Disturbance Tolerance Research Articles

Persistent coxsackievirus B infection and pathogenesis of type 1 diabetes mellitus.

Enteroviruses are believed to trigger or accelerate islet autoimmunity in genetically susceptible individuals, thereby resulting in loss of functional insulin-producing β-cells and type 1 diabetes mellitus (T1DM). Although enteroviruses are primarily involved in acute and lytic infections in vitro and in vivo, they can also establish a persistent infection. Prospective epidemiological studies have strongly associated the persistence of enteroviruses, especially coxsackievirus B (CVB), with the appearance of islet autoantibodies and an increased risk of T1DM. CVB can persist in pancreatic ductal and β-cells, which leads to structural or functional alterations of these cells, and to a chronic inflammatory response that promotes recruitment and activation of pre-existing autoreactive T cells and β-cell autoimmune destruction. CVB persistence in other sites, such as the intestine, blood cells and thymus, has been described; these sites could serve as a reservoir for infection or reinfection of the pancreas, and this persistence could have a role in the disturbance of tolerance to β-cells. This Review addresses the involvement of persistent enterovirus infection in triggering islet autoimmunity and T1DM, as well as current strategies to control enterovirus infections for preventing or reducing the risk of T1DM onset.

Gain-scheduled output-feedback control of uncertain input-delay LPV systems with saturation via polytopic differential inclusion

This paper examines the control design for parameter-dependent input-delay linear parameter-varying (LPV) systems with saturation constraints. A linear differential inclusion approach is implemented to formulate the saturation nonlinearity. Subsequently, a gain-scheduled dynamic output-feedback controller is structured to conform to the saturation representation. By means of a Lyapunov–Krasovskii functional, sufficient delay-dependent conditions are derived for the analysis and feedback control synthesis of the closed-loop system in the presence of uncertainties and exogenous disturbances. Disturbance rejection objectives following an induced -norm and an norm formulation are examined. Estimation of the domain of attraction with the parametrisation of the admissible LPV controllers is presented. Three different optimisation objectives with respect to disturbance rejection, disturbance tolerance, and domain of attraction expansion are formulated. The proposed design methodology is examined in the context of the air-fuel ratio (AFR) regulation in a spark ignition (SI) engine with a speed-dependent delay and model parameters in the presence of canister purge disturbances and AFR dynamics uncertainty. The injector is restricted in the amount of fuel it can deliver to the cylinder. The three-way catalytic converter's performance in terms of oxygen storage and emission reduction is taken into consideration. Closed-loop simulation results are provided to validate the methodology.

Adaptive Event-Triggered Output Feedback for Nonlinear Systems With Unknown Polynomial-of-Output Growth Rate

This paper investigates global stabilization via adaptive event-triggered output feedback for a class of uncertain nonlinear systems. Typically, unknown polynomial-function rate is admitted in the unmeasurable-state dependent growth of the systems. This calls for an advanced compensation strategy based on dynamic high gain, which in turn requires more intelligent execution in the event-triggered control architecture. To this end, a novel event-triggering mechanism is designed with two events separately evaluating the behaviors of dynamic gain and the controller signal. Particularly, the event on controller signal is enforced to suspend for a certain time after each execution to guarantee a positive lower bound for the inter-execution intervals. More importantly, the suspension time and the threshold therein are both online adjusted according to dynamic gain (rather than pre-specified), which could become small enough as the dynamic gain increases. This ensures timely execution for the effectiveness of adaptive compensation. Then, with the dynamic gain delicately designed to counteract the influence of the execution error, an event-triggered controller via adaptive output feedback is proposed to make the original system states and observer states converge to zero. Further attempt is performed for more efficient resource saving and disturbance tolerance.

The Relationship between Health Anxiety and Perceived Stress with Moral Distress in Emergency Nurses: The Mediating Role of Distress Tolerance

Background: Nurses in emergency departments are exposed to stress and ethical issues due to the specific nature of their job. Therefore, the aim of the present study was to present a relationship between health anxiety and perceived stress with Moral distress and mediation of turmoil tolerance in emergency department nurses. Methods: This descriptive correlational study was performed on 230 emergency nurses in Tehran in 1399 using available sampling method. In this study, the Cohen, Kamark and Marmelstein (1983) Perceived Stress Questionnaire, Salkowski and Warwick (2002), Simmons and Gahr (2005) Perturbation Tolerance, and Jamton's Moral Perturbation Questionnaire were used. Data analysis was performed by path analysis using SPSS-24 and Amos-24 software. Results: The findings of the study showed that perceived stress (t = 5.58) and health anxiety (t = 7.1) had a positive and direct effect on Moral distress and distress Tolerance(t = 8.33) on Moral distress. The effect is negative and direct (P <0.01). The results also showed that disturbance tolerance has a mediating role in the relationship between perceived fear and health anxiety with moral distress (P <0.01). Conclusion: distress Tolerance mediates the relationship between perceived stress and health anxiety with Moral distress. The findings of this study can be used to improve the degree of distress Tolerance and improve the level of work ethic and reduce the Moral distress of emergency department nurses.

Analysis of the Ability to Tolerate Body Balance Disturbance in Relation to Selected Changes in the Sagittal Plane of the Spine in Early School-Age Children.

The study aimed to estimate the ability to tolerate body balance disturbance in relation to selected changes in the sagittal plane of the spine in early school-age children. The study involved 189 children with an average age of 8.3 ± 0.7 years (aged 7–10). The tests included an interview, clinical examination (measurement of body weight and height, assessment of the course of the spinous processes of the thoracic and lumbar vertebrae, assessment of the location of selected anatomical landmarks of the torso), and a physical examination in which the shape of the spine surface was examined with the use of the photogrammetric method and the moiré effect projection. Body balance disturbance tolerance skills (BBDTS) were measured with the rotational test (RT). In the rotational test, the results of body balance disturbance tolerance skills show a slight but statistically significant correlation with the bodyweight of the examined children (Rs = 0.35, p < 0.001). This relationship was also statistically significant in the groups by gender. Among the measured indicators of the curvature of the spine in the sagittal plane, the correlation with the RT test result was mostly related to the α angle and the value was Rs = 0.15 (p = 0.04). In the group of girls, this correlation was stronger and amounted to Rs = 0.26 (p = 0.015). Among other measured correlations, the dependence of variables such as the bodyweight of the subjects and the α angle was shown. In conclusion, increasing lumbar lordosis results in the deterioration of balance disturbance tolerance skills. As body weight increases, body balance disturbance tolerance skills decrease.

Design of an Improved Impedance Controller for Powered Transtibial Prosthesis

With the rapid development of powered transtibial prostheses, the control of motorized actuators is a research hotspot. This study designs a double-loop impedance controller to improve the performance of the traditional controller. Including time-varying parameters, the designed controller is implemented on a novel elastic actuator. Under different loads of users’ weights, simulation tests are conducted in a working condition of walking, and the results show that the designed control system has outstanding performances in the control of an entire gait cycle. The error between output and reference of ankle joint position during walking is less than 0.013rad in each sample time. A position disturbance test demonstrates that the control also has a high tolerance of any position disturbance at the ankle joint. The double-loop impedance controller can replace traditional finite-state impedance control in the field of the powered transtibial prosthesis and has the potential to be applied in other relative fields.

Trade-offs in forest disturbance management for plant communities and ungulates

Land and wildlife managers use disturbance to reset forests to earlier successional stages and improve the quality and quantity of forage available to ungulates. However, management of vegetation communities to increase forage nutrition has additional implications for other non-forage vegetation. To evaluate responses of vegetation to management of fire and timber harvest, we measured and modeled 3 metrics of vegetative response in 3 forested areas in Montana, USA during 2017–2019: forage nutrition for mule deer (Odocoileus hemionus), invasive species biomass, and floristic quality, a measure of plant communities’ tolerance of disturbances and fidelity to particular environments using native species conservatism scores. We found differences in all 3 metrics of plant responses that were specific to disturbance type and study area, and associations between disturbance and vegetation outcomes that were both desirable and undesirable. Generally, deer forage nutrition and invasive species biomass both increased in disturbed areas, whereas floristic quality increased with disturbance in 2 study areas but decreased in the third. Biomass of particular invasive species varied according to both study area and disturbance type. Lastly, we used decision analysis to illustrate trade-offs and overall support for different management actions while also accounting for underlying differences among study areas. For example, management actions with the greatest increase in mule deer forage nutrition tended to also increase invasive species biomass. Compared to other management actions, low-severity harvest scored highly in 2 study areas due to its association with increased forage nutrition while also limiting invasive species biomass and maintaining floristic quality. However, different weighting schemes according to different management priorities among management outcomes alter the relative ranking of actions. Our data show area-specific trade-offs in vegetation outcomes that result from disturbance management, which can be combined with decision analysis to help managers balance objectives and compare potential management actions.

Metapopulations with habitat modification

Across the tree of life, organisms modify their local environment, rendering it more or less hospitable for other species. Despite the ubiquity of these processes, simple models that can be used to develop intuitions about the consequences of widespread habitat modification are lacking. Here, we extend the classic Levins metapopulation model to a setting where each of n species can colonize patches connected by dispersal, and when patches are vacated via local extinction, they retain a "memory" of the previous occupant-modeling habitat modification. While this model can exhibit a wide range of dynamics, we draw several overarching conclusions about the effects of modification and memory. In particular, we find that any number of species may potentially coexist, provided that each is at a disadvantage when colonizing patches vacated by a conspecific. This notion is made precise through a quantitative stability condition, which provides a way to unify and formalize existing conceptual models. We also show that when patch memory facilitates coexistence, it generically induces a positive relationship between diversity and robustness (tolerance of disturbance). Our simple model provides a portable, tractable framework for studying systems where species modify and react to a shared landscape.

Using interview surveys and multispecies occupancy models to inform vertebrate conservation.

Species distribution data are an essential biodiversity variable requiring robust monitoring to inform wildlife conservation. Yet, such data remain inherently sparse because of the logistical challenges of monitoring biodiversity across broad geographic extents. Surveys of people knowledgeable about the occurrence of wildlife provide an opportunity to evaluate species distributions and the ecology of wildlife communities across large spatial scales. We analyzed detection histories of 30 vertebrate species across the Western Ghats biodiversity hotspot in India, obtained from a large-scale interview survey of 2318 people who live and work in the forests of this region. We developed a multispecies occupancy model that simultaneously corrected for false-negative (non-detection) and false-positive (misidentification) errors that interview surveys can be prone to. Using this model, we integrated data across species in composite analyses of the responses of functional species groups (based on disturbance tolerance, diet, and body mass traits) to spatial variation in environmental variables, protection, and anthropogenic pressures. We observed a positive association between forest cover and the occurrence of species with low tolerance of human disturbance. Protected areas were associated with higher occurrence for species across different functional groups compared with unprotected lands. We also observed the occurrence of species with low disturbance tolerance, herbivores, and large-bodied species was negatively associated with developmental pressures, such as human settlements, energy production and mining, and demographic pressures, such as biological resource extraction. For the conservation of threatened vertebrates, our work underscores the importance of maintaining forest cover and reducing deforestation within and outside protected areas, respectively. In addition, mitigating a suite of pervasive human pressures is also crucial for wildlife conservation in one of the world's most densely populated biodiversity hotspots.

Grazing Intensity Rather than Host Plant's Palatability Shapes the Community of Arbuscular Mycorrhizal Fungi in a Steppe Grassland.

Arbuscular mycorrhizal fungi (AMF) are the predominant type of mycorrhizal fungi in roots and rhizosphere soil of grass species worldwide. Grasslands are currently experiencing increasing grazing pressure, but it is not yet clear how grazing intensity and host plant grazing preference by large herbivores interact with soil- and root-associated AMF communities. Here, we tested whether the diversity and community composition of AMF in the roots and rhizosphere soil of two dominant perennial grasses, grazed differently by livestock, change in response to grazing intensity. We conducted a study in a long-term field experiment in which seven levels of field-manipulated grazing intensities were maintained for 13 years in a typical steppe grassland in northern China. We extracted DNA from the roots and rhizosphere soil of two dominant grasses, Leymus chinense (Trin.) Tzvel. and Stipa grandis P. Smirn, with contrasting grazing preference by sheep. AMF DNA from root and soil samples was then subjected to molecular analysis. Our results showed that AMF α-diversity (richness) at the virtual taxa (VT) level varied as a function of grazing intensity. Different VT showed completely different responses along the gradient, one increasing, one decreasing, and others showing no response. Glomeraceae was the most abundant AMF family along the grazing gradient, which fits well with the theory of disturbance tolerance of this group. In addition, sheep-grazing preference for host plants did not explain much of the variation in AMF α-diversity. However, the two grass species exhibited different AMF community composition in their roots and rhizosphere soils. Roots exhibited a lower α-diversity and higher β-diversity within the AMF community than soils. Overall, our results suggest that long-term grazing intensity might have changed the abundance of functionally diverse AMF taxa in favor of those with disturbance-tolerant traits. We suggest our results would be useful in informing the choice of mycorrhizal fungi indicator variables when assessing the impacts of grassland management choices on grassland ecosystem functioning.

Investigations on grassland and nature reservation effect of horse grazing in Tapolca and Káli Basins (2008)

Examined areas can be found in the Tapolca and Káli Basins near Köveskál and Nemesgulács. Near Köveskál 2 horses were grazed on a 1 ha grassland, which was on a degraded association of Cynodonti-Poëtum angustifoliae. Control area was found close to the grazed grassland where Salvinio-Festucetum rupicolae association was found. The grassland was grazed formerly by sheep. Near Nemesgulács 4 horses were grazed on a 6 ha pasture under free range grazing system (0.7 horse/ha) on a Cynodonti- Poëtum angustifoliae grassland that is situated on a slope. Sample areas were selected the upper (UTS) and lower (LTS) third of the slope. This area formerly was as vineyard. 5-5 replicates of 2 by 2 m coenological quadrates were monitored on each sample area. Sward composition was investigated by Braun-Blanquet method (1964) in the grazing season of 2008. Ground cover (D) species composition and species number (n) were evaluated as analytical parameters. Relative nitrogen demand (NB), social behavior types (SBT) (Borhidi, 1995) and nature conservation value categories (TVK) (Simon, 2000) were also analyzed. At the LTS of the slope near Nemesgulács we could find species with bigger proportions indicating nutrient rich production sites and N indicating Artemisia vulgaris, characteristic species of manured sites appeared, too. At the UTS their proportion was smaller. The reason for this difference is the nutrient run off the slope and its accumulation at the LTS. The reason for the low nutritive value of the grassland are the lack of valuable Poaceae and pulses species and the low total cover. Valuable plant species were grazed out of the sward and negative effects of trampling could have been observed. Concerning the selective grazing preference of horses, the species composition of this area is not suitable for horse grazing. Instead of horses the area could be more suitable for sheep grazing. Pasture near Köveskál had extremely high proportion of species requiring nutrient rich conditions that can be probably due to frequent depositions of excreta and urine by grazing horses. Both control and pasture areas has the highest (approx. 35% absolute) cover of natural species with disturbance tolerance. The biggest difference in nature conservation value categories was the decrease of association composing species on the pasture. This was mainly caused by the grazing out of Poa angustifolia that was the most valuable species in the association. Overgrazing and grazing method applied caused very low plant cover on the grazed pasture.

Alternative biome states challenge the modelling of species' niche shifts under climate change

Abstract It is common to characterise the species niche using climate and global species distribution maps. This is then used to predict changes in distribution under a warming climate. This approach assumes that climate is a major driver of species distribution and that each species responds individually (sensu Gleason) to climate. However, in many world landscapes, for a given climate, strikingly different vegetation types co‐occur: forests and non‐forests. These two alternative biome states are maintained by different feedback processes and have radically different species with contrasting shade and disturbance tolerance traits. We propose that to improve predictions of species distribution changes under a novel climate, we need to consider the presence or absence of forest shade, as species are likely to respond individually only within their forest or non‐forest biome, and not across biomes. Synthesis. By considering shade as a biotic filter in niche modelling, we are not only improving our predictive capacity, but we are also reconciling the two views of communities: both the individualistic (within biome) and the organismal (across biomes) views of the community concept become relevant and complementary.

Landscape Structure and Seasonality: Effects on Wildlife Species Richness and Occupancy in a Fragmented Dry Forest in Coastal Ecuador

Despite high fragmentation and deforestation, little is known about wildlife species richness and occurrence probabilities in tropical dry forest (TDF) landscapes. To fill this gap in knowledge, we used a Sentinel-2-derived land-cover map, Normalized Difference Vegetation Index (NDVI) data and a multi-species occupancy model to correct for detectability to assess the effect of landscape characteristics on medium and large mammal occurrence and richness in three TDF areas that differ in disturbance and seasonality in Ecuador. We recorded 15 species of medium and large mammals, distributed in 12 families; 1 species is critically Endangered, and 2 are Near-Threatened. The results indicate that species occupancy is related to low forest cover and high vegetation seasonality (i.e., high difference in NDVI between the wet and dry seasons). We believe that the apparent negative effect of forest cover is an indicator of species tolerance for disturbance. The three sampling areas varied from 98% to 40% forest cover, yet species richness and occupancy were not significantly different among them. Vegetation seasonality indicates that more seasonal forests (i.e., those where most tree species lose their leaves during the dry season) tend to have higher mammal species occupancy compared to less seasonal, semi-deciduous forests. Overall, occupancy did not vary between the dry and wet seasons, but species-specific data indicate that some species exhibit higher occupancy during the wet season. This research offers a good understanding of mammal species’ responses to habitat disturbance and fragmentation in TDFs and provides insights to promote their conservation.

Barriers to restoration: Pollution alters nurse effects for an ecosystem engineer

Abstract Nurse plants modify the environment beneath their canopies to create favourable habitats for propagule recruitment. Nurse plants are potentially valuable tools for ecological restoration—yet empirical tests, particularly in polluted environments, remain rare. The few studies that do exist find that nurse plants positively affect propagule recruitment in polluted environments. Yet most tests have focused on pollution‐tolerant species in metal‐contaminated environments. Biotic interactions are highly context dependent, however, such that extrapolations to other suites of species and pollutant types appear premature. We examined changes in intraspecific nurse effects across pollution regimes for a pollution‐sensitive, macroalgal ecosystem engineer that is a target for intertidal restoration. In a manipulative field experiment, we out‐planted propagules in the presence and absence of conspecific canopies at unpolluted control shores and shores that received a partly remediated (low‐toxicity) sewage effluent. We then monitored the performance (survival and growth) of these propagules over time. Algal canopies facilitated the survival and early growth of propagules at control sites, but not at partially remediated sites where propagules performed poorly irrespective of canopy presence. Synthesis and applications. Using a pollution‐sensitive, macroalgal ecosystem engineer, we show for the first time that nurse‐plant effects can be contingent on pollution regime, and that exposure to pollution (even at low levels) can erode nurse effects. We caution that nurse plants are unlikely to be universal tools for ecological restoration, including systems where facilitative nurse effects naturally occur (in our case, macroalgal canopies on unpolluted rocky reefs). Management practitioners should carefully consider the disturbance (e.g. pollution) tolerance of target species, and test whether nurse effects are maintained under current disturbance regimes, before large‐scale translocations are attempted.

Collembola (Hexapoda) as Biological Drivers between Land and Sea

Simple SummaryCollembola also represent one of the most abundant and important taxa of soil invertebrates inhabiting tundra soils. We focused on the structure and distribution patterns of the collembolan communities along the environmental gradient from costal tundra to live macroalgae and aged macroalgae debris deposited across the sub-Arctic coastline. Our results imply that environmental filtering influences collembolan species distributions across the gradient studied and the sorting of species according to their respective functional traits, including dispersal ability. We also suggest that the competition—colonisation trade-off mechanism, which affected the relative importance of competition and environmental filtering, probably determined Collembola community composition over the examined gradient. We believe that our results may become the basis for further study explaining the importance of Collembola as biological drivers of connectivity between land and sea.Macroalgae debris accumulated onshore function as points of interaction between marine and terrestrial ecological systems, but knowledge of the importance of detritivores facilitating the introduction of organic matter via the detritus pathway into neighbouring ecosystems, is still poorly understood. In particular, not much is known about biodiversity patterns and the colonisation of macroalgal debris by terrestrial, detritivorous soil microarthropods in the harsh environmental conditions in the subpolar Arctic region. We hypothesised that (i) soil microarthropods of the coastal tundra, including Collembola, can cross the ecosystem boundary and colonise decaying and freshly exposed macroalgae; and (ii) various inundation regimes by sea water, microhabitat stability and decaying of macroalgae drive distribution patterns of collembolan species. Our results suggest that environmental filtering influences collembolan species’ distributions across the examined gradient and induces sorting of species according to their functional traits, including dispersal ability, resistance to disturbance and environmental tolerance.

Synchronization Control for Discrete-Time-Delayed Dynamical Networks With Switching Topology Under Actuator Saturations.

This article is concerned with the synchronization control problem for a class of discrete-time dynamical networks with mixed delays and switching topology. The saturation phenomenon of physical actuators is specifically considered in designing feedback controllers. By exploring the mixed-delay-dependent sector conditions in combination with the piecewise Lyapunov-like functional and the average-dwell-time switching, a sufficient condition is first established under which all trajectories of the error dynamics are bounded for admissible initial conditions and nonzero external disturbances, while the l2 - l∞ performance constraint is satisfied. Furthermore, the exponential stability of the error dynamics is ensured for admissible initial conditions in the absence of disturbances. Second, by using some congruence transformations, the explicit condition guaranteeing the existence of desired controller gains is obtained in terms of the feasibility of a set of linear matrix inequalities. Then, three convex optimization problems are formulated regarding the disturbance tolerance, the l2 - l∞ performance, and the initial condition set, respectively. Finally, two simulation examples are given to show the effectiveness and merits of the proposed results.

Competitors and ruderals go to town: plant community composition and function along an urbanisation gradient

Urbanisation is expected to function as a filter for plant species by changing the physiochemical environment, causing species turnover along an urbanisation gradient. Analyses of the functional traits of species characteristic of different urbanisation levels allow for comparisons across studies, irrespective of exact species composition. This study aims to examine how plant species and functional traits vary with urbanisation. An independent dataset obtained through the Global Biodiversity Information Facility was used to validate the identified indicator species. The study was performed in Trondheim, Norway. Indicator species of two different urbanisation levels were identified from a structured plot vegetation survey, and their functional traits were contrasted. The functional trait patterns were compared to patterns identified from an independent GBIF dataset. Changes in species composition along the urbanisation gradient identified a shift in environmental‐ and anthropogenic variables, filtering species with different functional traits. Indicators of urban areas displayed higher SLA, nitrogen affinity and disturbance tolerance than indicators from non‐urban areas. Not all functional trait differences observed between the indicator species from the vegetation survey were recognised in the independent dataset from GBIF. Nevertheless, the overall trends were consistent. Urbanisation favours species adhering to different trait syndromes than species outside of urban areas; disturbance‐over stress‐tolerance, and species adapted for rapid resource acquisition rather than species adapted for resource conservation.

Mixedwood silviculture in North America: the science and art of managing for complex, multi-species temperate forests

Temperate mixedwoods (hardwood–softwood mixtures) in central and eastern United States and Canada can be classified into two overarching categories: those with shade-tolerant softwoods maintained by light to moderate disturbances and those with shade-intolerant to mid-tolerant softwoods maintained by moderate to severe disturbances. The former includes red spruce (Picea rubens Sarg.), balsam fir (Abies balsamea (L.) Mill.), or eastern hemlock (Tsuga canadensis (L.) Carr.) in mixture with northern hardwood species; the latter includes pine (Pinus) – oak (Quercus) mixtures. Such forests have desirable socio-economic values, wildlife habitat potential, and (or) adaptive capacity, but management is challenging because one or more softwood species in each can be limited by depleted seed sources, narrow regeneration requirements, or poor competitive ability. Appropriate silvicultural systems vary among mixedwood compositions depending on shade tolerance and severity of disturbance associated with the limiting softwoods, site quality, and level of herbivory. Sustainability of mixedwood composition requires that stand structure and composition be managed at each entry to maintain vigorous trees of species with different growth rates and longevities and to encourage development of advance reproduction or seed-producing trees of desired species. Regardless of silvicultural system, maintaining seed sources of limiting softwoods, providing suitable germination substrates, and controlling competition are critical. Here, we describe commonalities among temperate mixedwoods in central and eastern North America and present a framework for managing them.

Mammals of Mt. Pinatubo, Luzon Island, Philippines: Extreme Resilience Following Catastrophic Disturbance

The catastrophic eruption of Mt. Pinatubo in 1991 destroyed the forests that covered the peak and impacted the surrounding habitat over a broad area of central Luzon. Information on the mammal fauna of Mt. Pinatubo prior to the eruption is limited but documents a variety of native mammals. In 2011 and 2012, we surveyed mammals at localities along an elevational gradient on the eastern slope of the mountain where vegetation had been devastated by pyroclastic flows and subsequent lahars, and habitat reflected early stages of plant succession. We documented eight species of bats (five fruit bats and three insectivorous bats), seven species of small nonvolant mammals (two non-native and five native rodents), and two native large mammals. Additional species of bats and non-volant mammals present in the vicinity of Mt. Pinatubo prior to the eruption or recently documented at other localities in the Zambales Mountains may be present in remnant forest habitat elsewhere on Pinatubo. Across five survey localities where habitat was in the early stages of regeneration, native species of small non-volant mammals were more widespread and much more abundant than were non-natives. The most abundant native species, Apomys sacobianus, may be endemic to Mt. Pinatubo. It is an extreme example of a “disturbance specialist” that thrives in a severely disturbed habitat. Results underscore the disturbance tolerance of many native small mammals of Luzon and reveal a resilience that is remarkable for a highly endemic insular fauna. Mt. Pinatubo presents opportunities for further studies on how natural disturbance has shaped the evolution of the Philippine biota and may influence its future conservation.

Phylogenetic diversity of two geographically overlapping lichens: isolation by distance, environment, or fragmentation?

AbstractAimPhylogenetic diversification is a precursor to speciation, but the underlying patterns and processes are not well‐studied in lichens. Here we investigate what factors drive diversification in two tropical, morphologically similar macrolichens that occupy a similar range but differ in altitudinal and habitat preferences, testing for isolation by distance (IBD), environment (IBE), and fragmentation (IBF).LocationNeotropics, Hawaii, Macaronesia.TaxonSticta andina, S. scabrosa (Peltigeraceae).MethodsWe analysed 395 specimens from 135 localities, using the fungal ITS barcoding marker to assess phylogenetic diversification, through maximum likelihood tree reconstruction, TCS haplotype networks, and Tajima's D. Mantel tests were employed to detect structure in genetic vs. geographic, environmental, and fragmentation distances. Habitat preferences were quantitatively assessed by statistical analysis of locality‐based BIOclim variables.ResultsSticta andina exhibited high phenotypic variation and reticulate phylogenetic diversity across its range, whereas the phenotypically uniform S. scabrosa contained two main haplotypes, one unique to Hawaii. Sticta andina is restricted to well‐preserved andine forests and paramos, naturally fragmented habitats due to disruptive topology, whereas S. scabrosa thrives in lowland to lower montane zones in exposed or disturbed microsites, representing a continuous habitat. Sticta scabrosa showed IBD only across its full range (separating the Hawaiian population) but not within continental Central and South America, there exhibiting a negative Tajima's D. Sticta andina did not exhibit IBD but IBE at continental level and IBF in the northern Andes.Main conclusionsAutecology, particularly preference for either low or high altitudes, indirectly drives phylogenetic diversification. Low diversification in the low altitude species, S. scabrosa, can be attributed to rapid expansion and effective gene flow across a more or less continuous niche due to disturbance tolerance. In contract, high diversification in the high altitude species, S. andina, can be explained by niche differentiation (IBE) and fragmentation (IBF) caused by the Andean uplift.