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opencc-zeroOct 2023View details →

Code and data for: Shining a light on elusive lynx: density estimation of three Eurasian lynx populations in Ukraine and Belarus

The Eurasian lynx is a large carnivore widely distributed across Eurasia. However, our understanding of population status is heterogeneous across their range, with some populations isolated that are at risk of reduced genetic variation and a complete lack of information about others. In many European countries, Eurasian lynx are monitored through demographic studies crucial for their conservation and management. Even so, there are only rough and fragmented population assessments from Ukraine and Belarus, despite strict protection in both countries and their importance for lynx connectivity across Europe. We monitored lynx from October 2020 to March 2021 and used camera-trapping in combination with spatial capture-recapture (SCR) methods in a Bayesian Framework to provide the first SCR density estimation of three lynx populations across Ukraine and Belarus, including the Ukrainian Chornobyl Exclusion Zone, Southern Belarus, and the Ukrainian Carpathians. Our density estimates varied within our study areas ranging from 0.45 to 1.54 individuals/100 km2. This work provides a substantial scientific component to the overall understanding of lynx conservation for a region where only broad information is available and opens the doors for further large-scale monitoring and trend assessments. The crucial information we provide can greatly enhance the range-wide assessments of the status of this protected species. We also discuss the implications for Eurasian lynx conservation, despite the geopolitical realities impacting species monitoring in the region. Our work serves as a baseline, not only for future conservation interventions but also to evaluate the effects of disturbance and threats to these protected populations.

opencc-zeroFeb 2024View details →

Lemur population density in Sahamalaza-Iles Radama National Park, Madagascar

The clearing and fragmentation of tropical forest is the single biggest threat to primate populations who depend on this habitat for survival. In contrast to primates that live in continuous, undisturbed forests, primate communities of fragmented forests need to adapt to decreased food availability and increased inter- and intraspecific competition typical of these degraded and anthropogenically disturbed habitats. Some primate species are highly sensitive to habitat fragmentation, whilst other species can adapt and even thrive in fragmented and degraded forests. Here, we assessed how forest fragmentation and associated edge-effects impact the population density of four species of nocturnal lemur in the Sahamalaza-Iles Radama National Park, North West Madagascar. We conducted 118 transect walks over a three-year period covering a total distance of 107 km to collect encounter rate (N/km) and population density (N/Ha) data for each species, which we then compared between the edge and core areas of a continuous forest and a fragmented forest. Our results were highly species-specific, with the population densities of two species (Lepilemur sahamalaza and Microcebus sambiranensis) increasing in edge and fragmented habitat, whilst we observed the opposite for Cheirogaleus medius. Mirza zaza density appeared consistent between the continuous and fragmented forest and in both edge and core areas. We also found evidence of species-specific population density relationships with fragment size, core area, and fragment shape; however, further work is needed to support these findings. This study demonstrates that some nocturnal lemurs can adapt to degraded habitats and thrive within fragmented forests, whilst other species are less capable of doing so.

Fig. 4 in Diversity And Density Of Mollusca (Gastropoda And Bivalvia) Population In The Euphrates River At Al-Nasiriyah, Southern Iraq

Fig. 4. Monthly variations in salinity values at Euphrates River during period study.

Fig. 5 in Diversity And Density Of Mollusca (Gastropoda And Bivalvia) Population In The Euphrates River At Al-Nasiriyah, Southern Iraq

Fig. 5. Monthly variations in dissolved oxygen values at Euphrates River during period study.

Fig. 3 in Diversity And Density Of Mollusca (Gastropoda And Bivalvia) Population In The Euphrates River At Al-Nasiriyah, Southern Iraq

Fig. 3. Monthly variations in pH values at Euphrates River during period study.

Fig. 2 in Diversity And Density Of Mollusca (Gastropoda And Bivalvia) Population In The Euphrates River At Al-Nasiriyah, Southern Iraq

Fig. 2. Monthly variations in water temperature values at Euphrates River during period study.

opencc-zeroMar 2024View details →

Rapid evolution of consumptive and non-consumptive predator effects on prey population densities, bioenergetics and stoichiometry

Predators can strongly influence prey populations not only through consumptive effects (CE) but also through non-consumptive effects (NCE) imposed by predation risk. Yet, the impact of NCE on bioenergetic and stoichiometric body contents of prey, traits that are shaping life histories, population and food web dynamics, is largely unknown. Moreover, the degree to which NCE can evolve and can drive evolution in prey populations is rarely studied. A 6-week outdoor mesocosm experiment with Caged-Fish (NCE) and Free-Ranging-Fish (CE and NCE) treatments was conducted to quantify and compare the effects of CE and NCE on population densities, bioenergetic and stoichiometric body contents of Daphnia magna, a keystone species in freshwater ecosystems. We tested for evolution of CE and NCE by using experimental populations consisting of D. magna clones from two periods of a resurrected natural pond population: a pre-fish period without fish and a high-fish period with high predation pressure. Both Caged-Fish and Free-Ranging-Fish treatments decreased the body size and population densities, especially in Daphnia from the high-fish period. Only the Free-Ranging-Fish treatment affected bioenergetic variables, while both the Caged-Fish and Free-Ranging-Fish treatments shaped body stoichiometry. The effects of CE and NCE were different between both periods indicating their rapid evolution in the natural resurrected population. Both the Caged-Fish and Free-Ranging-Fish treatments changed the clonal frequencies of the experimental Daphnia populations of the pre-fish as well as the high-fish period, indicating that not only CE but also NCE induced clonal sorting, hence rapid evolution during the mesocosm experiment in both periods. Our results demonstrate that CE as well as NCE have the potential to change not only the body size and population density but also the bioenergetic and stoichiometric characteristics of prey populations. Moreover, we show that these responses not only evolved in the studied resurrected population, but that CE and NCE also caused differential rapid evolution in a time frame of 6 weeks (ca. 4-6 generations). As NCE can evolve as well as can drive evolution, they may play an important role in shaping eco-evolutionary dynamics in predator-prey interactions.

opencc-zeroMar 2024View details →

Can livestock grazing dampen density dependent fluctuations in wild herbivore populations?

Conservation policy for the high mountains of Asia increasingly recognises the need to encompass large multi-use landscapes beyond the protected area network. Due to limited long-term research in this region, our understanding of even fundamental processes, such as factors regulating large mammal populations is poor. Understanding the factors that regulate animal populations, especially those generating cyclicity, is a long-standing problem in ecology. Long-term research across multiple taxa (mainly from Europe and North America) has focused on the relative roles of food and predation in generating cyclicity in population dynamics. It remains unclear how trophic interactions that are influenced by anthropogenic stressors can affect population dynamics in human-modified landscapes. We present a 10-year study to compare the effects of livestock grazing on density dependent dynamics in two populations of bharal, Pseudois nayaur, in the Himalaya. We combine this with a mechanistic understanding of whether density dependence in these two sites acts predominantly by affecting adult survival or recruitment. We compared and quantified density dependence in the bharal population by fitting Bayesian Gompertz state‐space (GSS) models. We found evidence for negative density dependence which indicates possible cyclic dynamics in the bharal population of the site (Tabo) with low livestock density. The population dynamics of this site were driven by recruited offspring – with a 2-year density dependent lag effect – rather than adult survival. In the site with high livestock density (Kibber), this density dependence was not detected. We postulate the potential role of excessive grazing by livestock in affecting offspring recruitment, thereby affecting the bharal population in Kibber. Synthesis and applications: Our results suggest that conservation action to facilitate wild herbivore population recovery, such as the development of protected areas and village reserves, needs to account for density dependent regulation. Sites with trophy hunting require continuous monitoring to understand the effects of density dependence so that appropriate hunting quotas can be formulated.

opencc-by-4.0Dec 2023View details →

Density of states and Crystal Orbital Hamilton Population Analysis of CO adsorbed on Co

This dataset pertains to an extensive study of the electronic structure of CO adsorbed on various active site topologies on cobalt. The following cobalt active site configurations were explored: <ul> <li>Co(0001) (fcc)</li> <li>Co(0001) (hcp)</li> <li>Co(11-21) 3f</li> <li>Co(11-21) B5</li> <li>Co(100)</li> <li>Co(110)</li> <li>Co55/Al2O3 (top)</li> <li>Co55/Al2O3 (interfacial site)</li> <li>Co52/Al2O3 (defect site)</li> <li>Co84/Al2O3 (nanorod)</li> <li>Co54/TiO2 (cluster)</li> <li>Co81/TiO2 (nanorod)</li> </ul> For each adsorption site, a density of states and crystal orbital hamilton population analysis was performed by means of the <a href="http://www.cohp.de/">Lobster</a> program. The original electronic structure calculations are performed using <a href="https://www.vasp.at/">VASP</a>. The input and output files for all calculations as well as the Python scripts how these files were parsed are found in this repository.

opencc-zeroMar 2024View details →

Fecal standing crop with real time correction using scat detection dogs to estimate population density

Population density is fundamental information for assessing the conservation status of species and support management and conservation actions for in situ populations, but is unknown for many forest species due to their difficulty in detection. The Fecal Standing Crop (FSC) method using detection dogs is an alternative for cryptic or elusive species. An intrinsic difficulty of FSC is the ability to find fecal samples in the field and to estimate the probability of which feces detection is influenced by degradation due to climatic conditions. Our goal was to propose a concurrent FSC parameter estimation using a scat detection dog under different climatic conditions and apply those parameters in a wild deer population. Ten fecal samples of gray brocket deer (Subulo gouazoubira) were placed weekly in a transect (24 x 1200 m) in both dry and wet seasons (12 weeks each). A scat detection dog was then employed to find experimental fecal samples to determine the FSC parameters that were subsequently used with naturally occurring fecal samples (also dog-detected) to estimate population density. The oldest dog found samples were 21 (Dry) and seven (Wet) days after placement, resulting in dog efficiency of 23% (Dry) and 30% (Wet). Adjusting the model to account for efficiency and scat durability, we estimated similar, seasonal, densities of 4.54 individuals km-2 (SD = 2.21, Dry) and 5.52 indiv. km-2 (SD = 3.71, Wet). Synthesis and applications: Our results demonstrate that our concurrent methodology corrected the effects of weather and habitat on FSC parameters thereby allowing for accurate population density estimation. Additionally, this method can provide reasonably precise density estimates with a logistically feasible sample size, as demonstrated by simulation. Following our recommendations, this method allows a reliable estimate of population density because it incorporates any influence of study area, dog ability, and climate in fecal sample detection, providing fundamental information for the conservation of many cryptic and elusive species.

opencc-zeroApr 2024View details →

Data from: genetic evidence of differential dispersal pattern in Asiatic wild dog: comparing populations with different pack size and tiger densities

Dispersal is a multi-causal, crucial life-history event in shaping the genetic and behavioral structure of mammals. We assessed the dispersal pattern of dholes aka Asiatic wild dog (Cuon alpinus), a social monogamous mammal at two tiger reserves of Maharashtra with different degrees of pack size and competition with tigers i.e. Tadoba-Andhari (TATR, smaller pack size, higher tiger density) and Nawegaon-Nagzira (NNTR, larger pack size, lower tiger density). We used the microsatellite data of 174 individual genotypes (98 males and 67 females) to assess the dispersal pattern of dholes from two populations with varying pack size, tiger density, and landscape connectivity using gene flow as a proxy. We compared the population structure, pairwise F statistics, assignment index, and relatedness across a spatial scale. Overall, the results suggested a difference in sex-bias dispersal pattern for the two sub-populations, exhibiting significant results for female-biased dispersal in the TATR population with a smaller pack size and higher tiger density. Our study highlights the variability in sex-biased dispersal patterns in two different populations which could be the consequence of different variables such as pack size, tiger density, and geographical scale. The study warrants further quantitative investigation including several factors including individual behavior, pack composition, pack size, tiger density, etc. In the present Anthropocene era, determining the sex bias in dispersal patterns for a short-range, pack-living carnivore will help in devising an effective conservation management plan for their long-term survival.

opencc-zeroDec 2021View details →

Counterintuitive scaling between population abundance and local density: implications for modelling transmission of infectious diseases in bat populations

1. Models of host-pathogen interactions help to explain infection dynamics in wildlife populations and to predict and mitigate the risk of zoonotic spillover. Insights from models inherently depend on the way contacts between hosts are modelled, and crucially, how transmission scales with animal density. 2. Bats are important reservoirs of zoonotic disease and are among the most gregarious of all mammals. Their population structures can be highly heterogenous, underpinned by ecological processes across different scales, complicating assumptions regarding the nature of contacts and transmission. Although models commonly parameterise transmission using metrics of total abundance, whether this is an ecologically representative approximation of host-pathogen interactions is not routinely evaluated. 3. We collected a 13-month dataset of tree-roosting Pteropus spp. from 2,522 spatially referenced trees across eight roosts to empirically evaluate the relationship between total roost abundance and tree-level measures of abundance and density – the scale most likely to be relevant for virus transmission. We also evaluate whether roost features at different scales (roost-level, subplot-level, tree-level) are predictive of these local density dynamics. 4. Roost-level features were not representative of tree-level abundance (bats per tree) or tree-level density (bats per m2 or m3), with roost-level models explaining minimal variation in tree-level measures. Total roost abundance itself was either not a significant predictor (tree-level 3-D density) or only weakly predictive (tree-level abundance). 5. This indicates that basic measures, such as total abundance of bats in a roost, may not provide adequate approximations for population dynamics at scales relevant for transmission, and that alternative measures are needed to compare transmission potential between roosts. From the best candidate models, the strongest predictor of local population structure was tree density within roosts, where roosts with low tree density had a higher abundance but lower density of bats (more spacing between bats) per tree. 6. Together, these data highlight unpredictable and counterintuitive relationships between total abundance and local density. More nuanced modelling of transmission, spread and spillover from bats likely requires alternative approaches to integrating contact structure in host-pathogen models, rather than simply modifying the transmission function.

opencc-zeroFeb 2022View details →

Local male breeding density affects extra‐pair paternity in a south temperate population of grass wrens Cistothorus platensis

Demographic factors can affect the frequency of extra-pair paternity (EPP) in birds, as the distribution and availability of potential mates in both space and time influence the rate of encounters between females and males. Over three breeding seasons, we intensively studied the breeding system of a south temperate population of grass wrens Cistothorus platensis by genotyping 73 broods (319 nestlings) and estimating EPP rates for those broods. Using five different radii (80, 160, 240, 320, and 400 m) around each nest with assigned paternity, we examined the effects of local breeding synchrony, male breeding density, and adult sex ratio (ASR) on the EPP rate. The majority of extra-pair offspring (~80%) were sired by neighboring males. Neither local breeding synchrony nor ASR consistently explained the EPP rate variation as their effects were only statistically significant within 320 m and 400 m. However, the EPP rate increased as the local male breeding density increased within every radius category, strongly suggesting that neighboring male abundance might play an important role in the extra-pair mating behavior in this species. Our study also highlights the relevance of using a local scale approach when studying mating behavior.

opencc-zeroJun 2022View details →

Density, parasitism, and sexual reproduction are strongly correlated in lake Daphnia populations

Many organisms can reproduce both asexually and sexually. For cyclical parthenogens, periods of asexual reproduction are punctuated by bouts of sexual reproduction, and the shift from asexual to sexual reproduction has large impacts on fitness and population dynamics. We studied populations of Daphnia dentifera to determine the amount of investment in sexual reproduction as well as the factors associated with variation in investment in sex. To do so, we tracked host density, infections by nine different parasites, and sexual reproduction in 15 lake populations of D. dentifera for three years. Sexual reproduction was seasonal, with male and ephippial female production beginning as early as late September and generally increasing through November. However, there was substantial variation in the prevalence of sexual individuals across populations, with some populations remaining entirely asexual throughout the study period and others shifting almost entirely to sexual females and males. We found strong relationships between density, prevalence of infection, parasite species richness, and sexual reproduction in these populations. However, strong collinearity between density, parasitism, and sexual reproduction means that further work will be required to disentangle the causal mechanisms underlying these relationships.

opencc-by-4.0Nov 2021View details →

Fig. 1 in Effect Of Farming And Rainfall On The Species Diversity, Population Density And Community Structure Of Birds Breeding In The Kalahari Woodland, Ne Namibia

Fig. 1. The location of the transect (indicated with red arrow).

opencc-by-4.0Nov 2021View details →

Fig. 2 in Effect Of Farming And Rainfall On The Species Diversity, Population Density And Community Structure Of Birds Breeding In The Kalahari Woodland, Ne Namibia

Fig. 2. Monthly rainfall in Katima Mulilo in 2014 and 2015.

opencc-by-4.0Nov 2021View details →

Fig. 4 in Effect Of Farming And Rainfall On The Species Diversity, Population Density And Community Structure Of Birds Breeding In The Kalahari Woodland, Ne Namibia

Fig. 4. Percentage of main nesting guilds in 2014 and 2015.

opencc-by-4.0Mar 2019View details →

Fig. 3 in Population Densities And Community Structure Of Birds Breeding In A Suburban Wooded Grassland In The Highveld Of Lesotho

Fig. 3. Comparison of main feeding (A) and nesting (B) guilds in avian community in 1998 and 2001.

opencc-zeroApr 2022View details →

Morphological plasticity in response to emergence time and population density in Abutilon theophrasti (Malvaceae)

Increased density and delayed emergence are two major biotic factors in nature that have profound and complex effects on plants. No studies have attempt to compare the responses of plants to the two factors via morphological plasticity, particularly in dynamic patterns. We subjected plants of Abutilon theophrasti to four emergence times and three planting densities and measured and analyzed a number of mass and morphological traits at different growth stages. Across both stages, plants emerged in late spring had the highest total mass, and spring and late-spring plants had higher stem mass allocation than later germinants, but plants with delayed emergence had higher leaf and reproductive mass allocation, more leaves and less lateral roots, but lower stem length, stem and root diameter than early-emerged plants. Plants at high density performed lower in total mass and most other traits, but performed better in stem allocation and length, with shorter petioles and lateral roots, than at lower densities. In competition for resources, plants will prefer stem elongation to leaf/root growth, and even at the cost of reproduction to ensure the survival of the present generations when competition is intense or lethal. By contrast, plants will prefer the investment into leaf and reproductive growth to stem/root growth, for offspring persistence, when shortened lifetime does not threaten the contemporary survival. The contrasting strategies revealed the intelligence of plants in balancing between survival, growth and reproduction, depending on environmental contexts.