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opencc-zeroJun 2022View details →

Data from: Estimating survival and adoption rates of dependent juveniles

1. Population growth and fitness are typically most sensitive to adult survival in long-lived species, but variation in recruitment often explains most of the variation in fitness, as past selection has canalized adult survival. Estimating juvenile survival until age of independence has proven challenging, because marking individuals in this age class may directly affect survival. For Greater Sage-grouse, uniquely marking juveniles in the first days of life likely results in adverse effects to survival, detection of juveniles is not perfect, and females adopt juveniles from other parents. These challenges are encountered by researchers studying avian and mammalian species with similar life histories, yet, methods do not exist that explicitly estimate all these components of the recruitment process. 2. We propose a novel data collection method and demographic model to simultaneously estimate rates of detection, survival, and adoption of juvenile individuals. Using multiple cameras to film the beginning of juvenile activity on specific days, we obtained counts of juveniles associated with marked females. Increases of juveniles to broods provided information that enabled us to estimate rates of adoption that can be applied at the population level. Losses from broods informed apparent survival. These losses could be attributed to death, or they could be chicks that were adopted by other females. 3. We found evidence that apparent survival of juveniles was influenced by localized weather patterns when chicks were young. Similarly, we found that young chicks were more susceptible to the adverse effect of attending females being flushed by an observer. Both of these patterns diminished quickly as chicks aged. We provide the first-ever estimates of interval-specific adoption rates. 4. Our results suggest that researchers should be cautious when designing studies to estimate juvenile survival. More importantly, they provide insight into adoption, a behavior that has been known to exist for decades.

opencc-zeroJun 2022View details →

Wildfire influences individual growth and breeding dispersal, but not survival and recruitment in a montane amphibian

Global wildfire regimes are changing rapidly, with widespread increases in the size, frequency, duration, and severity of wildfires. Whereas the effects of wildfire on ecological state variables such as occupancy, abundance, and species diversity are relatively well-documented, changes in population vital rates (e.g., survival, recruitment) and individual responses (e.g., growth, movement) to wildfire are more limited because of the detailed information needed on the same individuals both pre- and post-fire. We capitalized on the 2018 Roosevelt wildfire, which occurred during our six-year (2015–2020) capture-mark-recapture study of boreal toads (Anaxyrus boreas boreas; n = 1415) in the Bridger-Teton National Forest, USA, to evaluate the responses of population vital rates and individual metrics to wildfire. We employed robust design capture-recapture models to compare the growth, dispersal, survival, and recruitment of adult boreal toads pre- and post-fire at burned versus unburned sites. At burned locations, growth increased two-years post-fire compared with the year directly following wildfire and was higher two-years post-fire than any other interval during our study period. Boreal toads dispersed to alternative breeding patches more at burned sites than unburned sites and dispersal increased two-years post-fire compared with the year directly following wildfire. Annual survival and recruitment did not differ between pre- and post-fire years nor among pre-fire years, the year following wildfire, and two-years post-fire. We demonstrate that, in certain contexts, dispersal can play a major role in changes to state variables (e.g., abundance) after wildfire, as opposed to other vital rates such as survival and recruitment. Our study represents an important step towards understanding the biological processes that underlie observed patterns in state variables following wildfire, which ultimately will be critical for the effective management of species in landscapes experiencing shifts in fire activity.

opencc-by-4.0Jun 2022View details →

Survival data of Agriotes obscurus beetles exposed to Metarhizium brunneum sporulating cadavers

The dataset contains survival and mycosis data of Agriotes obscurus male beetles exposed to Metarhizium brunneum sporulating cadavers, or soil contaminated by sporulating cadavers.

opencc-zeroJun 2022View details →

Increasing adult density compromises survival following bacterial infections in Drosophila melanogaster

The density-dependent prophylaxis hypothesis predicts that risk of pathogen transmission increases with increase in population density, and in response to this, organisms mount a prophylactic immune response when exposed to high density. This prophylactic response is expected to help organisms improve their chances of survival when exposed to pathogens. Alternatively, organisms living at high densities can exhibit compromised defense against pathogens due to lack of resources and density associated physiological stress; the crowding stress hypothesis. We housed adult Drosophila melanogaster flies at different densities and measured the effect this has on their post-infection survival and resistance to starvation. We find that flies housed at higher densities show greater mortality after being infected with bacterial pathogens, while also exhibiting increased resistance to starvation. Our results are more in line with the density-stress hypothesis that postulates a compromised immune system when hosts are subjected to high densities.

opencc-zeroJul 2022View details →

Timing and synchrony of migration in a freshwater fish: consequences for survival

Animal migration is one of the most spectacular and visible behavioural phenomena in nature with profound implications for a range of ecological and evolutionary processes. Successful migration hinges on the ability to exploit temporary resources (e.g. food) and evade threats (e.g. predators) as they arise, and thus the timing of migration is often regarded as a dominant predictor of individual migratory success. However, with the exception of intensively studied taxa (mainly birds), relatively few studies have investigated inter-individual annual and seasonal variation in migratory timing and performance, or tested predictions on how migration across high and low predation-risk habitats may exert selection on migratory timing. In particular, studies that assess the survival consequences of variation in migratory timing remain rare, which is most likely due to the logistical challenges associated with monitoring survival success and population-level characteristics simultaneously. Here, we address the above-mentioned questions using roach Rutilus rutilus, a fish that migrates from lakes characterised by high-predation risk into low-risk streams during winter. Specifically, we used individual-based tracking of roach in two European lake systems over multiple migration periods (9 and 7 years, respectively), to obtain highly detailed (year-round scheduling, repeat journeys and the fate of individuals) data on the variability/synchrony of migratory timing in spring and autumn respectively. We report seasonal differences in the variability of migratory timing, with lower variance and higher migration synchrony in spring lake arrival timing as compared to autumn lake departure timing. Furthermore, the timing of autumn migration is more variable across years than the timing of spring migration. Secondly, we find that later arrival to the lake habitat is positively associated with apparent survival from one year to the next, whereas we found no effect of lake departure timing on survival probability. These findings represent rare evidence showing how intraspecific variation in timing in migratory fish differs across years and seasons, and how variation in timing can translate into survival consequences for prey in systems characterised by high predation risk.

opencc-zeroJul 2022View details →

Effects of temperature and wildflowers on survival and macronutrient stores of the alfalfa leafcutting bee under extended cold storage

Megachile rotundata (F.) is an important pollinator of alfalfa in the United States. Enhancing landscapes with wildflowers is a primary strategy for conserving pollinators and may improve sustainability of M. rotundata. Changing cold storage temperatures from a traditionally static thermal regime (STR) to a fluctuating thermal regime (FTR) improves overwintering success and extends M. rotundata's shelf life and pollination window. Whether floral resources enhance overwintering survival and/or interact with thermal regime are unknown. With these data sets we tested the combined effects of enhancing alfalfa fields with wildflowers and thermal regime on survival and macronutrient stores under extended cold storage (i.e., beyond one season). Megachile rotundata adults were released in alfalfa plots with and without wildflower strips summer 2017. Completed nests were harvested in September 2017 and stored in STR. After a year, cells were randomly assigned to remain in STR for 6 months or in FTR for a year of extended cold storage; emergence rates were observed monthly. Macronutrient levels (i.e., sugars, glycogen, trehalose and total lipids) of newly emerged females were assessed.

Survival data of Martes Americana and landscape variables associated with mortality events

To test the effects of seasonal heterogeneity on a reintroduced carnivore, American martens (Martes americana), we compared metrics of local and season-specific heterogeneity to traditional forest metrics on the survival of 242 individuals across 8 years and predicted a survival landscape for 13 reintroduction sites. We identified a set of variables that characterized potentially important drivers of marten survival, allowing for a comparison between heterogeneity metrics (i.e., complexity of vegetation, land cover, and abiotic conditions) and landscape variables representing composition and configuration. We summarized environmental conditions encountered by individuals by extracting landscape variables and measures of heterogeneity within 95% kernel density estimate. To test the influence of landscape variables and heterogeneity on survival, we modeled mortality risk from time-to-event data using a Bayesian framework.

Non-structural carbohydrates predict survival in saplings of temperate trees under carbon stress

1. Non-structural carbohydrates (NSCs) mediate plant survival when the plant's carbon (C) balance is negative, suggesting that NSCs could predict plant survival under C stress. To examine this possibility, we exposed saplings of six temperate tree species to diverse levels of C stress created by the combination of two light conditions (full light availability and deep shade) and two defoliation levels (severe defoliation and non-defoliation). We then measured survival, biomass, and total NSCs and soluble sugar (SSs) concentrations in different organs of both dead and live saplings. 2. We estimated mean NSCs and SSs contents and concentrations per sapling and fitted logistic generalized mixed-effects models to determine if NSCs and SSs predict survival. Using inverse prediction modelling, we also determined whether there is a common NSCs and SS threshold across species at the time of sapling's death. 3. Defoliation and shade reduced the mean sapling's NSCs and SSs contents, indicating C stress. Mean sapling NSCs and SSs contents and concentrations predicted survival and the robustness of the models improved with the inclusion of species. At death, saplings of the exotic deciduous tree species Acer pseudoplatanus exhibited significantly lower mean NSCs and SSs contents than saplings of the evergreen conifer species Podocarpus nubigenus and lower stem NSCs and SSs concentrations than the broadleaf evergreen species Drimys winteri. 4. The energetic role that NSCs and SSs play in plants under C stress was evidenced by the capacity of these compounds to predict sapling survival under C stress. No common threshold of NSCs and SSs contents or concentrations for sapling survival amongst species was found, indicating that the level of these compounds may not be good proxies for interspecific comparisons of tolerance to C stress. Presumably, there are species-specific limits for the mobilization and use of NSCs and SSs in metabolism. 5. Our results anticipate that the inclusion of NSCs and SSs in modelling will improve predictions regarding tree responses to ongoing climate change. Nonetheless, a better understanding of the many roles that carbohydrates play in plant survival under C stress is required to scale predictions up to the community level.

Cross-generational stressors affect telomeres and survival in house sparrows

Parental stress often has long-term consequences for offspring. However, the mechanisms underlying these effects and how they are shaped by conditions offspring subsequently experience are poorly understood. Telomeres, which often shorten in response to stress and predict longevity, may contribute to, and/or reflect these cross-generational effects. Traditionally, parental stress is expected to have negative effects on offspring telomeres, but experimental studies in captive animals suggest that these effects may depend on the subsequent conditions that offspring experience. Yet, the degree to which parental stress influences and interacts with stress experienced by offspring to affect offspring telomeres and survival in free-living organisms is unknown. To assess this, we experimentally manipulated the stress exposure of free-living parent and offspring house sparrows (Passer domesticus). We found a weak, initial, negative effect of parental stress on offspring telomeres, but this effect was no longer evident at the end of post-natal development. Instead, the effects of parental stress depended on the natural sources of stress that offspring experienced during post-natal development whereby some outcomes were improved under more stressful rearing conditions. Thus, the effects of parental stress on offspring telomeres and survival are context-dependent and may involve compensatory mechanisms of potential benefit under some circumstances.

Early nest initiation and vegetation density enhance nest survival in Wild Turkeys

The theory of adaptive habitat selection suggests resource selection by animals should reflect underlying quality, such that individual selection confers an adaptive advantage via increased fitness. Using resource selection functions and nest survival models, we demonstrated that visual obstruction at the nest site was adaptively significant but timing of nest initiation had the greatest effect on nest survival for eastern wild turkeys (Meleagris gallopavo silvestris). Predation risk is a selective pressure, and if individuals can perceive predation risk, they may respond by altering selection of nest site characteristics based on prior experience. We evaluated patterns in nest site selection of 387 wild turkeys and consequences of selection on reproductive success across the southeastern United States from 2014-2019. We monitored 549 nest sites and found that nest initiation date had the strongest effect on daily nest survival rates, wherein adult females at our earliest nest initiation date were ~ 4 times more likely to successfully nest than females at our latest nest initiation dates. Selection of nest sites with greater visual obstruction also increased daily nest survival rates as females were 1.17 (1.100 – 1.234; 95% CI) and 1.37 (1.258 – 1.486; 95% CI) times more likely to select sites for every 10 cm increase in visual obstruction and maximum vegetation height, respectively. Collectively, our results indicate that nest initiation date is likely the critical parameter driving wild turkey nest success, whereas vegetative conditions play a lesser role influencing nest success. Females nesting earlier may be in better body condition and show increased nest attentiveness, which may mediate nest success more than vegetation conditions around nest sites. Our work indicates that increasing the reproductive success of wild turkeys may hinge on females being able to nest as early as possible within the reproductive season.

The effects of temperature extremes on survival in two semi-arid Australian bird communities over three decades, with predictions to 2104

Aim: Organisms in arid and semi-arid regions are frequently exposed to climatic extremes and accordingly among the most vulnerable to climate change. Studies of seasonal differences in vital rates, which mediate effects of climate on viability, are rare in arid species limiting ability to project population trends. We quantified survival patterns for two bird communities as a function of expo-sure to temperature extremes in winter and summer, then project survival patterns to 2104. Location: semi-arid eastern Australia Time period: 1986-2016; 1986-2104 Major taxa studied: Birds Methods: Using mark recapture time-dependent Cormack-Jolly-Seber models and data for 37 species from two 30-year ringing programs, we tested for effects on 6-monthly survival of expo-sure to temperatures >38oC and <0oC. We then predicted future survival for different emission scenarios, testing whether changes in survival associated with warming winters would be suffi-cient to offset the effects of rising summer temperatures. Results: Survival probability declined strongly with increasing exposure to days >38oC and to a lesser extent to days <0oC, with temperature extremes explaining 43% and 13% of temporal varia-tion in survival among years, respectively. Summer survival patterns were similar across avian guilds but only survival of nectarivores declined in winter. Our models predict that gains in winter survival will not offset reductions in summer survival. Annual survival is predicted to decline sub-stantially by the end of the century: from 0.63 in 1986 to 0.43 in 2104 under an optimistic emis-sion scenario and to 0.11 under a pessimistic scenario. Main conclusions: We highlight the significance of temperature extremes for species' persistence in arid and semi-arid regions, comprising 70% of Australia's land mass, and 40% globally. Our demography-based results are consistent with physiological-based projections evaluating avian survival in arid and semi-arid regions globally and suggest rising summer temperatures pose a risk to population persistence in these regions.

opencc-zeroSep 2022View details →

Data from: Climatic stress decreases tick survival but increases rate of host-seeking behavior

Ticks are vectors of many diseases and are expanding in geographic distribution. However, how ticks will fare in their new environments where they may experience stressful climatic conditions at the expansion front remains unclear. Since there is a trade-off in ticks between behaviors that promote longevity and behaviors that promote reproduction, we hypothesized that extreme climatic stress reduces the survivorship of ticks but increases the frequency of tick host-seeking behavior or questing. Here, we used a novel method to simulate climatic stress on individual ticks of three species – Amblyomma americanum, Dermacentor variabilis, and Ixodes scapularis – to evaluate their survival, physiology, and questing behavior. The first experiment involved placing 144 adult ticks of each species in two temperature ranges (15-25 °C and 25-35 °C) and three relative humidity treatments (32% RH, 58% RH, and 84% RH). We assessed the ticks daily for survivorship and questing, and we measured water loss by comparing the mass of each tick when it died to when it was fully hydrated. In this first experiment, ticks in warmer and less humid conditions generally died faster than in cooler and more humid conditions. Ticks of all three species were more likely to quest shortly before their death and consistently died after losing approximately 50-56% of total body water content, but Ixodes reached that threshold much faster than the other two species. The second experiment involved placing 18 ticks of each species at 35 °C and 32% RH. We assessed the ticks every three hours for survivorship, questing, and water loss. Ticks again were more likely to quest shortly before their death. With frequent checks, we were able to measure the dehydration tolerance more accurately and the rate of water loss. Ticks of all three species consistently died after losing approximately 51% of total body water content. However, Ixodes lost water approximately 5× faster than Amblyomma and 11× faster than Dermacentor. These results demonstrate that severe climatic stress tilts the trade-off toward higher questing rates, but not higher overall questing time because of reduced survival rates. Further investigations of ticks' behavioral and physiological responses to abiotic stress are necessary to develop robust models of how climate change will affect the transmission of tick-borne diseases.

Data from: High predation risk decimates survival during the reproduction season

Predators attack conspicuous prey phenotypes that are present in the environment. Male display behaviour of conspicuous nuptial colouration becomes risky in the presence of a predator, and adult males face higher predation risk. High predation risk in one sex will lead to low survival and sex ratio bias in adult cohorts, unless the increased predation risk is compensated by higher escape rate. Here, we tested the hypothesis that sand lizards (Lacerta agilis) have sex-specific predation risk and escape rate. We expected the differences to manifest in changes in sex ratio with age, differences in frequency of tail autotomy, and in sex-specific survival rate. We developed a statistical model to estimate predation risk and escape rate, combining the observed sex ratio and frequency of tail autotomy with likelihood-based survival rate. Using a Bayesian framework, we estimated the model parameters. We projected the date of the tail autotomy events from growth rates derived from capture-recapture data measurements. We found statistically stable sex ratio in age groups, equal frequency of tail regenerates between sexes, and similar survival rate. Predation risk is similar between sexes, and escape rate increases survival by about 5%. We found low survival rate and a low number of tail autotomy events in females during months when sand lizards mate and lay eggs, indicating high predator pressure throughout reproduction. Our data show that gravid females fail to escape predation. The risks of reproduction season in an ectotherm are a convolution of morphological changes (conspicuous colouration in males, body allometry changes in gravid females), behaviour (nuptial displays), and environmental conditions which challenge lizard thermal performance. Performance of endotherm predators in cold spring months endangers gravid females more than displaying males in bright nuptial colouration.

Nutritional stress exacerbates impact of a novel insecticide on solitary bees' behaviour, reproduction and survival

Pesticide exposure and food stress are major threats to bees, but their potential synergistic impacts under field-realistic conditions remain poorly understood and are not considered in current pesticide risk assessments. We conducted a semi-field experiment to examine the single and interactive effects of the novel insecticide flupyradifurone (FPF) and nutritional stress on fitness proxies in the solitary bee Osmia bicornis. Individually marked bees were released into flight cages with monocultures of either buckwheat, wild mustard or purple tansy, which were assigned to an insecticide treatment (FPF or control) in a crossed design. Nutritional stress, which was high in bees foraging on buckwheat, intermediate on wild mustard and low on purple tansy, modulated the impact of insecticide exposure. Within the first day after application of FPF, mortality of bees feeding on buckwheat was 29 times higher compared to control treatments, while mortality of FPF exposed and control bees was similar in the other two plant species. Moreover, we found negative synergistic impacts of FPF and nutritional stress on offspring production, flight activity, flight duration, and flower visitation frequency. These results reveal that environmental policies and risk assessment schemes that ignore interactions among anthropogenic stressors will fail to adequately protect bees and the pollination services they provide.

Figure 3 in Impact of brood parasitoids and oophagy on survival of Asemonea tenuipes (Araneae: Salticidae: Asemoneinae) broods in Karnataka

Figure 3 (continued from previous page). 27-30, Views of Idris sp. parasitoids emerging from the third brood and, as adult wasps, moving over to the fourth brood, still attended by the female Asemonea. It is likely that this brood will also be infected. 31, View of cocoon (remnant of first brood) and exuviae remaining in second brood, the only successful brood of the four, under the first leaf. Note the presence of a Myrmarachne sp. (arrow) in this Asemonea nest. 32, Five days later the female Asemonea was gone, leaving only scattered eggs from her third and fourth broods on the underside of the second Ficus leaf.

Figure 3 in Impact of brood parasitoids and oophagy on survival of Asemonea tenuipes (Araneae: Salticidae: Asemoneinae) broods in Karnataka

Figure 3 (continued from previous page, continued on next page). 15-16, The mantispid emerged from its cocoon (apparently remnant of first brood) and molted. 17, Detail of empty mantispid cocoon. 18, Mantispid near spiderlings of the second brood. 19, Female Asemonea tending her third brood. 20, View of mantispid and second brood beneath lower leaf, and female attending third brood beneath upper Ficus microcarpa leaf.

Figure 3 in Impact of brood parasitoids and oophagy on survival of Asemonea tenuipes (Araneae: Salticidae: Asemoneinae) broods in Karnataka

Figure 3 (continued from previous page, continued on next page). 21, Mantispid near its empty cocoon and exuvium, also near the developing second brood. 22, About one week later the female Asemonea was gone but the third brood was developing normally. The emergent (instar II) spiderlings shown here most likely came from the second brood. 23, A female Asemonea, perhaps the original female, moved into the nest near the third brood. 24, Same female Asemonea feeding on a chironomid midge in her nest near the second brood. 25, Gravid female Asemonea near the third brood, now clearly infected with Idris sp. parasitoids. 26, Same female after depositing a fourth brood of 18 eggs near the infected third brood.

Figure 3 in Impact of brood parasitoids and oophagy on survival of Asemonea tenuipes (Araneae: Salticidae: Asemoneinae) broods in Karnataka

Figure 3 (continued from previous page, continued on next page). 7, Developing second brood (instar I) under the first leaf. 8, Female Asemonea with third brood under the second leaf (upper left) with cocoon that replaced the first brood and the developing second brood under the first leaf. 9-11,14, Cocoon and developing second brood. 12, Detail of small insect (Heteroptera) near the mantispid cocoon, from (10). 13, Female Asemonea attending her third brood of 10 eggs on the second leaf.

Figure 1 in Impact of brood parasitoids and oophagy on survival of Asemonea tenuipes (Araneae: Salticidae: Asemoneinae) broods in Karnataka

Figure 1 (continued from previous page). 8-9, The 9 instar I spiderlings continued to develop as the female returned to her original colour. 10-12, Still attended by the female, 7 remaining spiderlings molted to the emergent instar (instar II). 13, The female and all of her spiderlings were gone.

Figure 3 in Impact of brood parasitoids and oophagy on survival of Asemonea tenuipes (Araneae: Salticidae: Asemoneinae) broods in Karnataka

Figure 3 (continued on next page). 1-2, Female Asemonea tenuipes attending her nest including a mantispid cocoon and a normal brood of 19 eggs on the underside of a Ficus microcarpa leaf. 3-8, Eggs of the second brood of 19 eggs were hatching (3) as the female Asemonea tenuipes moved to a nearby leaf and deposited a new brood of 10 eggs (6).