Environmental determinants of Ixodes ricinus ticks and the incidence of Borrelia burgdorferi sensu lato, the agent of Lyme borreliosis, in Scotland.

Lyme borreliosis (LB) is the most common arthropod-borne disease of humans in the Northern hemisphere. In Europe, the causative agent, Borrelia burgdorferi sensu lato complex, is principally vectored by Ixodes ricinus ticks. The aim of this study was to identify environmental factors influencing questing I. ricinus nymph abundance and B. burgdorferi s.l. infection in questing nymphs using a large-scale survey across Scotland. Ticks, host dung and vegetation were surveyed at 25 woodland sites, and climatic variables from a Geographical Information System (GIS) were extracted for each site. A total of 2397 10 m2 transect surveys were conducted and 13 250 I. ricinus nymphs counted. Questing nymphs were assayed for B. burgdorferi s.l. and the average infection prevalence was 5·6% (range 0·8-13·9%). More questing nymphs and higher incidence of B. burgdorferi s.l. infection were found in areas with higher deer abundance and in mixed/deciduous compared to coniferous forests, as well as weaker correlations with season, altitude, rainfall and ground vegetation. No correlation was found between nymph abundance and infection prevalence within the ranges encountered. An understanding of the environmental conditions associated with tick abundance and pathogen prevalence may be used to reduce risk of exposure and to predict future pathogen prevalence and distributions under environmental changes.

Landscape genetics of a top neotropical predator.

Habitat loss and fragmentation as a consequence of human activities is a worldwide phenomenon and one of the major threats to global biodiversity. Habitat loss and fragmentation is particularly a concern in the biodiverse tropics, where deforestation is occurring at unprecedented rates. Although insects are one of the most diverse and functionally important groups in tropical ecosystems, the quantitative effect of landscape features on their gene flow remains unknown. Here, we used a robust landscape genetics approach to quantify the effect of ten landscape features (deforestation, mature forests, other forest types, the River Chagres, streams, stream banks, roads, sea, lakes and swamps) and interactions between them, on the gene flow of a neotropical forest keystone species, the army ant Eciton burchellii. The influence of landscape on E. burchellii's gene flow reflected the different dispersal capability of its sexes; aerial for males and pedestrian for females, and the different depths of population history inferred from microsatellites and mitochondrial DNA. In contrast to the gene flow-facilitating effect of mature forests, deforested areas were found to be strong barriers for E. burchellii's gene flow. Other forest types were found to be gene flow facilitators but only when interacting with mature secondary forests, therefore indicating the importance of mature forests for the survival of E. burchelii and its associate species. The River Chagres was identified as a major historical gene flow barrier for E. burchellii, suggesting that an important loss of connectivity may occur because of large artificial waterways such as the Panama Canal.

Ultradian activity rhythms in large groups of newly hatched chicks (Gallus gallus domesticus).

A clutch of young chicks housed with a mother hen exhibit ultradian (within day) rhythms of activity corresponding to the brooding cycle of the hen. In the present study clear evidence was found of ultradian activity rhythms in newly hatched domestic chicks housed in groups larger than natural clutch size without a mother hen or any other obvious external time-keeper. No consistent synchrony was found between groups housed in different pens within the same room. The ultradian rhythms disappeared with time and little evidence of group rhythmicity remained by the third night. This disappearance over time suggests that the presence of a mother hen may be pivotal for the long-term maintenance of these rhythms. The ultradian rhythm of the chicks may also play an important role in the initiation of brooding cycles during the behavioural transition of the mother hen from incubation to brooding. Computer simulations of individual activity rhythms were found to reproduce the observations made on a group basis. This was achievable even when individual chick rhythms were modelled as independent of each other, thus no assumptions of social facilitation are necessary to obtain ultradian activity rhythms on a group level.

Landscape features affect gene flow of Scottish Highland red deer (Cervus elaphus).

Landscape features have been shown to strongly influence dispersal and, consequently, the genetic population structure of organisms. Studies quantifying the effect of landscape features on gene flow of large mammals with high dispersal capabilities are rare and have mainly been focused at large geographical scales. In this study, we assessed the influence of several natural and human-made landscape features on red deer gene flow in the Scottish Highlands by analysing 695 individuals for 21 microsatellite markers. Despite the relatively small scale of the study area (115 x 87 km), significant population structure was found using F-statistics (F(ST) = 0.019) and the program structure, with major differentiation found between populations sampled on either side of the main geographical barrier (the Great Glen). To assess the effect of landscape features on red deer population structure, the ArcMap GIS was used to create cost-distance matrices for moving between populations, using a range of cost values for each of the landscape features under consideration. Landscape features were shown to significantly affect red deer gene flow as they explained a greater proportion of the genetic variation than the geographical distance between populations. Sea lochs were found to be the most important red deer gene flow barriers in our study area, followed by mountain slopes, roads and forests. Inland lochs and rivers were identified as landscape features that might facilitate gene flow of red deer. Additionally, we explored the effect of choosing arbitrary cell cost values to construct least cost-distance matrices and described a method for improving the selection of cell cost values for a particular landscape feature.