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.
Mating systems and patterns in reproductive success of fishes play an important role in ecology and evolution. While information on the reproductive ecology of many anadromous salmonids (Oncorhynchus spp.) is well-detailed, there is less information for non-anadromous species including the Yellowstone Cutthroat Trout (O. clarkii bouvieri), a species of recreational angling importance and conservation concern. Here, we used data from a parentage-based tagging study to describe the mating system of Yellowstone Cutthroat Trout from a spawning tributary of the South Fork Snake River, Idaho, and identify predictors of relative reproductive success. We detected evidence of monogamy, polygyny, and polyandry and showed that reproductive success was best explained by arrival time at the spawning ground and total length. Specifically, the largest adults arrived earliest in the season and produced a disproportionate number of offspring. Lastly, we estimated the effective number of breeders (Nb) and effective population size (Ne) and showed that while Nb was lower than Ne, both are sufficiently high to suggest Yellowstone Cutthroat Trout in Burns Creek represent a genetically stable and diverse population.
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.
The relative contributions of adaptation and drift to morphological diversification of the crania of echolocating mammals was investigated using two horseshoe bat species, Rhinolophus simulator and R. cf. simulator as test cases. We used 3D geometric morphometrics to compare the shapes of skulls of the two lineages collected at various localities in southern Africa. Shape variation was predominantly attributed to selective forces; the between population variance (B) was not proportional to the within population variance (W). Modularity was evident in the crania of R. simulator but absent in the crania of R. cf. simulator and the mandibles of both species. The skulls of the two lineages thus appeared to be under different selection pressures, despite the overlap in their distributions. Selection acted mainly on the nasal dome region of R. cf. simulator whereas selection acted more on the cranium and mandibles than on the nasal domes of R. simulator. Probably the relatively higher echolocation frequencies used by R. cf. simulator, the shape of the nasal dome, which acts as a frequency dependent acoustic horn, is more crucial than in R. simulator, allowing maximization of the intensity of the emitted calls and resulting in comparable detection distances. In contrast, selection pressure is probably more pronounced on the mandibles and cranium of R. simulator to compensate for the loss in bite force because of its elongated rostrum. The predominance of selection probably reflects the stringent association between environment and the optimal functioning of phenotypic characters associated with echolocation and feeding in bats.
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.
All organisms are susceptible to the environment and changing environmental conditions can infer structural modifications in predator-prey communities. A change in the environment can influence, for example, the mortality rate of both the prey and the predator, or determine how long the interaction between both partners is. This may have a substantial impact on ecological, but also evolutionary dynamics. Experimental studies, in which microbial populations are maintained by a repeated dilution into fresh conditions after a certain period of time, are able to dissipate underlying mechanisms in a controlled way. By design, dilution rate (modifying mortality) and transfer interval (determining the time of interaction) are crucial factors, but they often receive little attention in experimental design. We study data from a live predator-prey (bacteria and ciliates) system used to gain insight into eco-evolutionary principles and apply a mathematical model to predict how various dilution rates and transfer intervals would affect such an experiment. We find the ecological dynamics to be surprisingly robust for both factors. However, the evolutionary rates are expected to be affected. Our work predicts that the evolution of the anti-predator defence in the bacteria, and the evolution of the predation efficiency in the ciliates, both decrease with higher dilution rate, but increase with longer transfer intervals. Our results provide testable hypotheses for future studies of predator-prey systems and we hope this work will help improving our understanding how ecological and evolutionary processes together shape composition of microbial communities.
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.
Increasingly animal behaviour studies are enhanced through the use of accelerometry. To allow translation of raw accelerometer data to animal behaviours requires the development of classifiers. Here, we present the “rabc” package to assist researchers with the interactive development of such animal-behaviour classifiers based on datasets consisting out of accelerometer data with their corresponding animal behaviours. Using an accelerometer and a corresponding behavioural dataset collected on white stork (Ciconia ciconia), we illustrate the workflow of this package, including raw data visualization, feature calculation, feature selection, feature visualization, extreme gradient boost model training, validation, and, finally, a demonstration of the behaviour classification results.
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.
Stable isotope analysis is a universally recognized and efficient method of indicating trophic relationships that is widely applied in research. However, variations in natural isotopic abundance may lead to inaccuracies due to the effects of complex environmental conditions. This research compared the carbon and nitrogen isotopic niches of fish communities between diverse biotopes around the Yellow River estuary and adjacent sea areas, with the aim of revealing distinctions in stable isotopic niche metrics, trophic positions, and feeding preferences. Stable isotopic niche results indicated that the communities of estuarine habitants were compatible in most study biotopes, and may provide a corridor for energy and material transportation between Laizhou Bay and the open water. Local biocoenosis was embodied in the wider isotopic niche corresponding to frequent environmental changes and abiotic gradients. This implied that they used various food sources to adapt to the fickle environment, including marine-terrestrial boundaries and the estuary. Our analysis of the food source contribution indicated that allochthonous sources were considered major energy sources in estuarine areas directly affected by Yellow River-diluted water, while autochthonous benthic and pelagic producers dominated carbon input into the food web in Laizhou Bay and the open water. A significant variation in the fish δ15N characteristic was found within estuarine adjacent regions, so, together with the results from previous studies, we deemed the local high concentration of dissolved inorganic nitrogen as the original trigger of the abnormal δ15N characteristic in fishes via a transport process along food chains. These results provide a new perspective on the natural distinction of carbon and nitrogen isotopic niches. The detailed data reported here enhance our understanding of variations in fish communities in estuarine ecosystems.
1. Understanding the animal-habitat relationship at local scale is crucial in ecology, particularly to develop strategies for wildlife management and conservation. As this relationship is governed by environmental features and intra and inter-specific interactions, habitat selection of a population may vary locally between its core and edges. 2. This is particularly true for central place foragers, such as grey and harbour seals, whose trends in numbers vary among different regions in the Northeast Atlantic. Here, we aimed at studying how foraging habitat selection may vary locally with the influence of population trends and physical habitat features 3. Using GPS/GSM tags deployed in grey and harbour seal colonies of contrasting sizes, we investigate spatial patterns and foraging habitat selection by comparing trip characteristics and home range similarities, and fitting GAMM to the seal distribution and environmental data respectively. 4. We show that grey seal foraging habitat selection and spatial patterns differed markedly between regions. Grey seals may select environmental characteristics for their foraging habitat accounting for local differences in prey consumed. Spatial patterns were different might depend on local seal density and regional productivity, located from inshore to offshore areas for the limit ranges and core population respectively. Our results on foraging habitat selection reflected the coastal and sedentary behaviour of harbour seals. We found no difference in spatial patterns between colonies, except for the Inner Hebrides where seals foraged further, potentially reflecting density dependence pressure, as the number in this colony is higher. 5. These results suggest that local conditions might have a strong influence on population spatial ecology, highlighting as well the relevance of studying foraging habitat selection based on foraging behaviour at fine geographical scale, particularly if species are managed within regional units.
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.
Competition between the sympatric harbour (Phoca vitulina) and grey seals (Halichoerus grypus) is thought to underlie some recent local declines of the former while the population of the latter remains stable or increases. A better understanding of the interactions between these two species is critical to elucidate current changes. This study aims at identifying and quantifying the niche overlap between harbour and grey seals at their Southern European limit range, in the baie de Somme (Eastern English Channel, France), in a context of exponential increase in the number of resident harbour seals and visiting grey seals. Isotopic niche overlap was quantified between both species using whisker δ13C and δ15N isotopic values, taking intra- and interindividual variability into account. Dietary overlap was quantified from scat contents using hierarchical clustering. A high degree of trophic niche overlap was identified between both species. The narrower isotopic niche of harbour seals was nested within that of grey seals (58.2% [CI95%: 22.7-100%] overlap). Six diet clusters were identified from scat content analysis. Two of them gathered most of harbour seals’ scats (85.5 % [80.3-90.2%]) and around half of grey seals’ ones (46.8% [35.1-58.4%]) that almost exclusively contained benthic flatfish. Consumption of this type of prey was identified here to be the root cause of trophic overlap. This highlighted the potential for competition between the two species at their Southern European limit range, linked to foraging on benthic flatfish, in coastal waters close to their haulout sites, especially during spring/summer. We suggest that (1) interspecific competition for prey could occur/increase in the future if the number of grey and harbour seals still increase and/or if flatfish supply decrease in this area, and (2) harbour seals would be disadvantaged in such a case if they do not adapt, as being specialised on flatfish at the colony scale.