The fitness consequences of kin-biased dispersal in a cooperatively breeding bird

Cooperative alliances among kin may not only lead to indirect fitness benefits for group-living species, but can also provide direct benefits through access to mates or higher social rank. However, the immigrant sex in most species loses any potential benefits of living with kin unless immigrants disperse together or recruit relatives into the group in subsequent years. To look for evidence of small subgroups of related immigrants within social groups (kin substructure), we used microsatellites to assess relatedness between immigrant females of the cooperatively breeding superb starling, Lamprotornis superbus. We determined how timing of immigration led to kin subgroup formation and if being part of one influenced female fitness. Although mean relatedness in groups was higher for males than females, 26% of immigrant females were part of a kin subgroup with a sister. These immigrant sibships formed through kin recruitment across years more often than through coalitions immigrating together in the same year. Furthermore, females were more likely to breed when part of a kin subgroup than when alone, suggesting that female siblings form alliances that may positively influence their fitness. Ultimately, kin substructure should be considered when determining the role of relatedness in the evolution of animal societies.     

Fine‐scale spatiotemporal patterns of genetic variation reflect budding dispersal coupled with strong natal philopatry in a cooperatively breeding mammal

The relatedness structure of animal populations is thought to be a critically important factor underlying the evolution of mating systems and social behaviours. While previous work has shown that population structure is shaped by many biological processes, few studies have investigated how these factors vary over time. Consequently, we explored the fine‐scale spatiotemporal genetic structure of an intensively studied population of cooperatively breeding banded mongooses (Mungos mungo) over a 10‐year period. Overall population structure was strong (average F_ST = 0.129) but groups with spatially overlapping territories were not more genetically similar to one another than noncontiguous groups. Instead, genetic differentiation was associated with historical group‐fission (budding) events, with new groups diverging from their parent groups over time. Within groups, relatedness was high within but not between the sexes, although the latter increased over time since group formation due to group founders being replaced by philopatric young. This trend was not mirrored by a decrease in average offspring heterozygosity over time, suggesting that close inbreeding may often be avoided, even when immigration into established groups is virtually absent and opportunities for extra‐group matings are rare. Fine‐scale spatiotemporal population structure could have important implications in social species, where relatedness between interacting individuals is a vital component in the evolution of patterns of inbreeding avoidance, reproductive skew and kin‐selected helping and harming.     

Immigration and gene flow in a northern willow tit (Parus montanus) population

To study quantitatively the relationship between immigration rate and gene flow we used 9-year data from a willow tit Parus montanus population in a continuous forest habitat. We compared components of lifetime reproductive success, and parental survival rate between immigrant and resident (‘status’) birds by taking individual age into consideration also. Of the fitness components, survival was independent of status and sex, averaging 0.60 annually. Of the male and female breeders, on average 63.1% and 75.6%, respectively, originated from unknown natal areas, implying extensive immigration. Pair formation was nonassortative with respect to the origin of partners. The effect of status on reproductive success was significant only for females: immigrants produced larger clutches and hatched more young in all age classes studied. However, the difference between the groups diminished until fledging and the offspring produced by the immigrant females showed lower local survival rate (4.6% of the young) than did those by the residents (5.9%). Therefore, the contribution of immigrant females to the local gene pool was lower than expected on the basis of immigration rate. However, we propose that the result implies differential propensities to long-distance dispersal rather than overall survival prospects, since we detected no quality differences suggesting reduced survival chances among descendants of immigrant females. Therefore, gene flow into the population was slightly lower than immigration rate. It is possible that immigrant females are more prone to invest in progeny that effectively disperse further to search for new vacancies. The conditions prevailing during nestling growth may be crucial in determining whether an individual will later become a resident or leave the natal area, but the genetic component of this trait should also be considered. We suggest that widespread propagules is a better strategy than philopatry for a short-lived species to minimize the risk of losing all descendants in temporally and spatially varying conditions.     

Abrupt Decline in Tuberculosis among Foreign-Born Persons in the United States

While the number of reported tuberculosis (TB) cases in the United States has declined over the past two decades, TB morbidity among foreign-born persons has remained persistently elevated. A recent unexpected decline in reported TB cases among foreign-born persons beginning in 2007 provided an opportunity to examine contributing factors and inform future TB control strategies. We investigated the relative influence of three factors on the decline: 1) changes in the size of the foreign-born population through immigration and emigration, 2) changes in distribution of country of origin among foreign-born persons, and 3) changes in the TB case rates among foreign-born subpopulations. Using data from the U.S. National Tuberculosis Surveillance System and the American Community Survey, we examined TB case counts, TB case rates, and population estimates, stratified by years since U.S. entry and country of origin. Regression modeling was used to assess statistically significant changes in trend. Among foreign-born recent entrants (<3 years since U.S. entry), we found a 39.5% decline (-1,013 cases) beginning in 2007 (P<0.05 compared to 2000–2007) and ending in 2011 (P<0.05 compared to 2011–2014). Among recent entrants from Mexico, 80.7% of the decline was attributable to a decrease in population, while the declines among recent entrants from the Philippines, India, Vietnam, and China were almost exclusively (95.5%–100%) the result of decreases in TB case rates. Among foreign-born non-recent entrants (≥3 years since U.S. entry), we found an 8.9% decline (-443 cases) that resulted entirely (100%) from a decrease in the TB case rate. Both recent and non-recent entrants contributed to the decline in TB cases; factors contributing to the decline among recent entrants varied by country of origin. Strategies that impact both recent and non-recent entrants (e.g., investment in overseas TB control) as well as those that focus on non-recent entrants (e.g., expanded targeted testing of high-risk subgroups among non-recent entrants) will be necessary to achieve further declines in TB morbidity among foreign-born persons.     

Does harvest affect genetic diversity in grey wolves?

Harvest can affect vital rates such as reproduction and survival, but also genetic measures of individual and population health. Grey wolves (Canis lupus) live and breed in groups, and effective population size is a small fraction of total abundance. As a result, genetic diversity of wolves may be particularly sensitive to harvest. We evaluated how harvest affected genetic diversity and relatedness in wolves. We hypothesized that harvest would (a) reduce relatedness of individuals within groups in a subpopulation but increase relatedness of individuals between groups due to increased local immigration, (b) increase individual heterozygosity and average allelic richness across groups in subpopulations and (c) add new alleles to a subpopulation and decrease the number of private alleles in subpopulations due to an increase in breeding opportunities for unrelated individuals. We found harvest had no effect on observed heterozygosity of individuals or allelic richness at loci within subpopulations but was associated with a small, biologically insignificant effect on within‐group relatedness values in grey wolves. Harvest was, however, positively associated with increased relatedness of individuals between groups and a net gain (+16) of alleles into groups in subpopulations monitored since harvest began, although the number of private alleles in subpopulations overall declined. Harvest likely created opportunities for wolves to immigrate into nearby groups and breed, thereby making groups in subpopulations more related over time. Harvest appears to affect genetic diversity in wolves at the group and population levels, but its effects are less apparent at the individual level given the population sizes we studied.     

Niche evolution in Australian terrestrial mammals? Clarifying scale-dependencies in phylogenetic and functional drivers of co-occurrence

Interactive forces between competition and habitat filtering drive many biogeographic patterns over evolutionary time scales. However, the responsiveness of assemblages to these two forces is highly influenced by spatial scale, forming complex patterns of niche separation. We explored these spatial dependencies by quantifying the influence of phylogeny and functional traits in shaping present day native terrestrial mammal assemblages at multiple scales, principally by identifying the spatial scales at which niche evolution operates. We modelled the distribution of 53 native terrestrial mammal species across New South Wales, Australia. Using predicted distributions, we estimated the range overlap between each pair of species at increasing grain sizes (~0.8, 5.1, 20, 81, 506, 2,025, 8,100 km²). We employed a decision tree to identify how interactions among functional traits and phylogenetic relatedness translated to levels of sympatry at increasing spatial scales. We found that Australian terrestrial mammals displayed phylogenetic over-dispersion that was inversely related to spatial scale, suggesting that ecological processes were more influential than biogeographic sympatry patterns in defining assemblages of species. While the contribution of phylogenetic relatedness to patterns of co-occurrence decreased as spatial scale increased, the reverse was true for habitat preferences. At the same time, functional traits also operated at different scales, as dietary preferences dominated at local spatial scales (<10 km²) while body mass has a stronger effect at larger spatial scales. Our findings show that ecological and evolutionary processes operate at different scales and that Australian terrestrial mammals diverged slower along their micro-scale niche compared to their macro-scale niche. By combining phylogenetic and niche methods through the modelling of species distributions, we assessed whether specific traits were related to a particular niche. More importantly, conducting multi-scale spatial analysis avoids categorical assignment of traits-to-niches, providing a clearer relationship between traits and a species ecological niche and a more precise scaling for the axes of niche evolution.     

Ethnicity and race as ‘symbolic’: the use of ethnic and racial symbols in asserting a biracial identity

Contemporary research indicates that religious institutions can play bonding and bridging roles in the lives of immigrants, strengthening the bonds within immigrant groups while simultaneously connecting immigrants to the wider society. The majority of this research focuses on religious institutions in US cities with long histories of immigration and sizable immigrant populations. This article examines the role of religious institutions in the lives of refugees living in a city with a small, but rapidly growing immigrant population. Evidence from interviews with Catholic and Muslim refugees and participant observation at two houses of worship suggests that the functions of religious institutions differ for refugees from majority and minority religious traditions. Catholic refugees use their church for bonding and bridging purposes, while Muslim refugees use their mosque primarily for bonding purposes.     

Related male Drosophila melanogaster reared together as larvae fight less and sire longer lived daughters

Competition over access to reproductive opportunities can lead males to harm females. However, recent work has shown that, in Drosophila melanogaster, male competition and male harm of females are both reduced under conditions simulating male-specific population viscosity (i.e., in groups where males are related and reared with each other as larvae). Here, we seek to replicate these findings and investigate whether male population viscosity can have repercussions for the fitness of offspring in the next generation. We show that groups of unrelated-unfamiliar (i.e., unrelated individuals raised apart) males fight more intensely than groups of related-familiar males (i.e., full siblings raised together as larvae), supporting previous findings, and that exposure to a female is required to trigger these differential patterns of male–male competition. Importantly, we show that differences in male–male competition can be associated with transgenerational effects: the daughters of females exposed to unrelated-unfamiliar males suffered higher mortality than the daughters of females exposed to related-familiar males. Collectively, these results suggest that population structure (i.e., variation in the relatedness and/or larval familiarity of local male groups) can modulate male–male competition with important transgenerational consequences.     

Filtering across Spatial Scales: Phylogeny,Biogeography and Community Structure in Bumble Bees

Despite the expansion of phylogenetic community analysis to understand community assembly, few studies have used these methods on mobile organisms and it has been suggested the local scales that are typically considered may be too small to represent the community as perceived by organisms with high mobility. Mobility is believed to allow species to mediate competitive interactions quickly and thus highly mobile species may appear randomly assembled in local communities. At larger scales, however, biogeographical processes could cause communities to be either phylogenetically clustered or even. Using phylogenetic community analysis we examined patterns of relatedness and trait similarity in communities of bumble bees (Bombus) across spatial scales comparing: local communities to regional pools, regional communities to continental pools and the continental community to a global species pool. Species composition and data on tongue lengths, a key foraging trait, were used to test patterns of relatedness and trait similarity across scales. Although expected to exhibit limiting similarity, local communities were clustered both phenotypically and phylogenetically. Larger spatial scales were also found to have more phylogenetic clustering but less trait clustering. While patterns of relatedness in mobile species have previously been suggested to exhibit less structure in local communities and to be less clustered than immobile species, we suggest that mobility may actually allow communities to have more similar species that can simply limit direct competition through mobility.     

Multimorbidity and Its Patterns according to Immigrant Origin. A Nationwide Register-Based Study in Norway

Introduction

As the flows of immigrant populations increase worldwide, their heterogeneity becomes apparent with respect to the differences in the prevalence of chronic physical and mental disease. Multimorbidity provides a new framework in understanding chronic diseases holistically as the consequence of environmental, social, and personal risks that contribute to increased vulnerability to a wide variety of illnesses. There is a lack of studies on multimorbidity among immigrants compared to native-born populations.

Methodology

This nationwide multi-register study in Norway enabled us i) to study the associations between multimorbidity and immigrant origin, accounting for other known risk factors for multimorbidity such as gender, age and socioeconomic levels using logistic regression analyses, and ii) to identify patterns of multimorbidity in Norway for immigrants and Norwegian-born by means of exploratory factor analysis technique.

Results

Multimorbidity rates were lower for immigrants compared to Norwegian-born individuals, with unadjusted odds ratios (OR) and 95% confidence intervals 0.38 (0.37–0.39) for Eastern Europe, 0.58 (0.57–0.59) for Asia, Africa and Latin America, and 0.67 (0.66–0.68) for Western Europe and North America. Results remained significant after adjusting for socioeconomic factors. Similar multimorbidity disease patterns were observed among Norwegian-born and immigrants, in particular between Norwegian-born and those from Western European and North American countries. However, the complexity of patterns that emerged for the other immigrant groups was greater. Despite differences observed in the development of patterns with age, such as ischemic heart disease among immigrant women, we were unable to detect the systematic development of the multimorbidity patterns among immigrants at younger ages.

Conclusions

Our study confirms that migrants have lower multimorbidity levels compared to Norwegian-born. The greater complexity of multimorbidity patterns for some immigrant groups requires further investigation. Health care policies and practice will require a holistic approach for specific population groups in order to meet their health needs and to curb and prevent diseases.     

Behavioural and molecular evidence for selective immigration and group regulation in the social huntsman spider,Delena cancerides

Movement among social groups interacts with the costs and benefits of group‐living in complex ways. Unlike most other social spiders, the social huntsman spider, Delena cancerides, appears to enter foreign colonies, discriminates kin from non‐kin, and has very limited dispersal options because their bark retreats are rare, making this species an interesting model organism with which to examine the role of inter‐colony movement on group‐living. We examined movement among field colonies of D. cancerides in three ways: (1) by tracking the dispersal and immigration of marked spiders into foreign colonies; (2) by recording resident spiders' behaviour toward introduced immigrants; and (3) by inferring intra‐colony relatedness and immigration patterns through allozyme electrophoresis. Of the marked spiders, only young juveniles moved into neighbouring colonies, whereas subadults and adults did not. Introduced juveniles were tolerated in foreign colonies, whereas introduced adult males and subadults were usually attacked by the resident adult female, unless she had similar sized subadult/adult offspring of her own. Allozyme profiles from unmanipulated field colonies showed that 47% of sampled colonies contained at least one immigrant and that average within colony relatedness was below 0.5. These data align with previous research on the costs and benefits of group‐living for D. cancerides, suggesting that spiders actively seek and regulate group membership based on interests of both the immigrant and the colony. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

Spatiotemporal Clustering of Mycobacterium tuberculosis Complex Genotypes in Florida: Genetic Diversity Segregated by Country of Birth

BackgroundTuberculosis (TB) is caused by members of the Mycobacterium tuberculosis complex (MTBC). Although the MTBC is highly clonal, between-strain genetic diversity has been observed. In low TB incidence settings, immigration may facilitate the importation of MTBC strains with a potential to complicate TB control efforts.MethodsWe investigated the genetic diversity and spatiotemporal clustering of 2,510 MTBC strains isolated in Florida, United States, between 2009 and 2013 and genotyped using spoligotyping and 24-locus MIRU-VNTR. We mapped the genetic diversity to the centroid of patient residential zip codes using a geographic information system (GIS). We assessed transmission dynamics and the influence of immigration on genotype clustering using space-time permutation models adjusted for foreign-born population density and county-level HIV risk and multinomial models stratified by country of birth and timing of immigration in SaTScan.Conclusions/SignificanceAlmost five percent of TB cases reported in Florida during 2009–2013 were potentially due to recent transmission. Improvements to TB screening practices among the prison population and recent immigrants are likely to impact TB control. Due to the monomorphic nature of available markers, whole genome sequencing is needed to conclusively delineate recent transmission events between U.S. and foreign-born persons.     

Quantifying the contribution of immigration to population dynamics: a review of methods,evidence and perspectives in birds and mammals

The demography of a population is often reduced to the apparent (or local) survival of individuals and their realised fecundity within a study area defined according to logistical constraints rather than landscape features. Such demographics are then used to infer whether a local population contributes positively to population dynamics across a wider landscape context. Such a simplistic approach ignores a fundamental process underpinning population dynamics: dispersal. Indeed, it has long been accepted that immigration contributed by dispersers that emigrated from neighbouring populations may strongly influence the net growth of a local population. To date however, we lack a clear picture of how widely immigration rate varies both among and within populations, in relation to extrinsic and intrinsic ecological conditions, even for the best‐studied avian and mammalian populations. This empirical knowledge gap precludes the emergence of a sound conceptual framework that ought to inform conservation and population ecology. This review, conducted on both birds and mammals, has thus three complementary objectives. First, we describe and evaluate the relative merits of methods used to quantify immigration and how they relate to widely applicable metrics. We identify two simple and unifying metrics to measure immigration: the immigration rate i_t defined as the ratio of the number of immigrants present in the population at time t + 1 and the total breeding population in year t, and π_t , the proportion of immigrants among new recruits (i.e. new breeders). Two recently developed methods are likely to provide the most valuable data on immigration in the near future: individual parentage (rather than population) assignments based on genetic sampling, and spatially explicit integrated population models combining multiple sources of demographic data (survival, fecundity and population counts). Second, we report on a systematic literature review of studies providing a quantitative measure of immigration. Although the diversity of methods employed precludes detailed analyses, it appears that the number of immigrants exceeds locally born individuals in recruitment for most avian populations (median π_t  = 0.57, N = 45 estimates from 37 studies), a figure twofold higher than estimated for mammalian populations (median π_t  = 0.26, N = 33 estimates from 11 studies). Third, recent quantitative studies reveal that immigration can be the main driver of temporal variation in population growth rates, across a wide array of demographic and spatial contexts. To what extent immigration acts as a regulatory process has however been considered only rarely to date and deserves more attention. Overall, it is likely that most populations benefit from immigrants without necessarily being sink populations. Furthermore, we suggest that quantitative estimates of immigration should be core to future demographic studies and plead for more empirical evidence about the ways in which immigration interacts with local demographic processes to shape population dynamics. Finally, we discuss how to tackle spatial population dynamics by exploring, beyond the classical source–sink framework, the extent to which populations exchange individuals according to spatial scale and type of population distribution throughout the landscape.     

Size and socio-economic resources of core discussion networks in the Netherlands: differences by national-origin group and immigrant generation

This study examines differences in the size and socio-economic resources of core discussion networks across national-origin groups and immigrant generation. The analysis is based on the Netherlands Longitudinal Lifecourse Study (2008–10), a nationally representative, large-scale survey of the Dutch population that contains an over-sample of first- and second-generation immigrants from Turkey and Morocco, the two largest non-western immigrant groups in the Netherlands. Results show that Dutch majority members have larger and more resourceful core discussion networks than Turks and Moroccans. Second-generation immigrants from Turkey and Morocco have larger core discussion networks than their foreign-born parents. However, there is no clear evidence for intergenerational increase in resources. The larger and more resourceful core discussion networks of the Dutch are partly attributable to the Dutch being higher educated and employed more often.     

Coexistence and invasibility in a two-species competition model with habitat-preference

The outcome of competition among species is influenced by the spatial distribution of species and effects such as demographic stochasticity, immigration fluxes, and the existence of preferred habitats. We introduce an individual-based model describing the competition of two species and incorporating all the above ingredients. We find that the presence of habitat preference—generating spatial niches—strongly stabilizes the coexistence of the two species. Eliminating habitat preference—neutral dynamics—the model generates patterns, such as distribution of population sizes, practically identical to those obtained in the presence of habitat preference, provided an higher immigration rate is considered. Notwithstanding the similarity in the population distribution, we show that invasibility properties depend on habitat preference in a non-trivial way. In particular, the neutral model results more invasible or less invasible depending on whether the comparison is made at equal immigration rate or at equal distribution of population size, respectively. We discuss the relevance of these results for the interpretation of invasibility experiments and the species occupancy of preferred habitats.     

Highlighting the contrasts,downplaying the divergences: insertion and visibility tactics of Brazilians in Portugal

Although many scholars point to the importance of gender in structuring the immigrant experience, many immigrant women themselves do not attribute much importance to the role that gender plays in their lives. To explore this issue further, we investigate how thirty-two foreign-born Latinas define their experiences in Utah, a new immigrant destination that has received little empirical attention. The women in our sample indicated five major challenges they faced in their everyday lives: social isolation, language difficulty, racial-ethnic prejudice, poverty and lack of documentation. Most of the women described these challenges in terms of social class, race-ethnicity and immigrant status, rather than gender. We argue that migration research needs to be more attuned to axes of oppression other than gender and more attentive to how immigrant women, themselves, interpret their everyday lives.     

Gene flow and immigration rate in an island population of great tits

It is generally recognized that immigration and gene flow cannot be equated, but few detailed quantitative comparisons of these processes have been made over the entire lifetime of individual animals. We analyzed data collected in a longterm study of an island population of great tits Parus major, and tested two assumptions frequently made in population genetic studies. (1) The assumption that there is no difference in reproductive output between immigrant and resident breeding birds was refuted for females but not for males. Lifetime production of local recruits (LRS) was reduced by 37% in immigrant females, because female immigrants tended to leave the island after breeding, and thus reproduced for fewer years. Female LRS was density dependent, but the effect of density was independent of status (resident/immigrant). (2) The assumption that mating was random with respect to status was also refuted: assortative mating was found, even when temporal and spatial aggregation of immigrants was controlled for. Thus both assumptions were refuted, and gene flow was lower than immigration rate.     

Extra‐pair offspring are less heterozygous than within‐pair offspring in American redstarts Setophaga ruticilla

The vast majority of bird species are socially monogamous; however, extra‐pair paternity is nearly ubiquitous and a number of theories have been proposed to explain the prevalence of this mixed mating strategy. Here, we test the genetic compatibility hypothesis – the idea that females seek extra‐pair copulations with males whose genes are more compatible with her own. For this study, we examined eight years of paternity data (2004–2011) from a Nearctic‐Neotropical migratory bird, the American redstart Setophaga ruticilla, breeding in southeastern Ontario, Canada. We predicted that females paired with genetically similar males (higher relatedness) would be more likely to produce extra‐pair offspring and that extra‐pair offspring would have higher levels of heterozygosity than within‐pair offspring. Alternatively, because this population experiences high levels of immigration, females may produce extra‐pair offspring with more genetically similar males because of the potential for outbreeding depression. Using five highly variable microsatellite markers, we examined patterns of relatedness among social pairs as well as measures of offspring heterozygosity. In contrast to our predictions, we found no difference in relatedness between social pairs where the females produced extra‐pair offspring and social pairs where the females produced only within‐pair offspring. However, extra‐pair offspring were significantly less heterozygous than within‐pair offspring. Together, these findings suggest that females a) are not engaging in extra‐pair fertilizations based on relatedness to their social mate and b) appear to be mating with extra‐pair males that are more genetically similar to themselves. We suggest there may be benefits for females to mate with genetically similar extra‐pair males in highly outbred populations with high rates of immigration, such as for maintaining co‐adapted gene complexes or genes coding for local adaptations.     

Labour market competition and immigration attitudes in an established gateway

Although anti-immigrant sentiment is often attributed to economic competition with foreign-born workers, research has provided contradictory results. This paper combines survey and occupation data to re-examine the relationship between immigration attitudes and labour market competition in Houston, an established immigration gateway. I analyse data from multiple waves of the Houston Area Survey and the American Community Survey, the Bureau of Labor Statistics, and O*NET. Results indicate that labour market competition is associated with preferences for reducing immigration in Houston. Those working in occupations with recent increases in the number of foreign-born workers, that require less education, and that have higher rates of unemployment are more likely to prefer to reduce future legal immigration, even after controlling for perceived economic and cultural threats. These results support other research at the occupation and industry levels and suggest that labour market competition is a factor in shaping immigration attitudes.