Alien Invasions, Ecological Restoration in Cities and the Loss of Ecological Memory

After a community or ecosystem is lost, it may leave behind an ecological memory. The site history, soil properties, spores, seeds, stem fragments, mycorrhizae, species, populations, and other remnants may influence the composition of the replacement community or ecosystem to varying degrees. The remnants may also hold the site to a trajectory that has implications for ecological restoration. This is true in urban situations in particular where repeated disturbance has masked the history of the site. The ecological memory remaining may be insufficient for a site to heal itself; restoration activities are required to direct the future of the site. Conversely, in light of climate change and other rapidly changing environments, the existing ecological memory may be poorly suited to the new conditions and restoration projects need to create new and perhaps novel ecosystems. The loss of ecological memory facilitates the establishment of foreign invasive species. These invasives may eventually create a new stability domain with its own ecological memory and degree of resilience. To be successful, invasive species control must address both internal within patch memory of invasives and external between patch memory. Further research is necessary to document and conserve ecological memory for ecological restoration in response to future ecosystem changes.     

城市与区域生态关联研究进展

城市及其周边区域正在面临日益严峻的环境污染、生态恶化、资源短缺等问题。这些问题的出现,与长期以来城市发展过程中忽视城市与区域的生态关联密切相关。研究城市与区域的生态关联,对于解决城市与区域的生态环境问题、指导新型城镇化建设具有重要的理论意义与实践价值。主要从以下3个方面系统总结了城市与区域生态关联的研究进展:(1)城市发展对周边区域的生态环境影响,包括直接的胁迫和间接的影响;(2)区域对城市发展的生态支撑;(3)城市与周边区域社会、经济、生态关联的相互作用机制。指出了当前城市与区域生态关联研究中存在的问题和不足:1)城市对周边区域生态环境直接影响的研究较多,且多侧重城市对周边区域的负面影响,对其间接影响的研究较为缺乏;2)周边区域对城市发展生态支撑作用的研究相对缺乏、认识不够深入;3)对城市与周边区域生态关联作用机制的研究较为缺乏。未来的研究要将城市和区域作为统一整体,进一步完善城市与区域生态关联的理论框架,耦合社会经济的相互作用,定量解析城市与区域的生态关联,为城市与区域的可持续发展提供科学依据。     

Thinking systemically about ecological interventions: what do system archetypes teach us?

To address the need for more holistic approaches to ecological management and restoration, we examine ecosystem interventions through the lens of systems thinking and in reference to systems archetypes, as developed in relation to organizational management in the business world. Systems thinking is a holistic approach to analysis that focuses on how a system's constituent parts interrelate and how systems work over time and within the context of larger systems. Systems archetypes represent patterns of behavior that have been observed repeatedly. These archetypes help relate commonly observed responses to environmental problems with their effect on important feedback processes to better anticipate connections between actions and results. They highlight situations where perceived solutions actually result in worse or unintended consequences, and where changing goals may be either appropriate or inappropriate. The archetypes can be applied to practical examples, and can provide guidance to help make appropriate intervention decisions in similar circumstances. Their use requires stepping back from immediately obvious management decisions and taking a more systemic view of the situation. A catalog of archetypes that describe common patterns of systems behavior may inform management by helping to diagnose system dynamics earlier and identifying interactions among them.     

Digestive physiology: a view from molecules to ecosystem

Digestive physiology links physiology to applications valued by society, such as understanding ecology and ecological toxicology and managing and conserving species. Here I illustrate this applied and integrative perspective with several avian case studies. The match between digestive features and diet provides evidence of tradeoffs that preclude doing well on all possible substrates with a single digestive design, and this influences ecological niche partitioning. But some birds, such as wild house sparrow (Passer domesticus) nestlings, are digestively very flexible. Their intestinal maltase activity and mRNA for intestinal maltase glucoamylase specifically and reversibly change when they switch among foods with different starch content. Houses sparrows and many other birds absorb hydrolyzed water-soluble monomers, such as glucose, mainly passively via tight junctions between enterocytes (i.e., paracellular absorption). Such species might be good models for studying this process, which is important biomedically for absorption of drugs. High paracellular absorption may enhance absorption of low molecular weight, natural water-soluble toxins. Also, reliance of American robins (Turdus migratorius) on passive absorption makes them less sensitive to types of plant toxins that inhibit mediated glucose absorption, such as phlorizin or the flavanoid isoquercetrin. Determining absorption of environmental contaminants is another important ecological application. Common loon (Gavia immer) chicks absorbed 83% of methyl mercury in fish meals, eliminate the mercury slowly, and consequently are predicted in the wild to bioaccumulate mercury to higher concentrations than in their foods. The quantitative details can be used to set regulatory levels for mercury that will protect wildlife.     

Why do morphological phylogenies vary in quality? An investigation based on the comparative history of lizard clades

Phylogenies based on morphology vary considerably in their quality: some are robust and explicit with little conflict in the data set, whereas others are far more tenuous, with much conflict and many possible alternatives. The main primary reasons for untrue or inexplicit morphological phylogenies are: not enough characters developed between branching points, uncertain character polarity, poorly differentiated character states, homoplasy caused by parallelism or reversal, and extinction, which may remove species entirely from consideration and can make originally conflicting data sets misleadingly compatible, increasing congruence at the expense of truth. Extinction differs from other confounding factors in not being apparent either in the data set or in subsequent analysis. One possibility is that variation in the quality of morphological phylogenies has resulted from exposure to different ecological situations. To investigate this, it is necessary to compare the histories of the clades concerned. In the case of explicit morphological phylogenies, ecological and behavioural data can be integrated with them and it may then be possible to decide whether morphological characters are likely to have been elicited by the environments through which the clade has passed. The credibility of such results depends not only on the phylogeny being robust but also on its detailed topology: a pectinate phylogeny will often allow more certain and more explicit statements to be made about historical events. In the case of poor phylogenies, it is not possible to produce detailed histories, but they can be compared with robust phylogenies in the range of ecological situations occupied, and whether they occupy novel situations in comparison with their outgroups. LeQuesne testing can give information about niche homoplasy, and it may also be possible to see if morphological features are functionally associated with ecological parameters, even if the direction of change is unknown. Examination of the robust and explicit phylogeny of the semaphore geckoes (Pristurus) suggests that its quality does stem from a variety of environmental factors. The group has progressed along an ecological continuum, passing through a series of increasingly severe niches that appear to have elicited many morphological changes. The fact that niches are progressively filled reduces the likelihood of species reinvading a previous one with related character reversal. Because the niches of advanced Pristurus are virtually unique within the Gekkonidae the morphological changes produced are also very rare and therefore easy to polarize. Ecological changes on the main stem of the phylogeny are abrupt and associated character states consequently well differentiated.(ABSTRACT TRUNCATED AT 400 WORDS)     

Social context hinders humans but not ravens in a short-term memory task

Using resources shared within a social group—either in a cooperative or a competitive way—requires keeping track of own and others’ actions, which, in turn, requires well-developed short-term memory. Although short-term memory has been tested in social mammal species, little is known about this capacity in highly social birds, such as ravens. We compared ravens (Corvus corax) with humans in spatial tasks based on caching, which required short-term memory of one's own and of others’ actions. Human short-term memory has been most extensively tested of all social mammal species, hence providing an informative benchmark for the ravens. A recent study on another corvid species (Corvus corone) suggests their capacity to be similar to the humans’, but short-term memory skills have, to date, not been compared in a social setting. We used spatial setups based on caches of foods or objects, divided into individual and social conditions with two different spatial arrangements of caches (in a row or a 3 × 3 matrix). In each trial, a set of three up to nine caches was presented to an individual that was thereafter allowed to retrieve all items. Humans performed better on average across trials, but their performance dropped, when they had to keep track of partner's actions. This differed in ravens, as keeping track of such actions did not impair their performance. However, both humans and ravens demonstrated more memory-related mistakes in the social than in the individual conditions. Therefore, whereas both the ravens’ and the humans’ memory suffered in the social conditions, the ravens seemed to deal better with the demands of these conditions. The social conditions had a competitive element, and one might speculate that ravens’ memory strategies are more attuned to such situations, in particular in caching contexts, than is the case for humans.     

The Shifting of Ecological Restoration Benchmarks and Their Social Impacts: Digging Deeper into Pleistocene Re‐wilding

Current and projected rates of species loss prompt us to look for innovative conservation efforts. One such proposal is that large areas of North America be re‐wilded with old world species that descended from Pleistocene mega‐fauna. We argue that this approach overlooks many important ecological, evolutionary, cultural, and economic issues and detracts from conservation efforts by adding another arbitrary restoration benchmark. Our objectives are to specifically address the shifting benchmark for ecological restoration, explore the social dimensions of Pleistocene re‐wilding, which have been largely overlooked, and discuss why we think Pleistocene re‐wilding is not a proactive approach for conservation. This is not intended as a critique of innovative approaches. Instead it is an argument that human and ecological factors need to be considered in depth before any restoration initiative can be practically implemented. Proactive approaches should consider historical conditions while managing based on the present, should plan for the future, and should allow adaptation to changing conditions. We support the strategy to restore ecological interactions using species that coevolved with these interactions, bearing in mind the complexities of the socio‐ecological dimensions of any management action.     

From Metaphor to Measurement: Resilience of What to What?

Resilience is the magnitude of disturbance that can be tolerated before a socioecological system (SES) moves to a different region of state space controlled by a different set of processes. Resilience has multiple levels of meaning: as a metaphor related to sustainability, as a property of dynamic models, and as a measurable quantity that can be assessed in field studies of SES. The operational indicators of resilience have, however, received little attention in the literature. To assess a system's resilience, one must specify which system configuration and which disturbances are of interest. This paper compares resilience properties in two contrasting SES, lake districts and rangelands, with respect to the following three general features: (a) The ability of an SES to stay in the domain of attraction is related to slowly changing variables, or slowly changing disturbance regimes, which control the boundaries of the domain of attraction or the frequency of events that could push the system across the boundaries. Examples are soil phosphorus content in lake districts woody vegetation cover in rangelands, and property rights systems that affect land use in both lake districts and rangelands. (b) The ability of an SES to self-organize is related to the extent to which reorganization is endogenous rather than forced by external drivers. Self-organization is enhanced by coevolved ecosystem components and the presence of social networks that facilitate innovative problem solving. (c) The adaptive capacity of an SES is related to the existence of mechanisms for the evolution of novelty or learning. Examples include biodiversity at multiple scales and the existence of institutions that facilitate experimentation, discovery, and innovation. Received 20 March 2001; accepted 6 June 2001.     

The influence of sociality on the conservation biology of social insects

Social insects (ants, bees, wasps and termites) as a group are species rich and ecologically dominant. Many are outstanding "ecological engineers", or providers of "ecosystem services", or potential bioindicator species. Few social insects are currently formally classified as Threatened, but this is almost certainly due to a lack of information on population sizes and trends in scarce species. The main influence that sociality has on threats faced by social insects is in reducing effective population sizes, increasing population genetic subdivision and possibly reducing levels of genetic variation relative to solitary species. The main influence that sociality has on threats from social insects is via its role in the ecological success of invasive species, which frequently pose a major hazard to native biotas. In some cases, social features underpinning ecological success in the original range almost certainly contribute to the success of invasive social insects. However, recent studies show or strongly suggest that, in some of the most notoriously invasive populations of ants, bees and wasps, novel social traits have arisen that greatly enhance the rate of spread and ecological competitiveness of these populations. Sociality can therefore represent either a liability or an asset in its contribution to the persistence of social insect populations.     

How Attention Can Create Synaptic Tags for the Learning of Working Memories in Sequential Tasks

Intelligence is our ability to learn appropriate responses to new stimuli and situations. Neurons in association cortex are thought to be essential for this ability. During learning these neurons become tuned to relevant features and start to represent them with persistent activity during memory delays. This learning process is not well understood. Here we develop a biologically plausible learning scheme that explains how trial-and-error learning induces neuronal selectivity and working memory representations for task-relevant information. We propose that the response selection stage sends attentional feedback signals to earlier processing levels, forming synaptic tags at those connections responsible for the stimulus-response mapping. Globally released neuromodulators then interact with tagged synapses to determine their plasticity. The resulting learning rule endows neural networks with the capacity to create new working memory representations of task relevant information as persistent activity. It is remarkably generic: it explains how association neurons learn to store task-relevant information for linear as well as non-linear stimulus-response mappings, how they become tuned to category boundaries or analog variables, depending on the task demands, and how they learn to integrate probabilistic evidence for perceptual decisions.     

Climate change threatens protected areas of the Atlantic Forest

Only 7 % of the Atlantic Forest Biodiversity Hotspot is currently protected, though it holds 18 % of all amphibian species in South America. How effective would the Atlantic Forest network of protected areas (PAs) be in a changing climate? Are there some intrinsic features of PAs that drive species loss or gain inside them? We addressed these questions by modeling the ecological niches of 430 amphibian species in the Atlantic Forest and projecting their distributions into three future climate change simulations. We then assessed changes in species richness inside PAs for different time frames and tested their significance via null model. The number of species should decline within Atlantic Forest network of PAs under changing climate conditions. Only altitude was a good predictor of species gains or lost inside PAs. Therefore, we suggest that new PAs established in highlands would be more effective to alleviate the effects of climate change on this imperiled fauna.     

Building time-budgets from bioacoustic signals to measure population-level changes in behavior: a case study with sperm whales in the Gulf of Mexico

Evaluating changes in the collective behavior of a population can be an indirect method for inferring organismal responses to changing environmental conditions. Apex predators, such as the sperm whale (Physeter macrocephalus), can provide valuable insights into the ecosystem processes of the deep sea, where little direct observation can be made. Sperm whales are often difficult to observe at sea, as they inhabit deep, offshore waters and spend most of their lives beneath the surface. However, sperm whales are extremely amenable to passive acoustic monitoring, as their vocalizations are well-studied, highly distinguishable, produced regularly, and can be detected at relatively long ranges (>10 km). Sperm whales produce distinct clicks in two behavioral contexts (social interaction or foraging/prey capture); thus, we can use acoustic detection of these vocalizations to infer patterns of large-scale, collective behavior, which is similar to studying calling frogs or insects indicating their reproductive phenology. We recorded behaviorally-specific sperm whale vocalizations at three sites in the Northern Gulf of Mexico in July 2010 and 2011. We used these recordings to construct population-level time budgets, an empirical collective metric of behavior, based on the ratio of hours in a day with social clicks to the hours in a day with foraging clicks, and represented this as an “acoustic activity index.” Our index showed significant differences in the proportions of social and foraging behavior across the range of sperm whales in the Northern Gulf of Mexico, and the proportion of social activity increased by more than a factor of two from 2010 to 2011. These differences support previous evidence of differential habitat use by sperm whales in the Gulf of Mexico, and suggest possible changes in environmental conditions between years. Thus, the acoustic activity index may provide a powerful way to evaluate changes in behavior and link them to changing ecological conditions. This novel application of bioacoustics to constructing time budgets and creating a behaviorally-based index at the population scale can serve as an indicator of ecological change, and greatly enhance our ability to understand the behavior and ecology of many acoustically active species.     

Eradication revisited: dealing with exotic species

Invasions of nonindigenous species threaten native biodiversity, ecosystem functioning, animal and plant health, and human economies. The best solution is to prevent the introduction of exotic organisms but, once introduced, eradication might be feasible. The potential ecological and social ramifications of eradication projects make them controversial; however, these programs provide unique opportunities for experimental ecological studies. Deciding whether to attempt eradication is not simple and alternative approaches might be preferable in some situations.     

Small world patterns in food webs

The analysis of some species-rich, well-defined food webs shows that they display the so-called small world behavior shared by a number of disparate complex systems. The three systems analysed (Ythan estuary web, Silwood web and the Little Rock lake web) have different levels of taxonomic resolution, but all of them involve high clustering and short path lengths (near two degrees of separation) between species. Additionally, the distribution of connections P(k) which is skewed in all the webs analysed shows long tails indicative of power-law scaling. These features suggest that communities might be self-organized in a non-random fashion that might have important consequences in their resistance to perturbations (such as species removal). The consequences for ecological theory are outlined.     

Short-term depression and transient memory in sensory cortex

Persistent neuronal activity is usually studied in the context of short-term memory localized in central cortical areas. Recent studies show that early sensory areas also can have persistent representations of stimuli which emerge quickly (over tens of milliseconds) and decay slowly (over seconds). Traditional positive feedback models cannot explain sensory persistence for at least two reasons: (i) They show attractor dynamics, with transient perturbations resulting in a quasi-permanent change of system state, whereas sensory systems return to the original state after a transient. (ii) As we show, those positive feedback models which decay to baseline lose their persistence when their recurrent connections are subject to short-term depression, a common property of excitatory connections in early sensory areas. Dual time constant network behavior has also been implemented by nonlinear afferents producing a large transient input followed by much smaller steady state input. We show that such networks require unphysiologically large onset transients to produce the rise and decay observed in sensory areas. Our study explores how memory and persistence can be implemented in another model class, derivative feedback networks. We show that these networks can operate with two vastly different time courses, changing their state quickly when new information is coming in but retaining it for a long time, and that these capabilities are robust to short-term depression. Specifically, derivative feedback networks with short-term depression that acts differentially on positive and negative feedback projections are capable of dynamically changing their time constant, thus allowing fast onset and slow decay of responses without requiring unrealistically large input transients.     

Integrating ecological and cultural values toward conservation and utilization of shrine/temple forests as urban green space in Japanese cities

In Japan, forests associated with shrines and temples are recognized as important components of urban green space, which can potentially function as centers for ecosystem conservation in rapidly urbanizing Japanese cities. In addition to their ecological value, shrine/temple forests have social value, providing recreational and aesthetic needs to residents of urban areas. We review the historical development of shrine/temple forests in Japan and discuss current conservation issues from both ecological and sociological perspectives. Generally, shrine forests are minimally managed and public access is discouraged, whereas temple forests are intensively managed for public display. Shrines tend to be spatially scattered across the landscape but associated with specific geographical features, whereas temples tend to be clustered. Their wide and random distribution in urban areas suggests that shrine forests can potentially be used as stepping stones in the urban green space network, whereas spatially clustered temple forests can be integrated to form large areas of green space. Species diversity of shrine/temple forests declines with decreasing area. The distribution pattern of species is not completely nested, indicating that although conservation of large forest fragments may be effective for maintaining landscape-level biodiversity, smaller forest fragments and adjacent precincts are sometimes significant because rare species occasionally inhabit them. Active management and ecological restoration, such as removal of invasive species, are also important to maintain the desirable near-natural forest conditions. A working group including the owner, community, regional government, and ecologists should be involved in creating an effective, long-term management plan. Because social and cultural values are diverse, basic ecological studies of shrine/temple forests would contribute a scientific basis that fosters public confidence in the process.     

Ecological aspect in the systematics of fungi

The main morphological features of fungi representing different evolutionary lines are discussed.Environmental situations which stimulate morphological changes are regarded.It is suggested to define ecological significance of fungal morphological characters,dividing them to the ecologically inert(the main characters determining evolutionary line) and ecologically active-characters which submerged to the changes with the changing of environmental conditions.Two main strategies for fungi in nature are described:raising competitive ability to win conquer for substratum,for the place in ecosystem,and the second way for less competitive species-to adapt to more stressful natural conditions and to occupy ecological niches becoming free.Some examples of analysis of adaptation to substrata and climatic zones by fungi are shown.     

The phylogenetic interpretation of biological surveys

The ecological attributes of two species may be similar through convergent evolution or common ancestry. The extent of similarity by descent can be evaluated by comparing them with their most closely‐related outgroup in a given phylogeny. I describe a method of nested sister‐group analysis for estimating ecological similarity based on landscape features or on co‐distribution. The phylogeny is dissected into triplets, each comprising two sister taxa and their outgroup. For a triplet at any phylogenetic level, the similarity of sister groups with respect to some given character can be compared with their joint similarity to the outgroup to give a single test of similarity by descent. Each comparison is independent, and the full set of triplets provides a complete accounting of phylogenetic variation at all levels. This procedure was applied to 188 moderately abundant species of dicots in two independent surveys from adjoining districts of midland England, supplemented by physical surveys of landscape attributes obtained from digitized maps of the same districts. The co‐distribution of sister species was consistently more positive than the co‐distribution of random species pairs, demonstrating the existence of a phylogenetic signal at some level. When sister species are compared with their most closely‐related outgroup, however, neither landscape attributes nor co‐distribution showed any overall similarity arising from common ancestry, in the sense that ecological attributes are not generally conserved after lineage splitting. Instead, the distribution of similarity is strikingly similar to random data. The lack of ecological similarity between closely‐related groups was attributed to rapid character change at or shortly after the splitting of lineages, coupled with a lack of correlation between successive lineage splits.     

Flexible and conservative features of social systems in tufted capuchin monkeys: comparing the socioecology of Sapajus libidinosus and Sapajus nigritus

Socioecological models assume that primates adapt their social behavior to ecological conditions, and predict that food availability and distribution, predation risk and risk of infanticide by males affect patterns of social organization, social structure and mating system of primates. However, adaptability and variation of social behavior may be constrained by conservative adaptations and by phylogenetic inertia. The comparative study of closely related species can help to identify the relative contribution of ecological and of genetic determinants to primate social systems. We compared ecological features and social behavior of two species of the genus Sapajus, S. nigritus in Carlos Botelho State Park, an area of Atlantic Forest in S?o Paulo state, and S. libidinosus in Fazenda Boa Vista, a semi-arid habitat in Piauí state, Brazil. S. libidinosus perceived higher predation risk and fed on clumped, high quality, and usurpable resources (fruits) all year round, whereas S. nigritus perceived lower predation risk and relied on evenly distributed, low-quality food sources (leaves) during periods of fruit shortage. As predicted by socioecology models, S. libidinosus females were philopatric and established linear and stable dominance hierarchies, coalitions, and grooming relationships. S. nigritus females competed less often, and could transfer between groups, which might explain the lack of coalitions and grooming bonds among them. Both populations presented similar group size and composition and the same polygynous mating system. The species differed from each other in accordance with differences in the characteristics of their main food sources, as predicted by socioecological models, suggesting that phylogenetic inertia does not constrain social relationships established among female Sapajus. The similarity in mating systems indicates that this element of the social system is not affected by ecological variables and thus, is a more conservative behavioral feature of the genus Sapajus.     

Going Beyond a Mean-field Model for the Learning Cortex: Second-Order Statistics

Mean-field models of the cortex have been used successfully to interpret the origin of features on the electroencephalogram under situations such as sleep, anesthesia, and seizures. In a mean-field scheme, dynamic changes in synaptic weights can be considered through fluctuation-based Hebbian learning rules. However, because such implementations deal with population-averaged properties, they are not well suited to memory and learning applications where individual synaptic weights can be important. We demonstrate that, through an extended system of equations, the mean-field models can be developed further to look at higher-order statistics, in particular, the distribution of synaptic weights within a cortical column. This allows us to make some general conclusions on memory through a mean-field scheme. Specifically, we expect large changes in the standard deviation of the distribution of synaptic weights when fluctuation in the mean soma potentials are large, such as during the transitions between the “up” and “down” states of slow-wave sleep. Moreover, a cortex that has low structure in its neuronal connections is most likely to decrease its standard deviation in the weights of excitatory to excitatory synapses, relative to the square of the mean, whereas a cortex with strongly patterned connections is most likely to increase this measure. This suggests that fluctuations are used to condense the coding of strong (presumably useful) memories into fewer, but dynamic, neuron connections, while at the same time removing weaker (less useful) memories.