Deterministic processes structure bacterial genetic communities across an urban landscape

Land-use change is predicted to act as a driver of zoonotic disease emergence through human exposure to novel microbial diversity, but evidence for the effects of environmental change on microbial communities in vertebrates is lacking. We sample wild birds at 99 wildlife-livestock-human interfaces across Nairobi, Kenya, and use whole genome sequencing to characterise bacterial genes known to be carried on mobile genetic elements (MGEs) within avian-borne Escherichia coli (n=241). By modelling the diversity of bacterial genes encoding virulence and antimicrobial resistance (AMR) against ecological and anthropogenic forms of urban environmental change, we demonstrate that communities of avian-borne bacterial genes are shaped by the assemblage of co-existing avian, livestock and human communities, and the habitat within which they exist. In showing that non-random processes structure bacterial genetic communities in urban wildlife, these findings suggest that it should be possible to forecast the effects of urban land-use change on microbial diversity

The genetic sex-determination system predicts adult sex ratios in tetrapods

The adult sex ratio (ASR) has critical effects on behaviour, ecology and population dynamics, but the causes of variation in ASRs are unclear. Here we assess whether the type of genetic sex determination influences the ASR using data from 344 species in 117 families of tetrapods. We show that taxa with female heterogamety have a significantly more male-biased ASR (proportion of males: 0.55 ± 0.01 (mean ± s.e.m.)) than taxa with male heterogamety (0.43 ± 0.01). The genetic sex-determination system explains 24% of interspecific variation in ASRs in amphibians and 36% in reptiles. We consider several genetic factors that could contribute to this pattern, including meiotic drive and sex-linked deleterious mutations, but further work is needed to quantify their effects. Regardless of the mechanism, the effects of the genetic sex-determination system on the adult sex ratio are likely to have profound effects on the demography and social behaviour of tetrapods.</p

Male incubation in Northern Lapwings: effects on egg temperature and potential benefits to females

The Northern Lapwing Vanellus vanellus is a polygynous shorebird where both parents incubate . However, males show great individual variation with respect to incubation constancy, possibly resulting in variable degrees of incubation costs in females. Here, the influence of male incubation on egg temperature at the end of female recesses is examined by using a theoretical model of egg cooling combined with observations of incubation rhythm and ambient temperature. Estimated egg temperatures were higher after male incubation than when the nests were left uncovered, and consequently eggs were warmer on average in nests with higher male attentiveness . I suggest that this results in higher costs of egg re-warming in females that are less helped by their males in incubation . Moreover, ambient temperatures in the period of observations never exceeded 20°C. Still, egg temperatures were significantly higher than the presumed physiological zero temperature (25°C) with male intermittent incubation . However, there was no difference when males were absent during recesses . These results could potentially indicate fitness benefits to female Northern Lapwings, male care influencing length of incubation periods and embryo survival . Such trends could not be detected in this study, though

Dispersal and age at first breeding in Norwegian Northern Lapwings (Vanellus vanellus)

Dispersal and age at first breeding were studied in Northern Lapwings from south Norway. In total, 40 adult birds (twomales) and 114 chicks were colour-ringed. Therewere no sex differences in returning rates of birds ringed as chicks (n = 10males and 14 females). Norwere there sex differences in natal and breeding dispersal distances.When sexes were pooled, natal dispersal was longer than breeding dispersal (median distances 160 m and 62 m, respectively). Also, colour-ringed females were more likely than males to breed in their second calendar year. Analyses of a separate data set of regular ring recoveries largely confirmed the relatively low degree of natal dispersal in Norwegian Northern Lapwings. In total, 72% of birds reported during the breeding season (total n = 104) were found within 10 kmfrom their natal site.Dispersal distances observed inNorway are similar to those reported from a comprehensive British study, and from Europe in general

Migrating Lesser Spotted Woodpeckers Dendrocopos minor along the coast of southern Norweay: where do they come from?

The Lesser SpottedWoodpecker (Dendrocopos minor) is a partialmigrant in Fennoscandia, where migratory autumn irruptions outside the regular breeding areas occur in some years. Little is known about themigration of this species along the coast of southern Norway, but such migrants might have an eastern origin. We evaluated this hypothesis, and the possibility that birds come from a more local population, by correlating the numbers ringed at Lista Bird Observatory with breeding-population indices from three regions: Sweden,Møre og Romsdal and Agder. Overall, 99 birds were trapped and ringed at Lista in autumn during 1989–2008 (median = 3.5, range 0–19). We found no correlation between numbers caught at Lista and the population indices fromMøre og Romsdal. There was, however, a significant positive correlation between Lista numbers and the population index from the local Agder region. Breeding-population indices from Sweden were acquired from (1) long-term (1975–2009) summer point counts in observer-chosen routes, and (2) a combination of point counts and line transects along fixed routes systematically distributed across the country (1998–2008). Population trends differed somewhat between these two methods, the latter indicating an increasing population size whereas the former showed a more stable situation. The fixed-routes data were positively correlated with Lista catch numbers, whereas the indices from summer point counts were not. These results suggest that migrating Lesser SpottedWoodpeckers captured in autumn at Lista Bird Observatorymay come from an extensive area in Scandinavia, including more local regions. There was no sex bias in the captured birds, but 98% were in their first year. Hence, migration intensity probably reflects reproductive output in source populations

Red-spotted Bluethroats Luscinia s. svecica migrate along the Indo-European flyway: a geolocator study

Capsule Red-spotted Bluethroats Luscinia s. svecica from two European breeding populations spent the boreal winter on the Indian sub-continent. Aim Tracking the migration of Red-spotted Bluethroats from Europe to the hitherto unknown non-breeding areas and back. Methods Light-level geolocators were deployed on male Bluethroats at breeding sites in the Czech Republic (n = 10) and in Norway (n = 30). Recorded light intensity data were used to estimate the locations of non-breeding sites and migration phenology during the annual cycle. Results Bluethroats spent the boreal winter in India (n = 3) and Pakistan (n = 1), on average more than 6000 km from their breeding areas. Autumn migration started in August (n = 1) or early September (n = 2), and lasted for 26–74 days. Spring migration commenced on 8 and 9 April (n = 2) and lasted for about a month. During both autumn and spring migration, birds stopped over two or three times for more than 3 days. Conclusion This study for the first time showed where Red-spotted Bluethroats from European breeding populations stay during the boreal winter. This seems to be the first time that a passerine bird has been tracked along the Indo-European flyway