Continental-scale patterns of pathogen prevalence: a case study on the corncrake

Pathogen infections can represent a substantial threat to wild populations, especially those already limited in size. To determine how much variation in the pathogens observed among fragmented populations is caused by ecological factors, one needs to examine systems where host genetic diversity is consistent among the populations, thus controlling for any potentially confounding genetic effects. Here, we report geographic variation in haemosporidian infection among European populations of corncrake. This species now occurs in fragmented populations, but there is little genetic structure and equally high levels of genetic diversity among these populations. We observed a longitudinal gradient of prevalence from western to Eastern Europe negatively correlated with national agricultural yield, but positively correlated with corncrake census population sizes when only the most widespread lineage is considered. This likely reveals a possible impact of local agriculture intensity, which reduced host population densities in Western Europe and, potentially, insect vector abundance, thus reducing the transmission of pathogens. We conclude that in the corncrake system, where metapopulation dynamics resulted in variations in local census population sizes, but not in the genetic impoverishment of these populations, anthropogenic activity has led to a reduction in host populations and pathogen prevalence

Cost effectiveness of a community based prevention and treatment of acute malnutrition programme in Mumbai slums, India

Children in slums are at high risk of acute malnutrition and death. Cost-effectiveness of community-based management of severe acute malnutrition programmes has been demonstrated previously, but there is limited evidence in the context of urban slums where programme cost structure is likely to vary tremendously. This study assessed the cost-utility of adding a community based prevention and treatment for acute malnutrition intervention to Government of India Integrated Child Development Services (ICDS) standard care for children in Mumbai slums. The intervention is delivered by community health workers in collaboration with ICDS Anganwadi community health workers. The analysis used a decision tree model to compare the costs and effects of the two options: standard ICDS services with the intervention and prevention versus standard ICDS services alone. The model used outcome and cost data from the Society for Nutrition, Education & Health Action's Child Health and Nutrition programme in Mumbai slums, which delivered services to 12,362 children over one year from 2013 to 2014. An activity-based cost model was used, with calculated costs based on programme financial records and key informant interviews. Cost data were coupled with programme effectiveness data to estimate disability adjusted life years (DALYs) averted. The community based prevention and treatment programme averted 15,016 DALYs (95% Uncertainty Interval [UI]: 12,246-17,843) at an estimated cost of $23 per DALY averted (95%UI:19-28) and was thus highly cost-effective. This study shows that ICDS Anganwadi community health workers can work efficiently with community health workers to increase the prevention and treatment coverage in slums in India and can lead to policy recommendations at the state, and potentially the national level, to promote such programmes in Indian slums as a cost-effective approach to tackling moderate and severe acute malnutrition

The genetic basis of color-related local adaptation in a ring-like colonization around the Mediterranean.

Uncovering the genetic basis of phenotypic variation and the population history under which it established is key to understand the trajectories along which local adaptation evolves. Here, we investigated the genetic basis and evolutionary history of a clinal plumage color polymorphism in European barn owls (Tyto alba). Our results suggest that barn owls colonized the Western Palearctic in a ring-like manner around the Mediterranean and meet in secondary contact in Greece. Rufous coloration appears to be linked to a recently evolved nonsynonymous-derived variant of the melanocortin 1 receptor (MC1R) gene, which according to quantitative genetic analyses evolved under local adaptation during or following the colonization of Central Europe. Admixture patterns and linkage disequilibrium between the neutral genetic background and color found exclusively within the secondary contact zone suggest limited introgression at secondary contact. These results from a system reminiscent of ring species provide a striking example of how local adaptation can evolve from derived genetic variation

Photolariats: synthesis, metal ion complexation and photochromism

International audiencePhotolariat development, as an extension to the family of synthetic photochromic crown ether receptors, or photocrowns, is reported. Incorporated additional chelating groups, namely two anisoles or thioanisoles, contribute in completing the metal ion coordination sphere with different affinities and selectivities for a range of ions. Single-crystal X-ray diffraction analysis suggests that the thermally stable trans-form of the receptor is unsuitable for ion binding, consistent with spectrophotometric and NMR titration results, which is largely improved in the cis-form as the basis for the photocontrolled ion coordination/ejection. In terms of the azobenzene-containing receptor photochemistry, a photostationary state highly enriched in the cis-form (94:6, cis-/trans-) is reached, with slow thermal return (1.1-1.4 × 10− 5 s− 1) in the dark, which can undergo multiple cycles without discernable photodegradation

Cirsium species show disparity in patterns of genetic variation at their range-edge, despite similar patterns of reproduction and isolation

Genetic variation was assessed across the UK geographical range of Cirsium acaule and Cirsium heterophyllum. A decline in genetic diversity and increase in population divergence approaching the range edge of these species was predicted based on parallel declines in population density and seed production reported seperately. Patterns were compared with UK populations of the widespread Cirsium arvense.Populations were sampled along a latitudinal transect in the UK and genetic variation assessed using microsatellite markers. Cirsium acaule shows strong isolation by distance, a significant decline in diversity and an increase in divergence among range-edge populations. Geographical structure is also evident in C. arvense, whereas no such patterns are seen in C.heterophyllum. There is a major disparity between patterns of genetic variation in C. acaule and C. heterophyllum despite very similar patterns in seed production and population isolation in these species. This suggests it may be misleading to make assumptions about the geographical structure of genetic variation within species based solely on the present-day reproduction and distribution of populations

Genomic basis of insularity and ecological divergence in barn owls (Tyto alba) of the Canary Islands.

Islands, and the particular organisms that populate them, have long fascinated biologists. Due to their isolation, islands offer unique opportunities to study the effect of neutral and adaptive mechanisms in determining genomic and phenotypical divergence. In the Canary Islands, an archipelago rich in endemics, the barn owl (Tyto alba), present in all the islands, is thought to have diverged into a subspecies (T. a. gracilirostris) on the eastern ones, Fuerteventura and Lanzarote. Taking advantage of 40 whole-genomes and modern population genomics tools, we provide the first look at the origin and genetic makeup of barn owls of this archipelago. We show that the Canaries hold diverse, long-standing and monophyletic populations with a neat distinction of gene pools from the different islands. Using a new method, less sensitive to structure than classical F <sub>ST</sub> , to detect regions involved in local adaptation to insular environments, we identified a haplotype-like region likely under selection in all Canaries individuals and genes in this region suggest morphological adaptations to insularity. In the eastern islands, where the subspecies is present, genomic traces of selection pinpoint signs of adapted body proportions and blood pressure, consistent with the smaller size of this population living in a hot arid climate. In turn, genomic regions under selection in the western barn owls from Tenerife showed an enrichment in genes linked to hypoxia, a potential response to inhabiting a small island with a marked altitudinal gradient. Our results illustrate the interplay of neutral and adaptive forces in shaping divergence and early onset speciation

Living on the edge: how philopatry maintains adaptive potential

Without genetic variation, species cannot cope with changing environments, and evolution does not proceed. In endangered species, adaptive potential may be eroded by decreased population sizes and processes that further reduce gene flow such as philopatry and local adaptations. Here, we focused on the philopatric and endangered loggerhead sea turtle (Caretta caretta) nesting in Cape Verde as a model system to investigate the link between adaptive potential and philopatry. We produced a dataset of three complementary genomic regions to investigate female philopatric behaviour (mitochondrial DNA), male-mediated gene flow (microsatellites) and adaptive potential (major histocompatibility complex, MHC). Results revealed genetically distinct nesting colonies, indicating remarkably small-scale philopatric behaviour of females. Furthermore, these colonies also harboured local pools of MHC alleles, especially at the margins of the population's distribution, which are therefore important reserves of additional diversity for the population. Meanwhile, directional male-mediated gene flow from the margins of distribution sustains the adaptive potential for the entire rookery. We therefore present the first evidence for a positive association between philopatry and locally adapted genomic regions. Contrary to expectation, we propose that philopatry conserves a high adaptive potential at the margins of a distribution, while asymmetric gene flow maintains genetic connectivity with the rest of the population

How a haemosporidian parasite of bats gets around: the genetic structure of a parasite, vector and host compared.

Parasite population structure is often thought to be largely shaped by that of its host. In the case of a parasite with a complex life cycle, two host species, each with their own patterns of demography and migration, spread the parasite. However, the population structure of the parasite is predicted to resemble only that of the most vagile host species. In this study, we tested this prediction in the context of a vector-transmitted parasite. We sampled the haemosporidian parasite Polychromophilus melanipherus across its European range, together with its bat fly vector Nycteribia schmidlii and its host, the bent-winged bat Miniopterus schreibersii. Based on microsatellite analyses, the wingless vector, and not the bat host, was identified as the least structured population and should therefore be considered the most vagile host. Genetic distance matrices were compared for all three species based on a mitochondrial DNA fragment. Both host and vector populations followed an isolation-by-distance pattern across the Mediterranean, but not the parasite. Mantel tests found no correlation between the parasite and either the host or vector populations. We therefore found no support for our hypothesis; the parasite population structure matched neither vector nor host. Instead, we propose a model where the parasite's gene flow is represented by the added effects of host and vector dispersal patterns

Characterization of microsatellite markers in the tsetse fly, Glossina pallidipes

Glossina pallidipes is a vector of African trypanosomiasis. Here we characterize eight new polymorphic microsatellite loci in 288 G. pallidipes sampled from 12 Kenya populations. The number of alleles per locus ranged from four to 36 with a mean of 20.5 ± 10.1. Expected single locus heterozygosities varied from 0.044 to 0.829. Heterozygosity averaged 0.616 ± 0.246. No linkage disequilibrium was found. We also report results in eight other tsetse species estimated by using the primers developed in G. pallidipes. The primers worked best in G. swynnertoni and G. austeni and worst in G. m. morsitans and G. m. submorsitans

Cost effectiveness of a community based prevention and treatment of acute malnutrition programme in Mumbai slums, India

Children in slums are at high risk of acute malnutrition and death. Cost-effectiveness of community-based management of severe acute malnutrition programmes has been demonstrated previously, but there is limited evidence in the context of urban slums where programme cost structure is likely to vary tremendously. This study assessed the cost-utility of adding a community based prevention and treatment for acute malnutrition intervention to Government of India Integrated Child Development Services (ICDS) standard care for children in Mumbai slums. The intervention is delivered by community health workers in collaboration with ICDS Anganwadi community health workers. The analysis used a decision tree model to compare the costs and effects of the two options: standard ICDS services with the intervention and prevention versus standard ICDS services alone. The model used outcome and cost data from the Society for Nutrition, Education & Health Action’s Child Health and Nutrition programme in Mumbai slums, which delivered services to 12,362 children over one year from 2013 to 2014. An activity-based cost model was used, with calculated costs based on programme financial records and key informant interviews. Cost data were coupled with programme effectiveness data to estimate disability adjusted life years (DALYs) averted. The community based prevention and treatment programme averted 15,016 DALYs (95% Uncertainty Interval [UI]: 12,246–17,843) at an estimated cost of $23 per DALY averted (95%UI:19–28) and was thus highly cost-effective. This study shows that ICDS Anganwadi community health workers can work efficiently with community health workers to increase the prevention and treatment coverage in slums in India and can lead to policy recommendations at the state, and potentially the national level, to promote such programmes in Indian slums as a cost-effective approach to tackling moderate and severe acute malnutrition