Ecological Contingencies Research Articles

A theory for context-dependent effects of mammalian trampling on ecosystem nitrogen cycling.

Large mammalian herbivores substantially impact ecosystem functioning. As their populations are dramatically altered globally, disentangling their consumptive and non-consumptive effects is critical to advance mechanistic understanding and improve prediction of effects over ecosystem and Earth-system spatial extents. Mathematical models have played an important role in clarifying potential mechanisms of herbivore zoogeochemistry, based mostly on their consumptive effects as primary consumers and recyclers of organic and inorganic matter via defecation and urination. Trampling is a ubiquitous effect among walking vertebrates, but the consequences and potential mechanisms of trampling in diverse environments remain poorly understood. We derive a novel mathematical model of large mammalian herbivore effects on ecosystem nitrogen cycling, focusing on how trampling and environmental context impact soil processes. We model herbivore trampling with a linear positive or negative additive effect on soil-mediated nitrogen cycling processes. Combining analytical and numerical analyses, we find trampling by large mammalian herbivores is likely to decrease nitrogen mineralisation rate across diverse environments, such as temperate grassland and boreal forest. These effects are mediated by multiple potential mechanisms, including trampling-induced changes to detritivore biomass and functioning (e.g. rate of organic matter consumption). We also uncover scenarios where trampling can increase nitrogen mineralisation rate, contingent on the environment-specific relative sensitivity of detritivore mineral-nitrogen release and detritivore mortality, to trampling. In contrast to some consumptive mechanisms, our results suggest the pace of soil nitrogen cycling prior to trampling has little influence over the direction of the trampling net effect on nitrogen mineralisation, but that net effects may be greater in slow-cycling systems (e.g. boreal forests) than in fast-cycling systems (e.g. grasslands). Our model clarifies the potential consequences of previously overlooked mechanisms of zoogeochemistry that are common to all terrestrial biomes. Our results provide empirically testable predictions to guide future progress in empirical and theoretical studies of herbivore effects in diverse environmental contexts. Resolving ecological contingencies around animal consumptive and non-consumptive effects will improve whole-ecosystem management efforts such as restoration and rewilding.

Beyond spatial overlap: harnessing new technologies to resolve the complexities of predator–prey interactions

Predation risk, the probability that a prey animal will be killed by a predator, is fundamental to theoretical and applied ecology. Predation risk varies with animal behavior and environmental conditions, yet attempts to understand predation risk in natural systems often ignore important ecological and environmental complexities, relying instead on proxies for actual risk such as predator–prey spatial overlap. Here we detail the ecological and environmental complexities driving disconnects between three stages of the predation sequence that are often assumed to be tightly linked: spatial overlap, encounters and prey capture. Our review highlights several major sources of variability in natural predator–prey systems that lead to the decoupling of spatial overlap estimates from actual encounter rates (e.g. temporal activity patterns, predator and prey movement capacity, resource limitations) and that affect the probability of prey capture given encounter (e.g. predator hunger levels, temporal, topographic and other environmental influences on capture success). Emerging technologies and statistical methods are facilitating a transition to a more spatiotemporally detailed, mechanistic understanding of predator–prey interactions, allowing for the concurrent examination of multiple stages of the predation sequence in mobile, free‐ranging animals. We describe crucial applications of this new understanding to fundamental and applied ecology, highlighting opportunities to better integrate ecological contingencies into dynamic predator–prey models and to harness a mechanistic understanding of predator–prey interactions to improve targeting and effectiveness of conservation interventions.

Ecological trade‐offs in development and defence in a specialist moth when feeding on four congeneric host plants

AbstractHerbivore diet breadth has been hypothesised to be driven by plant quality (physiological efficiency hypothesis) or natural enemies (enemy‐free space hypothesis). These hypotheses on their own are now known to be insufficient explanations for the range of herbivore diet breadths and more integrative approaches consider how trade‐offs and ecological contingencies shape host plant use by herbivores. I carried out laboratory experiments to test whether physiological efficiency and defence against natural enemies trade off when larvae of the ornate bella moth, Utetheisa ornatrix (L.) (Lepidoptera: Erebidae), a genus‐specialist pod‐boring herbivore, feeds on leaves and pods of four Crotalaria species (Fabaceae). Different components of U. ornatrix physiological efficiency traded off amongst each other and with defence against adult predation by the spider Lycosa erythrognatha Lucas (Araneae: Lycosidae). Crotalaria micans Link provided the highest survival and fast development but low pupal weight and defence. Crotalaria ochroleuca G. Don provided poor survival, slow development, and low defence, but high pupal weight. Crotalaria pallida Aiton provided slow development and intermediate survival and pupal weight, but the best defence. Crotalaria vitellina Ker Gawl. provided high survival, fast development, and efficient defence, but low pupal weight. Compared to leaves, feeding on green seeds provided greater defence against predation, and developmental benefits, independent of host plant species, but there was a large cost in boring into the pod to reach the seeds. I therefore provide evidence that the trade‐offs among physiological efficiency components and between physiological efficiency and defence could maintain multiple host plant use in specialist herbivores. I also show that feeding on green seeds incurs a cost through pod‐boring but gives the moth benefits in adult defence. Therefore, the evolution of host plant use and pod‐boring in insect herbivores could be driven by defence as much as by physiological efficiency.

"These Jests of God": Arrowsmith and Tropical Medicine's Racial Ecology.

This essay explores Sinclair Lewis's Arrowsmith (1925) through the medical-ethical and ecological contingencies of U.S. tropical medicine during the early twentieth century. With an eye kept on the novel's well-known "St. Hubert " chapters, the essay queries the dangerous compromises that even the most well-intentioned medical professionals have made and can make in the name of scientific progress. The novel, I argue, organizes around and yet moves beyond the traditional outbreak narrative to unravel the various political, economic, and cultural strands of U.S. imperial medicine. The novel's platform for applied sanitary science helps me revisit famed public health campaigns, particularly those from Cuba and Panama, and draw out new ways of understanding race and place in the context of global health intervention.

Invasive Phragmites australis management outcomes and native plant recovery are context dependent.

The outcomes of invasive plant removal efforts are influenced by management decisions, but are also contingent on the uncontrolled spatial and temporal context of management areas. Phragmites australis is an aggressive invader that is intensively managed in wetlands across North America. Treatment options have been understudied, and the ecological contingencies of management outcomes are poorly understood. We implemented a 5‐year, multi‐site experiment to evaluate six Phragmites management treatments that varied timing (summer or fall) and types of herbicide (glyphosate or imazapyr) along with mowing, plus a nonherbicide solarization treatment. We evaluated treatments for their influence on Phragmites and native plant cover and Phragmites inflorescence production. We assessed plant community trajectories and outcomes in the context of environmental factors. The summer mow, fall glyphosate spray treatment resulted in low Phragmites cover, high inflorescence reduction, and provided the best conditions for native plant recruitment. However, returning plant communities did not resemble reference sites, which were dominated by ecologically important perennial graminoids. Native plant recovery following initial Phragmites treatments was likely limited by the dense litter that resulted from mowing. After 5 years, Phragmites mortality and native plant recovery were highly variable across sites as driven by hydrology. Plots with higher soil moisture had greater reduction in Phragmites cover and more robust recruitment of natives compared with low moisture plots. This moisture effect may limit management options in semiarid regions vulnerable to water scarcity. We demonstrate the importance of replicating invasive species management experiments across sites so the contingencies of successes and failures can be better understood.

The Great Divergence Reconsidered: Or, Is it Time to Reconsider the Great Divergence Debate?

Twenty years ago, Kenneth Pomeranz’s The Great Divergence (2000) reshaped debates over the historical causes of Europe’s rapid nineteenthcentury industrialization and economic growth. By comparing the Yangzi Delta region of China to Britain, Pomeranz asserted that Europe was not exceptionally dynamic before the nineteenth century and that its divergence from Asia owed to colonial exploitation of the Americas and ecological contingencies, namely abundant coal deposits. Some recent studies have sought to refute or refine Pomeranz’s thesis using the Indian subcontinent as an historical case study. This essay reviews three of these works and, in doing so, demonstrates current methodological limitations of this debate. Specifically, recent scholarship, although seeking to critique Pomeranz, employs his two-way comparative methodology, but in a manner that operates within a Eurocentric teleology and takes the European historical experience as normative. Instead, I propose that scholars inquire after the historical connections among societies’ plural-yet-connected historical trajectories.

High-Throughput Sequencing for Understanding the Ecology of Emerging Infectious Diseases at the Wildlife-Human Interface

Rising rates of emerging infectious diseases (EIDs) demand creative, efficient, and integrative investigations to understand their transmission, ecological contingencies, and dynamics at wildlife-human interfaces. High-throughput sequencing (HTS) methodologies provide enormous potential to unravel these contingencies to improve our understanding, but their potential is only just starting to be realized. While recent work has largely focused on novel pathogen discovery at likely interfaces, high-throughput methods can also allow disease ecologists to better explore the critical effects of climate, seasonality, and land-use changes on EIDs. HTS can facilitate the creation of entire host-pathogen networks, integrate important microbiome and co-infection data, and even pinpoint important exposure routes at interfaces through environmental media. Here we highlight studies at the frontier of HTS and disease ecology research, identify current limitations, and outline promising future applications for EIDs.

Planificación y transformaciones urbanas de época augustea en Carthago Nova

The configuration of the urban sites has been setting of social, economic and ideological processes through the time, pertaining to the population entities willing to settle in the occupied site. The administrative planning of urban sectors involved in public or private uses was materialized in the necessary enablement of private or residential areas and public craft or industrial commercial and burial areas. The site of Carthago Nova was not exempt from this in its preRoman and Roman occupations. Its political and temporal progression showed a series of transformations of the urban fabric that were not unconnected to the topographic constraints of the primal physical environment and holocenic ecological contingencies. Bringing out the conjunction of this singular palaeotopography, which has a geomorphological dynamic and a geotectonic origin, with the evidence of significant transformations in Augustan period, is the focus of this work, in which data are shown from an ongoing research.

Revisiting Mediation in the Social and Behavioral Sciences

The process of mediation is of critical importance to the social and behavioral sciences and to evolutionary social psychology in particular. As with the concept of evolutionary adaptation, however, one can argue that causal mediation is in need of explicit theoretical justification and empirical support. Mainstream evolutionary social psychology proposes, for example, that organisms are “adaptation executers”, and not “fitness maximizers”. The execution of adaptations is triggered by fitness-relevant ecological contingencies at both ultimate and proximate levels of analysis. This logic is essentially equivalent to what methodologists refer to as the process of mediation; the adaptations to be executed (or not, depending upon the prevailing environmental circumstances) causally mediate the effects of the ecological contingencies upon the fitness outcomes. Thus, the process of mediation can be generally conceptualized as a causal chain of events leading to a given outcome or set of outcomes. If a predictor variable operates through an intervening variable to affect a criterion variable, then mediation is said to exist. Nevertheless, it does not appear that some psychologists (particularly evolutionary-social psychologists) are sufficiently well-versed in the fundamental logic and quantitative methodology of establishing causal mediation to support such claims. In the current paper, we set out to review the ways researchers support their use of mediation statements and also propose critical considerations on this front. We start with more conventional methods for testing mediation, discuss variants of the conventional approach, discuss the limitations of such methods as we see them, and end with our preferred mediation approach. DOI:10.2458/azu_jmmss_v04i1_figueredo3

Revisiting Mediation in the Social and Behavioral Sciences

The process of mediation is of critical importance to the social and behavioral sciences and to evolutionary social psychology in particular. As with the concept of evolutionary adaptation, however, one can argue that causal mediation is in need of explicit theoretical justification and empirical support. Mainstream evolutionary social psychology proposes, for example, that organisms are “adaptation executers”, and not “fitness maximizers”. The execution of adaptations is triggered by fitness-relevant ecological contingencies at both ultimate and proximate levels of analysis. This logic is essentially equivalent to what methodologists refer to as the process of mediation; the adaptations to be executed (or not, depending upon the prevailing environmental circumstances) causally mediate the effects of the ecological contingencies upon the fitness outcomes. Thus, the process of mediation can be generally conceptualized as a causal chain of events leading to a given outcome or set of outcomes. If a predictor variable operates through an intervening variable to affect a criterion variable, then mediation is said to exist. Nevertheless, it does not appear that some psychologists (particularly evolutionary-social psychologists) are sufficiently well-versed in the fundamental logic and quantitative methodology of establishing causal mediation to support such claims. In the current paper, we set out to review the ways researchers support their use of mediation statements and also propose critical considerations on this front. We start with more conventional methods for testing mediation, discuss variants of the conventional approach, discuss the limitations of such methods as we see them, and end with our preferred mediation approach. DOI:10.2458/azu_jmmss_v04i1_figueredo3

Revisiting Mediation in the Social and Behavioral Sciences

The process of mediation is of critical importance to the social and behavioral sciences and to evolutionary social psychology in particular. As with the concept of evolutionary adaptation, however, one can argue that causal mediation is in need of explicit theoretical justification and empirical support. Mainstream evolutionary social psychology proposes, for example, that organisms are “adaptation executers”, and not “fitness maximizers”. The execution of adaptations is triggered by fitness-relevant ecological contingencies at both ultimate and proximate levels of analysis. This logic is essentially equivalent to what methodologists refer to as the process of mediation; the adaptations to be executed (or not, depending upon the prevailing environmental circumstances) causally mediate the effects of the ecological contingencies upon the fitness outcomes. Thus, the process of mediation can be generally conceptualized as a causal chain of events leading to a given outcome or set of outcomes. If a predictor variable operates through an intervening variable to affect a criterion variable, then mediation is said to exist. Nevertheless, it does not appear that some psychologists (particularly evolutionary-social psychologists) are sufficiently well-versed in the fundamental logic and quantitative methodology of establishing causal mediation to support such claims. In the current paper, we set out to review the ways researchers support their use of mediation statements and also propose critical considerations on this front. We start with more conventional methods for testing mediation, discuss variants of the conventional approach, discuss the limitations of such methods as we see them, and end with our preferred mediation approach.

Do plant–plant signals mediate herbivory consistently in multiple taxa and ecological contexts?

It is becoming increasingly accepted that plant–plant signals can affect plant defense against herbivores. In a few taxa, both the mechanisms of plant–plant signaling and the ecological consequences are well described. However, the current adaptive explanations for plant–plant signaling rely heavily on many ecological contingencies, such as the behavior of herbivores and genetic structure of plant neighborhoods, making it unclear how frequently plant–plant signaling is important across the plant kingdom. Moreover, these same ecological contingencies mean that it may be beneficial for a plant to release a publicly available cue to coordinate its (or its neighbor's) defenses following herbivory in some cases, but it may be disadvantageous in others. In this paper, we focus on recent studies that expand the taxonomic breadth of plant–plant signaling about herbivores that bring classic plant–plant signaling systems into a broader ecological context, and those that find either no consequence or counterintuitive consequences of plant–plant signaling. There is currently a need to explore plant–plant signaling in taxonomically diverse plants and in various ecological settings.

Spatial distribution of nests constrains the strength of sexual selection in a warbler

In socially monogamous species, extra-pair paternity may increase the strength of intersexual selection by allowing males with preferred phenotypes to monopolize matings. Several studies have found relationships between male signals and extra-pair mating, but many others fail to explain variation in extra-pair mating success. A greater appreciation for the role that ecological contingencies play in structuring behavioural processes may help to reconcile contradictory results. We studied extra-pair mating in a spatial context in the common yellowthroat (Geothlypis trichas), a territorial wood warbler. Over the course of 6 years, we observed 158 breeding attempts by 99 males, resulting in a total of 369 nests and 520 sampled nestlings. The spatial distribution of territories varied greatly, with males having between 0 and 10 close neighbours and between three and 39 neighbouring nestlings close enough to represent extra-pair siring opportunities. Both within-pair and extra-pair reproductive success increased with breeding density, but the opportunity for sexual selection and strength of selection varied with density. Total variance in reproductive success was highest at low density and was mostly explained by variation in within-pair success. In contrast, at high density, both within-pair and extra-pair successes contributed substantially to variance in reproductive success. The relationships between plumage and extra-pair mating also varied by density; plumage was under strong sexual selection via extra-pair mating success at high density, but no selection was detected at low density. Thus, ecological factors that structure social interactions can drive patterns of sexual selection by facilitating or constraining the expression of mating preferences.

Ecological contingencies in women's calorie regulation psychology: A life history approach

We used insights from life history theory and the critical fat hypothesis to explore how environmental harshness influences women's food and weight regulation psychology. As predicted by our theoretical model, women who grew up in poorer, more unpredictable environments responded to harshness cues in their adult environments by exhibiting a greater desire for food (Studies 1 and 2) and a diminished concern with calorie restriction and weight loss (Study 3). In sharp contrast, women who grew up in more predictable, wealthier environments responded to these cues by exhibiting a diminished desire for food and increased concern with calorie restriction and weight loss. This research provides novel insights into the role that local environmental factors play in women's food and weight regulation psychology.

Aproximación arqueológica al estudio de los paisajes aterrazados en el área central valenciana

A pesar de la importancia de las terrazas agrícolas en la configuración actual del paisaje valenciano, su estudio arqueológico ha sido prácticamente desatendido. Con el objetivo de entender la profundidad histórica de estos parcelarios de montaña, en el siguiente artículo se realiza una revisión de las evidencias arqueológicas de terrazas residenciales y agrícolas en el área central de valenciana desde la prehistoria hasta época romana. Estas evidencias se ponen en relación con paisajes aterrazados de otros ámbitos geográficos con la finalidad de entender las contingencias ecológicas y socio-históricas que condujeron a la construcción de estos paisajes antropogénicos.

Separate but interlocking accounts of the behavior of both speaker and listener: When the listener speaks is there more to listening then just listening?

The very fact that behavior analysts have so carefully analyzed the speaker in terms of maintaining variables, but disregard the listener's behavior as broadly receptive unless the listener vocalizes (then applying the operants of the speaker until the listener, stops vocalizing) seems to be missing the point of Skinner's original analysis in the first place. This paper seeks to point out the need for greater research and development in the area of listener responding, including when the listener vocalizes and take the current analysis of verbal behavior beyond the broad category of receptive behavior to a place where we can scientifically separate the many non-vocative and vocative responses of the listener allowing behavior analysts to have a greater ability to accurately analyze the total verbal discourse. INTRODUCTION Our interest in the listener is not; however, merely an interest in what happens to the verbal stimuli created by the speaker. In a complete account of a verbal episode we need to show that the behavior of the listener does in fact provide the conditions we have assumed in explaining the behavior of the speaker. We need separate but interlocking accounts of the behaviors of both speaker and listener if our explanation of verbal behavior is to be complete. In explaining the behavior of the speaker we assume a listener who will reinforce his behavior in certain ways. In accounting for the behavior of the listener we assume a speaker whose behavior bears a certain relation to environmental conditions. The interchanges between them must explain all the conditions thus assumed. The account of the whole episode is then complete. (Skinner, p.34, 1957) Skinner (1957) notes that we must examine both the speaker and listener for two separate yet interlocking accounts of the behavior produced in the exchanges between them. In his treatment of verbal behavior he asserts that one cannot properly elucidate the functions for the responding of speaker without taking into account the responding of the listener and the ecological contingencies in which the behavior is emitted. In Skinner's text he further attempts to delineate verbal behavior in such a way as too remove the need for mentalistic terms such as intention and meaning to explain the cause of verbal behavior. What he left us with is a framework upon which behavior analysts can begin to discover more about the various operants at work in verbal behavior without explaining why it occurs, but instead how it comes about. child acquires verbal behavior when relatively unpatterned vocalizations, selectively reinforced, gradually assume forms which produce appropriate consequences in a given verbal community. In formulating this process we do not need to mention stimuli occurring prior to the behavior to be reinforced. It is difficult, if not impossible, to discover stimuli which evoke specific vocal responses in the young child. There is no stimulus which makes a child say B or A or E, as one may make him salivate by placing a lemon drop in his mouth.... (Skinner, p.31, 1957) Practitioners, who are involved in curriculum development for children of specialty populations, are increasingly becoming aware that training curriculums need to foster a child's growth and development past basic commenting and requesting. This article explores the area of complex verbal operant such as the building of autoclitic frames, self-generation of rules, self-editing and the corresponding development of listener behavior. It is hoped that the curriculums suggested by these comprehensive theoretical components begin to undergo field testing, efficacy, and effectiveness research, and finally find there way into curriculums for children with speech and language delays, developmental disabilities, children with attention difficulty, and oppositional behavior. BEHAVIOR ANALYSIS AND THE SPEAKER Skinner (1957) laid out a functional model of speaker behavior. …

Traumatic Stress, Ecological Contingency, and Sexual Behavior: Antecedents and Effects of Sexual Precociousness. Sexual Mobility, and Adolescent Childbearing in Antigua

Previous studies try to account for variance in adolescent sexual precociousness, sexual mobility, and childbearing by reference either to sociological risk factors (e.g., poverty, social class, opportunitiesjbr sexual activity, or the absence of constraints on sexual activity) or to an evolved, domain‐specific cognitive mechanism. However, these forms of behavioral variation may reflect an evolved mental mechanism that creates behavioral plasticity and adaptability by assigning emotional weights to choice alternatives in all behavioral domains. Because it should act as a selective mechanismfor choice alternatives, this emotional mechanism should create enhanced ability to avoid predation (social exploitation) and to obtain access to resources, given the properties of specific environments. Sexual precociousness, sexual mobility, and childbearing thus should be determined by ecological contingencies that bear on how girls may best empower themselves. The findings of the present study support this ecological contingency hypothesis and show no effect for sociological and evolutionary psychology predictors. What we now characterize stress‐induced morbidity thus may consist of adaptive responses to environments in which children find themselves subject to predation and denial of access to resources.

Ecological considerations support color physicalism

AbstractWe argue that any theory of color physicalism must include consideration of ecological interactions. Ecological and sensorimotor contingencies resulting from relative surface motion and observer motion give rise to measurable effects on the spectrum of light reflecting from surfaces. These contingencies define invariant manifolds in a sensory-spatial space, which is the physical underpinning of all subjective color experiences.

An Evolutionary Ecological Approach to the Study of Learning Behavior Using a Robot-Based Model

We are interested in the construction of ecological models of the evolution of learning behavior using methodological tools developed in the field of evolutionary robotics. In this article, we explore the applicability of integrated (i.e., nonmodular) neural networks with fixed connection weights and simple 'leaky-integrator' neurons as controllers for autonomous learning robots. In contrast to Yamauchi and Beer (1994a), we show that such a control system is capable of integrating reactive and learned behaviour without explicitly needing hand-designed modules, dedicated to a particular behavior, or an externally introduced reinforcement signal. In our model, evolutionary and ecological contingencies structure the controller and the behavioral responses of the robot. This allows us to concentrate on examining the conditions under which learning behavior evolves.

Ontogeny of Vocalization in the Greater Rhea

Abstract The call-notes of the Greater Rhea chick were classified according to their acoustical structure and behavioral context. Both rate of vocalization and tonal quality of call-notes were found to deteriorate as a function function of maturation. Call-note production was completely eliminated by 7 weeks of age. Greater Rhea adults are silent except for such relatively infrequent vocalizations as "hissing" that sometimes accompanies agonistic behavior and a disyllabic "grunt" that only the male produces as part of a courtship display. Tracheal growth and a marked reduction in the intrusion of the internal tympanic membranes into the bronchial passages could contribute to the deterioration of vocalization. The use of vocalization as the primary channel of communication is replaced by visual display in the adults. These modalities are best suited to the ecological contingencies facing the chick and adult, respectively.