Spatial clustering of drug-resistant tuberculosis in Hlabisa subdistrict, KwaZulu-Natal, 2011-2015.

SETTING: Incidencerates of tuberculosis (TB) in South Africa are among the highest in the world, and drug resistance is a major concern. Understanding geographic variations in disease may guide targeted interventions. OBJECTIVE: To characterise the spatial distribution of drug-resistant TB (DR-TB) in a rural area of KwaZulu-Natal, South Africa, and to test for clustering. DESIGN: This was a cross-sectional analysis of DR-TB patients managed at a rural district hospital from 2011 to 2015. We mapped all patients in hospital data to local areas, and then linked to a population-based demographic surveillance system to map the patients to individual homesteads. We used kernel density estimation to visualise the distribution of disease and tested for clustering using spatial scan statistics. RESULTS: There were 489 patients with DR-TB in the subdistrict; 111 lived in the smaller demographic surveillance area. Spatial clustering analysis identified a high-risk cluster (relative risk of DR-TB inside vs. outside cluster 3.0, P < 0.001) in the south-east, a region characterised by high population density and a high prevalence of human immunodeficiency virus infection. CONCLUSION: We have demonstrated evidence of a geographic high-risk cluster of DR-TB. This suggests that targeting interventions to spatial areas of highest risk, where transmission may be ongoing, could be effective

Increased allocation to reproduction reduces future competitive ability in a burying beetle

1. The existence of a trade-off between current and future reproduction is a fundamental prediction of life-history theory. Support for this prediction comes from brood size manipulations, showing that caring for enlarged broods often reduces the parent's future survival or fecundity. However, in many species, individuals must invest in competing for the resources required for future reproduction. Thus, a neglected aspect of this trade-off is that increased allocation to current reproduction may reduce an individual's future competitive ability. 2. We tested this prediction in the burying beetle, Nicrophorus vespilloides, a species where parents care for their offspring and where there is fierce competition for resources used for breeding. 3. We manipulated reproductive effort by providing females with either a small brood of 10 larvae or a large brood of 40 larvae and compared the ability of these females, and virgin females that had no prior access to a carcass, to compete for a second carcass against a virgin competitor. 4. We found that increased allocation to current reproduction reduced future competitive ability, as females that had cared for a small brood were more successful when competing for a second carcass against a virgin competitor than females that had cared for a large brood. In addition, the costs of reproduction were offset by the benefits of feeding from the carcass during an initial breeding attempt, as females that had cared for a small brood were better competitors than virgin females that had no prior access to a carcass, whilst females that had cared for a large brood were similar in competitive ability to virgin females. 5. Our results add to our understanding of the trade-off between current and future reproduction by showing that this trade-off can manifest through differences in future competitive ability and that direct benefits of reproduction can offset some of these costs. 16-Apr-2020Read me for "Data from RichardsonStephensSmiseth_JournalofAnimalEcology.csv" This data file consists of a comma separated values spreadsheet (.csv), which provides data for the effects of allocation to reproduction via brood size manipulation on future competitive ability in contests for a carcass. Each line in the spreadsheet represents an individual, experimental female. female_id – individual ID of the female. eclosion – date of eclosion. death – date of death. lifespan – number of days lived from eclosion to death. treatment_code – experimental treatment (control = no breeding attempt, ten = brood of ten larvae, forty = brood of forty larvae). won – outcome of the contest (Y = female won, N = female lost, NA = unclear). outcome_clear – was the outcome of the contest clear? (Y = yes, N = no). size – size of the female, measured as pronotum width (mm). competitor_size – size of the virgin female competitor measured as pronotum width (mm). size_difference – absolute difference in size between focal female and her competitor (mm). brood_size – number of larvae in the experimental brood at dispersal. dot – number and placement of identifying marks (1 or 2 = number of dots, L or R = left or right elytra). female_pre_mass – female mass prior to initial reproductive attempt (g). female_post_mass – female mass after initial reproductive attempt (g). female_mass_change – female mass change during initial reproductive attempt (g). brood_mass_pre – mass of the brood of larvae when cross fostered and given to the female (g). brood_mass_post – mass of the brood of larvae at dispersal from the carcass (g). breeding_carcass_mass – mass of the mouse carcass used for breeding (g). competition_carcass_mass – mass of the mouse carcass females competed for (g). Funding provided by: Natural Environment Research CouncilCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000270Award Number: NE/L002558/

Dynamics in numbers of group-roosting individuals in relation to pair-sleeping occurrence and onset of egg-laying in European Bee-eaters Merops apiaster

Sleeping in the nest at the beginning of the breeding season is common for birds nesting in cavities. Here, we report evidence that European Bee-eaters Merops apiaster sleep in pairs in the nesting burrow. In 3.2 % of the nest checks we found two individuals sleeping together. This behaviour ceased once hatching started. A decrease in the number of birds at a communal roost coincided with the incidences of pair-sleeping and initiation of egg-laying. Thus, checking the burrows of European Bee-eaters at beginning of the breeding season increases the chance of observing pair-sleeping

Does the use of nest materials in a ground-nesting bird result from a compromise between the risk of egg overheating and camouflage?

Many studies addressing the use of nest materials by animals have focused on only one factor to explain its function. However, the consideration of more than one factor could explain the apparently maladaptive choice of nest materials that make nests conspicuous to predators. We experimentally tested whether there is a trade-off in the use of nest materials between the risks of egg predation versus protection from overheating. We studied the ground-nesting Kentish plover, Charadrius alexandrinus, in southern Spain. We added materials differing in thermal properties and coloration to the nests, thus affecting rates of egg heating, nest temperature and camouflage. Before these manipulations, adults selected materials that were lighter than the microhabitat, probably to buffer the risk of egg overheating. However, the adults did not keep the lightest experimental materials, probably because they reduced camouflage, and this could make the nests even more easily detectable to predators. In all nests, adults removed most of the experimental materials independently of their properties, so that egg camouflage returned to the original situation within a week of the experimental treatments. Although the thermal environment may affect the choice of nest materials by plovers, ambient temperatureswere not so high at our study site as to determine the acceptance of the lightest experimental materials

Egg investment in response to helper presence in cooperatively breeding Tibetan ground tits

Life-history theory predicts a trade-off between current and future reproduction to maximize lifetime fitness. In cooperatively breeding species, where offspring care is shared between breeders and helpers, helper presence may influence the female breeders' egg investment, and consequently, survival and future reproductive success. For example, female breeders may reduce egg investment in response to helper presence if this reduction is compensated by helpers during provisioning. Alternatively, female breeders may increase egg investment in response to helper presence if helpers allow the breeders to raise more or higher quality offspring successfully. In the facultatively cooperative-breeding Tibetan ground tit Pseudopodoces humilis, previous studies found that helpers improve total nestling provisioning rates and fledgling recruitment, but have no apparent effects on the number and body mass of fledglings produced, while breeders with helpers show reduced provisioning rates and higher survival. Here, we investigated whether some of these effects may be explained by female breeders reducing their investment in eggs in response to helper presence. In addition, we investigated whether egg investment is associated with the female breeder's future fitness. Our results showed that helper presence had no effect on the female breeders' egg investment, and that egg investment was not associated with breeder survival and reproductive success. Our findings suggest that the responses of breeders to helping should be investigated throughout the breeding cycle, because the conclusions regarding the breeders' adjustment of reproductive investment in response to being helped may depend on which stage of the breeding cycle is considered

By hook or by crook? Morphometry, competition and cooperation in rodent sperm

Background Sperm design varies enormously across species and sperm competition is thought to be a major factor influencing this variation. However, the functional significance of many sperm traits is still poorly understood. The sperm of most murid rodents are characterised by an apical hook of the sperm head that varies markedly in extent across species. In the European woodmouse Apodemus sylvaticus (Muridae), the highly reflected apical hook of sperm is used to form sperm groups, or “trains,” which exhibited increased swimming velocity and thrusting force compared to individual sperm. Methodology/Principal Findings Here we use a comparative study of murine rodent sperm and demonstrate that the apical hook and sperm cooperation are likely to be general adaptations to sperm competition in rodents. We found that species with relatively larger testes, and therefore more intense sperm competition, have a longer, more reflected apical sperm hook. In addition, we show that sperm groups also occur in rodents other than the European woodmouse. Conclusions Our results suggest that in rodents sperm cooperation is more widespread than assumed so far and highlight the importance of diploid versus haploid selection in the evolution of sperm design and function

Dynamics of phenotypic change: wing length declines in a resident farmland passerine despite survival advantage of longer wings

In many taxa, environmental changes that alter resource availability and energetics, such as climate change and land use change, are associated with changes in body size. We use wing length as a proxy for overall structural body size to examine a paradoxical trend of declining wing length within a Yellowhammer Emberiza citrinella population sampled over 21 years, in which it has been previously shown that longer wings are associated with higher survival rates. Higher temperatures during the previous winter (prior to the moult determining current wing length) explained 23% of wing length decrease within our population, but changes may also be correlated with non-climatic environmental variation such as changes in farming mechanisms linked to food availability. We found no evidence for within-individual wing length shrinkage with age, but our data suggested a progressive decline in the sizes of immature birds recruiting to the population. This trend was weaker, although not significantly so, among adults, suggesting that the decline in the sizes of recruits was offset by higher subsequent survival of larger birds post-recruitment. These data suggest that ecological processes can contribute more than selection to observed phenotypic trends and highlight the importance of long-term studies for providing longitudinal insights into population processes