Density-dependent immigration promotes population stability in a long-distance migratory bird

The spatial structure of populations determines the relative importance of reproduction, survival and movement on population dynamics. However, the mechanisms by which local individuals and immigrants interact and the subsequent effects of immigrants on productivity are poorly known. We developed an integrated population model (IPM) to study the extent and consequences of immigration on the dynamics of a neotropical migrant (American redstart, Setophaga ruticilla) over an 11-year period in Ontario, Canada. New immigrants represented the majority of the study population each year with higher immigration rates for males than females and for first-year breeders than breeders in their second year or older. Immigration was negatively density dependent, with immigrants replacing previously established breeders in a compensatory manner following their death or emigration. Because of the tradeoff between immigration and apparent survival, neither had a strong influence on population growth and reproductive output was most strongly correlated with a change in abundance between years. However, if immigration ceased, the study population would become locally extinct within 7 years and thus immigrants were essential for local population persistence. We found no evidence for reduced breeding success when immigrants represented a higher proportion of the study population. Our research highlights the importance of movement in the stability of open populations and the strong correlation between the fates of local breeders and the number of immigrants entering the population. We recommend the use of IPMs to address the spatial scale over which immigration occurs and how different scales influence its contribution to population dynamics.     

Immigrants' Cultural Identities as Sources of Civic Engagement

Immigrant parents (first generation) and adolescents (second generation) from El Salvador and India (N = 80) took part in interviews on civic engagement. The immigrants were almost unanimous in regarding civic engagement as important. They also were engaged themselves, more so at the community than the political level. One third of immigrants were engaged in community activities that specifically had a cultural focus or occurred through cultural organizations, and the comparable number for political activities was 25%. Cultural motives (i.e., a cultural or immigrant sense of self) were twice as likely to be mentioned as sources of engagement rather than disengagement. Qualitative analyses of these cultural motives revealed seven engagement themes (e.g., cultural tradition of service) and three of disengagement (e.g., ethnic exclusion).     

Introduction: Comparative Perspectives on the Indigenous Rights Movement in Africa and the Americas

Using ethnographic case studies, these "In Focus" articles explore the indigenous rights movements in two regions, Africa and the Americas, where the histories, agendas, and dynamics of the movements are at once similar and different. They consider a range of relevant questions about the politics of representation, recognition, resources, and rights as these movements engage shifting political and economic landscapes; transnational discourses, alliances, and organizations; and the complicated cultural politics of inclusion and exclusion invoked by the term indigenous. As such, they offer a critical, comparative perspective on the issues of culture, power, representation, and difference inherent in the complicated alliances, articulations, and tensions that have produced and transformed the transnational indigenous rights movement. This introduction provides a brief history of the movement, highlights some major themes in previous anthropological work, reviews the insights of the section articles, and explores some of the ways in which anthropologists have engaged with the movement. [Keywords: indigenous peoples, social movements, cultural politics, ethnography]     

A synergetic theory of environmentally-specified and learned patterns of movement coordination

Rhythmic movement patterns have served as a model case for developing a synergetic theory of biological coordination. In part I of this work we extended the approach to environmentally-specified and learned movement patterns on the level of the collective variable relative phase. Here we show that an identical strategy may be applied to the same problem at the level of the component oscillators. Coordinative patterns and their dynamics are derived from the coupled component dynamics and their interaction with the environment. Thus, behavioral patterns are shown to arise in a purely self-organized fashion. New directions for further research (e.g. dynamics of action-perception systems) follow from the oscillator theory. Finally the relationship between our approach and other kinds of analyses of temporal order (e.g. phase resetting) is addressed.     

The reliability of relative anion-cation permeabilities deduced from reversal (Dilution) potential measurements in ion channel studies

Measurements of anion-cation permeability ratios (e.g., P _Cl/P _Na) are most readily made by measuring changes in zero-current reversal potential when the salt concentration on one side of the membrane (e.g., external NaCl) is decreased. This is particularly useful for measuring changes in ion selectivity in wild-type and mutant channels, such as those of the ligand-gated ion channel superfamily, and has shown that many of these channels have a significant permeability to counter-ions. One Brownian dynamics study of ion permeation through such narrow ion channels failed to observe such counter-ion movement, although later, another Brownian dynamics study did observe counter-ion movement through simulations of the same channels. The question has been raised as to the reliability of such reversal potential measurements for determining permeability ratios, particularly given the use of an equation such as the Goldman-Hodgkin-Katz (GHK) equation, which is often used to calculate such ratios. A new derivation of the GHK equation in terms of activity coefficients is also included. The application of irreversible thermodynamics will be shown to qualitatively support the reliability of such experimental anion-cation permeability values derived from reversal potential measurements. It will then be shown that for such zero-current situations, different electrodiffusion models, with very different underlying assumptions, produce almost identical relative permeabilities (and reversal potentials). Finally, the results of the two Brownian dynamics simulation studies and the relationship between reversal potentials and relative permeability will be discussed.     

'LABNOTE', a laboratory notebook system designed for academic genomics groups.

We have developed a relational laboratory database system, adapted to the daily book-keeping needs of laboratories that must keep track of information acquired on hundreds or thousands of clones in an effective and user-friendly fashion. Data, whether final or related to experiments in progress, can be accessed in many different ways, e.g. by clone name, by gene, by experiment or through DNA sequence. Updating, import and export of results is made easier by specially developed tools. This system, in network version, serves several groups in our Institute and (over the Internet) elsewhere, and is instrumental in collaborative studies based on expression profiling. It can be used in many similar situations involving progressiveaccumulation of information on sets of clones or related objects.     

Long-term anti-kindling effects of desynchronizing brain stimulation: a theoretical study

In a modeling study we show that desynchronization stimulation may have powerful anti-kindling effects. For this, we incorporate spike-timing-dependent plasticity into a generic network of coupled phase oscillators, which serves as a model network of synaptically interacting neurons. Two states may coexist under spontaneous conditions: a state of uncorrelated firing and a state of pathological synchrony. Appropriate stimulation protocols make the network learn or unlearn the pathological synaptic interactions, respectively. Low-frequency periodic pulse train stimulation causes a kindling. Permanent high-frequency stimulation, used as golden standard for deep brain stimulation in medically refractory movement disorders, basically freezes the synaptic weights. In contrast, desynchronization stimulation, e.g., by means of a multi-site coordinated reset, has powerful long-term anti-kindling effects and enables the network to unlearn pathologically strong synaptic interactions. We propose desynchronization stimulation for the therapy of movement disorders and epilepsies.     

Categorical inequality,institutional ambivalence,and permanently failing institutions: the case of immigrants and barriers to health care in America

Abstract

I draw on the theories of Charles Tilly, Robert K. Merton, Eleanor Barber, Marshall Meyer, and Lynne Zucker to develop a three-part framework for understanding the organizational and institutional interface between social services like health care and disadvantaged minorities like immigrants. Tilly's theory of durable inequality is transposed to categorical inequalities in organizations and law. His vocabulary of motives is expanded to include categorical entrenchment, restitution, and compensation. These embedded inequalities lead to institutional ambivalence in the provision of services and to permanently failing institutions that work poorly, waste resources, or provide uneven quality, yet do not collapse but endure while resisting reform. One rationale for resistance is ‘moral hazard’ by individuals; but the theory of moral hazard is biased and partial, because provider moral hazard and insurer moral hazard are more prevalent. The specific manifestations of these concepts and dynamics between them warrant further research in different contexts.     

Precarious Alliances: The Cultural Politics and Structural Predicaments of the Indigenous Rights Movement in Tanzania

Since 1990, over one hundred indigenous nongovernmental organizations (INGOs) have emerged in predominantly Maasai areas in Tanzania, attempting to organize people around diverse claims of a common "indigenous" identity based on ethnicity, mode of production, and a long history of political and economic disenfranchisement. Despite attempts to foster unity and promote common political agendas, the indigenous rights movement has been fractured by sometimes quite hostile disagreements over priorities, competition over resources, and tensions over membership and representation. This article explores the complicated causes and consequences of these tensions by focusing on the discussions, disagreements, and silences that occurred during a recent attempt to reconcile indigenous groups in Tanzania. The workshop offers a unique window on the cultural, political, and historical dynamics of the indigenous rights movement in northern Tanzania, the principles and practices of inclusion and exclusion that have defined and shaped the movement, and the internal and external stresses that have made alliances within and among the INGOs, donors, and the government precarious, at best. [Keywords: indigenous peoples, social movements, cultural politics, Maasai, Tanzania]     

Immigration in wild groups of golden lion tamarins (Leontopithecus rosalia)

Seventeen territorial groups of wild golden lion tamarins were monitored for periods of 10–76 months. Immigration into established groups was rare (0.48 immigrating individuals per group per year) and occurred mostly in the context of replacement of breeding individuals. Nonreplacement immigration events usually occurred in conjunction with some other change in group composition (e.g., an emigration or another immigration). Aggression by resident tamarins toward potential immigrants appeared to be the proximate factor limiting movement into groups. Most such aggression was intrasexual, but potential female immigrants were sometimes chased by male as well as female residents. Immigration was highly male biased (85% of individuals). Factors possibly contributing to this bias were inheritance of breeding positions by adult daughters (reducing female and increasing male immigration opportunities), ability of males but not females to join groups already containing a same-sex breeding individual, and the fact that potential female immigrants appeared to face some intersexual as well as intrasexual aggression. Male and female roles in the maintenance of a monogynous mating system are considered in light of these results. Contrasts with data from intruder studies on captive golden lion tamarins [French & Inglett, Animal Behaviour 37:487–497, 1989] are discussed. © 1996 Wiley-Liss, Inc.     

‘Feeding the Caregiver’: Internal and External Relations in a Matrilineal Life-Cycle Ritual,West Gao

ABSTRACT

Due to the rule of matriclan exogamy, a West Gao father belongs to a different matriclan to that of his wife and children. During a feast known as fangamu taego, children present their father with gifts to acknowledge his care. Acting as a pivot within the sequence of life-cycle rituals in West Gao, fangamu taego provides a ritual space in which two opposed modes of relationality are brought together. During the exchanges that constitute the feast, relationships flowing internally to each matriclan are weighed against external relationships forged between matriclans. The relational interplay elaborated during fangamu taego is predicated upon ancestrally mediated relationships of emplacement with regard to a specific territory. This comes into focus during a further set of transactions instigated by the feast involving use rights in land and its organic products. The ‘matter’ of these exchanges participate in two distinct relational modes simultaneously: they both activate pre-existing internal relationships and figure as ‘terms’ in the temporary construction of external relationships. Ultimately, fangamu taego captures an interplay between the relative permanence and impermanence of different relational configurations in the West Gao lived world.     

Identifying Movement States From Location Data Using Cluster Analysis

ABSTRACT Animal movement studies regularly use movement states (e.g., slow and fast) derived from remotely sensed locations to make inferences about strategies of resource use. However, the number of movement state categories used is often arbitrary and rarely inferred from the data. Identifying groups with similar movement characteristics is a statistical problem. We present a framework based on k-means clustering and gap statistic for evaluating the number of movement states without making a priori assumptions about the number of clusters. This allowed us to distinguish 4 movement states using turning angle and step length derived from Global Positioning System locations and head movements derived from tip switches in a neck collar of free-ranging elk (Cervus elaphus) in west central Alberta, Canada. Based on movement characteristics and on the linkage between each state and landscape features, we were able to identify inter-patch movements, intra-patch foraging, rest, and inter-patch foraging movements. Linking behavior to environment (e.g., state-dependent habitat use) can inform decisions on landscape management for wildlife.     

Animal rights activists' representations of animals and animal rights: An exploratory study

Abstract

During the last 30 years, supporters of the animal rights movement have questioned the use of animals for human benefit and have campaigned for improvements in their welfare. In the present study, activists' representations of animals and animal rights were investigated by interviewing 23 participants (from three animal welfare and animal rights organizations) during four focus-group discussions. Results show that the activists' representations were generated from the love/pain thema, which on the one hand showed the compassion and love the activists have for animals, and on the other hand the suffering that animals can endure. Moreover, differences were found in this study in the way that members of the three animal welfare and rights organizations constructed their views of animals. While members of two out of the three organizations aimed to protect abandoned animals, members of the Anti-Vivisection League faced the contradictions within the human–animal relationship and endorsed a more coherent approach to animals. These findings are interpreted in light of previous studies conducted on the animal rights movement and of recent developments in social representation theory.     

Dynamics and bifurcations of two coupled neural oscillators with different connection types

In this paper we present an oscillatory neural network composed of two coupled neural oscillators of the Wilson-Cowan type. Each of the oscillators describes the dynamics of average activities of excitatory and inhibitory populations of neurons. The network serves as a model for several possible network architectures. We study how the type and the strength of the connections between the oscillators affect the dynamics of the neural network. We investigate, separately from each other, four possible connection types (excitatory→excitatory, excitatory→inhibitory, inhibitory→excitatory, and inhibitory→inhibitory) and compute the corresponding bifurcation diagrams. In case of weak connections (small strength), the connection of populations of different types lead to periodicin-phase oscillations, while the connection of populations of the same type lead to periodicanti-phase oscillations. For intermediate connection strengths, the networks can enter quasiperiodic or chaotic regimes, and can also exhibit multistability. More generally, our analysis highlights the great diversity of the response of neural networks to a change of the connection strength, for different connection architectures. In the discussion, we address in particular the problem of information coding in the brain using quasiperiodic and chaotic oscillations. In modeling low levels of information processing, we propose that feature binding should be sought as a temporally coherent phase-locking of neural activity. This phase-locking is provided by one or more interacting convergent zones and does not require a central “top level” subcortical circuit (e.g. the septo-hippocampal system). We build a two layer model to show that although the application of a complex stimulus usually leads to different convergent zones with high frequency oscillations, it is nevertheless possible to synchronize these oscillations at a lower frequency level using envelope oscillations. This is interpreted as a feature binding of a complex stimulus.     

Dispersal Status Influences Hormones and Behavior in the Male Spotted Hyena

Male spotted hyenas (Crocuta crocuta) reach puberty at 24 months of age and then invariably emigrate from their natal clans 1 to 38 months later. Thus there are two classes of reproductively mature males in everyCrocutaclan: adult natal males born in the clan and adult immigrant males born elsewhere. In one free-living hyena population in Kenya, these two groups of males were compared with respect to measures of aggression, social dominance, sexual behavior, and circulating hormone levels. Adult natal males engaged in higher hourly rates of aggression than did immigrants, won all fights with immigrants, and were socially dominant to immigrants. In addition, adult natal males engaged in far lower hourly rates of sexual behavior with resident females than did immigrants, and natal males were never observed to copulate with natal females. Mean basal plasma cortisol values did not differ between the two groups of adult males, but cortisol concentrations in immigrants were positively correlated with tenure in the clan and with immigrant male social rank. Adult natal males had plasma testosterone levels significantly lower than those of immigrants. Social rank and plasma testosterone values were positively correlated among immigrant males. Thus two different relationships appear to exist between circulating testosterone and social rank in maleCrocuta:one apparent in immigrants and the other in natal adult males. Our results suggest that dispersal might disinhibit testosterone secretion in postpubertal male hyenas.     

Optomotor control of the force of flight in Drosophila and Musca

Specialized networks of movement detectors in the antero-inferior field of the eyes of the fruitfly, Drosophila melanogaster, and the housefly, Musca domestica, respond to upward (or downward) drift of the retinal images by excitation (or inhibition) of the lift-generating force of flight. The influence of the direction of pattern movement upon the altitude control response has been investigated under conditions of fixed flight in still air. Matched model analysis of the available response curves suggests the predominance of unidirectional movement detectors in these networks. Homologous wingbeat-inhibiting detectors in the specified fields of the eyes of the two species respond preferentially to pattern movement from antero-superior to postero-inferior. The arrangement of wingbeat-exciting detectors seems to follow different schemes: These detectors respond preferentially to movement from inferior to superior in Drosophila, and to movement from antero-inferior to postero-superior in Musca. The wingbeat-exciting network in Musca is restricted to a comparatively small antero-equatorial area of the specified fields of the eyes. The combination of the two types of detectors in this area establishes a powerful lift control system which is particularly sensitive to minute deviations from a given level of flight.     

Key stimuli of prey for toads (Bufo bufo L.): Configuration and movement patterns

Summary The ability of the Common ToadBufo bufo (L.) to distinguish between a worm-like and an antiworm-like (e.g., a bar at right angles to its direction of motion) moving stripe is not generally altered by movement dynamics, such as velocity of motion or by particular movement patterns—so far as has been investigated. A small square stimulus, however, with its indifferent shape is more attractive as prey for the toad when displaced in a stepwise manner, rather than moved at corresponding continuous (constant) velocity. Step frequencies of 1 to 2 cps were found to have optimal releasing values.Supported by the Deutsche Forschungsgemeinschaft Ew 7/6     

Network analysis as a tool to understand social development in spider monkeys

The emerging field of network science has demonstrated that an individual's connectedness within their social network has cascading effects to other dimensions of life. Like humans, spider monkeys live in societies with high fission–fusion dynamics, and are remarkably social. Social network analysis (SNA) is a powerful tool for quantifying connections that may vary as a function of initiating or receiving social behaviors, which has been described as shifting social roles. In primatology, the SNA literature is dominated by work in catarrhines, and has yet to be applied to the study of development in a platyrrhine model. Here, SNA was utilized in combination with R-Index social role calculation to characterize social interaction patterns in juvenile and adult Colombian spider monkeys (Ateles fusciceps rufiventris). Connections were examined across five behaviors: embrace, face-embrace, grooming, agonism, and tail-wrapping from 186 hr of observation and four network metrics. Mann–Whitney U tests were utilized to determine differences between adult and juvenile social network patterns for each behavior. Face-embrace emerged as the behavior with different network patterns for adults and juveniles for every network metric. With regard to social role, juveniles were receivers, not initiators, for embrace, face-embrace, and grooming (ps < .05). Network and social role differences are discussed in light of social development and aspects of the different behaviors.     

Birthplace‐dependent dispersal: are directions of natal dispersal determined a priori?

Sib–sib or, more generally, family resemblance for dispersal seems a widespread characteristic of vertebrates, and the birthplace has the potential to shape the dynamics and features of animal populations. Dispersal studies have often stressed the fundamental link between the fate of dispersers and population dynamics, but few have focused on the dispersal directions of individuals, despite the profound implications that this may have on population distribution, structure, dynamics and viability. We investigated the directions followed by 72 radio‐tagged dispersers (43 males and 29 females from 14 nest sites) in an eagle owl Bubo bubo population, and assessed their a) inter‐individual distances during dispersal and b) age at dispersal departure. For siblings, as well as potential‐siblings (i.e. individuals born in the same nest in different years), the birthplace influenced inter‐individual distances and dispersal directions, i.e. dispersers from the same nest moved to similar locations during the study; moreover, in each year, individuals from the same birthplace moved across the same areas in a short time period. Finally, siblings and potential‐siblings born in the same nest in different years started dispersal at similar ages. Based on the movement patterns of dispersers we discuss: a) the potential implications of the birthplace‐dependent dispersal on the ideal free distribution theory, as well as in terms of kin competition, inbreeding avoidance and population dynamics; and, more generally, b) the effect of the temporal features of the natal dispersal on the concept of habitat suitability vs density of individuals developed by the ideal free distribution theory.     

Institutions,information exchange,and migrant social networks in Rome

While a considerable body of work examines immigrant networks, inadequate attention has been devoted to understanding how networks regulate the relationship between immigrants and host institutions. A rich immigrant process may reinforce current power structures by providing a convenient buffer between the elite and challengers. Conversely, immigration may challenge the status quo. I employ social network analysis to examine three understudied immigrant groups in Rome, Bangladeshis, Filipinos, and Peruvians. I find that they have developed systems of problem-solving and sense-making that often interrupt their interactions with host institutions. The state tolerates this because it situates immigrants’ concerns outside its sphere of responsibility.