Survival Under Conditions of Environmental Stress: Variability of Brain Morphology and Behavior in the House Mouse

Two populations of laboratory mice lived outdoors in open pens for two years. Thereafter, some of them were bred in the laboratory. Morphometric analysis showed that the size of the synaptic projection area of mossy fibers (in the CA3 region of the hippocampus), which has an important functional role, and some behavioral traits of the open-pen mouse progeny had significant genetically determined differences from those in the initial population. This was attributed to differential breeding accounted for by the influence of severe environmental factors. Under environmental stress, selection occurred in the population and the mice with behavioral and neuromorphological characteristics differing from those of the control group proved to be better adapted to such conditions.     

磷酸三苯酯对斑马鱼早期生命阶段的神经毒性研究

磷酸三苯酯(triphenyl phosphate,TPP)作为多溴联苯醚类阻燃剂的替代产品,是一类生产和需求量均相当高的有机磷酸酯类阻燃剂,目前已在多种环境介质以及生物体内均有不同程度检出。由于结构和有机磷农药具有相似性,其对生物的神经毒性值得关注。本研究以斑马鱼为实验动物,研究了TPP(5~625%g·L-1)的胚胎发育毒性和行为毒性,并通过检测乙酰胆碱酯酶活性以及神经系统相关基因的转录水平,探讨其可能的毒性机制。研究发现,TPP可导致斑马鱼胚胎孵化时间延长,体长变短,心率变慢。同时,TPP暴露也可以影响斑马鱼幼鱼在持续光照和明暗周期刺激下的游泳行为,表现为低浓度增加而高浓度降低其游泳速度。而TPP暴露后幼鱼乙酰胆碱酯酶活性以及神经发育相关基因转录水平的变化可能是导致其行为毒性的原因。虽然实验中所设定的暴露浓度高于环境中一般浓度,但TPP在短期暴露中所表现出的胚胎和神经发育毒性表明TPP对于水生生物可能存在一定风险,需要进一步研究加以确认。     

Integrating functional connectivity and fire management for better conservation outcomes

Globally, the mean abundance of terrestrial animals has fallen by 50% since 1970, and populations face ongoing threats associated with habitat loss, fragmentation, climate change, and disturbance. Climate change can influence the quality of remaining habitat directly and indirectly by precipitating increases in the extent, frequency, and severity of natural disturbances, such as fire. Species face the combined threats of habitat clearance, changing climates, and altered disturbance regimes, each of which may interact and have cascading impacts on animal populations. Typically, conservation agencies are limited in their capacity to mitigate rates of habitat clearance, habitat fragmentation, or climate change, yet fire management is increasingly used worldwide to reduce wildfire risk and achieve conservation outcomes. A popular approach to ecological fire management involves the creation of fire mosaics to promote animal diversity. However, this strategy has 2 fundamental limitations: the effect of fire on animal movement within or among habitat patches is not considered and the implications of the current fire regime for long-term population persistence are overlooked. Spatial and temporal patterns in fire history can influence animal movement, which is essential to the survival of individual animals, maintenance of genetic diversity, and persistence of populations, species, and ecosystems. We argue that there is rich potential for fire managers to manipulate animal movement patterns; enhance functional connectivity, gene flow, and genetic diversity; and increase the capacity of populations to persist under shifting environmental conditions. Recent methodological advances, such as spatiotemporal connectivity modeling, spatially explicit individual-based simulation, and fire-regime modeling can be integrated to achieve better outcomes for biodiversity in human-modified, fire-prone landscapes. Article impact statement: Land managers may conserve populations by using fire to sustain or enhance functional connectivity.     

Scale dependency in effectiveness,isolation, and social‐ecological spillover of protected areas

Protected areas are considered vital for the conservation of biodiversity. Given their central role in many conservation strategies, it is important to know whether they adequately protect biodiversity within their boundaries; whether they are becoming more isolated from other natural areas over time; and whether they play a role in facilitating or reducing land‐cover change in their surroundings. We used matching methods and national and local analyses of land‐cover change to evaluate the combined effectiveness (i.e., avoided natural‐cover loss), isolation (i.e., changes in adjacent areas), and spillover effects (i.e., impacts on adjacent areas) of 19 national parks in South Africa from 2000 to 2009. All parks had either similar or lower rates of natural‐cover loss than matched control samples. On a national level, mean net loss of natural cover and mean net gain of cultivation cover decreased with distance from park boundary, but there was considerable variation in trends around individual parks, providing evidence for both increased isolation and buffering of protected areas. Fourteen parks had significant positive spillover and reduced natural‐cover loss in their surroundings, whereas five parks experienced elevated levels of natural‐cover loss. Conclusions about social‐ecological spillover effects from protected areas depended heavily on the measures of land‐cover change used and the scale at which the results were aggregated. Our findings emphasize the need for high‐resolution data when assessing spatially explicit phenomena such as land‐cover change and challenge the usefulness of large‐scale (coarse grain, broad extent) studies for understanding social‐ecological dynamics around protected areas.     

Tropical amphibians in shifting thermal landscapes under land‐use and climate change

Land‐cover and climate change are both expected to alter species distributions and contribute to future biodiversity loss. However, the combined effects of land‐cover and climate change on assemblages, especially at the landscape scale, remain understudied. Lowland tropical amphibians may be particularly susceptible to changes in land cover and climate warming because many species have narrow thermal safety margins resulting from air and body temperatures that are close to their critical thermal maxima (CT_max). We examined how changing thermal landscapes may alter the area of thermally suitable habitat (TSH) for tropical amphibians. We measured microclimates in 6 land‐cover types and CT_max of 16 frog species in lowland northeastern Costa Rica. We used a biophysical model to estimate core body temperatures of frogs exposed to habitat‐specific microclimates while accounting for evaporative cooling and behavior. Thermally suitable habitat area was estimated as the portion of the landscape where species CT_max exceeded their habitat‐specific maximum body temperatures. We projected changes in TSH area 80 years into the future as a function of land‐cover change only, climate change only, and combinations of land‐cover and climate‐change scenarios representing low and moderate rates of change. Projected decreases in TSH area ranged from 16% under low emissions and reduced forest loss to 30% under moderate emissions and business‐as‐usual land‐cover change. Under a moderate emissions scenario (A1B), climate change alone contributed to 1.7‐ to 4.5‐fold greater losses in TSH area than land‐cover change only, suggesting that future decreases in TSH from climate change may outpace structural habitat loss. Forest‐restricted species had lower mean CT_max than species that occurred in altered habitats, indicating that thermal tolerances will likely shape assemblages in changing thermal landscapes. In the face of ongoing land‐cover and climate change, it will be critical to consider changing thermal landscapes in strategies to conserve ectotherm species.     

Effect of scale on trait predictors of species responses to agriculture

Species persistence in human‐altered landscapes can depend on factors operating at multiple spatial scales. To understand anthropogenic impacts on biodiversity, it is useful to examine relationships between species traits and their responses to land‐use change. A key knowledge gap concerns whether these relationships vary depending on the scale of response under consideration. We examined how local‐ and large‐scale habitat variables influence the occupancy dynamics of a bird community in cloud forest zones in the Colombian Chocó‐Andes. Using data collected across a continuum of forest and agriculture, we examined which traits best predict species responses to local variation in farmland and which traits best predict species responses to isolation from contiguous forest. Global range size was a strong predictor of species responses to agriculture at both scales; widespread species were less likely to decline as local habitat cover decreased and as distance from forest increased. Habitat specialization was a strong predictor of species responses only at the local scale. Open‐habitat species were particularly likely to increase as pasture increased, but they were relatively insensitive to variation in distance to forest. Foraging plasticity and flocking behavior were strong predictors of species responses to distance from forest, but not their responses to local habitat. Species with lower plasticity in foraging behaviors and obligate flock‐following species were more likely to decline as distance from contiguous forest increased. For species exhibiting these latter traits, persistence in tropical landscapes may depend on the protection of larger contiguous blocks of forest, rather than the integration of smaller‐scale woodland areas within farmland. Species listed as threatened or near threatened on the International Union for Conservation of Nature Red List were also more likely to decline in response to both local habitat quality and isolation from forest relative to least‐concern species, underlining the importance of contiguous forests for threatened taxa.     

Effects of landscape transformation on bird colonization and extinction patterns in a large‐scale,long‐term natural experiment

Conversion of agricultural land to forest plantations is a major driver of global change. Studies on the impact of forest plantations on biodiversity in plantations and in the surrounding native vegetation have been inconclusive. Consequently, it is not known how to best manage the extensive areas of the planet currently covered by plantations. We used a novel, long‐term (16 years) and large‐scale (30,000 ha) landscape transformation natural experiment (the Nanangroe experiment, Australia) to test the effects of land conversion on population dynamics of 64 bird species associated with woodland and forest. A unique aspect of our study is that we focused on the effects of plantations on birds in habitat patches within plantations. Our study design included 56 treatment sites (Eucalyptus patches where the surrounding matrix was converted from grazed land to pine plantations), 55 control sites (Eucalyptus patches surrounded by grazed land), and 20 matrix sites (sites within the pine plantations and grazed land). Bird populations were studied through point counts, and colonization and extinction patterns were inferred through multiple season occupancy models. Large‐scale pine plantation establishment affected the colonization or extinction patterns of 89% of studied species and thus led to a comprehensive turnover in bird communities inhabiting Eucalyptus patches embedded within the maturing plantations. Smaller bodied species appeared to respond positively to plantations (i.e., colonization increased and extirpation of these species decreased in patches surrounded by plantations) because they were able to use the newly created surrounding matrix. We found that the effects of forest plantations affected the majority of the bird community, and we believe these effects could lead to the artificial selection of one group of species at the expense of another.     

Meta‐Analysis of the Effects of Forest Fragmentation on Interspecific Interactions

Forest fragmentation dramatically alters species persistence and distribution and affects many ecological interactions among species. Recent studies suggest that mutualisms, such as pollination and seed dispersal, are more sensitive to the negative effects of forest fragmentation than antagonisms, such as predation or herbivory. We applied meta‐analytical techniques to evaluate this hypothesis and quantified the relative contributions of different components of the fragmentation process (decreases in fragment size, edge effects, increased isolation, and habitat degradation) to the overall effect. The effects of fragmentation on mutualisms were primarily driven by habitat degradation, edge effects, and fragment isolation, and, as predicted, they were consistently more negative on mutualisms than on antagonisms. For the most studied interaction type, seed dispersal, only certain components of fragmentation had significant (edge effects) or marginally significant (fragment size) effects. Seed size modulated the effect of fragmentation: species with large seeds showed stronger negative impacts of fragmentation via reduced dispersal rates. Our results reveal that different components of the habitat fragmentation process have varying impacts on key mutualisms. We also conclude that antagonistic interactions have been understudied in fragmented landscapes, most of the research has concentrated on particular types of mutualistic interactions such as seed dispersal, and that available studies of interspecific interactions have a strong geographical bias (arising mostly from studies carried out in Brazil, Chile, and the United States). Meta‐Análisis de los Efectos de la Fragmentación del Bosque sobre las Interacciones Interespecíficas     

F-127改性纳米零价铁及对水中2,4-DCP的去除

为了增强纳米零价铁的分散性,本研究采用环境友好型材料Pluronic F-127对纳米零价铁(NZVI)进行表面改性,形成分散型纳米零价铁(F-NZVI),并用于水中2,4-DCP的去除.通过不同质量比的F-NZVI颗粒沉降试验和对2,4-DCP的去除试验,发现存在沉降去除和悬浮去除两个阶段,确定F-127与NZVI颗粒的最佳质量比为2∶1,2,4-DCP最大去除率为72.32%.通过SEM、FTIR、XRD、XPS对样品进行表面形貌、组成和晶体结构分析,发现F-127对提高NZVI分散性和抗氧化性有显著作用.通过控制不同因素研究F-NZVI去除水中2,4-DCP的最优条件,实验结果表明,当2,4-DCP初始浓度为20 mg·L~(-1)时,F-NZVI去除2,4-DCP的最佳pH值为5,F-NZVI最佳投加量为3 g·L~(-1).     

Connectivity in an Agricultural Landscape as Reflected by Interpond Movements of a Freshwater Turtle

Abstract:  Connectivity is a measure of how landscape features facilitate movement and thus is an important factor in species persistence in a fragmented landscape. The scarcity of empirical studies that directly quantify species movement and determine subsequent effects on population density have, however, limited the utility of connectivity measures in conservation planning. We undertook a 4-year study to calculate connectivity based on observed movement rates and movement probabilities for five age-sex classes of painted turtles ( Chrysemys picta ) inhabiting a pond complex in an agricultural landscape in northern Virginia (U.S.A.). We determined which variables influenced connectivity and the relationship between connectivity and subpopulation density. Interpatch distance and quality of habitat patches influenced connectivity but characteristics of the intervening matrix did not. Adult female turtles were more influenced by the habitat quality of recipient ponds than other age-sex classes. The importance of connectivity on spatial population dynamics was most apparent during a drought. Population density and connectivity were low for one pond in a wet year but dramatically increased as other ponds dried. Connectivity is an important component of species persistence in a heterogeneous landscape and is strongly dependent on the movement behavior of the species. Connectivity may reflect active selection or avoidance of particular habitat patches. The influence of habitat quality on connectivity has often been ignored, but our findings highlight its importance. Conservation planners seeking to incorporate connectivity measures into reserve design should not ignore behavior in favor of purely structural estimates of connectivity.