Natural Refuges Research Articles

Effects of landscape variation on thermoregulation and performance in Apis mellifera honey bee colonies: insights from mtDNA haplotypes

In a year-long research study, we delved into the thermoregulation and performance of twenty-one honey bee colonies situated in three distinct landscape settings: 1- Urban, 2- Agricultural (AG), and 3- Non-agricultural (Non-AG) environments. All colonies, consistent in size, were equipped with sensors designed to record inner hive temperature and humidity. Additionally, colonies were placed on precision electronic scales for weight monitoring. Varroa mite infestations were documented at seven different time points throughout the experiment. Colonies were genetically analyzed for subspecies and haplotype identification using the in silico DraI mtDNA COI-COII test. Our results unveiled an overall significant (p < 0.001) weight gain (5.76 kg) in colonies located within the urban setting, in stark contrast to both AG and Non-AG locations. Notably, colonies situated in the natural refuge center (Non-AG) experienced a weight loss of −0.05 kg, signaling a lack of sustainable forage resources in such a setting. Similarly, the inner hive temperature was significantly (p < 0.001) higher in the urban area (33.65 °C) with a significantly lower relative humidity (61.2%) compared to both other locations. Among the locations, the temperature variable displayed the strongest significant correlation (p < 0.001) with a positive correlation coefficient (r = 0.95). Two distinct mtDNA haplotypes were identified: C1 and C2j, characterizing the ligustica and carnica maternal origin, respectively. These haplotypes consistently demonstrated significant differences in their thermoregulation and weight gain, irrespective of the landscape compositions. The C1 haplotype displayed significantly higher weight gain alongside lower inner hive temperature and humidity levels compared to the C2j haplotype. No differences in mite infestation were observed between the various locations or haplotypes. Our data underscores the substantial impact of landscape composition on honey bee performance. It also unveils significant variations in thermoregulation and adaptation between haplotypes, shedding light on the multifaceted relationship between environmental factors, genetics, and bee colony dynamics.

Tadpoles in lotic waters, habitat specialization, and human population density lead tree frogs (Hylinae) to higher extinction risk

Analyzing patterns of vulnerability to extinction across clades and traits that make species more prone to extinction are crucial steps towards prioritization of conservation efforts. Here we identified genera more vulnerable to extinction than expected by chance within the anuran subfamily Hylinae. We also investigated a broad range of intrinsic and extrinsic factors and their interactions as predictors of a proxy for extinction risk (IUCN Red List status). By conducting simulation analyses, we found that binary threat status is not randomly distributed across Hylinae genera, with Charadrahyla, Hyloscirtus, Isthmohyla, Plectrohyla, and Sarcohyla containing more threatened species than expected by chance. By using model selection and average approaches, we found strong support for increased likelihood of threatened status as habitat diversity decreases and human population density increases, and for species with larvae inhabiting lotic waters to be more threatened than those with larvae inhabiting lentic waters. Overall, our results were robust to different treatments of Data Deficient species (threatened or non-threatened). However, results were affected by the inclusion of geographic range size as another predictor, with habitat diversity becoming a non-significant predictor of threatened status. Our results highlight the importance of simultaneously analyzing both intrinsic and extrinsic predictors in correlative studies of extinction risk. Additionally, they underscore the need for conservation research and programs focused on both larvae and adults of organisms with biphasic life cycles and the establishment and evaluation of effectiveness of natural refuges far from areas under high human pressures, such as privately and community protected areas.

Heterogeneity in Arbuscular Mycorrhizal Fungi and Plant Communities of the Brazilian Cerrado, Transitional Areas toward the Caatinga, and the Atlantic Forest.

The Cerrado is the most diverse tropical savanna worldwide and the second-largest biome in South America. The objective of this study was to understand the heterogeneity and dynamics of arbuscular mycorrhizal fungi (AMF) in different types of natural Cerrado vegetation and areas that are transitioning to dryer savannas or tropical rainforests and to elucidate the driving factors responsible for the differences between these ecosystems. Twenty-one natural sites were investigated, including typical Cerrado forest, typical Caatinga, Atlantic Rainforest, transitions between Cerrado and Caatinga, Cerrado areas near Caatinga or rainforest, and Carrasco sites. Spores were extracted from the soils, counted, and morphologically analyzed. In total, 82 AMF species were detected. AMF species richness varied between 36 and 51, with the highest richness found in the area transitioning between Cerrado and Caatinga, followed by areas of Cerrado close to Caatinga and typical Cerrado forest. The types of Cerrado vegetation and the areas transitioning to the Caatinga shared the highest numbers of AMF species (32-38). Vegetation, along with chemical and physical soil parameters, affected the AMF communities, which may also result from seasonal rainfall patterns. The Cerrado has a great AMF diversity and is, consequently, a natural refuge for AMF. The plant and microbial communities as well as the diversity of habitats require urgent protection within the Cerrado, as it represents a key AMF hotspot.

Forest fragments matter: a look into the species richness and diversity patterns of birds in a small, isolated, Protected Landscape in Mindanao Island, Philippines

The establishment of Protected Areas is deemed of critical importance in global conservation initiatives, particularly in biodiverse regions and global biodiversity hotspots, such as the Philippines. However, the crucial role played by smaller Protected Areas in biodiversity conservation is frequently overlooked, making this a particular area of research interest. The Initao-Libertad Protected Landscape and Seascape (hereinafter – ILPLS) is one of the last remaining karst forests with natural vegetation and refuge for wildlife conservation on the island of Mindanao, the Philippines. However, the landscape component of this Protected Area is very small (ca. 506 000 m2), bisected by a road, and heavily disturbed by illegal logging and frequent tourist visits. From 2014 to 2018, we assessed the community structure and revealed patterns of bird diversity in ILPLS. We recorded a total of 814 individuals of birds from 36 species and nine feeding guilds from a total sampling effort of 558 230.40 mist-net hours in the Protected Areas' two management zones, namely the Special Protection Zone (SPZ) and Tourism Zone (TZ). ILPLS has a high level of endemism at 33% (12 species), including nine Philippine endemics and three Mindanao Island endemics. We also recorded Gorsachius goisagi, a globally threatened species categorised by IUCN as Vulnerable. Species richness was higher in the SPZ than in the TZ (p = 0.012), whereas no significant differences were observed in the Shannon index values (p = 0.101) and mean capture rates (p = 0.378) between the two management zones. Species and feeding guild assemblages did not differ between the two management zones (p = 0.939) but varied between vertical strata (p = 0.001). Here, we show how this small, protected landscape harbours a comparatively diverse bird community, including restricted-range species and species with high conservation priority. This suggests that forest fragments, even of this size, are important habitats for bird conservation efforts and should not be undervalued. We recommend extending such studies to other fragments, especially those that are still not protected, to improve our biodiversity database, further our understanding of biodiversity and fragment dynamics, and make a case for the protection of other forest fragment habitats.

Evolution of life cycles of nematodes parasitizing woody plants as a result of ecological and phylogenetic co-adaptations with hosts and vectors

Fundamental aspects in the evolution of nematodes parasitizing woody plants are reviewed. 1) Nematode faunal lists of natural refigia are useful to predict the risks of opportunistic pathogens becoming true pathogens in the forest and park communities. 2) Nematode composition in natural refugia gives a chance to identify nematode antagonists of insect vectors of dangerous fungal and nematode infections, which can be potentially used as of the biological agents for woody plants’ protection. 3) Dauers of the ancestors of wood-inhabiting nematodes played a role as a survival stage in the detritus decomposition succession, and they later acquired the functions of dispersion and adaptations for transmission using insect vectors. 4) When inspecting wilted trees, it is necessary to use dauers for diagnostics, as sexually mature nematodes may absent in tree tissues. 5) Plant parasitic nematodes originated from members of the detritus food web and retained a detritivorous phase in the life cycle as a part of the propagative generation. 6) Vectors in the life cycles of plant parasitic nematodes are inherited from the ancestral detritivorous nematode associations, rather than inserted in the dixenic life cycle of the ‘nematode-fungus-plant’ association. 7) Despite the significant difference in the duration of the nematode-tree and nematode-vector phases of the life cycle, the actual parasitic nematode specificity is twofold: firstly to the vector and secondly to the natural host plant (as demonstrated in phytotests excluding a vector).

Cooling wisdom of ‘water towns’: How urban river networks can shape city climate?

‘Water town’, a city design idea featuring buildings sitting along rivers and their associated riparian vegetation, serves as natural refuges for citizens to escape the dual challenges of heatwaves and urban heat islands. We investigated the multi-scale cooling effect of river networks in Shanghai, a typical modern city widely known as an assemblage of water towns. At the neighborhood scale, we conducted a series of field experiments along various rivers with different characteristics during the 2022 heatwave periods in central Shanghai. At the city scale, we first quantified the cooling impact of urban river networks by integrating remotely sensed data and fine-resolution urban river network maps. We found that the width of rivers, coverage ratio, density, and morphology of river networks are the key factors affecting the cooling potential. The confluence or proximity of river tributaries can also bring an enhanced cooling effect than standalone ones. Rivers were found to be all-day cool spots compared to adjacent city streets, with greater daytime cooling intensity (1–3 °C) than at night (0–0.6 °C). Compared to vegetation which has more spatial coverage within the city, rivers are constrained by a linear shape along certain paths but possess the ability to flow, which is beneficial for cooling by carrying cool water from upstream parks and offering wind corridors. The atmospheric cooling capability of 20% of river coverage is equivalent to 30% of tree canopy coverage in a neighborhood. The city-scale cooling effect yields a 36.9% cooling area with a maximum cooling extent of 5.5 °C. The disparities in cooling effect between river networks and standalone rivers primarily manifest in confluence areas and the reinforced cooling within dense river networks. Each additional confluence in local river networks leads to a mean increase of 3% in cooling area and 0.01 °C cooling intensity. Our study implies that urban watercourses cannot be neglected in urban climatic studies and should be incorporated into a new conceptualization of water-included urban local climate zone classifications in the world urban database.

Impact of anthropogenic infrastructure on aquatic and avian predator–prey interactions in a modified lowland river

Abstract The relationship between aquatic and avian predators and prey is a fundamental process that influences the ecological dynamics of freshwater communities; a landscape of fear underpins spatial and temporal habitat use of prey, i.e., non‐consumptive predation effects. For example, complex marginal vegetation and other natural in‐river refuges are known to be important for prey to manage predation risk and predators must alter their behaviour in response to habitat patches prey occupy. However, it is unclear how prey respond to predators, and vice versa, in heavily modified degraded lowland rivers with a high degree of river maintenance measures; a component critical for flood risk management globally. Such modifications could lead to prey seeking refuge at hazardous anthropogenic infrastructure, but a robust quantification of predator–prey interactions in this context is required to develop this understanding. Using multi‐beam sonar (Dual‐Frequency Identification Sonar), we non‐invasively and simultaneously quantified the temporal rate of predator–prey interactions, the attack behaviour of predators, and the refuge seeking behaviour of prey at a pumping station intake during winter in a heavily modified lowland river. Prey fish experienced temporally dynamic, density‐dependant, and species‐specific predation risks from two dissimilar predators (i.e., aquatic vs. avian); pike (Esox lucius) and cormorant (Phalacrocorax carbo). Generalised linear modelling revealed that prey refuge use was positively associated with predator attack rate. Non‐consumptive effects were evidenced by quantified changes to shoal structure (density, area), shoaling (group aggregation), and schooling (coordinated directional movement), including diurnal migrations to and from the pumping station intake for refuge. Our results show that in the absence of natural refuge habitats the natural landscape of fear shifted and speculate that prey fish were paradoxically dependant on hazardous anthropogenic infrastructure, i.e., a pumping station intake, for refuge from predators in a degraded lowland river. These findings strongly enhance our understanding of the impact of anthropogenic infrastructure on predator–prey interactions by demonstrating how flood risk management, including river maintenance measures, and associated anthropogenic infrastructure can impact the behavioural game played between aquatic and avian predators and their prey.

Acalypha ostryifolia: a natural refuge for Chloridea virescens and Helicoverpa zea (Lepidoptera: Noctuidae) in the Southern United States

Abstract The tobacco budworm, Chloridea virescens (F.), and corn earworm, Helicoverpa zea (Boddie) (heliothines), have had a long-intertwined relationship with respect to their importance as pests in agricultural production systems. Previous studies have examined the impacts of early-season wild host plants on local population density and distribution of these 2 insects on cultivated crops such as cotton, Gossypium hirsutum L., and soybean, Glycine max L. Additional studies have examined the importance of wild host plants, which act as a refuge of nonexposed populations of C. virescens and H. zea to insecticidal toxins from the soil bacterium, Bacillus thuringiensis (Bt) Berliner. The current study examined hophornbeam copperleaf, Acalypha ostryifolia Riddell, as a host plant for mid-late season populations of C. virescens and H. zea. Patches of A. ostryifolia were sampled along roadsides and the edges of fields from 2014 to 2020 in Mississippi, USA, to examine larval density, species composition, and parasitism of heliothines on this wild host plant. Insects were collected from the end of June through October. The largest densities (based on the number of caterpillars per sweep) of heliothines were over one larva per sweep. Overall, 49.5% of the collected caterpillars were determined to be tobacco budworms, while 50.5% were corn earworms. Parasitism rates ranged from approximately 1–30%, increasing throughout the season. In general, densities of heliothines encountered on A. ostryifolia were greater than densities reported for other wild host plants. Hophornbeam copperleaf is an important natural refuge for both heliothines from Bt toxins and synthetic insecticide applications.

The Role of Cold-Water Thermal Refuges for Stream Salmonids in a Changing Climate—Experiences from Atlantic Canada

Thermal refuges are becoming increasingly influential for dictating the population status and spatial distribution of cold-water stenotherm salmonids in the mid- to southern extent of their range. The global climate is predicted to continue to warm, and therefore, the overall thermal suitability of freshwater habitats for stream salmonids is predicted to decline in concert. However, stream and river thermal heterogeneity will offer considerable resiliency for these populations. Thermal refuges are formed by many physical processes; common natural refuges include cold tributary plumes, groundwater springs, alcoves, and hyporheic upwellings. However, many anthropogenically formed refuges (such as stratified reservoirs or cold-water tailrace outflows) also exist in hydropower-regulated rivers. The significance of these refuges to stream salmonids depends on their size and temperature differential, but also other habitat characteristics such as their depth, flow velocity, Froude number, and many biotic factors within the refuges. Modern technologies such as drone-mounted thermal infrared cameras and other remote sensing techniques allow for the efficient identification of such refuges, and inexpensive options include the identification of refuges during ice cover using orthophotographs. Behavioural thermoregulation, i.e., salmonids aggregating in cold-water refuges, can be either facultative or obligate and the timing of these events is governed by life stage, species, and population-specific physiologically regulated cumulative thresholds that are inherently related to the recent thermal history, or hysteresis, of each individual. Salmonids appear to have an excellent spatial cognition for locating and relocating cold-water refuges, and their spatial distribution is largely affected by the availability of the cold-water refuges during the warm-water period in many thermally stressed rivers. Gregarious behaviour is the norm for salmonid fishes within the thermal refuges; however, the size/microhabitat hierarchy appears to dictate the within-refuge distribution at the micro-scale. There continues to be a great impetus for protecting—and in carefully determined cases creating—cold-water refuges in the future. A thorough understanding of what a “goldilocks” refuge is for various salmonids and their different life stages will be imperative as cold-water restoration is gaining popularity. Finally, disentangling the roles of the climate-induced and landscape activity-induced warming potential of fluvial freshwater will be important to ensure continued environmentally responsible landscape activities in future waterscapes.

Partial refuges from biological control due to intraspecific variation in protective host traits.

Predicting how much of a host or prey population may be attacked by their natural enemies is fundamental to several subfields of applied ecology, particularly biological control of pest organisms. Hosts or prey can occupy refuges that prevent them from being killed by natural enemies, but habitat or ecological refuges are challenging or impossible to predict in a laboratory setting-which is often where efficacy and specificity testing of candidate biological control agents is done. Here we explore how intraspecific variation in continuous traits of individuals or groups that confer some protection from natural enemy attack-even after the natural enemy has encountered the prey-could provide partial refuges. The size of these trait-based refuges (i.e., the proportion of prey that survive natural enemy encounters due to protective traits) should depend on the relationship between trait values and host/prey susceptibility to natural enemy attack and on how common different trait values are within a host/prey population. These can be readily estimated in laboratory testing of natural enemy impact on target or nontarget prey or hosts as long as sufficient host material is available. We provide a general framework for how intraspecific variation in protective host traits could be integrated into biological control research, specifically with reference to nontarget testing as part of classical biological control programs. As a case study, we exposed different host clutch sizes of target (pest) and nontarget (native species) stink bug (Hemiptera: Pentatomidae) species to a well-studied exotic biocontrol agent, the egg parasitoid Trissolcus japonicus (Hymenoptera: Scelionidae). We predicted that the smallest and largest clutches would occupy trait-based refuges from parasitism. Although we observed several behavioral and reproductive responses to variation in host egg mass size by T. japonicus, they did not translate to increases in host survival large enough to change the conclusions of nontarget testing. We encourage researchers to investigate intraspecific variation in a wider variety of protective host and prey traits and their consequences for refuge size.

Specific Habitat Elements (Refuges and Leaf Litter) Are Better Predictors of Sceloporus Lizards in Central Mexico Than General Human Disturbance

Human land transformation alters features of the landscape that may favor or eliminate biodiversity. Understanding habitat use among species in human-affected ecosystems can inform the management of habitats and conservation of species. The Trans-Mexican Volcanic Belt in central Mexico is a biological hot spot for lizard species diversity that is under considerable anthropogenic pressures including grazing, agriculture, urbanization, and climate change. Here, we used species-occupancy modeling to (1) identify habitat characteristics that are essential to predicting the presence of Sceloporus torquatus and S. grammicus lizards, (2) determine if disturbance predicts species occupancy, and (3) determine which features, if any, predict our ability to detect each species in the wild. We found that S. torquatus lizards were more likely to be present in areas with large boulders and abundant refuges, whereas S. grammicus lizards were more common in forests with leaf litter. Human disturbance and urban disruption did not predict the occupancy of either species, with lizards making use of artificial as well as natural refuges in human settlements as well as protected areas. Although we found only weak evidence that habitat and climate predicted detection probabilities, Sceloporus lizards (particularly S. grammicus) were somewhat more easily detected in high humidity, perhaps because of generally higher activity levels. Our results emphasize the importance of understanding the detailed physical characteristics that allow each species to persist, even in disturbed habitats. This can better inform conservation efforts so that resources are allocated to ensure that these characteristics, like rocks and trees, are readily available in both pristine and human-modified areas.

Managing Practical Resistance of Lepidopteran Pests to Bt Cotton in China

China is one of the major cotton producers globally with small farmers. Lepidopteran pests have always been the main factor affecting cotton production. To reduce the occurrence of and damage caused by lepidopteran pests, China has employed a pest control method focused on planting Bt (Cry1Ac) cotton since 1997. Chinese resistance management tactics for the main target pests, the cotton bollworm and pink bollworm, were also implemented. For polyphagous (multiple hosts) and migratory pests such as the cotton bollworm (Helicoverpa armigera), the "natural refuge" strategy, consisting of non-Bt crops such as corn, soybean, vegetables, peanuts, and other host crops, was adopted in the Yellow River Region (YRR) and Northwest Region (NR). For a single host and weak migration ability pest, such as the pink bollworm (Pectinophora gossypiella), the seed mix refuge strategy yields a random mixture within fields of 25% non-Bt cotton by sowing second-generation (F2) seeds. According to field monitoring results for more than 20 years in China, practical resistance (Bt cotton failure) of target pests was avoided, and there were no cases of Bt (Cry1Ac) failure of pest control in cotton production. This indicated that this Chinese resistance management strategy was very successful. The Chinese government has decided to commercialize Bt corn, which will inevitably reduce the role of natural refuges; therefore, this paper also discusses adjustments and future directions of cotton pest resistance management strategies.

On the use of the finite element method in the study of the stress-strain state of the contour of the Annie Cave on Mount Arsia

People who have visited the surface of Mars for the first time cannot survive in conditions of such dangers as radiation, micrometeorites and dust storms. But we offer the caves found on this Mars as a way to use them as a natural refuge from these environmental hazards. The gravitational field on the surface of Mars is about three times weaker than on Earth, and the magnetic field is too weak. Therefore, creatures that have left Earth, including humans, can live on the surface of Mars for only 30-40 seconds. Even the most powerful spacesuit can save a person's life for just a few hours. Martian caves weaken solar radiation almost three times and do not let it inside. Therefore, the study of Martian caves, conducting scientifically based research to make them the first habitat, is an urgent problem today. Therefore, it is advantageous to use the mountain caves of Mars as an underground habitat. Since atmospheric protection is minimal at high altitudes, scientific studies of the strength and stability of the inner edges to Martian gravity are carried out to turn these caves into living quarters, such as mines, tunnels. Under the influence of various forces (gravitational, temperature, low-current, tectonic, etc.) of such structures on Mars, a mechanical and mathematical model is being developed to study the strength of cave dwellings, habitats.

Mobile animals and immobile protected areas: improving the coverage of nature reserves for Asian elephant conservation in China

AbstractMany protected areas worldwide have been established to protect the last natural refuges of flagship animal species. However, long-established protected areas do not always match the current distributions of target species under changing environmental conditions. Here we present a case study of the Asian elephant Elephas maximus in Xishuangbanna, south-west China, to evaluate whether the established protected areas match the species’ current distribution and to identify key habitat patches for Asian elephant conservation. Our results show that currently only 24.5% of the predicted Asian elephant distribution in Xishuangbanna is located within Xishuangbanna National Nature Reserve, which was established for elephant conservation. Based on the predicted Asian elephant distribution, we identified the most important habitat patches for elephant conservation in Xishuangbanna. The three most important patches were outside Xishuangbanna National Nature Reserve and together they contained 43.3% of the estimated food resources for Asian elephants in all patches in Xishuangbanna. Thus, we identified a spatial mismatch between immobile protected areas and mobile animals. We recommend the inclusion of the three identified key habitat patches in a new national park currently being planned by the Chinese authorities for the conservation of the Asian elephant.

Neustonic tadpoles do not detect and respond to insect predator

ABSTRACT Prey animals use various signals to detect their predators and respond accordingly to enhance their survival. Since responding to a predator is costly, prey species may cut cost by using other strategies such as behavioural tactics, morphological changes, seeking natural refuge or unique habitat acquisition. Tadpoles of Microhyla nilphamariensis have a transparent body and live in a neustonic environment, which provides them protection against benthic predators. As a result, we investigated the predator detection mechanism in M. nilphamariensis tadpoles using different cues from an insect predator, dragonfly larvae, to determine if the presence of natural shelter and unique habitat acquisition influences the chemo-ecology of predator recognition in this species. We also exposed these tadpoles to active caged predators and a stress hormone, corticosterone (CORT) to study physiological mechanism underlying their behavioural anti-predator responses toward alarm cues. In the predator avoidance assay, M. nilphamariensis tadpoles did not respond to the predator using visual or chemical signals. The tadpoles did not change their activity in response to alarm, heterospecific, kairomones, and dietary cues released from the predator. Pre-conditioning of M. nilphamariensis tadpoles with caged predator and different concentrations of CORT also did not alter their activity in response to alarm cues. These results clearly demonstrated that neustonic tadpoles of M. nilphamariensis do not detect and respond to co-existing insect predator. We discuss these results in the context of unique habitat occupied by these prey tadpoles, the presence of alternate prey, and inherent factors such as transparent body.

Soft coral reproductive phenology along a depth gradient: Can "going deeper" provide a viable refuge?

Many species across a wide range of taxa and habitats display phenological shifts and differences in response to both environmental gradients and climate change. Moreover, the wide‐scale decline of numerous ecosystems is leading to increasing efforts to identify zones that might serve as natural refuges from various disturbances, including ocean warming. One such refuge was suggested to be that of the deep coral reefs, but whether depth can provide coral populations with a viable and reproductive refuge remains unclear. Given the global coral‐reef degradation and the key role that corals play as ecosystem engineers, their reproductive ecology has been widely studied. A particular knowledge gap nonetheless exists regarding coral reproductive phenology along a depth gradient. Filling in this gap may uncover the environmental cues that regulate coral reproduction, leading to better predictions of population connectivity, and their possible responses to climate change and other environmental changes. Here, using long‐term in situ observations of the soft coral Rhytisma fulvum's reproductive activity along its entire depth range (0–45 m), we examined the relationship among several environmental factors and the coral's reproductive phenology and activity over five successive annual breeding seasons. Compared with the shallow depths, a lower number of reproducing colonies was found in habitats deeper than 30 m, highlighting possible constraints on coral reproduction at the deeper end of their range. Our results further revealed that an increase in seawater temperature over 1–2‐day intervals during the breeding season correlated with the onset of reproductive activity along the depth gradient, leading to different reproductive periodicities in different depths. These differences suggest that differential temperature regimes and reproductive timing across depth may create intraspecific temporal reproductive segregation, possibly reducing connectivity among populations along a depth gradient. Moreover, we found high variability among years in both the timing of breeding activities and in the level of reproductive synchrony among corals from different depths. Overall, our study questions whether depth can provide a long‐term and viable refuge for corals in the face of global environmental changes.

Too hot to hunt: Mechanistic predictions of thermal refuge from cat predation risk

AbstractMany threatened species depend on climatic microrefugia, but places with harsh climates for predators may also play a refugial role. Feral cats threaten many native species in arid Australia. Although cats can persist in regions with no free water, their abundance should depend on the availability of microclimates that protect them from harsh environmental conditions. We developed a biophysical model of feral cat heat stress and used it to explore how behavior and microhabitat features influence water requirements and activity. Tests of model predictions against fine‐scale GPS and microclimate data highlight the importance of refuges, particularly rabbit burrows. Continent‐wide simulations show large but temporally varying areas of the arid zone that would be lethal for cats without access to deep or shaded burrows. Our approach can identify locations that may act as natural refuges for native prey, and where habitat management strategies may be effective in controlling cat abundance.

Shelter use by horses during summer in relation to weather conditions and horsefly (Tabanidae) prevalence

National legislation requires shelter access for horses kept outside during winter, whereas there are no requirements for shelter access to provide shade and a refuge from biting insects during summer. This study investigated use of artificial shelters by 10 horse groups continuously for eight summer weeks (2019: 5 groups, 2020: 5 groups, n = 42, 3 – 5 horses per group). Shelter use was recorded every 30 min, using wildlife cameras mounted inside the shelters, i.e., 48 recordings per day for 56 days (a total of 2688 recordings per group where each horse inside the shelter was identified and its behaviour noted). Daily weather conditions were recorded, and horsefly (Tabanidae) prevalence was quantified one day per week using H-traps (i.e. eight trap catches per group). The groups represented a variety of compositions (horse breed, age, gender) and shelter types (design, size). Across all groups and shelter types, shelter use increased on warmer days and the daily rhythm of shelter-seeking behaviour changed; on warmer days, shelter-seeking increased significantly during the day, whereas night-time use was unaffected. Further, significantly more horses were inside on days with the highest trap catch of horseflies compared to days with the lowest catch. We conclude that regardless of group composition and shelter type, horses make increased use of artificial shelters on warm summer days. Since all horses had access to natural shade in their pastures and shelter temperatures were generally higher than outdoor temperatures, we suggest that the increased shelter use on warm summer days was related to nuisance from biting insects. This is supported by the higher shelter use on days with a high horsefly catch. We recommend provision of shelter access to horses kept on summer pastures with limited opportunities to seek natural refuge from biting insects.

Wildlife associates of nine-banded armadillo (Dasypus novemcinctus) burrows in Arkansas.

The Nine‐banded Armadillo (Dasypus novemcinctus) is a widespread burrowing species with an expanding geographic range across the southeastern and midwestern United States. Armadillos dig numerous, large burrows within their home ranges and these burrows are likely used by a diverse suite of wildlife species as has been reported for other burrowing ecosystem engineers such as Gopher Tortoises (Gopherus polyphemus), Desert Tortoises (Gopherus agassizi), and Black‐tailed Prairie Dogs (Cynomys ludovicianus). We used motion‐triggered game cameras at 35 armadillo burrows in 4 ecoregions of Arkansas and documented 19 species of mammals, 4 species of reptile, 1 species of amphibian, and 40 species of bird interacting with burrows. Bobcat (Lynx rufus), Coyote (Canis latrans), Eastern Cottontail (Sylvilagus floridanus), Gray Fox (Urocyon cinereoargenteus), Gray Squirrel (Sciurus carolinensis), Northern Raccoon (Procyon lotor), Virginia Opossum (Didelphis virginiana), and unidentified rodents (mice and rats) were documented using burrows in all four ecoregions. We documented wildlife hunting, seeking shelter, rearing young in, and taking over and modifying armadillo burrows. The rate of use was highest in the Mississippi Alluvial Valley, a landscape dominated by agriculture, where natural refugia may be limited and rodents are abundant. Armadillo burrows are clearly visited and used by numerous wildlife species to fulfill various life stage requirements, and this list will likely expand if more attention is devoted to understanding the role of armadillos burrows. Armadillos are important ecosystem engineers, and their ecological role warrants more investigation and attention as opposed to only being viewed and managed as agricultural and garden pests.

Modeling the evolution of resistance in cotton bollworm to concurrently planted Bt cotton and Bt maize in China

Transgenic maize expressing toxins derived from the bacterium Bacillus thuringiensis (Bt) may be commercially planted in northern China where Bt cotton has been planted for more than two decades. While Bt maize brings additional benefits for insect control, it complicates the resistance management of cotton bollworm (CBW), Helicoverpa armigera (Lepidoptera, Noctuidae), a common target of Bt cotton and Bt maize. Here we developed two-locus population genetic models to assess the risk of resistance in CBW in which four cases of Bt cotton and Bt maize and two types of refuges are considered. Model simulations showed that the time to resistance (TTR) is longest in the case of two-toxin Bt cotton & two-toxin Bt maize, followed by the cases of two-toxin Bt cotton & one-toxin Bt maize, one-toxin Bt cotton & two-toxin Bt maize, and one-toxin Bt cotton & one-toxin Bt maize. With 25% of cotton seed mixed refuge and 20% of maize seed mixed refuge, the TTRs in the four cases by order are 54, 13, 9, and 7 generations, respectively. With additional natural refuges, the differences in the TTRs among the four cases are greater. Sensitivity analysis showed that among the parameters examined, the initial frequency of resistance alleles and fitness cost are the ones to which the TTRs are most and least sensitive, respectively. We concluded that when natural refuges are scarce, planting both two-toxin Bt cotton and two-toxin Bt maize instead of one-toxin ones are necessary to combat CBW resistance to concurrently planted Bt cotton and Bt maize in northern China.