Do trout respond to riparian change? A meta‐analysis with implications for restoration and management

相似文献   

Measuring and monitoring restored ecosystems: can remote sensing be applied to the ecological recovery wheel to inform restoration success?

The commencement of the United Nations Decade on Ecosystem Restoration has highlighted the urgent need to improve restoration science and fast-track ecological outcomes. The application of remote sensing for monitoring purposes has increased over the past two decades providing a variety of image datasets and derived products suitable to map and measure ecosystem properties (e.g. vegetation species, community composition, and structural dimensions such as height and cover). However, the operational use of remote sensing data and derived products for ecosystem restoration monitoring in research, industry, and government has been relatively limited and underutilized. In this paper, we use the Society for Ecological Restoration (SER) ecological recovery wheel (ERW) to assess the current capacity of drone-airborne-satellite remote sensing datasets to measure each of the SER's recommended attributes and sub-attributes for terrestrial restoration projects. Based on our combined expertise in the areas of ecological monitoring and remote sensing, a total of 11 out of 18 sub-attributes received the highest feasibility score and show strong potential for remote sensing assessments; while sub-attributes such as gene flows, all trophic levels and chemical and physical substrates have a reduced capacity for monitoring. We argue that in the coming decade, ecologists can combine remote sensing with the ERW to monitor restoration recovery and reference ecosystems for improved restoration outcomes at the local, regional, and landscape scales. The ERW approach can be adapted as a monitoring framework for projects to utilize the benefits of remote sensing and inform management through scalable, operational, and meaningful outcomes.     

Why do Hymenopteran workers drift to non-natal groups? Generalized reciprocity and the maximization of group and parental success

Eusocial Hymenoptera are often characterized by having facultatively or obligately sterile worker castes. However, findings across an increasing number of species are that some workers are non-natal—they have ‘drifted’ away from where they were born and raised. Moreover, drifters are often indistinguishable from natal workers in the work and benefits provided to joined groups. This seems an evolutionary paradox of providing benefits to potentially unrelated individuals over close kin. Rather than being mistakes, drifting is proposed to be adaptive if joiners either gain inclusive fitness by preferentially moving to other kin groups or through generalized reciprocity in which exchanging workers across groups raises group-level genetic diversity and creates social heterosis. It is unclear, however, if reciprocity is unlikely because of a susceptibility to cheating. In resolving this question, a series of evolutionary simulations show: (1) Reciprocity can persist under a range of genetic assumptions and scenarios of cheating, (2) cheating almost always evolves, but can be expressed in a variety of ways that are not always predictable, (3) the inclusive fitness hypothesis is equally or more susceptible to cheating. Moreover, existing data in Hymenoptera (although not extensive) are more consistent with generalized reciprocity. This supports a hypothesis that drifting, as a phenomenon, may more often reflect maximization of group and parental fitness rather than fitness gains for the individual drifters.     

Why are incubation periods longer in the tropics? A common-garden experiment with house wrens reveals it is all in the egg

Incubation periods of Neotropical birds are often longer than those of related species at temperate latitudes. We conducted a common-garden experiment to test the hypothesis that longer tropical incubation periods result from longer embryo development times rather than from different patterns of parental incubation behavior. House wrens, one of few species whose geographic range includes tropical equatorial and temperate high latitudes, have incubation periods averaging 1.2 days longer at tropical latitudes. We incubated eggs of house wrens in Illinois and Panama under identical conditions in mechanical incubators. Even after factoring out differences in egg size, tropical house wrens still required 1.33 days longer, on average, to hatch. We conclude that parental attendance patterns do not account for latitudinal differences in incubation period but that some other as yet unmeasured factor intrinsic to the egg or embryo, or both, extends development time in the tropics.     

Assisted reproductive technologies: how to minimize the risks and complications in developing countries?

¹ Correspondence address. E-mail: petra.desutter{at}ugent.be In 2% of assisted reproductive techniques (ART) cycles complicationsoccur. Some are preventable, some are not. In this paper, wewill discuss risks and complications of the standard ‘Western’approach in ART today and point to some measures to be takenwhen implementing ART in developing countries, where resourcesand access to medical care may be limited. Ovarian hyperstimulationsyndrome (OHSS, and its thrombo-embolic complications) is responsiblefor the majority of cycle-related complications, followed bybleeding and infection at oocyte retrieval. ART pregnanciesare complicated by first-trimester bleeding more often thanspontaneous pregnancies, they are more often ectopic, but themajor complication is the very high incidence of multiple pregnancies,when more than one embryo is transferred. OHSS can be preventedby screening patients at risk and by using mild or no stimulation.Simple measures can minimize the risks of bleeding or infection.Obviously single embryo transfer is the only way to avoid multiplepregnancies, which have a highly increased risk for severe maternaland neonatal morbidity and mortality (mainly due to prematurity).Special attention should be given to pre-existing pathologies.Risk minimization of ART in developing countries is not onlymandatory from an economical but also an ethical point of view.     

Why species composition is not a good indicator to assess restoration success? Counter‐response to Reid (2015)

The absence of species composition among the indicators of restoration success, recommended for the Brazilian Atlantic Forest by Suganuma and Durigan, was criticized by Reid. In his critic, Reid argues that species composition can be (1) predictable from site history and restoration technique and (2) a surrogate for poor ecosystem functioning and lack of resilience. We disagree on the deterministic view behind the first argument, and the latter is still controversial. Even though, we recommended richness as a good indicator of ecosystem functioning instead of composition—which depends on the exhaustive labor of botanical identification.     

Why does Daphne pseudomezereum drop its leaves in the summer? An adaptive alternative to surviving forest shade

Daphne pseudomezereum A. Gray (Dpm) appears to be the only woody species in the north temperate forest that sheds its leaves in the summer while remaining green over winter (i.e. wintergreen leaf habit). Yet, the reason for this odd leaf habit has not been explored. To this end, we examined the microclimatic settings and ecophysiological traits of Dpm and its three native congeners in a field study of eight natural populations. In addition, we conducted a common garden experiment using Dpm plants where potential carbon gain across the seasons was estimated, using actual field microclimate data. Together, these data tested the hypothesis that Dpm retained traits of an open-grown upland ancestor, unable to adapt to the deep summer shade, it survived by becoming summer dormant and wintergreen. Our hypothesis was supported by patterns of leaf ecophysiological traits and carbon gain simulations in Dpm, consistent with the energetic feasibility of a summer dormancy followed by an autumn leaf sprout. We also conclude that carbon deficit driven by low light and high respiration cost is the trigger for the leaf habit of Dpm and assert that its phenological strategy represents a rare but viable alternative strategy for persistence in the temperate understory.     

Can soil seed banks contribute to the restoration of dune slacks under conservation management?

Questions: Does the soil seed bank resemble the former early successional stages of a dune slack system more than the established later successional vegetation? Does it have the potential to contribute to the conservation of a highly endangered habitat? Location: Dune slacks at Newborough Warren, UK. Methods: The composition of the soil seed bank in two depth layers was determined using the seedling emergence method between March 2004 and April 2005. Long-term monitoring data on the floristic composition of the established vegetation were obtained from the national conservation agency, and additional monitoring was undertaken in 2003. Floristic composition, seed weights, seed longevity of component species and Ellenberg indicator values were used to compare the seed bank and established vegetation. Results: The soil seed bank was diverse and contained typical dune slack species, species of early successional stages and species of conservation interest. A comparison between the composition of the seed bank and historical data on the composition of the established vegetation showed that the seed bank reflects earlier successional stages more closely than the current aboveground vegetation. This study increases the scarce information currently available on the seed bank ecology of several species, including two orchid species. Conclusions: The soil seed bank can be expected to contribute to vegetation change after disturbance. Stimulation of germination from the seed bank through management may contribute to the conservation of both characteristic and threatened species typical of dune slacks.     

Egg-size variation and reproductive success in the Herring Gull Lams argentatus: adaptive or constrained size of the last egg?

Herring Gull Larus argentatus eggs from a study colony in the Baltic showed a slight but significant variation in egg size within the laying sequence. Last-laid eggs were only about 5% smaller by volume than first eggs. There was no significant difference in dry yolk weight or dry albumen weight, although possible differences were evident. The chicks had nearly equal hatching weights and equally long tarsi. There was no differential mortality in the third chick in the study colony, and there were no indications of egg-size-mediated mortality. The birds in the colony produced an average of 1.45 fledglings per pair. Compared with several other studied colonies, the difference in egg size within a clutch was low, and a comparison of colonies from northwestern Europe suggests that variance within the clutch is negatively correlated with fledging success, so that a large difference in size between first and last eggs is associated with low fledging success. We suggest that the size of the last egg in the clutch reflects the feeding potential in the environment and is mainly a nonadaptive response to poor feeding conditions during laying.     

Why does the subject speak? Prejudgement in fieldwork with Naxalites and Hindu rioters

This article explores the shifting trajectory of dramaturgical encounters with ‘subjects’ in two disparate contexts of violence in contemporary India: Naxalites in Jharkhand and Bihar; and participants in the 2002 riots in Gujarat. It argues that why (and thereby what) the subject speaks has to be located within the larger text of performances in the ‘field’, involving the prejudgement (in a Gadamerian sense) of both researcher and subject. Limits and possibilities to prior knowledges of both predetermine outcomes of interaction and inform the enterprise of doing theory in troubled contexts.     

Why does land-use history facilitate non-native plant invasion? A field experiment with Celastrus orbiculatus in the southern Appalachians

Although historic land use is often implicated in non-native plant invasion of forests, little is known about how land-use legacies might actually facilitate invasion. We conducted a 2-year field seeding experiment in western North Carolina, USA, to compare germination and first-year seedling survival of Celastrus orbiculatus Thunb. in stands that had been cultivated and abandoned a century earlier and were dominated by tulip poplar (Liriodendron tulipifera L.), and in paired stands that had never been cultivated and were dominated by oaks (Quercus spp.). Experiments were conducted at five sites with paired tulip poplar and oak stands by varying litter mass (none, low, or high) and litter type (tulip poplar or oak). We also performed reciprocal soil translocations using pots seeded with C. orbiculatus. Soil moisture and temperature were measured throughout the growing season. Germination and survival were highest in the tulip poplar stands. Germination was also higher in plots with low litter mass. Seedling survival was highest in plots with low litter mass or no litter. Soil moisture was higher in tulip poplar stands and under low-mass litter. Differences in germination and survival among the potted plants were minimal, suggesting that soil type and ambient site conditions were less important than litter conditions for C. orbiculatus establishment. Our results suggest that the low litter mass and mesic soil conditions that are characteristic of tulip poplar stands may confer higher invasibility and explain the higher abundance of C. orbiculatus in areas with successional overstory communities associated with historically cultivated forests.     

Metabolic flexibility: the key to long-term evolutionary success in Bryozoa?

Oxygen consumption (MO2) and activity were evaluated in Antarctic Bryozoa. Three species representing two different morphologies, flat sheet, laminar forms, Isoseculiflustra tenuis and Kymella polaris, and the bush form Camptoplites bicornis were used. In Bryozoa, activity is measured as the proportion of colony zooids with their lophophores extended. In I. tenuis and K. polaris, residual analysis showed that the percentage of zooids with extended lophophores was not correlated with colony MO2. Lophophore extension is, therefore, a poor measure of activity, and other costs (e.g. growth, reproduction, storage) probably form the major metabolic costs. MO2 per unit of ash-free dry mass (AFDM) in the laminar forms was low compared with other Antarctic marine invertebrates, but not lower than brachiopods and echinoderms. However, the lowest rate here, 16.8 microg O2 g AFDM(-1) h(-1) for a K. polaris colony, is (to our knowledge) the lowest for any animal so far reported. MO2 per unit of AFDM for C. bicornis, however, is among the highest reported for sessile or slow moving Antarctic marine ectotherms, with values similar to those for bivalve and gastropod molluscs. The highest rate, 527 microg O2 g AFDM(-1) h(-1) for one colony is (to our knowledge) the highest reported for polar animals of this type. Extreme diversity in metabolic strategy may explain the bryozoan long evolutionary record and great success in shallow marine environments worldwide.     

What does it take to do successful adaptive management? A case study highlighting Coastal Grassy Woodland restoration at Yanakie Isthmus

The case study of the Yanakie Isthmus Coastal Grassy Woodland Restoration Program, Victoria, Australia, illustrates the steps necessary to deliver a complex, long‐term adaptive management project involving a range of stakeholders at a landscape scale. Perspectives of the land manager, scientist and volunteer help to convey successes and lessons learned.     

Can we project changes in fish abundance and distribution in response to climate?

Large‐scale and long‐term changes in fish abundance and distribution in response to climate change have been simulated using both statistical and process‐based models. However, national and regional fisheries management requires also shorter term projections on smaller spatial scales, and these need to be validated against fisheries data. A 26‐year time series of fish surveys with high spatial resolution in the North‐East Atlantic provides a unique opportunity to assess the ability of models to correctly simulate the changes in fish distribution and abundance that occurred in response to climate variability and change. We use a dynamic bioclimate envelope model forced by physical–biogeochemical output from eight ocean models to simulate changes in fish abundance and distribution at scales down to a spatial resolution of 0.5°. When comparing with these simulations with annual fish survey data, we found the largest differences at the 0.5° scale. Differences between fishery model runs driven by different biogeochemical models decrease dramatically when results are aggregated to larger scales (e.g. the whole North Sea), to total catches rather than individual species or when the ensemble mean instead of individual simulations are used. Recent improvements in the fidelity of biogeochemical models translate into lower error rates in the fisheries simulations. However, predictions based on different biogeochemical models are often more similar to each other than they are to the survey data, except for some pelagic species. We conclude that model results can be used to guide fisheries management at larger spatial scales, but more caution is needed at smaller scales.     

Circadian rhythmicity and photoperiodism in the pitcher-plant mosquito: adaptive response to the photic environment or correlated response to the seasonal environment?

Many plants and animals use the length of day or photoperiod to cue their seasonal patterns of development, reproduction, dormancy, and migration. Among temperate arthropods, the median or critical photoperiod increases with latitude or altitude. Concomitantly, in beetles, moths, mites, flies, and mosquitoes, there is a declining expression of a rhythmic, presumably circadian-based, component of photoperiodic response. It has been proposed that the long summer days in the north select for a reduced response to light by the circadian clock, which results in this declining rhythmic expression and, consequently, longer northern critical photoperiods. However, these patterns might also be due to direct, seasonal selection on the critical photoperiod itself, which results in a correlated reduction in the rhythmic component as a result of internal physiological constraints within the organism. Using standard light duration and selection experiments, we show that evolution of photoperiodic time measurement in the mosquito, Wyeomyia smithii, results from the direct response of critical photoperiod to seasonal selection and a correlated response of the rhythmic component of photoperiodic time measurement. We conclude that expression of the circadian clock is necessary neither for the central mechanism of photoperiodic time measurement nor for the adaptive modification of critical photoperiod.     

Why do we need drugs to treat the patient with obesity?

Objective:

Obesity is a public health problem, which increases the risk of chronic diseases and mortality. Weight loss can reduce mortality and improve most of the detrimental health consequences of obesity.

Design and Methods:

This paper was developed from two presentations to the US Food and Drug Administration (FDA), which has responsibility for reviewing and approving drugs to treat obesity.

Results:

A weight loss of 5% or more is sufficient to significantly reduce health risks in individuals with impaired glucose tolerance, hypertension, or nonalcoholic fatty liver disease. Slightly more weight loss (16% on average, achieved by surgery) reduces mortality. The goal of medicating for obesity is to help more patients achieve more weight loss. A barrier to drug approval has been the concern that weight loss medications might be used by individuals with little or no health risks, thus mandating a low side effect profile for approval of any drug. This limits the options for patients who have obesity‐related health problems that could improve with weight loss. Recently the FDA signaled interest in identifying health benefits in higher risk patients that might justify medications with higher risk; however, the potential impact on a large segment of the population has led the FDA to consider requiring a cardiovascular outcome trial for all obesity medications, either prior to or after approval.

Conclusion:

This review argues that drugs are needed for obesity because they enhance behaviorally induced weight loss and that new medications for obesity are needed in the approval process.     

Transfer seeds,hay, or soil blocks? The importance of the completeness of biological inputs to address dispersal and establishment limitations during the restoration of plant assemblages in floodplain grasslands

This study investigated different techniques of grassland restoration to overcome dispersal or establishment limitation, which are key processes influencing early-successional plant community assembly. A fully randomized in situ experiment was set up in a former arable land in a floodplain along the Garonne river (south-western France) to test for the effect of (1) the type and completeness of the biological input (any biological material—seed, hay, and soil—transferred to the site under restoration), (2) soil disturbance by deep tillage, and (3) their interaction on plant community dynamics for 5 years. All inputs influenced the plant community structure and composition. The effects depended on the type of the input but not necessarily in link with its completeness. High density and diversity seed mixture led to high levels of richness and relative abundance of target species like soil blocks, the input considered as the most complete. During the first year, hay transfer mostly influenced community assembly through negative litter effects. Delayed germination of several species contributed to buffer these early effects. This study supports the importance of dispersal limitation during early succession in degraded grassland ecosystems whereas soil disturbance had only subtle effects on the seed bank and standing plant community, indicating that competition and establishment limitation were of secondary importance in our study system. Our results suggest that even low-frequency immigration events (e.g. when a few seeds are transferred within hay) can be of great importance providing that a sufficiently long time period is considered for grassland restoration.