Range Overlap Research Articles

A machine learning species distribution model for the critically endangered East Pacific leatherback turtle Dermochelys coriacea

The Eastern Pacific population of leatherback turtles Dermochelys coriacea is Critically Endangered, with incidental capture in coastal and pelagic fisheries as one of the major causes. Given the population’s broad geographic range, status, and extensive overlap with fisheries throughout the region, identifying areas of high importance is essential for effective conservation and management. In this study, we created a machine-learning species distribution model trained with remotely sensed environmental data and fishery-dependent leatherback presence (n = 1088) and absence data (>500000 fishing sets with no turtle observations) from industrial and small-scale fisheries that operated in the eastern Pacific Ocean between 1995 and 2020. The data were obtained through a participatory collaboration between the Inter-American Convention for the Protection and Conservation of Sea Turtles and the Inter-American Tropical Tuna Commission as well as non-governmental organizations to support the quantification of leatherback vulnerability to fisheries bycatch. A daily process was applied to predict the probability of leatherback occurrence as a function of dynamic and static environmental covariates. Coastal areas throughout the region were highlighted as important habitats, particularly highly productive feeding areas over the continental shelf of Ecuador, Peru, and offshore from Chile, and breeding areas off Mexico and Central America. Our model served as the basis to quantify leatherback vulnerability to fisheries bycatch and the potential efficacy of conservation and management measures (Griffiths & Wallace et al. 2024; Endang Species Res 53:295-326). In addition, this approach can provide a modeling framework for other data-limited vulnerable populations and species.

Homeward bound: annual breeding home range size and overlap in Broad-winged Hawks ( Buteo platypterus ) and the effects of sex, productivity, and ecoregion

Homeward bound: annual breeding home range size and overlap in Broad-winged Hawks ( Buteo platypterus ) and the effects of sex, productivity, and ecoregion

Stable seasonal migration patterns in giant pandas.

A critical function of animal movement is to maximize access to essential resources in temporally fluctuating and spatially heterogeneous environments. Seasonally mediated resource fluctuations may influence animal movements, enabling them to track changing resource distributions, resulting in annual migration patterns. The conservation-dependent giant panda ( Ailuropoda melanoleuca) displays seasonal movement patterns; however, the key factor driving these seasonal migration patterns remains poorly understood. Here, we used GPS tracking collars to monitor the movements of six giant pandas over a 12-year period across different elevations, and performed statistical analysis of seasonal migration directions, routes, habitat revisitation, home range overlap, first arrival events, and stability. Our results revealed a compelling pattern of seasonal migrations that facilitated the ability of the pandas to forage at the appropriate time and place to maximize nutritional intake. Our results indicated that pandas utilize spatial memory to locate reliable food resources, as evidenced by their annual return to the same or similar winter and summer home ranges and the consistently maintained percentage of home range overlap. These novel insights into giant panda foraging and movement ecology not only enhance our understanding of its ability to adapt to nutritionally poor dietary resources but also provide important information for the development of resource utilization-based protection and management strategies.

Movement and ranging behaviour of long-nosed potoroos (Potorous tridactylus) in south-west Victoria, Australia

Context A comprehensive understanding of movements and space use can underpin the effective management of threatened species. GPS dataloggers can collect large amounts of high-quality movement data, and recent advances in statistical approaches allow for robust estimates of home range size to be generated. Until recently, technological and practical constraints have generally restricted the collection of movement data via GPS dataloggers to larger species. However, reductions in the size and weight of GPS dataloggers now allow for this technology to be applied to smaller species. Aims The aim of this study was to describe the home range and movement patterns of a nationally vulnerable, native Australian ground-dwelling mammal, the long-nosed potoroo (Potorous tridactylus), in south-west Victoria, mainland Australia. Methods We attached GPS dataloggers to 40 long-nosed potoroos between 2020 and 2022 and estimated home range size using dynamic Brownian Bridge movement models. We evaluated the influence of physiological factors such as body mass and sex on home range size and described patterns of home range overlap between and within sexes. Key results Mean home range sizes were estimated to be 13.73 ha (95% CI: 10.9–16.6) and 6.67 ha (95% CI: 5.49–7.85) for males and females respectively. Home range size scaled with body mass in males but not females, and ranges were largely overlapping – although there was some evidence of intrasexual spatial partitioning of core range areas in females. Conclusions Ours is the first application of GPS dataloggers to this species, and our home range estimates are over twice as large as other reported estimates for mainland Australia. Long-nosed potoroos may range across larger areas than previously predicted on mainland Australia. Implications This knowledge may be used to optimise the management of long-nosed potoroo populations before and after fire – a key threatening process for this species. Our study highlights the value of integrating GPS dataloggers and robust home range estimators when describing the movement ecology of a population.

A tale of two crickets: global climate and local competition shape the distribution of European Oecanthus species (Orthoptera, Gryllidae)

Climate change is reshaping species’ distributions around the globe, yet different factors may drive species’ responses at different spatial scales from global to local. Environmental conditions and biotic interactions may thus change in relative importance in terms of influencing species’ occurrence according to the considered spatial extent, making a multi-scale approach key to understanding species’ distributions and future range dynamics. In this study, we tested the relative roles of climate and interspecific competition in shaping the distributions of two cryptic species of Orthopterans at global and regional scales. Namely, we assessed the spatial responses to climate change in two Oecanthus tree crickets (O. pellucens and O. dulcisonans) that show ecological and morphological resemblance, and partial range overlap. We found significant and species-specific associations with bioclimatic variables related to temperature and to precipitation. We also observed divergence in predicted responses between the two species, showing massive range loss for O. pellucens and slight expansion for O. dulcisonans under future scenarios. This result was also supported by environmental niche analysis, indicating O. pellucens as a significantly more specialized taxon in terms of climatic niche. At a regional scale, we present evidence for how interspecific competition may play a strong and asymmetrical role in determining species’ presence, with only O. pellucens being significantly affected by O. dulcisonans, and not vice-versa. Our results shed light on the potential responses of Orthopterans to climate change, and on the spatial-specific respective roles of climate and competition in shaping species’ distributions. Moreover, we highlight how, within cryptic species complexes, competition dynamics and niche specialization may represent key elements in determining winners and losers in the race against climate change.

Resource use divergence facilitates the evolution of secondary syntopy in a continental radiation of songbirds (Meliphagoidea): insights from unbiased co‐occurrence analyses

Allopatric speciation followed by the evolution of range overlap (sympatry) allows the build‐up of regional diversity. However, local species richness requires that species co‐occur locally (syntopy). Importantly, correct estimates of syntopy must be available to identify ecological traits facilitating it. We thus provide a method to correctly estimate local co‐occurrence and demonstrate it on the evolution of secondary syntopy. First, we performed probabilistic co‐occurrence analyses on simulated data across a sympatry gradient from 0 to 100%. Second, we extracted 116 species pairs younger than 10 My from a dated phylogeny of Meliphagoidea songbirds. We constructed a presence–absence matrix of 58 species across 470 sites based on 37 250 censuses in Australia and Tasmania from 1989 to 1995. We also constructed a spatial mask based on species ranges, identifying sites within versus outside the area of sympatry. We ran both unconstrained and range mask‐constrained co‐occurrence analyses. We compared the resulting syntopy and predicted it by species ecology. Simulations and exact analyses showed that co‐occurrence analyses must be limited to sites in the area of sympatry between species. Without this spatial limit, syntopy was negatively biased, especially in common species. Accordingly, syntopy was negatively biased in Meliphagoidea when data from all sites were used, but this bias decreased with increasing sympatry, in agreement with numerical and exact analyses. When using correct estimates, syntopy increased with increasing divergence in the use of foraging stratum (ground, shrub, subcanopy and canopy) and with decreasing divergence in diet. In conclusion, we introduced a general method for calculating local species co‐occurrence and confirmed its validity by simulations. We illustrated its use by analyzing the evolution of secondary syntopy in a phylogenetic framework. We found support for both niche divergence (foraging stratum) and niche conservatism (diet) in facilitating evolutionary transitions to secondary syntopy, allowing the build‐up of local species richness.

Seasonal resource selection and movement ecology of free‐ranging horses in the western United States

AbstractUnderstanding factors driving resource selection and habitat use of different species is an important component of management and conservation. Feral horses (Equus caballus) are free ranging across various vegetation types in the western United States, yet few studies have quantified their resource selection and seasonal use. We conducted a study to determine effects of vegetation community, distance to water, and topographic variables on seasonal resource selection in 2 feral horse populations in Great Basin sagebrush (Artemisia spp.) ecosystems of west‐central Utah, USA: Conger Herd Management Area (HMA) and Frisco HMA. We deployed global positioning system (GPS) radio‐collars on 38 female horses and GPS‐transmitters braided and glued into the tail hair of 14 males, collecting locations every 2 hours for 1–4 years between 2016 and 2020. We calculated home range size and core use area of social groups (harems) and bachelor males using auto‐correlated kernel density estimators for each biologically defined season (breeding, fall, and winter) per study year. We examined seasonal home range size and overlap of harem groups and bachelor males and compared movement speed of bachelors and harems among seasons. We determined seasonal resource selection in a use‐availability framework using resource selection functions. We hypothesized that horses would select for areas of high herbaceous vegetation, that water would be a key variable in resource selection models like other equids, and home range size in winter would be largest because horses can eat snow for hydration and could therefore roam farther from surface water. Mean annual home range size was 103.12 ± 37.38 km2 (SD) for Conger harems and 117.47 ± 32.75 km2 for Frisco harems. At Conger there was no difference in home range size between harem groups and bachelor males, but home range size was smaller in winter than other seasons, whereas winter home range size at Frisco was larger than other seasons. Bachelor males moved at higher speeds than harems during all seasons, and harem groups from both populations had lower movement speeds in winter. Harem groups had distinct winter ranges with little overlap on breeding season ranges. In both populations, all horses selected for herbaceous vegetation types and avoided forest relative to shrubland throughout the year. Harems at Frisco were consistently located closer to water sources, whereas selection for water sources by Conger harems varied seasonally, with winter having the lowest selection. Harem groups at Conger had an average of 10.6% of their home ranges outside the HMA boundary and Frisco harems had up to 66.8% outside, likely because of the horseshoe shape of Frisco HMA in which shrub meadows (foraging areas) comprise the horseshoe center, which is outside the HMA. Our results highlight the importance of water sources, which were a key predictor of horse movement patterns in our study. We emphasize the utility of telemetry devices to understand resource selection of feral horses at a fine scale, enabling management to be more targeted and facilitate planning.

Preparation of upconversion NaYF4:Yb/Tm@NaYF4:Yb-Cit-CD for doxorubicin detection

Doxorubicin hydrochloride (DOX), an anthraquinone-based antibiotic, is widely used in human tumors treatment. However, the residues of DOX in body would pose a threat to the health of heart and liver. Herein, a photochemical sensor NaYF4:Yb/Tm@NaYF4:Yb-Cit-CD (UCNPs) for detecting DOX has been developed in this paper. The fluorescence emission spectrum of UCNPs under 980 nm laser excitation has a wide range overlap with UV–vis absorption spectrum of DOX. Therefore, the fluorescence emission of UCNPs at 480 nm can be quenched by DOX. The UCNPs sensor has displayed a linear range of 0.05–20 μg/mL with a detection limit (LOD) of 0.005 μg/mL for DOX. Furthermore, the results of recovery for DOX in human serum samples is 98.68–104.20% and in accord with those obtained by HPLC and UV–vis.

Predictive mapping of two endemic oak tree species under climate change scenarios in a semiarid region: Range overlap and implications for conservation

Quercus infectoria and Quercus libani are two important species distributed across most of the Kurdistan Region of Iraq's mountain ranges (KRI). They have significant ecological, medicinal, and socioeconomic values. Recent studies have documented how plant distributions have been impacted by climate change. This study's goal is to establish the existing distributions of both species, measure the consequences of prospective environmental conditions on their distributions, predict possible habitat distributions, map the overlapped habitat ranges for the species in the KRI, and identify the key factors influencing their distributions. For these aims, distribution data points of the species, different environmental factors, including the existing climate, three emission predictions for the 2050s, 2070s, and 2090s of two general circulation models (GCMs), a machine learning approach, and geospatial techniques were used. Modeling revealed that the total magnitude of the habitat increase for the species would be less than the overall magnitude of the habitat contraction. The yearly mean temperature, yearly precipitation, and minimum temperature during the coldest period mostly alter the target species' geographic dispersion. Across the three emission scenarios of the both models, Q. infectoria habitat would contract by 2760.9–2856.9 km2 (5.36–5.55%), 2856.9–3357.2 km2 (5.55–6.52%) and 2822.1–3400.2 km2 (5.48–6.60%), whereas it would expand by 1153.3–1638.9 km2 (2.24–3.18%), 761.0–1556.8 km2 (1.48–3.02%), and 721.5–1547.1 km2 (1.40–3.00%) for the 2050s, 2070s, and 2090s, respectively. A similar pattern was also noted for Q. libani. The two species' habitat ranges in KRI would be considerably reduced due to climate change. The species' estimated area would extend mostly to the east and southeast of the KRI at high altitudes. The mountain areas, notably those where the species overlap by 1767.2–1807.5 km2 (3.43–3.51%) for the two GCMs, must be the primary objective of conservation efforts. This research presents new baseline data for future research on mountain forest ecosystems and the techniques of biodiversity conservation to reduce climate change's effects in Iraq.

RETRACTED ARTICLE: Changes in management shape the spatial ecology of wild ponies in relation to habitat conservation

Large herbivores are key regulators of open habitats across the world. Free roaming ponies have a prominent ecological role in many Atlantic landscapes, where different habitats with conservation interest are linked to ponies’ occurrence. The traditional management of wild ponies, which implies minimum human intervention, is declining in Galicia, NW Spain. Changes in the management regimes include the confinement of ponies in fenced areas, the use of improved pastures (IPs) and rotation between fields. Indirect effects of these changes are expected on the ecological condition of important habitats for conservation such as dry and wet heathlands and bogs. We studied social structure, spatial ecology and habitat use in 29 mares fitted with global positioning system (GPS) collars and field observations in two areas of Galicia dominated by wet heaths and blanket bogs (Xistral), and dry heaths (Sabucedo). We used spatial location and field observations to identify each band, and calculated band size, sex ratio, home range (HR) and core areas size and overlap, and habitat use. We addressed differences and adjusted Generalized Linear Models (GLMs) for these variables as functions of the type of management: free roaming vs rotation, use of IPs, fencing, and available ranging area. Larger bands were found in smaller commons, fenced and with rotation management. Home ranges, but not core area, varied as a function of the available ranging area. Bands overlap more on fenced areas with rotation management. Increasing management may concentrate grazing pressure by reducing HR and increasing bands overlapping areas, and this may have a long-term effect on habitat quality and conservation.

The social system of the lava lizard, Microlophus atacamensis: the interplay between social structure and social organization

BackgroundAnimal social systems can be described through four main components: social structure, social organization, mating system, and care system. Social structure describes the relationships between individuals in a population, while social organization describes the group composition, size, and spatiotemporal variation of a population. We use the frameworks of social structure and social organization to study the social system of Microlophus atacamensis, a lizard found in the rocky intertidal zone along the Chilean coast. The area M. atacamensis inhabits poses specific challenges stemming from their use of two distinct habitat types in the intertidal zone: they forage in the cool areas near the water’s edge and use large rocks in more inland areas for basking and refuge.MethodsOur assessment of their social system focused on two separate populations: one to characterize social structure by means of focal observations and social network analysis, and a second to assess social organization via home range and core area analyses. Further, we examined the social system in two habitat types that comprise the intertidal zone: cobble fields and interspersed large rocks.ResultsSocial network analysis revealed an interconnected network with a few highly central individuals. Body size influenced the outcomes of aggressive interactions, with interactions being more common in cobble fields where males had more associates and more repeated interactions than females. Spatial analyses revealed that the social organization of M. atacamensis is characterized by (1) high home range overlap, specifically in the cobble fields and (2) relatively exclusive core areas dispersed across both habitat types.ConclusionA social system is composed of both cooperative and competitive behaviors. While our study focused on competitive interactions, the extent and influence of cooperative behaviors is still unclear and merits future research. We suggest that M. atacamensis has a variable social system in which territoriality on large rocks affects access to stationary resources in that habitat (e.g., basking sites and refuges), while competition in the cobble fields could lay the foundation for a system of dominance relationships controlling access to variable food resources in cobble field areas of the intertidal zone.

Habitat selection and space use overlap between feral horses, pronghorn, and greater sage‐grouse in cold arid steppe

AbstractPopulations of feral horses (Equus ferus caballus) in the western United States have increased during the past decade, consequently affecting co‐occurring wildlife habitat. Feral horses may influence 2 native wildlife species, greater sage‐grouse (Centrocercus urophasianus; sage‐grouse) and pronghorn (Antilocapra americana) through mechanisms of habitat alteration and competition. Wyoming, USA, contains the largest populations of pronghorn and sage‐grouse of any state and also has the highest degree of range overlap between feral horses and these species. Consequently, the effects that horses may have on pronghorn and sage‐grouse populations in Wyoming have implications at local, state, and population‐wide levels. Managers need information concerning habitat selection and space use overlap among these species to develop appropriate management strategies; yet this information is absent for most feral horse management areas. To address this knowledge need, we attached global positioning system (GPS) transmitters to horses, pronghorn, and sage‐grouse within the greater Bureau of Land Management–Adobe Town Herd Management Area in southern Wyoming and northern Colorado, USA, between 2017 and 2021 to evaluate habitat selection and space use of all species during 3 biologically relevant seasons: spring (Apr–Jun; sage‐grouse breeding, nesting, and early‐brood rearing; pronghorn late gestation and early parturition), summer (Jul–Oct; sage‐grouse summer and late‐brood rearing; pronghorn late parturition and breeding), and winter (Nov–Mar; non‐breeding season). Feral horses selected flatter slopes and shorter mean shrub height across all seasons and were closer to water in spring and summer. Pronghorn habitat selection was similar to horses, but they also avoided oil and gas well pads year‐round. During spring, sage‐grouse selected greater herbaceous cover, flatter slopes, and areas farther from well pads. In summer, sage‐grouse selected greater mean shrub height, flatter slopes, and were closer to water. In winter, sage‐grouse selected flatter slopes and areas with greater vegetation production during the preceding summer. Our results indicate strong year‐round overlap in space use between horses and pronghorn, whereas overlap between horses and sage‐grouse is greatest during the summer in this region. Consequently, managers should recognize the potential for horses to influence habitat quality of pronghorn and sage‐grouse in the region.

Mapping the changing distribution of two important pollinating giant honeybees across 21000 years

Pollinators play an important role in ecosystems, but global climate change threatens the diversity and geographical distribution of pollinators. Bees are some of the most important pollinators and are particularly sensitive to climate change and environmental change. Apis laboriosa and Apis dorsata are two species of giant honeybees distributed in Asia, and play important roles in their ecosystems. In this study, we analyzed the key factors affecting the distribution of two species, as well as their potential suitable areas and possible co-existence regional changes under the global climate change. We collected and filtered global distribution data of A. laboriosa and A. dorsata, then used eight climatic variables and Community Climate System Model version 4 (CCSM4) to simulate their potential suitable areas for the past, present and future (using two different climate scenarios) using MaxEnt. Finally, we used ArcGIS 10.2 and ENMTools to calculate range overlap and niche overlap of the two species in order to infer areas of co-existence. Temperature-related variables had the largest contribution to the model simulation. Among these variables, temperature seasonality (Bio 4) and mean temperature of coldest quarter (Bio 11) showed the strongest influence on the distributions of two giant honeybees. Under the current climate scenario, the species overlap in Nepal and Yunnan of China, with low niche overlap index. Between the last-glacial maximum to the present both honeybees moved northwest to their present range. A. laboriosa is projected to move to the northeast and A. dorsata may move southeast. Only 6.6% of overlapping distribution is currently protected, and further work is needed to protect these key areas.

Geographic Range Overlap Rather than Phylogenetic Distance Explains Rabies Virus Transmission among Closely Related Bat Species.

The cross-species transmission (CST) of pathogens can have dramatic consequences, as highlighted by recent disease emergence events affecting human, animal and plant health. Understanding the ecological and evolutionary factors that increase the likelihood of disease agents infecting and establishing in a novel host is therefore an important research area. Previous work across different pathogens, including rabies virus (RABV), found that increased evolutionary distance between hosts reduces the frequency of cross-species transmission and of permanent host shifts. However, whether this effect of host relatedness still holds for transmission among recently diverged hosts is not well understood. We aimed to ask if high host relatedness can still increase the probability of a host shift between more recently diverged hosts, and the importance of this effect relative to ecological predictors. We first addressed this question by quantifying the CST frequency of RABV between North American bat species within the genus Myotis, using a multi-decade data set containing 128 nucleoprotein (N) RABV sequences from ten host species. We compared RABV CST frequency within Myotis to the rates of CST between nine genera of North American bat species. We then examined whether host relatedness or host range overlap better explains the frequency of CST seen between Myotis species. We found that at the within genus scale, host range overlap, rather than host relatedness best explains the frequency of CST events. Moreover, we found evidence of CST occurring among a higher proportion of species, and CST more frequently resulting in sustained transmission in the novel host in the Myotis dataset compared to the multi-genus dataset. Our results suggest that among recently diverged species, the ability to infect a novel host is no longer restricted by physiological barriers but instead is limited by physical contact. Our results improve predictions of where future CST events for RABV might occur and clarify the relationship between host divergence and pathogen emergence.

Stable isotopes indicate reduced body condition of caribou in disturbed areas

Abstract Understanding the impacts of disturbance on individual fitness is important for wildlife management, and critical for the conservation of species at risk. We compared the fitness and seasonal range use of 39 woodland caribou in Ontario study areas contrasted by their level of human disturbance. We previously showed that wolf density in the disturbed site was higher, likely due to human-modified landscapes favoring moose, the primary prey of wolves. In this paper we address three objectives. First, because the assimilation of dietary nitrogen is heavily influenced by metabolic processes related to stress, we hypothesized that ratios of nitrogen isotopes (N) may indicate changes in body condition in ungulates and be useful proxies for changes in fitness. Second, we predicted that increased predation risk from wolves in disturbed areas would result in measurable declines in caribou body condition. Third, we hypothesized that one mechanism for fitness declines among caribou in the disturbed area was increased wolf activity restricting caribou seasonal movements. We showed change in N in the tissues of caribou was correlated with body condition scoring using fat assessment. We used GPS collars to quantify seasonal range use and found that fitness was higher, and seasonal range overlap was lower, in caribou using the nondisturbed area. Winter fitness declines were significantly larger in the more disturbed area. Our study identifies another mechanism by which the cumulative effects of human-disturbed landscapes on caribou fitness could contribute to global declines in caribou populations.

The taxonomic status of Crimson-crested Turaco Menelikornis (leucotis) donaldsoni

White-cheeked Turaco Menelikornis (leucotis) leucotis and Crimson-crested Turaco M. (l.) donaldsoni have long been treated as conspecific. Because of the lack of data concerning their distribution and areas of potential geographical overlap, they have been considered to be parapatric at most. In 2019 and 2021, we conducted a field study that produced nearly 40 records of the two taxa. In the study area, which stretched 120 km north to south from the upper Shabelle Valley via the Oda and Bale Mts. to Harenna Forest, both leucotis and donaldsoni occurred. The presence of both taxa was recorded across c.50 km west to east, which indicates an area of range overlap of about 6,000 km2. Sympatry between leucotis and donaldsoni, together with clear differences in morphology (mainly crest colour) as well as molecular evidence, strongly support treating them as different species.

Electrical and Optical Test of a Semi-Combustible Plasma Generator via a Plasma Ignition Simulator

Electrothermal-chemical (ETC) launch technology can considerably increase the ballistic performance and optimize the fire range and range overlap of a 155-mm unimodular charge howitzer. To discuss the plasma ignition process of a semi-combustible plasma generator (SCPG) with a special tubular semi-combustible medium, a plasma ignition simulator (PIS) for the 155-mm unimodular charge howitzer is designed and manufactured to provide a realistic chamber environment. The optical and electrical measurements of a hybrid arc controlled ablation (ACA) plasma are operated via several sensors, a high-speed digital camera, and a compact spectrometer. Test results show that the PIS can satisfy the design requirements of the research of the plasma ignition process. When the discharge voltage is 6.5 kV, hybrid plasma propagation in the simulator chamber is observed and detected. The electronic excitation temperature of the hybrid plasma is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\approx 15$ </tex-math></inline-formula> 860 K, and the hybrid plasma propagation velocity is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\approx 1000$ </tex-math></inline-formula> m/s. These transient propagating hybrid plasmas are enough to ignite all unimodular charges in the chamber within 1.0 ms. The results provide an important reference for future ETC launch tests.

Phenological drivers of ungulate migration in South America: characterizing the movement and seasonal habitat use of guanacos

BackgroundMigration is a widespread strategy among ungulates to cope with seasonality. Phenology, especially in seasonally snow-covered landscapes featuring “white waves” of snow accumulation and “green waves” of plant green-up, is a phenomenon that many migratory ungulates navigate. Guanacos (Lama guanicoe) are native camelids to South America and might be the last ungulate in South America that migrates. However, a detailed description of guanacos´ migratory attributes, including whether they surf or jump phenological waves is lacking.MethodsWe quantified the migratory movements of 21 adult guanacos over three years in Patagonia, Argentina. We analyzed annual movement patterns using net squared displacement (NSD) and home range overlap and quantified snow and vegetation phenology via remotely sensed products.ResultsWe found that 74% of the individual guanacos exhibited altitudinal migrations. For migratory guanacos, we observed fidelity of migratory ranges and residence time, but flexibility around migration propensity, timing, and duration of migration. The scarce vegetation and arid conditions within our study area seemed to prevent guanacos from surfing green waves; instead, guanacos appeared to avoid white waves.ConclusionOur study shows that guanaco elevational migration is driven by a combination of vegetation availability and snow cover, reveals behavioral plasticity of their migration, and highlights the importance of snow phenology as a driver of ungulate migrations.

Projected bioclimatic distributions in Nearctic Bovidae signal the potential for reduced overlap with protected areas.

Assumptions about factors such as climate in shaping species' realized and potential distributions underlie much of conservation planning and wildlife management. Climate and climatic change lead to shifts in species distributions through both direct and indirect ecological pressures. Distributional shifts may be particularly important if range overlap is altered between interacting species, or between species and protected areas. The cattle family (Bovidae) represents a culturally, economically, and ecologically important taxon that occupies many of the world's rangelands. In contemporary North America, five wild bovid species inhabit deserts, prairies, mountains, and tundra from Mexico to Greenland. Here, we aim to understand how future climate change will modify environmental characteristics associated with North American bovid species relative to the distribution of extant protected areas. We fit species distribution models for each species to climate, topography, and land cover data using observations from a citizen science dataset. We then projected modeled distributions to the end of the 21st century for each bovid species under two scenarios of anticipated climate change. Modeling results suggest that suitable habitat will shift inconsistently across species and that such shifts will lead to species‐specific variation in overlap between potential habitat and existing protected areas. Furthermore, projected overlap with protected areas was sensitive to the warming scenario under consideration, with diminished realized protected area under greater warming. Conservation priorities and designation of new protected areas should account for ecological consequences of climate change.

Exploitation of an ancestral pheromone biosynthetic pathway contributes to diversification in Heliconius butterflies.

During courtship, male butterflies of many species produce androconial secretions containing male sex pheromones (MSPs) that communicate species identity and affect female choice. MSPs are thus likely candidates as reproductive barriers, yet their role in speciation remains poorly studied. Although Heliconius butterflies are a model system in speciation, their MSPs have not been investigated from a macroevolutionary perspective. We use GC/MS to characterize male androconial secretions in 33 of the 69 species in the Heliconiini tribe. We found these blends to be species-specific, consistent with a role in reproductive isolation. We detected a burst in blend diversification rate at the most speciose genus, Heliconius; a consequence of Heliconius and Eueides species using a fatty acid (FA) metabolic pathway to unlock more complex blends than basal Heliconiini species, whose secretions are dominated by plant-like metabolites. A comparison of 10 sister species pairs demonstrates a striking positive correlation between blend dissimilarity and range overlap, consistent with character displacement or reinforcement in sympatry. These results demonstrate for the first time that MSP diversification can promote reproductive isolation across this group of butterflies, showcasing how implementation of an ancestral trait, the co-option of the FA metabolic pathway for pheromone production, can facilitate rapid speciation.