Phenology of brown bear breeding season and related geographical cues

© 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited[EN] Knowledge about breeding biology is often incomplete in species with complex reproductive strategies. The brown bear Ursus arctos is a polygamous seasonal breeder inhabiting a wide variety of habitats and environmental conditions. We compiled information about brown bear breeding season dates from 36 study areas across their distribution range in the Palearctic and Nearctic regions and investigated how their breeding phenology relates to geographical factors (latitude, photoperiod, altitude and region). Brown bear matings were observed for 8 months, from April to November, with a peak in May–July. We found a 59-day difference in the onset of bear breeding season among study areas, with an average 2.3 days delay for each degree of latitude northwards. The onset of the breeding season showed a strong relationship with photoperiod and latitude, but not with region (i.e. Palearctic vs Nearctic) and altitude. First observations of bear mating occurred earlier in areas at lower latitudes. Photoperiod ranged between 14 and 18 hours at the beginning of the season for most of the study areas. The duration of the breeding season ranged from 25 to 138 days among study areas. None of the investigated factors was related to the length of the breeding season. Our results support the relevance of photoperiod to the onset of breeding, as found in other ursids, but not a shorter breeding season at higher latitudes, a pattern reported in other mammals. Our findings suggest a marked seasonality of bear reproductive behaviour, but also certain level of plasticity. Systematic field observations of breeding behaviour are needed to increase our knowledge on the factors determining mating behaviour in species with complex systems and how these species may adapt to climate change.SIWe thank Marjan Artnak, Peter Bajc, Matic Brenk, Tomáš Flajs, Uroš Grželj, Robert Hlavica, Aleš Jagodnik, Peter Klančar, Anton Marinčič, Mariusz Nędzyński, Borut Semenič and Vladimir Vician for providing information about their observations of bear mating. Robert Gatzka assisted with data collection in the Biezszcady Mountains. We thank Jon Swenson and Jumpei Tomiyasu for their help in the literature search. AGR and NS were supported by the BearConnect project funded by the National Science Centre in Poland (2016/22/Z/NZ8/00121) through the 2015-2016 BiodivERsA COFUND call for research proposals, with the national funders ANR/DLR-PT/UEFISCDI/NCN/RCN. Additional funding from the Polish Ministry of Science and Higher Education (project NN304- 294037, NS, IEC, KB), the National Science Centre in Poland (project DEC-2013/08/M/NZ9/ 00469, NS), the National Centre for Research and Development (GLOBE, POL-NOR/198352/85/ 2013, NS, TZK, FZ) and Slovenian Research Agency (P4-0059, MK) is acknowledged. AGR and NS conceived the study and wrote a first draft of the paper; AGR and NS compiled the data, AGR analyzed the data; all authors provided data and comments that improved the manuscript. We thank two anonymous reviewers for useful comments on the previous versions of the manuscript

Integrated population models poorly estimate the demographic contribution of immigration

Estimating the contribution of demographic parameters to changes in population growth is essential for understanding why populations fluctuate. Integrated population models (IPMs) offer a possibility to estimate the contributions of additional demographic parameters, for which no data have been explicitly collected—typically immigration. Such parameters are often subsequently highlighted as important drivers of population growth. Yet, accuracy in estimating their temporal variation, and consequently their contribution to changes in population growth rate, has not been investigated. To quantify the magnitude and cause of potential biases when estimating the contribution of immigration using IPMs, we simulated data (using northern wheatear Oenanthe oenanthe population estimates) from controlled scenarios to examine potential biases and how they depend on IPM parameterization, formulation of priors, the level of temporal variation in immigration and sample size. We also used empirical data on populations with known rates of immigration: Soay sheep Ovis aries and Mauritius kestrel Falco punctatus with zero immigration and grey wolf Canis lupus in Scandinavia with near-zero immigration. IPMs strongly overestimated the contribution of immigration to changes in population growth in scenarios when immigration was simulated with zero temporal variation (proportion of variance attributed to immigration = 63% for the more constrained formulation and real sample size) and in the wild populations, where the true number of immigrants was zero or near-zero (kestrel 19.1%–98.2%, sheep 4.2%–36.1% and wolf 84.0%–99.2%). Although the estimation of the contribution of immigration in the simulation study became more accurate with increasing temporal variation and sample size, it was often not possible to distinguish between an accurate estimation from data with high temporal variation versus an overestimation from data with low temporal variation. Unrealistically, large sample sizes may be required to estimate the contribution of immigration well. To minimize the risk of overestimating the contribution of immigration (or any additional parameter) in IPMs, we recommend to: (a) look for evidence of variation in immigration before investigating its contribution to population growth, (b) simulate and model data for comparison to the real data and (c) use explicit data on immigration when possible

Network Structure of Vertebrate Scavenger Assemblages at the Global Scale: Drivers and Ecosystem Functioning Implications

The organization of ecological assemblages has important implications for ecosystem functioning, but little is known about how scavenger communities organize at the global scale. Here, we test four hypotheses on the factors affecting the network structure of terrestrial vertebrate scavenger assemblages and its implications on ecosystem functioning. We expect scavenger assemblages to be more nested (i.e. structured): 1) in species‐rich and productive regions, as nestedness has been linked to high competition for carrion resources, and 2) regions with low human impact, because the most efficient carrion consumers that promote nestedness are large vertebrate scavengers, which are especially sensitive to human persecution. 3) We also expect climatic conditions to affect assemblage structure, because some scavenger assemblages have been shown to be more nested in colder months. Finally, 4) we expect more organized assemblages to be more efficient in the consumption of the resource. We first analyzed the relationship between the nestedness of the scavenger assemblages and climatic variables (i.e. temperature, precipitation, temperature variability and precipitation variability), ecosystem productivity and biomass (i.e. NDVI) and degree of human impact (i.e. human footprint) using 53 study sites in 22 countries across five continents. Then, we related structure (i.e. nestedness) with its function (i.e. carrion consumption rate). We found a more nested structure for scavenger assemblages in regions with higher NDVI values and lower human footprint. Moreover, more organized assemblages were more efficient in the consumption of carrion. However, our results did not support the prediction that the structure of the scavenger assemblages is directly related to climate. Our findings suggest that the nested structure of vertebrate scavenger assemblages affects its functionality and is driven by anthropogenic disturbance and ecosystem productivity worldwide. Disarray of scavenger assemblage structure by anthropogenic disturbance may lead to decreases in functionality of the terrestrial ecosystems via loss of key species and trophic facilitation processes

Effects of Wolves on Elk and Cattle Behaviors: Implications for Livestock Production and Wolf Conservation

BACKGROUND: In many areas, livestock are grazed within wolf (Canis lupus) range. Predation and harassment of livestock by wolves creates conflict and is a significant challenge for wolf conservation. Wild prey, such as elk (Cervus elaphus), perform anti-predator behaviors. Artificial selection of cattle (Bos taurus) might have resulted in attenuation or absence of anti-predator responses, or in erratic and inconsistent responses. Regardless, such responses might have implications on stress and fitness. METHODOLOGY/PRINCIPAL FINDINGS: We compared elk and cattle anti-predator responses to wolves in southwest Alberta, Canada within home ranges and livestock pastures, respectively. We deployed satellite- and GPS-telemetry collars on wolves, elk, and cattle (n = 16, 10 and 78, respectively) and measured seven prey response variables during periods of wolf presence and absence (speed, path sinuosity, time spent head-up, distance to neighboring animals, terrain ruggedness, slope and distance to forest). During independent periods of wolf presence (n = 72), individual elk increased path sinuosity (Z = -2.720, P = 0.007) and used more rugged terrain (Z = -2.856, P = 0.004) and steeper slopes (Z = -3.065, P = 0.002). For cattle, individual as well as group behavioral analyses were feasible and these indicated increased path sinuosity (Z = -2.720, P = 0.007) and decreased distance to neighbors (Z = -2.551, P = 0.011). In addition, cattle groups showed a number of behavioral changes concomitant to wolf visits, with variable direction in changes. CONCLUSIONS/SIGNIFICANCE: Our results suggest both elk and cattle modify their behavior in relation to wolf presence, with potential energetic costs. Our study does not allow evaluating the efficacy of anti-predator behaviors, but indicates that artificial selection did not result in their absence in cattle. The costs of wolf predation on livestock are often compensated considering just the market value of the animal killed. However, society might consider refunding some additional costs (e.g., weight loss and reduced reproduction) that might be associated with the changes in cattle behaviors that we documented

Protein tyrosine phosphatases expression during development of mouse superior colliculus

Protein tyrosine phosphatases (PTPs) are key regulators of different processes during development of the central nervous system. However, expression patterns and potential roles of PTPs in the developing superior colliculus remain poorly investigated. In this study, a degenerate primer-based reverse transcription-polymerase chain reaction (RT-PCR) approach was used to isolate seven different intracellular PTPs and nine different receptor-type PTPs (RPTPs) from embryonic E15 mouse superior colliculus. Subsequently, the expression patterns of 11 PTPs (TC-PTP, PTP1C, PTP1D, PTP-MEG2, PTP-PEST, RPTPJ, RPTPε, RPTPRR, RPTPσ, RPTPκ and RPTPγ) were further analyzed in detail in superior colliculus from embryonic E13 to postnatal P20 stages by quantitative real-time RT-PCR, Western blotting and immunohistochemistry. Each of the 11 PTPs exhibits distinct spatiotemporal regulation of mRNAs and proteins in the developing superior colliculus suggesting their versatile roles in genesis of neuronal and glial cells and retinocollicular topographic mapping. At E13, additional double-immunohistochemical analysis revealed the expression of PTPs in collicular nestin-positive neural progenitor cells and RC-2-immunoreactive radial glia cells, indicating the potential functional importance of PTPs in neurogenesis and gliogenesis

Genes to Diseases (G2D) Computational Method to Identify Asthma Candidate Genes

Asthma is a complex trait for which different strategies have been used to identify its environmental and genetic predisposing factors. Here, we describe a novel methodological approach to select candidate genes for asthma genetic association studies. In this regard, the Genes to Diseases (G2D) computational tool has been used in combination with a genome-wide scan performed in a sub-sample of the Saguenay−Lac-St-Jean (SLSJ) asthmatic familial collection (n = 609) to identify candidate genes located in two suggestive loci shown to be linked with asthma (6q26) and atopy (10q26.3), and presenting differential parent-of-origin effects. This approach combined gene selection based on the G2D data mining analysis of the bibliographic and protein public databases, or according to the genes already known to be associated with the same or a similar phenotype. Ten genes (LPA, NOX3, SNX9, VIL2, VIP, ADAM8, DOCK1, FANK1, GPR123 and PTPRE) were selected for a subsequent association study performed in a large SLSJ sample (n = 1167) of individuals tested for asthma and atopy related phenotypes. Single nucleotide polymorphisms (n = 91) within the candidate genes were genotyped and analysed using a family-based association test. The results suggest a protective association to allergic asthma for PTPRE rs7081735 in the SLSJ sample (p = 0.000463; corrected p = 0.0478). This association has not been replicated in the Childhood Asthma Management Program (CAMP) cohort. Sequencing of the regions around rs7081735 revealed additional polymorphisms, but additional genotyping did not yield new associations. These results demonstrate that the G2D tool can be useful in the selection of candidate genes located in chromosomal regions linked to a complex trait

Scavenging in the Anthropocene: Human impact drives vertebrate scavenger species richness at a global scale

Understanding the distribution of biodiversity across the Earth is one of the most challenging questions in biology. Much research has been directed at explaining the species latitudinal pattern showing that communities are richer in tropical areas; however, despite decades of research, a general consensus has not yet emerged. In addition, global biodiversity patterns are being rapidly altered by human activities. Here, we aim to describe large‐scale patterns of species richness and diversity in terrestrial vertebrate scavenger (carrion‐consuming) assemblages, which provide key ecosystem functions and services. We used a worldwide dataset comprising 43 sites, where vertebrate scavenger assemblages were identified using 2,485 carcasses monitored between 1991 and 2018. First, we evaluated how scavenger richness (number of species) and diversity (Shannon diversity index) varied among seasons (cold vs. warm, wet vs. dry). Then, we studied the potential effects of human impact and a set of macroecological variables related to climatic conditions on the scavenger assemblages. Vertebrate scavenger richness ranged from species‐poor to species rich assemblages (4–30 species). Both scavenger richness and diversity also showed some seasonal variation. However, in general, climatic variables did not drive latitudinal patterns, as scavenger richness and diversity were not affected by temperature or rainfall. Rainfall seasonality slightly increased the number of species in the community, but its effect was weak. Instead, the human impact index included in our study was the main predictor of scavenger richness. Scavenger assemblages in highly human‐impacted areas sustained the smallest number of scavenger species, suggesting human activity may be overriding other macroecological processes in shaping scavenger communities. Our results highlight the effect of human impact at a global scale. As speciesrich assemblages tend to be more functional, we warn about possible reductions in ecosystem functions and the services provided by scavengers in human‐dominated landscapes in the Anthropocene

Functional biogeography of vertebrate scavengers drives carcass removal across biomes

Resumen del trabajo presentado en el XVI Congreso Nacional de la AEET 2023: la ecología en una biosfera humanizada, celebrado en Almería entre el 16 y el 20 de octubre de 2023.Vertebrate scavengers play a crucial role in food web stability and cycling of organic matter and nutrients. However, the global factors that influence their functional biogeography and impact on ecosystem functioning at regional and local levels remain poorly understood. We aim to address this challenge by analyzing a global dataset covering 49 regions in all inhabited continents, including information on 1,847 locally monitored carcasses and 204 vertebrate scavenger species along with their functional traits. We investigate the importance of biogeographical (spatial), environmental and anthropogenic factors in structuring vertebrate scavengers¿ functional trait composition, diversity and abundance. Additionally, we investigate how these biodiversity attributes affect carcass removal at regional and local scales. Our results show that the functional trait composition of assemblages across studied regions was primarily explained by latitude and lon¬gitude, suggesting a strong biogeographical signature. In addition, while functional richness remained unexplained, scavenger abundance responded to both environmental and spatial factors. Further, we found that carcass removal was mainly driven by functional composition, but with the relative importance of particular functional traits varying from local to regional scales. At the local scale, carcass removal was positively related to large carnivorous species with large home ranges, while at the regional scale, carcass removal was better explained by the presence of vultures, other raptors and diurnal birds. Our study provides a better understanding of the factors controlling the func¬tional biogeography of terrestrial vertebrates and their role in maintaining essential ecological functions and services.Peer reviewe

Brown bear attacks on humans : a worldwide perspective

The increasing trend of large carnivore attacks on humans not only raises human safety concerns but may also undermine large carnivore conservation efforts. Although rare, attacks by brown bears Ursus arctos are also on the rise and, although several studies have addressed this issue at local scales, information is lacking on a worldwide scale. Here, we investigated brown bear attacks (n = 664) on humans between 2000 and 2015 across most of the range inhabited by the species: North America (n = 183), Europe (n = 291), and East (n = 190). When the attacks occurred, half of the people were engaged in leisure activities and the main scenario was an encounter with a female with cubs. Attacks have increased significantly over time and were more frequent at high bear and low human population densities. There was no significant difference in the number of attacks between continents or between countries with different hunting practices. Understanding global patterns of bear attacks can help reduce dangerous encounters and, consequently, is crucial for informing wildlife managers and the public about appropriate measures to reduce this kind of conflicts in bear country.Peer reviewe