of trees, shrubs, herbs, ferns, and bryophytes was investigated in study plots established at 200-m elevational intervals from 1800 to 2800 m. The changes in plant diversity (alpha and beta diversities, plant functional types, and elevational ranges) with elevation were analyzed in relation to climatic factors and elevational diversity gradient hypotheses, that is, mass effect, mid-domain effect, and Rapoport’s elevational rule. A comparison of alpha and beta diversities revealed that different plant groups respond variably to elevation; the alpha diversity of trees and ferns decreased, that of herbs increased, whereas the alpha diversity of shrubs and bryophytes showed a U-shaped relationship and a hump-shaped pattern. The beta diversity of shrubs, herbs, and bryophytes increased above the subalpine–alpine transition ecotone. In accordance with these changes, the dominance of evergreen shrubs and graminoids increased above this ecotone, whereas that of evergreen trees and liverworts decreased. None of the plant groups showed a wide elevational range at higher elevations. These elevational patterns of plant groups were explained by climatic factors, and not by elevational diversity gradient hypotheses. These patterns were further influenced by plant–plant interactions via competition for light availability and physical habitat alternation.
1. The volatiles from damaged plants induce defense in neighboring plants. The phenomenon is called plant-plant communication, plant talk or plant eavesdropping. Plant-plant communication has been reported to be stronger between kin plants than genetically far plants in sagebrush. 2. Why do plants distinguish volatiles from kin or genetically far plants? We hypothesize that plants respond only to important conditions; the induced defense is not free of cost for the plant. To clarify the hypothesis, we conducted experiments and investigations using goldenrod of 4 different genotypes. 3. The arthropods community on tall goldenrods were different among 4 genotypes. The response to volatiles was stronger from genetically close plants to the emitter than from genetically distant plants from the emitter. The volatiles from each genotype of goldenrods were different; and they were categorized accordingly. Moreover, the arthropod community on each genotype of goldenrods were different. 4. Synthesis: Our results support the hypothesis: goldenrods respond to volatiles from genetically close plants because they would have similar arthropod species. These results are important clues elucidating adaptive significance of plant-plant communication.
1. The dissimilarity and hierarchy of trait values that characterize niche and fitness differences, respectively, have been increasingly applied to infer mechanisms driving community assembly and to explain species co-occurrence patterns. Here, we predict that limiting similarity should result in the spatial segregation of functionally similar species, while functionally similar species will be more likely to co-occur together either due to environmental filtering or competitive exclusion of inferior competitors (hereafter hierarchical competition). 2. We used a fully mapped 50-ha subtropical forest plot in southern China to explore how pairwise spatial associations were influenced by trait dissimilarity and hierarchy between species in order to gain insight into assembly mechanisms. We assessed pairwise spatial associations using two summary statistics of spatial point patterns at different spatial scales and compared the effects of trait dissimilarity and trait hierarchy of different functional traits on the interspecific spatial associations. These comparisons allow us to disentangle the effects of limiting similarity, environmental filtering and hierarchical competition on species co-occurrence. 3. We found that trait dissimilarity was generally negatively correlated with interspecific spatial associations, meaning that species with similar trait values were more likely to co-occur together and thus supporting environmental filtering or hierarchical competition. We further found that leaf area, wood density and maximum height had stronger trait hierarchy effects on the pairwise spatial associations relative to their corresponding trait dissimilarity effects, which suggests that hierarchical competition played a more (or at least equally) important role in structuring our forest community compared to environmental filtering. 4. This study employed a novel method to disentangle the relative importance of multiple assembly mechanisms in structuring co-occurrence patterns, especially the mechanisms of environmental filtering and hierarchical competition, which lead to indistinguishable co-occurrence patterns. This study also reinforced the importance of trait hierarchy rather than trait dissimilarity in driving neighborhood competition.
The Lesser White-fronted Goose (Anser erythropus), smallest of the “grey” geese, is listed as Vulnerable on the IUCN Red List and protected in all range states. There are three sub-populations, with the least studied being the East Asian sub-population, shared between Russia and China. The extreme remoteness of breeding enclaves makes them largely inaccessible to researchers. As a substitute for visitation, remotely tracking birds from wintering grounds allows exploration of their summer range. Over a period of three years, and using highly accurate GPS tracking devices, eleven individuals of A. erythropus were tracked from the key wintering site of Dongting Lake, China, to breeding, molting, and staging sites in north-eastern Russia. Data obtained from that tracking, bolstered by ground survey and literature records, were used to model the summer distribution of A. erythropus. Although earlier literature suggests the summer range is patchy, the model confirms a contiguous summer range. The most suitable habitats are located along the coasts of the Laptev Sea, primarily the Lena-Delta, in the Yana-Kolyma Lowland, and smaller lowlands of Chukotka with narrow riparian extensions upstream along major rivers such as the Lena, Indigirka and Kolyma. The probability of A. erythropus presence is related to sites with altitude less than 500 m with abundant wetlands, especially riparian habitat, and a climate with precipitation of warmest quarter around 55 mm and mean temperature of wettest quarter around 14oC. Human disturbance also affects site suitability, with a gradual decrease in species presence starting around 160 km from human settlements. Remote tracking of animal species can bridge the knowledge gap required for robust estimation of species distribution patterns in remote areas. Better knowledge of species’ distribution is important in understanding the large-scale ecological consequences of rapid global change and establishing conservation management strategies.
For procellariiform seabirds, wind and body morphology are crucial determinants of flight costs and flight speeds. During chick-rearing, parental seabirds commute frequently to provision their chicks, and their body mass changes between outbound and return legs. In Antarctica, the typical diurnal katabatic winds which blow stronger in the mornings, form al natural experiment to investigate flight behaviours in response to wind conditions. We GPS-tracked three closely related species of sympatrically breeding Antarctic fulmarine petrels which differ in wing loading and aspect ratio and investigated their flight behaviour in response to wind and changes in body mass. All three species reached higher flight speeds under stronger tailwinds, especially on return legs from foraging, when wing loading was increased since birds carried food for their chicks. Flight speeds decreased under stronger headwinds. Antarctic petrels (Thalassoica antarctica; intermediate body mass, highest wind loading and aspect ratio) responded stronger to changes in wind speed and direction than cape petrels (Daption capense; lowest body mass, wing loading and aspect ratio) or southern fulmars (Fulmarus glacialoides; highest body mass, intermediate wing loading and aspect ratio). Birds did not adjust their flight direction in relation to wind direction nor maximum distance to nest when they encountered strong headwinds on their outbound commutes. However, birds appeared to adjust the timing of commutes to those hours of the day when headwinds were weakest and they were more likely to encounter favourable tail- and crosswinds. Despite these adaptations to the predictable diurnal wind conditions, birds frequently encountered unfavourably strong headwinds, possibly as a result of weather systems disrupting the katabatics coupled with the need to feed. How the predicted decrease in Antarctic near-coastal wind speeds over the remainder of the century will affect flight costs and breeding success which ultimately drives population trajectories remains to be seen.
Tree functional traits together with processes such as forest regeneration, growth, and mortality affect forest and tree structure. Forest management inherently impacts these processes. Moreover, forest structure, biodiversity, resilience, and carbon uptake can be sustained and enhanced with forest management activities. To assess structural complexity of individual trees, comprehensive and quantitative measures are needed, and they are often lacking for current forest management practices. Here, we utilized 3D information from individual Scots pine (Pinus sylvestris L.) trees obtained with terrestrial laser scanning (TLS) to first, assess effects of forest management on structural complexity of individual trees, and second, understand relationship between several tree attributes and structural complexity. We studied structural complexity of individual trees represented by a single scale independent metric called “box dimension”. This study aimed at identifying drivers affecting structural complexity of individual Scots pine trees in boreal forest conditions. The results showed that thinning increased structural complexity of individual Scots pine trees. Furthermore, we found a relationship between structural complexity and stem and crown size and shape as well as tree growth. Thus, it can be concluded that forest management affected structural complexity of individual Scots pine trees in managed boreal forests, and stem, crown, and growth attributes were identified as drivers of it.
1.Ectomycorrhizal (ECM) roots are evolutionary strategies of plants for effective nutrient uptake under varying abiotic conditions. Formation and morphological differentiations of ECM roots are important strategies in foraging environments. However, little is known on how such strategies mediate the nutrients of the below- and aboveground tissues and the balances among nutrient elements across environmental gradients. 2.We studied the function of ECM symbiosis in Abies faxoniana across its distributional range in Southwest China. The effects of differential ECM strategies, i.e. the contact exploration type, the short-distance exploration type, and the medium-distance exploration type, and root tips functional traits, etc., on root and foliar N and P and N:P ratio were examined across natural environmental gradients. 3.The ECM symbionts preferentially facilitated P uptake in A. faxoniana under both N and P limitations. The uptakes of N and P were primarily promoted by the effectiveness of ECM roots, e.g. ECM root tips per unit biomass, superficial area of ECM root tips, the ratio of living and dead root tips, but negatively related to the ECM proliferations and morphological differentiations. Generally, plant N and P nutrients were always promoted by the contact exploration type, while negatively affected by the short-distance exploration type in A. faxoniana. Root and foliar N and P nutrients were expected to be affected by the medium-distance exploration type in dynamics. Especially, root P limitation could be relieved when the frequency of medium-distance exploration type up to c.15%, whilst root N limitation was strengthen when the frequency of medium-distance exploration type over 20%. 4.We suggest that both below- and above-ground nutritional traits of host tree species could be strongly affected by ECM symbiosis in natural environments. The ECM strategies responding to environmental conditions significantly affect the plant nutrient uptakes and trade-offs. ECM soil exploration types are the great supplementary mechanisms for plant nutrient uptake.
Texas horned lizards (Phrynosoma cornutum) have a number of ways to avoid predation, including camouflage, sharp cranial horns, flattening of the body, and the ability to squirt blood from the eyes. These characteristics and their relatively low survival rates in the wild suggests these lizards are under high predation pressure. These lizards have been declining in much of their eastern range due to increased urbanization, agriculture, and loss of prey species. However, they can be still be found in some small south Texas towns where they can reach densities that are much higher (~50 lizards/ha) than in natural areas (~4-10 lizards/ha). We hypothesized that one reason for the high densities observed in these towns may be due to reduced predation pressure. We used model Texas horned lizards to test whether predation levels were lower in two south Texas towns than on a nearby ranch. We constructed models from urethane foam, a material that is ideal for preserving marks left behind by predators. Models (n = 126) and control pieces of foam (n = 21) were left in the field for 9 days in each location in early and late summer and subsequent predation marks were categorized by predator taxa. We observed significantly more predation attempts on the models than on controls and significantly fewer attempts in town (n = 1) compared to the ranch (n = 60). On the ranch, avian predation attempts appear to be common especially when the models did not match the color of the soil. Our results suggest that human modified environments that have suitable habitat and food resources may provide a refuge for some prey species like horned lizards from predators.
Connectivity of marine populations is shaped by complex interactions of biological and physical processes across the seascape. The influence of environmental features on the genetic structure of populations has key implications to the dynamics and persistence of populations, and an understanding of spatial scales and patterns of connectivity is crucial for management and conservation. This study employed a seascape genetics approach combining larval dispersal modeling and population genomic analysis based on RADseq to examine environmental factors influencing patterns of genetic structure and connectivity for a highly-dispersive mud crab, Scylla olivacea (Herbst, 1796) in the Sulu Sea. Dispersal simulations reveal widespread but asymmetric larval dispersal influenced by persistent southward and westward surface circulation features in the Sulu Sea. Despite potential for widespread dispersal, significant genetic differentiation was detected among eight Sulu Sea populations based on 1,655 single-nucleotide polymorphism (SNP) markers (FST = 0.0057, p = 0.001) and a subset of 1,643 putatively neutral SNP markers (FST = 0.0042, p = 0.001). Oceanography influences genetic structure, as redundancy analysis (RDA) revealed significant contribution of asymmetric ocean currents to neutral genetic variation (R2adj = 0.133; p = 0.035). Genetic structure may also reflect demographic factors, with divergent populations characterized by low effective population sizes (Ne < 50). Pronounced latitudinal genetic structure was recovered for loci putatively under selection (FST = 0.2390, p = 0.001), significantly correlated with variability in mean sea surface temperatures during peak spawning months of S. olivacea (R2adj = 0.763; p = 0.041), suggesting putative signatures of selection and local adaptation of early life history stages to thermal clines. This study contributes to the growing body of literature documenting population genetic structure and local adaptation for highly-dispersive marine species, and provides information useful for spatial management of the fishery resource.
Aim: In theory, long-distance dispersal (LDD) outside a species’ range contributes to genetic divergence. However, previous studies have not discriminated this process from vicariant speciation in migratory bird species. We conducted an integrative phylogeographic approach to test the LDD hypothesis, which predicts that a Japanese migratory bird subspecies diverged from a population in the coastal region of the East China Sea (CRECS) via LDD over the East China Sea (ECS). Location: East Asia Taxon: Brown Shrike (Lanius cristatus) Methods: Both a haplotype network and a multi-locus gene network of its three subspecies were reconstructed to examine from which continental population the Japanese subspecies diverged. A species distribution model (SDM) for the Japanese subspecies was constructed using bioclimatic variables under the maximum entropy algorithm. It was projected to the climate of the last glacial maximum (LGM) to infer the candidate source area of colonisation. A migratory route of the Japanese subspecies, which possibly reflects a candidate past colonisation route, was tracked by light-level geolocators. Results: Molecular phylogenetic networks suggest that the Japanese subspecies diverged from a population in the CRECS. The SDM inferred that the emerged continental shelf of the ECS and the present CRECS were suitable breeding areas for the Japanese subspecies during the LGM. A major migratory route for the Japanese subspecies was inferred between the CRECS and the Japanese archipelago across the ECS. Main conclusions: Our integrative approach supported the LDD hypothesis for divergence of the Japanese subspecies of the Brown Shrike. Shrinkage and expansion of the ECS may have been responsible for successful colonisation and isolation of the new population. Vicariance was inferred for divergence of the subspecies in the northeast Asian continent from the Japanese population. Our framework provides a new phylogeographic scenario in this region, and discriminating LDD and vicariance models should improve our understanding of the phylogeographic histories of migratory species.