Ecological Systems Model Research Articles

Place-Consciousness and Bronfenbrenner's Ecological Systems Model: A Discussion of Recurring Issues that Undermine the Teaching of Indigenous Histories in New Zealand and Australian Schools

This article draws upon a ‘tale from the field’ (Van Maanen, 1988) to encourage New Zealand and Australian teachers of history and social studies to appraise how their own perceptions of place and teaching about Indigenous peoples’ histories impact upon their students’ learning. Moreover, it explains why Uri Bronfenbrenner's (1979) ecological systems model (despite its limitations) can assist the process of critiquing the teaching of Indigenous histories in schools on both sides of the Tasman Sea. It concludes that place conscious Indigenous land-based learning experiences, resulting from mutually beneficial collaborations with Indigenous communities, are needed to enhance the teaching of Indigenous peoples’ histories in both countries.

Evaluation of ecological systems and the recycling of undesirable outputs: An efficiency study of regions in China

A balance between environmental regulation and economic prosperity has become a major issue of concern to attain a sustainable society in China. This study proposes the application of Data Envelopment Analysis (DEA) for measuring the efficiencies of the ecological systems in various regions of that country. The proposed approach differs from most of the previous ecological systems models in that we view it in a two stage setting; the first stage models the ecological system itself, and from an economic perspective, while the second stage (decontamination system) models water recycling as a feedback process, and the treatment of other undesirable outputs coming from the first stage. There, we separate polluting gases and water into two parts; one part is treated, while the other is discharged. The model considers two major desirable outputs from the first stage, namely Population and Gross Region Product by expenditure (GRP), as well as undesirable variables in the form of consumed water, and certain pollutants, namely nitrogen oxide, sulfur dioxide and soot. At the same time, these undesirable outputs from the first stage are inputs to the second decontamination stage. As well, recycled water is fed back into stage 1. Thus, intermediate variables such as consumed water and waste gas emission simultaneously play dual roles of both outputs and inputs in the ecological system.

Stochastic assembly produces heterogeneous communities in the Caenorhabditis elegans intestine.

Host-associated bacterial communities vary extensively between individuals, but it can be very difficult to determine the sources of this heterogeneity. Here, we demonstrate that stochastic bacterial community assembly in the Caenorhabditis elegans intestine is sufficient to produce strong interworm heterogeneity in community composition. When worms are fed with two neutrally competing, fluorescently labeled bacterial strains, we observe stochastically driven bimodality in community composition, in which approximately half of the worms are dominated by each bacterial strain. A simple model incorporating stochastic colonization suggests that heterogeneity between worms is driven by the low rate at which bacteria successfully establish new intestinal colonies. We can increase this rate experimentally by feeding worms at high bacterial density; in these conditions, the bimodality disappears. These results demonstrate that demographic noise is a potentially important driver of diversity in bacterial community formation and suggest a role for C. elegans as a model system for ecology of host-associated communities.

The role of latitudinal, genetic and temperature variation in the induction of diapause of Papilio glaucus (Lepidoptera: Papilionidae).

A key adaptation in insects for dealing with variable environmental conditions is the ability to diapause. The tiger swallowtail butterflies, Papilio glaucus and P. canadensis are ideal species to explore the genetic causes and population genetic consequences of diapause because divergence in this trait is believed to be a salient factor in maintaining a hybrid zone between these species. Yet little is known about the factors that influence diapause induction in this system. Here we explored how spatial (latitudinal), environmental (temperature) and genetic (hybridization) factors affect diapause induction in this system. Specifically, a series of growth chamber experiments using wild caught individuals from across the eastern United States were performed to: (1) evaluate how critical photoperiod varies with latitude, (2) isolate the stage in which induction occurs, (3) test whether changes in temperature affected rates of diapause induction, and (4) explore how the incidence of diapause is affected in hybrid offspring. We find that induction occurs in the larval stage, is not sensitive to a relatively broad range of temperatures, appears to have a complex genetic basis (i.e., is not simply a dominant trait following a Mendelian inheritance pattern) and that the critical photoperiod increases by 0.4 h with each increasing degree in latitude. This work deepens our understanding of how spatial, environmental and genetic variation influences a key seasonal adaptation (diapause induction) in a well-developed ecological model system and will make possible future studies that explore how climatic variation affects the population dynamics and genetics of this system.

MELA: Modelling in Ecology with Location Attributes

Ecology studies the interactions between individuals, species and the environment. The ability to predict the dynamics of ecological systems would support the design and monitoring of control strategies and would help to address pressing global environmental issues. It is also important to plan for efficient use of natural resources and maintenance of critical ecosystem services. The mathematical modelling of ecological systems often includes nontrivial specifications of processes that influence the birth, death, development and movement of individuals in the environment, that take into account both biotic and abiotic interactions. To assist in the specification of such models, we introduce MELA, a process algebra for Modelling in Ecology with Location Attributes. Process algebras allow the modeller to describe concurrent systems in a high-level language. A key feature of concurrent systems is that they are composed of agents that can progress simultaneously but also interact - a good match to ecological systems. MELA aims to provide ecologists with a straightforward yet flexible tool for modelling ecological systems, with particular emphasis on the description of space and the environment. Here we present four example MELA models, illustrating the different spatial arrangements which can be accommodated and demonstrating the use of MELA in epidemiological and predator-prey scenarios.

Применение теории информации и когнитивных технологий для моделирования эколого-социально-экономических систем (АСК-анализ влияния экологических и производственно-экономических и факторов на здоровье населения)

Применение теории информации и когнитивных технологий для моделирования эколого-социально-экономических систем (АСК-анализ влияния экологических и производственно-экономических и факторов на здоровье населения)

Ecological Systems Theory Approach to Corporate Social Responsibility: Contextual Perspectives From Meeting Planners

Business reputation, competitive advantage, differentiation, and regulatory adherence are all factors that are pushing corporate social responsibility (CSR) center stage within the international meetings industry. However, attempts to simplify what is essentially a complex and contextual driven movement through certification and guides has created an incomplete understanding of the salient issues; contemporaneously ignoring contextual variables rather than acknowledging these and the impact these variables have on CSR practice and acceptance. The purpose of this article is to explore the contextual debate of CSR adaptation and practice within the meetings sector within a framework of an ecological systems theory. The authors applied a constant comparison process across 90 interview transcripts in order to establish a rigorous audit trail of analysis. Eight practices were identified: Green Technology, Legislation, Transparency and Reliability, Nonfinancial Donations, Workforce, Community Engagement, Supply Chain Management, and Volunteer Labor. These eight practices were then applied to the constructs of an ecological systems model and an exploration of contextual factors was considered. In recognizing a systems approach to CSR there is an acceptance that there is not one best method and that different values, implementation approaches, and evaluation mechanisms of CSR can lead to similar results.

Antiretroviral medication treatment for all HIV-infected individuals: a protocol using innovative multilevel methodologies to evaluate New York City's universal ART policy among problem substance users.

BackgroundThe intersection of HIV-related health outcomes and problem substance use has been well documented. New York City continues to be a focal point of the U.S. HIV epidemic. In 2011, the NYC Department of Health and Mental Hygiene (NYC DOHMH) issued a recommendation that all HIV infected individuals should be offered antiretroviral therapy (ART) regardless of CD4 cell count or other indicators of disease progression. This policy is based in the concept of “treatment as prevention,” in which providing ART to people living with HIV (PLWH) greatly reduces the likelihood of HIV transmission, while also improving individual health. The “ART for ALL” (AFA) study was designed to inform modifications to and identify gaps in the implementation of universal ART, and specifically to help guide allocation of resources to obtain local policy goals for increasing viral suppression among PLWH who have problem substance use.Methods/DesignThe AFA Study is informed by two complementary frameworks: Glasgow and colleagues’ RE-AIM model, a multi-level framework developed to guide the evaluation of implementation of new policies, and Bronfrenbrenner’s ecological systems model, which conceptualizes the bi-directional interplay between people and their environment. Using multi-level data and mixed methods, the primary aims of the AFA Study are to assess rates of viral load suppression, using the NYC HIV Surveillance Registry, within 12 months of HIV diagnosis with (a) yearly cohorts of high-risk-to-transmit, difficult-to-treat, substance using patients recruited from NYC Sexually Transmitted Disease clinics and a large detoxification unit and (b) yearly cohorts of all newly HIV diagnosed people in NYC. Further goals include (c) recruiting cross-sectional samples of HIV/AIDS service providers to assess ART initiation with problem substance users and d) examining geographic factors that influence rates of viral load suppression. An Implementation Collaborative Board meets regularly to guide study procedures and interpret results.DiscussionThe AFA Study has the unique strength of accessing and analyzing data at multiple levels using mixed methodology, taking advantage of NYC DOHMH biomedical surveillance data. If successful, others may benefit from lessons learned to inform local and state policies to improve the health of PLWH and further reduce HIV transmission.

Comparing process-based and constraint-based approaches for modeling macroecological patterns.

Ecological patterns arise from the interplay of many different processes, and yet the emergence of consistent phenomena across a diverse range of ecological systems suggests that many patterns may in part be determined by statistical or numerical constraints. Differentiating the extent to which patterns in a given system are determined statistically, and where it requires explicit ecological processes, has been difficult. We tackled this challenge by directly comparing models from a constraint-based theory, the Maximum Entropy Theory of Ecology (METE) and models from a process-based theory, the size-structured neutral theory (SSNT). Models from both theories were capable of characterizing the distribution of individuals among species and the distribution of body size among individuals across 76 forest communities. However, the SSNT models consistently yielded higher overall likelihood, as well as more realistic characterizations of the relationship between species abundance and average body size of conspecific individuals. This suggests that the details of the biological processes contain additional information for understanding community structure that are not fully captured by the METE constraints in these systems. Our approach provides a first step towards differentiating between process- and constraint-based models of ecological systems and a general methodology for comparing ecological models that make predictions for multiple patterns.

Rotifers in Lake Orta: a potential ecological and evolutionary model system

<p>Lake Orta experienced for a few decades a unique history of chronic pollution, with extreme changes in pH and copper concentration. Currently, the lake has recovered to its almost pristine oligotrophic conditions, but its sediments still preserve the record of all the changes that happened since the establishment of the first polluting factories in the 1920s, through to the liming activities in 1989-1990, and to the recovery phase that is still going on. Here we review the current knowledge for Lake Orta regarding rotifers, a diverse component of the zooplankton of the lake, through studies on living organisms and on their resting stages accumulated in the sediments. We also report a brief review of what is known in general on the effects of changes in pH and copper concentration on rotifers at the population, species and community level, providing expectations for such effects on the rotifers of Lake Orta. Then, we conclude our review with a perspective on the potential use of rotifers hatched from the resting stages in the sediment of Lake Orta with the description of experiments that can be performed in the future in the framework of resurrection ecology, in order to understand the mechanisms of past and future changes in the environment.</p>

An ecological systems model of trait resilience: Cross-cultural and clinical relevance

The study explored how scores on the three dimensions of the Engineering, Ecological, and Adaptive Capacity (EEA) trait resilience scale, derived from Holling's ecological systems theory of resilience, demonstrate fit within higher-order bifactor models of measurement, cultural invariance, and associations with clinical caseness of affect. Three samples (295 US adults, and 179 Japanese and 251 Polish university students) completed the EEA trait resilience scale. In addition, a subsample of US adults were administered the Ten-Item Personality Inventory and the Hospital Anxiety and Depression Scale). Across all samples, a higher-order bifactor model provided the best fit of the data, with salience of loadings on the three group factors. A multi-group comparison found configural invariance, but neither metric nor scalar invariance, for EEA resilience scores across the three samples. Among the US sample, engineering and adaptive trait resilience scores predicted clinical caseness of depression, and adaptive trait resilience scores predicted clinical caseness of anxiety, after controlling for sex, age, income, education, employment, and personality. The findings suggest the cross-cultural replicability of the structure (but not the meaning) of the three-factor EEA measure of trait resilience, and its relevance for predicting clinical caseness of affect among a US sample.

A Bayesian approach for temporally scaling climate for modeling ecological systems.

With climate change becoming more of concern, many ecologists are including climate variables in their system and statistical models. The Standardized Precipitation Evapotranspiration Index (SPEI) is a drought index that has potential advantages in modeling ecological response variables, including a flexible computation of the index over different timescales. However, little development has been made in terms of the choice of timescale for SPEI. We developed a Bayesian modeling approach for estimating the timescale for SPEI and demonstrated its use in modeling wetland hydrologic dynamics in two different eras (i.e., historical [pre‐1970] and contemporary [post‐2003]). Our goal was to determine whether differences in climate between the two eras could explain changes in the amount of water in wetlands. Our results showed that wetland water surface areas tended to be larger in wetter conditions, but also changed less in response to climate fluctuations in the contemporary era. We also found that the average timescale parameter was greater in the historical period, compared with the contemporary period. We were not able to determine whether this shift in timescale was due to a change in the timing of wet–dry periods or whether it was due to changes in the way wetlands responded to climate. Our results suggest that perhaps some interaction between climate and hydrologic response may be at work, and further analysis is needed to determine which has a stronger influence. Despite this, we suggest that our modeling approach enabled us to estimate the relevant timescale for SPEI and make inferences from those estimates. Likewise, our approach provides a mechanism for using prior information with future data to assess whether these patterns may continue over time. We suggest that ecologists consider using temporally scalable climate indices in conjunction with Bayesian analysis for assessing the role of climate in ecological systems.

Mean-Field Semantics for a Process Calculus for Spatially-Explicit Ecological Models

We define a mean-field semantics for S-PALPS, a process calculus for spatially-explicit, individual-based modeling of ecological systems. The new semantics of S-PALPS allows an interpretation of the average behavior of a system as a set of recurrence equations. Recurrence equations are a useful approximation when dealing with a large number of individuals, as it is the case in epidemiological studies. As a case study, we compute a set of recurrence equations capturing the dynamics of an individual-based model of the transmission of dengue in Bello (Antioquia), Colombia.

Exploring Connections between Students' Psychological Sense of School Membership and Their Resilience, Self-Efficacy, and Leadership Skills

Throughout the history of psychological research, scholars have investigated the fundamental want to build and keep social bonds and ties with others and have thus generated a large pool of constructs with different names but essentially analogous meanings. This desire has been variously discussed as the need for belongingness (Baumeister & Leary, 1995; Goodenow, 1993b; Maslow, 1954), the affiliative motive (McClelland, 1987), and the need for relatedness (Alderfer, 1969; Deci & Ryan, 1991). While terminology may differ, there are certain undeniable overlaps in the way different theorists have conceptualized this need. McClelland (1987) contended that individuals with a high need for affiliation seek harmonious with people who make them feel accepted. Baumeister and Leary (1995) proposed the 'belongingness hypothesis' pointing out that human beings have a pervasive drive to form and maintain at least a minimum quantity of lasting, positive, and significant interpersonal relationships (p. 497).Belongingness is relevant for almost all aspects of existence. Taking Bronfenbrenner's ecological systems model (1979) into account, experiences are embedded within a number of systems ranging from micro-systems (comprising of an individual's immediate environment) to the macro-systems (encompassing the overarching social fabric of a community).The need for social approval, acceptance, and connectedness within significant social circles is especially strong during adolescence. As it is a developmental phase characterized by a heightened need for the search of personal identity outside of familial boundaries, adolescents tend to engage more in the exploration of social contexts beyond family and family relations. It is a period when a young person's of personal place is still largely malleable and susceptible to influence in both positive and negative directions (Goodenow, 1993, p. 81). School forms part of a young person's 'microsystem' and is therefore a central social setting exerting influence on their psycho-social development (Bronfenbrenner, 1979). Students' experiences with and in school, including their relations and interactions with their peers, teachers, and school authorities, may thus serve as a vital link in understanding the development of their psycho-social capacities.Psychological sense of school membershipIn the past few decades, the idea of a 'community' has cropped up in the academic discourse concerning schools. The term community is often used to refer to the same concept that expressions like 'belongingness' or 'connectedness' describe. Belonging in a school community means that the student has friendly interactions with others, perceives being valued and accepted by them, and is engaged in the pursuit of shared institutional goals (Goodenow, 1991).Of the diverse experiences that children have in school, an encompassing sense of being attached to or being a part of the school is of prime importance. Studies have related the students' sense of belongingness or school membership to positive academic outcomes (Goodenow, 1993; Osterman, 2000; Sanchez, Colon, E Voelkl, 1995), increased student motivation (Goodenow, 1993), positive attitudes toward learning (Roeser, Midgley, & Urdan, 1996), decreased health-risk behaviors (Bond et al., 2007; McNeely & Falci, 2004), and low social rejection and school problems ( Anderman, 2002), among other variables.Finn ( 1989), based on his review of the literature on student dropout behavior from school, proposed the 'participation-identification model'. The model postulates that when students identify with their school, they develop a sense of attachment and belonging toward the school, which facilitates an increased commitment and participation in school activities and larger school goals. This identificationparticipation may be instrumental in decreased drop-out rates from school through a decrement in the at-risk students' sense of alienation. …

Pleistocene radiation of the serpentine-adapted genus Hesperolinon and other divergence times in Linaceae (Malpighiales).

Hesperolinon (western flax; Linaceae) is endemic to the western United States, where it is notable for its high and geographically concentrated species diversity on serpentine-derived soils and for its use as a model system in disease ecology. We used a phylogenetic framework to test a long-standing hypothesis that Hesperolinon is a neoendemic radiation. Five plastid and two ribosomal nuclear DNA gene regions were sampled from 105 populations of Hesperolinon, including all 13 recently recognized species across their known ranges. We used these data to generate population-level phylogenies of Hesperolinon. We also generated a robustly sampled chronogram of Linaceae using an eight-gene, 100-taxon supermatrix calibrated using fossil Linum pollen and a published chronogram of Malpighiales. Most diversification in Hesperolinon has taken place in the past 1-2 million yr, much more recently than previous estimates. Only the earliest-diverging species, H. drymarioides, was resolved as a clade. Denser taxon and gene sampling generally support previously proposed relationships within Linaceae, but with more recent diversification of key clades. Hesperolinon is an excellent example of edaphic neoendemism, in support of Raven and Axelrod's hypothesis for the genus. Dense population-level sampling reveals a complex of incipient species, with clades poorly aligned with traditional morphological circumscriptions, likely due in part to continued gene flow. The diversification of Linaceae is more recent than previously estimated, and other recent radiations (e.g., Hugonia) warrant further study.

Disruption of endosperm development is a major cause of hybrid seed inviability between Mimulus guttatus and Mimulus nudatus.

Divergence of developmental mechanisms within populations could lead to hybrid developmental failure, and might be a factor driving speciation in angiosperms. We investigate patterns of endosperm and embryo development in Mimulus guttatus and the closely related, serpentine endemic Mimulus nudatus, and compare them to those of reciprocal hybrid seed. We address whether disruption in hybrid seed development is the primary source of reproductive isolation between these sympatric taxa. M. guttatus and M. nudatus differ in the pattern and timing of endosperm and embryo development. Some hybrid seeds exhibit early disruption of endosperm development and are completely inviable, while others develop relatively normally at first, but later exhibit impaired endosperm proliferation and low germination success. These developmental patterns are reflected in mature hybrid seeds, which are either small and flat (indicating little to no endosperm) or shriveled (indicating reduced endosperm volume). Hybrid seed inviability forms a potent reproductive barrier between M. guttatus and M. nudatus. We shed light on the extent of developmental variation between closely related species within the M. guttatus species complex, an important ecological model system, and provide a partial mechanism for the hybrid barrier between M. guttatus and M. nudatus.

Natural Products from Photorhabdus and Other Entomopathogenic Bacteria.

Although the first natural products (NP) from Photorhabdus and Xenorhabdus bacteria have been known now for almost 30years, a huge variety of new compounds have been identified in the last 5-10years, mainly due to the application of modern mass spectrometry. Additionally, application of molecular methods that allow the activation of NP production in several different strains as well as efficient heterologous expression methods have led to the production and validation of many new compounds. In this chapter we discuss the benefit of using Photorhabdus as a model system for microbial chemical ecology. We also examine non-ribosomal peptide synthetases as the most important pathway for NP production. Finally, we discuss the origin and function of all currently known NPs and the development of the molecular and chemical tools used to identify these NPs faster.

Comparing process-based and constraint-based approaches for modeling macroecological patterns

Ecological patterns arise from the interplay of many different processes, and yet the emergence of consistent phenomena across a diverse range of ecological systems suggests that many patterns may in part be determined by statistical or numerical constraints. Differentiating the extent to which patterns in a given system are determined statistically, and where it requires explicit ecological processes, has been difficult. We tackled this challenge by directly comparing models from a constraint-based theory, the Maximum Entropy Theory of Ecology (METE) and models from a process-based theory, the size-structured neutral theory (SSNT). Models from both theories were capable of characterizing the distribution of individuals among species and the distribution of body size among individuals across 76 forest communities. However, the SSNT models consistently yielded higher overall likelihood, as well as more realistic characterizations of the relationship between species abundance and average body size of conspecific individuals. This suggests that the details of the biological processes contain additional information for understanding community structure that are not fully captured by the METE constraints in these systems. Our approach provides a first step towards differentiating between process- and constraint-based models of ecological systems and a general methodology for comparing ecological models that make predictions for multiple patterns.

A Population Biology Perspective on the Stepwise Infection Process of the Bacterial Pathogen Pasteuria ramosa inDaphnia.

The infection process of many diseases can be divided into series of steps, each one required to successfully complete the parasite's life and transmission cycle. This approach often reveals that the complex phenomenon of infection is composed of a series of more simple mechanisms. Here we demonstrate that a population biology approach, which takes into consideration the natural genetic and environmental variation at each step, can greatly aid our understanding of the evolutionary processes shaping disease traits. We focus in this review on the biology of the bacterial parasite Pasteuria ramosa and its aquatic crustacean host Daphnia, a model system for the evolutionary ecology of infectious disease. Our analysis reveals tremendous differences in the degree to which the environment, host genetics, parasite genetics and their interactions contribute to the expression of disease traits at each of seven different steps. This allows us to predict which steps may respond most readily to selection and which steps are evolutionarily constrained by an absence of variation. We show that the ability of Pasteuria to attach to the host's cuticle (attachment step) stands out as being strongly influenced by the interaction of host and parasite genotypes, but not by environmental factors, making it the prime candidate for coevolutionary interactions. Furthermore, the stepwise approach helps us understanding the evolution of resistance, virulence and host ranges. The population biological approach introduced here is a versatile tool that can be easily transferred to other systems of infectious disease.

The beta‐diversity of species interactions: Untangling the drivers of geographic variation in plant–pollinator diversity and function across scales

Geographic patterns of biodiversity have long inspired interest in processes that shape the assembly, diversity, and dynamics of communities at different spatial scales. To study mechanisms of community assembly, ecologists often compare spatial variation in community composition (beta-diversity) across environmental and spatial gradients. These same patterns inspired evolutionary biologists to investigate how micro- and macro-evolutionary processes create gradients in biodiversity. Central to these perspectives are species interactions, which contribute to community assembly and geographic variation in evolutionary processes. However, studies of beta-diversity have predominantly focused on single trophic levels, resulting in gaps in our understanding of variation in species-interaction networks (interaction beta-diversity), especially at scales most relevant to evolutionary studies of geographic variation. We outline two challenges and their consequences in scaling-up studies of interaction beta-diversity from local to biogeographic scales using plant-pollinator interactions as a model system in ecology, evolution, and conservation. First, we highlight how variation in regional species pools may contribute to variation in interaction beta-diversity among biogeographic regions with dissimilar evolutionary history. Second, we highlight how pollinator behavior (host-switching) links ecological networks to geographic patterns of plant-pollinator interactions and evolutionary processes. Third, we outline key unanswered questions regarding the role of geographic variation in plant-pollinator interactions for conservation and ecosystem services (pollination) in changing environments. We conclude that the largest advances in the burgeoning field of interaction beta-diversity will come from studies that integrate frameworks in ecology, evolution, and conservation to understand the causes and consequences of interaction beta-diversity across scales.