Mapping migrants' inclusion: an analytical framework for examining policy output

Comparative studies on the extension of rights, including naturalization rights, to migrants have grown exponentially. We propose a theoretically informed analytical framework to examine state policies relating to the extension of rights to aliens and citizenship acquisition. It consists of three frames: the rights frame, the citizenship eligibility frame and the earned citizenship frame. The framework enables the examination and mapping of policy developments in this broad field, while also elucidating how the notions of membership, status and identity – key constructs associated with the nation state – are articulated in states’ policy attempts to ‘integrate’ migrants, and, importantly, how they are reformulated over time. In the process, the framework nuances ideas about the coherence and stability of national citizenship regimes, brings greater conceptual clarity to the field, and delimits and delineates the citizenship construct. It also provides scope for additional and new comparative insights within and across states.     

Introduction: gender,migration and the media

Abstract

Mediated representations of gender, ethnicity and migration play an increasingly important role in the way these categories are understood in the public sphere and the private realm. As media often intervene in processes of individual and institutional communication, they provide frameworks for the production and consumption of representations of these categories. Thus media – in their production, representations and consumption – need to be analysed, not only as reflections as pre-existing socio-political realities, but also as constitutive elements in the production of meanings of the self and the Other. This special issue includes a number of articles that examine the articulations of gendered ethnic identities and of gendered citizenship as these are shaped in media production, media representations and media consumption.     

RECOMBINATION AND MIGRATION RATES IN NATURAL POPULATIONS OF BACILLUS SUBTILIS AND BACILLUS MOJAVENSIS

We have investigated the rates of recombination and migration in native populations of two closely related, naturally competent Bacillus species. Native soil isolates of Bacillus subtilis and Bacillus mojavensis were obtained from three continents and, within North America, from populations at a range of geographical distances from one another. The rate of recombination within populations of each species was estimated from restriction-site data for three genes. Recombination was shown to occur within each species at about the same rate as neutral mutation, whatever the geographical scale or phylogenetic scale over which strains were sampled. The rate of migration between populations was estimated by a cladistic analysis and was shown to be high (i.e., Nm > 1), even among populations on different continents. The level of migration within each species is sufficient to prevent neutral geographical divergence within species.     

Allozyme diversity in relation to geographic distribution and population size inLathyrus vernus (L.) Bernh. (Fabaceae)

Lathyrus vernus (L.) Bernh. is a diploid, long-lived perennial and insect-pollinated herb with no special adaptation to long-distance dispersal. It occurs on neutral soil in deciduous forests throughout western Eurasia. Due to specific habitat preferences,L. vernus has a fragmented distribution with isolated populations. We investigated allozyme variation at eleven loci in 20 populations ofL. vernus from one geographically central region (the Czech Republic and the Slovak Republic) and two geographically marginal regions (southern and central Sweden) in the species present-day distribution. There was a clear differentiation between the three regions and the genetic distance between the populations was highly correlated with geographic distance. The total genetic diversity (H_T) was 0.354. The proportion of genetic diversity due to differentiation between regions, and to differentiation between populations within regions, accounted for 10% each. There was no difference in level of genetic diversity between the three regions. No significant difference in level of genetic diversity was found between small and large populations. The genetic diversity inL. vernus may either be a result of the long generation-time of the species or peculiarities in the post-glacial migration species, e.g. survival only in refugia far east of the sampled populations and/or migration as a continuous process not involving founder-events.     

Income inequality and depression: a systematic review and meta‐analysis of the association and a scoping review of mechanisms

Most countries have witnessed a dramatic increase of income inequality in the past three decades. This paper addresses the question of whether income inequality is associated with the population prevalence of depression and, if so, the potential mechanisms and pathways which may explain this association. Our systematic review included 26 studies, mostly from high‐income countries. Nearly two‐thirds of all studies and five out of six longitudinal studies reported a statistically significant positive relationship between income inequality and risk of depression; only one study reported a statistically significant negative relationship. Twelve studies were included in a meta‐analysis with dichotomized inequality groupings. The pooled risk ratio was 1.19 (95% CI: 1.07‐1.31), demonstrating greater risk of depression in populations with higher income inequality relative to populations with lower inequality. Multiple studies reported subgroup effects, including greater impacts of income inequality among women and low‐income populations. We propose an ecological framework, with mechanisms operating at the national level (the neo‐material hypothesis), neighbourhood level (the social capital and the social comparison hypotheses) and individual level (psychological stress and social defeat hypotheses) to explain this association. We conclude that policy makers should actively promote actions to reduce income inequality, such as progressive taxation policies and a basic universal income. Mental health professionals should champion such policies, as well as promote the delivery of interventions which target the pathways and proximal determinants, such as building life skills in adolescents and provision of psychological therapies and packages of care with demonstrated effectiveness for settings of poverty and high income inequality.     

REPEATED REVERSALS OF HOST-PREFERENCE EVOLUTION IN A SPECIALIST INSECT HERBIVORE

A tree of mitochondrial DNA (mtDNA) haplotypes was constructed to estimate the number of evolutionary changes of host-plant preference needed to account for variation among 24 populations of the butterfly Euphydryas editha. Using 17 restriction endonucleases, 22 mtDNA haplotypes were found among 24 populations of this butterfly species. We allowed for the possibility of haplotypes to acquire particular preferences either from evolutionary change at their local sites or from migration to populations where those preferences occurred. After we had taken these estimates of migration into account, a minimum of 10 evolutionary changes of host preference (reduced from 22) was needed to explain the pattern of use of five host-plant genera among these populations. Analysis of allozyme variation among a partially overlapping set of populations also suggested multiple host shifts. Although genetic variation of host preference is largely responsible for interpopulation variation of diet, repeated reversals of preference evolution have occurred. However, host preferences were not distributed randomly with respect to phylogeny, and some tendency toward evolutionary conservation of preference also was indicated. The haplotype of E. editha most closely related to the sister species, E. chalcedona, used a principal host of E. chalcedona. Our results suggest that host shifts occur frequently in E. editha, are a result of both migration and local evolution, and have not been associated with speciation in these insects.     

The computer program structure for assigning individuals to populations: easy to use but easier to misuse

The computer program Structure implements a Bayesian method, based on a population genetics model, to assign individuals to their source populations using genetic marker data. It is widely applied in the fields of ecology, evolutionary biology, human genetics and conservation biology for detecting hidden genetic structures, inferring the most likely number of populations (K), assigning individuals to source populations and estimating admixture and migration rates. Recently, several simulation studies repeatedly concluded that the program yields erroneous inferences when samples from different populations are highly unbalanced in size. Analysing both simulated and empirical data sets, this study confirms that Structure indeed yields poor individual assignments to source populations and gives frequently incorrect estimates of K when sampling is unbalanced. However, this poor performance is mainly caused by the adoption of the default ancestry prior, which assumes all source populations contribute equally to the pooled sample of individuals. When the alternative ancestry prior, which allows for unequal representations of the source populations by the sample, is adopted, accurate individual assignments could be obtained even if sampling is highly unbalanced. The alternative prior also improves the inference of K by two estimators, albeit the improvement is not as much as that in individual assignments to populations. For the difficult case of many populations and unbalanced sampling, a rarely used parameter combination of the alternative ancestry prior, an initial ALPHA value much smaller than the default and the uncorrelated allele frequency model is required for Structure to yield accurate inferences. I conclude that Structure is easy to use but is easier to misuse because of its complicated genetic model and many parameter (prior) options which may not be obvious to choose, and suggest using multiple plausible models (parameters) and K estimators in conducting comparative and exploratory Structure analysis.     

GENETIC VARIATION IN CACTOPHILIC DROSOPHILA FOR OVIPOSITION ON NATURAL YEAST SUBSTRATES

Theory predicts that environmental heterogeneity in space or in time can maintain genetic polymorphism. Stable polymorphisms are expected to be more readily maintained if there are genotype specific habitat preferences. Genotype specific preferences for oviposition sites in Drosophila could be a major factor promoting habitat selection, and thus the maintenance of genetic variation. This hypothesis is being tested using the cactophilic species, D. buzzatii and D. aldrichi, where available evidence indicates a potential for such habitat selection, the habitats (oviposition sites) being yeast species found in the natural environment of these flies (cactus rots). Genetic variation for oviposition preferences was tested using isofemale lines—for D. buzzatii, a total of 60 lines from seven localities widely distributed through the species range in Australia, and for D. aldrichi, 21 lines from three of these localities. Females were given a choice of five yeast species as oviposition sites. Genetic variation for oviposition preferences on these natural substrates was demonstrated. There was significant variation among isofemale lines within populations in their patterns of preferences for oviposition on the five yeast species. However, analyses of preferences for each yeast species separately showed that the genetic variation for preferences relates to only three of the five species. Heritabilities of individual female preferences for these three species were low, ranging up to 9%. Little geographic differentiation was apparent among populations, most likely due to similar selection regimes within each population. Within populations, this kind of habitat selection could act to maintain polymorphisms, both at loci determining the habitat preferences and at other loci in linkage disequilibrium with them.     

Citizenship and Resource Competition in Nigeria

This article discusses the growing tension between constitutionally defined citizenship and socially accepted practices of “we–they dichotomies” as a turbulent component of the national question discourse in Nigeria. It examines the adoption of dual citizenship across the country as well as how this generates violent ethnic conflict. Importantly, while citizenship refers to one’s full membership of a sovereign political community acquired either by birth, naturalisation or any other process legitimised and recognised by the supreme law of the state, indigeneship, on the other hand, is a discriminatory policy employed by local or provincial governments for protecting the rights of their so–called indigenous populations to employment, political power and other resources of the regions or states against domination by alien populations and outsiders. It is argued that while such distinctions have been made possible inter alia by Nigeria’s multi–ethnic character, the ensuing struggles and tensions have been driven by the normless competition over resource allocation. These have especially been the case in instances where ethno–territorial cleavages have been the primary beneficiaries and targets of such resource allocation. This article discusses land as a major economic resource over which heated ethnic conflicts have taken place in Nigeria. Drawing on the conflicts between Hausa–Fulani pastoralists and Yoruba farmers in South–Western Nigeria, it examines the question of how disputed access to land and water has underlain an almost permanent basis of conflict in Nigeria as well as their implications for the country’s fledgling democracy. How does the struggle over land affect the articulation of the citizenship question in Nigeria? How have scarcity and competition over resources affected the contest over citizenship and the forging of nationhood among natives and settlers in South–Western Nigeria? How have colonial framings of socially accepted practices of indigeneship entrenched an understanding of the state in Nigeria as a representation of permanently defined subnational conceptions of ethnic citizenship? What role can the state in Nigeria play towards transforming the multiplicities of traditional societies into coherent political societies as a basis for (i) eliciting deference and devotion from the individual to the claims of the state, and ultimately for (ii) increasing cultural homogeneity, political integration and value consensus? Drawing on data generated from an ethnographic study carried out in South–Western Nigeria between October 2009 and March 2015, this study interrogates these questions.     

The limits of post-national citizenship: European Muslims,human rights and the hijab

Innovative approaches to citizenship emerged in the 1990s. Post-national theory suggested that European minorities no longer needed national citizenship because supra-national political structures such as the European Court of Human Rights (ECtHR) offered them protections. Denationalized citizenship held that universal human rights were now available at the national level too as the Council of Europe's member countries had to incorporate human rights principles within their own jurisdictions. New forms of claims-making among European Muslims were cited as evidence of this trend as religious claims, especially relating to the hijab, began to be made through human rights litigation. This paper demonstrates the limits of post-nationalism through a discussion of the outcomes of such claims. While European Muslims are indeed mobilizing around human rights, there is no evidence – at the level of litigation – that this has helped them to win recognition of their religious or cultural rights. This paper explores the reasons for this.     

The ecology and evolution of partial migration

Partial migration, where populations of animals are composed of a mixture of resident and migratory individuals, is a widespread phenomenon in nature. It has been reported to occur in all major vertebrate groups, and can have significant ecological consequences. Here we give an overview of the ecology and evolution of partial migration in animals. We firstly review the different types of partial migration, and assess the ecological drivers responsible for driving individual differences in migratory tendency within populations. A variety of factors can be important in promoting the evolution of partial migration, including competition for resources or breeding opportunities, predation risk and intraspecific niche diversity. Often various factors act synergistically to create complex patterns of movement polymorphism within populations. The question of how partial migration is maintained over evolutionary timescales is also addressed. Whilst many theoretical considerations of partial migration utilise an evolutionary stable state (ESS) paradigm, empirical evidence for this is lacking. Rather the evidence suggests that partial migration is mostly condition dependent, and the optimum outcome for an individual is dependent upon its phenotype. What determines whether an individual follows a migratory or resident strategy is discussed in light of new theory and empirical data which supports the idea that environmentally responsive genetic thresholds are important across a range of species, from birds to fish, in proximately shaping migratory tendency. Finally we espouse our vision of how partial migration research will develop in the future, and suggest a number of exciting directions that studies into migratory dimorphism may take in the coming years.     

Characterizing population and individual migration patterns among native and restored bighorn sheep (Ovis canadensis)

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Social structure of Atlantic spotted dolphins,Stenella frontalis,following environmental disturbance and demographic changes

Extreme environmental events and demographic changes can have variable effects on the social structure of animal populations. This study compared the social structure of a community of Atlantic spotted dolphins in the Bahamas before and after two hurricanes. Approximately 36% of the individuals were lost, with no subsequent increase in immigration. The majority of the social structure characteristics were consistent with results from a long‐term study covering the previous 12 yr, including community structure with definitive social clusters, sex preferences and overall association patterns. However some changes occurred, though still constrained within sex preferences. Posthurricane there was a decrease in social differentiation and increased cohesion within clusters and across age class. Males retained or made new first order alliances, however, only one second order alliance was evident, revealing a simplified alliance structure. Juvenile individuals made alliance level associations, unprecedented from long‐term analysis. Although other studies have shown stark restructuring, this study showed that less drastic changes within overall social structure stability can occur. Persistence and evolutionary changes in populations through environmental and/or demographic perturbations may depend on the social structure of a population or community. Understanding the processes involved in social development is paramount for conservation of diverse populations.     

Do evolutionary constraints on thermal performance manifest at different organizational scales?

The two foremost hypotheses on the evolutionary constraints on an organism's thermal sensitivity – the hotter‐is‐better expectation, and the specialist–generalist trade‐off – have received mixed support from empirical studies testing for their existence. Could these conflicting results reflect confusion regarding the organizational level (i.e. species > population > individual) at which these constraints should manifest? We propose that these evolutionary constraints should manifest at different organizational levels because of differences in their underlying causes and requirements. The hotter‐is‐better expectation should only manifest across separate evolutionary units (e.g. species, populations), and not within populations. The specialist–generalist trade‐off, by contrast, should manifest within as well as between separate evolutionary units. We measured the thermal sensitivity of sprint performance for 440 rainforest sun skinks (Lampropholis coggeri) representing 10 populations, and used the resulting performance curves to test for evidence for the hypothesized constraints at two organizational levels: (i) across populations and (ii) within populations. As predicted, the hotter‐is‐better expectation was evident only at the across‐population level, whereas the specialist–generalist trade‐off was evident within, as well as across, populations. Our results suggest that, depending on the processes that drive them, evolutionary constraints can manifest at different organizational levels. Consideration of these underlying processes, and the organizational level at which a constraint should manifest, may help resolve conflicting empirical results.     

No evidence for size‐assortative mating in the wild despite mutual mate choice in sex‐role‐reversed pipefishes

Size‐assortative mating is a nonrandom association of body size between members of mating pairs and is expected to be common in species with mutual preferences for body size. In this study, we investigated whether there is direct evidence for size‐assortative mating in two species of pipefishes, Syngnathus floridae and S. typhle, that share the characteristics of male pregnancy, sex‐role reversal, and a polygynandrous mating system. We take advantage of microsatellite‐based “genetic‐capture” techniques to match wild‐caught females with female genotypes reconstructed from broods of pregnant males and use these data to explore patterns of size‐assortative mating in these species. We also develop a simulation model to explore how positive, negative, and antagonistic preferences of each sex for body size affect size‐assortative mating. Contrary to expectations, we were unable to find any evidence of size‐assortative mating in either species at different geographic locations or at different sampling times. Furthermore, two traits that potentially confer a fitness advantage in terms of reproductive success, female mating order and number of eggs transferred per female, do not affect pairing patterns in the wild. Results from model simulations demonstrate that strong mating preferences are unlikely to explain the observed patterns of mating in the studied populations. Our study shows that individual mating preferences, as ascertained by laboratory‐based mating trials, can be decoupled from realized patterns of mating in the wild, and therefore, field studies are also necessary to determine actual patterns of mate choice in nature. We conclude that this disconnect between preferences and assortative mating is likely due to ecological constraints and multiple mating that may limit mate choice in natural populations.     

Can migrants escape from density dependence?

Migration is thought to maximize growth by enabling individuals to escape from density dependence, but this has rarely been tested at the individual level in natural populations. We employed linear mixed modeling of the spacing between consecutive scale growth rings to reconstruct individual growth profiles of a paradigmatic fish migrant, the sea trout (Salmo trutta) and related these to estimates of year class strength over a 13‐year period. Variation in scale growth was 1.3 times greater among individuals than within individuals in freshwater and 10 times greater at sea. Scale growth was inversely related to year class strength, both in freshwater (before migration) and at sea (after migration). Competition for patchily distributed resources is the most plausible explanation of the negative density‐dependent growth observed in freshwater and, to a lesser extent, in the marine environment. Our study provides some of the strongest evidence for a role of density dependence in determining partial migrations because although migrants can maximize growth by moving into the sea, they do not appear to become free from density dependence constraints completely. This has implications for conservation and suggests that sea trout and other anadromous fish displaying partial migrations may not be best managed on a river by river basis, but rather from a broader, coastal perspective.     

Extreme levels of intra-specific divergence among Cape Peninsula populations of the Cape galaxias,Galaxias zebratus Castelnau 1861, reveals a possible species complex

The Cape galaxias, Galaxias zebratus, is part of the paleao-endemic fauna characteristic of the south-western Cape, South Africa, and is the only galaxiid found in continental Africa. A 284-bp fragment of the cytochrome b region of the mtDNA was sequenced from 48 individual galaxiids, representing 10 populations from the Cape Peninsula. Five sequences, for four additional populations sampled at the extremes of the species range, were obtained from the literature. Analysis of cyt b mtDNA from these 14 populations of G. zebratus revealed five distinct and highly divergent lineages with low levels of intra-population mtDNA haplotype diversity. A new and distinct genetic lineage is described from the southern part of the Cape Peninsula. Estimates of genetic divergence between populations ranged from <1% to >17%. The observed level of sequence divergence represents the largest yet reported for any single fish species. The distribution of these lineages and their degree of sequence divergence refutes a model of isolation by distance. Results suggest that periods of low sea level may have been important in creating opportunities and alternative routes for dispersal and migration for Cape Peninsula populations.     

Comparative ecology of Gammarus pulex (L.) and Asellus aquaticus (L.) II: fungal preferences

This paper continues to explore niche differentiation in Gammarus pulex and Asellus aquaticus by analysis of their food preferences. Individuals from both species discriminated between leaf discs colonized by different fungal species and exhibited strong preferences for Anguillospora longissima and Heliscus lugdunensis. Fungal preferences were not correlated with the relative abundance of fungi in the field and there was considerable intra-population variability in food preferences — both between individuals and for the same individual through time. Niche overlap between animals from all four study populations was high and there was no evidence of differences in the potential trophic niches of animals from sympatric and allopatric populations.     

Spatial and temporal genetic differentiation and effective population size of brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis>, L.) in small Danish rivers

The spatial and temporal genetic structure of brown trout populations from three small tributaries of Lake Hald, Denmark, was studied using analysis of variation at eight microsatellite loci. From two of the populations temporal samples were available, separated by up to 13 years (3.7 generations). Significant genetic differentiation was observed among all samples, however, hierarchical analysis of molecular variance (AMOVA) showed that differentiation among populations accounted for a non-significant amount of the genetic differentiation, whereas differentiation among temporal samples within populations was highly significant (0.0244, P<0.001). Estimates of effective population size (N _e) using a maximum-likelihood based implementation of the temporal method, yielded small values (N _e ranging from 33 to 79). When a model was applied that allows for migration among populations, N _e estimates were even lower (24–54), and migration rates were suggested to be high (0.13–0.36). All samples displayed a clear signal of a recent bottleneck, probably stemming from a period of unfavourable conditions due to organic pollution in the 1970–1980’s. By comparison to other estimates of N _e in brown trout, Lake Hald trout represent a system of small populations linked by extensive gene flow, whereas other populations in larger rivers exhibit much higher N _e values and experience lower levels of immigration. We suggest that management considerations for systems like Lake Hald brown trout should focus both on a regional scale and at the level of individual populations, as the future persistence of populations depends both on maintaining individual populations and ensuring sufficient migration links among these populations.     

Unraveling the relative contribution of inter‐ and intrapopulation functional variability in wild populations of a tadpole species

Functional traits are increasingly recognized as an integrative approach by ecologists to quantify a key facet of biodiversity. And these traits are primarily expressed as species means in previous studies, based on the assumption that the effects of intraspecific variability can be overridden by interspecific variability when studying functional ecology at the community level. However, given that intraspecific variability could also have important effects on community dynamics and ecosystem functioning, empirical studies are needed to investigate the importance of intraspecific variability in functional traits. In this study, 256 Scutiger boulengeri tadpole individuals from four different populations are used to quantify the functional difference between populations within a species, and the relative contribution of inter‐ and intrapopulation variability in functional traits. Our results demonstrate that these four populations differ significantly in functional attributes (i.e., functional position, functional richness, and low functional overlap), indicating that individuals from different populations within a species should be explicitly accounted for in functional studies. We also find similar relative contribution of inter‐ (~56%) and intrapopulation (~44%) variation to the total variability between individuals, providing evidence that individuals within populations should also be incorporated in functional studies. Overall, our results support the recent claims that intraspecific variability cannot be ignored, as well as the general idea of “individual level” research in functional ecology.