Mires in the Maluti Mountains of Lesotho.

Contains fulltext : 149842.pdf (publisher's version ) (Open Access)11 p

Functional traits of trees on and off termite mounds:Understanding the origin of biotically-driven heterogeneity in savannas

Questions In African savannas, Macrotermes termites contribute to small-scale heterogeneity by constructing large mounds. Operating as islands of high nutrient and water availability and low fire frequency, these mounds support distinct, diverse communities of trees that have been shown to be highly attractive to browsers. However, the distinct traits of tree species on termite mounds have hardly been studied, even though this may help to understand processes determining (1) their characteristic community structure and (2) attractiveness for browsers. Here, we compare functional trait and browser preference values between tree species on and off termite mounds. Location Hluhluwe-iMfolozi Park, Kwazulu-Natal, South Africa. Methods We recorded tree community compositions for 16 large Macrotermes natalensis mounds and 16 control plots of 100 m2 each in a paired design. For each observed tree species we measured 22 traits, related to water and nutrient use, fire tolerance, light competition and anti-herbivore defence, and compared average trait values between mound and control communities. Furthermore, we investigated the feeding preferences of ungulate browsers for the most common tree species and how this was linked to their associated traits. Results Termite mounds supported tree communities that were distinct from the surrounding savanna vegetation. Mounds hosted more evergreen and less leguminous tree species than control communities, and the dominant species were less mechanically defended, less nutritious, had larger leaves and lower wood density than the species dominating control plots. Browsers preferred leguminous tree species with high leaf N and P content, which were relatively rare on termite mounds. Conclusions Overall, we conclude that termite mounds in this savanna form small refuges for tree species that seem less adapted to fire (more evergreens), have low nutrient availability (less nitrogen fixers) and suffer from water stress (larger leaf sizes) than typical savanna trees. Surprisingly, despite their reputation as browsing hotspots, the tree species dominating mounds are less nutritious and less preferred by browsers than tree species of the surrounding savanna, which may be explained by the relatively nutrient-rich nature of this savanna or intraspecific trait differences

State dependence explains individual variation in nest defence behaviour in a long-lived bird

Parental care, such as nest or offspring defence, is crucial for offspring survival in many species. Yet, despite its obvious fitness benefits, the level of defence can consistently vary between individuals of the same species. One prominent adaptive explanation for consistent individual differences in behaviours involves state dependency: relatively stable differences in individual state should lead to the emergence of repeatable behavioural variation whereas changes in state should lead to a readjustment of behaviour. Therefore, empirical testing of adaptive state dependence requires longitudinal data where behaviour and state of individuals of the same population are repeatedly measured. Here, we test if variation in states predicts nest defence behaviour (a 'risky' behaviour) in a long-lived species, the barnacle goose Branta leucopsis. Adaptive models have predicted that an individual's residual reproductive value or 'asset' is an important state variable underlying variation in risk-taking behaviour. Hence, we investigate how nest defence varies as a function of time of the season and individual age, two state variables that can vary between and within individuals and determine asset. Repeated measures of nest defence towards a human intruder (flight initiation distance or FID) of females of known age were collected during 15 breeding seasons. Increasing values of FID represent increasing shyness. We found that females strongly and consistently differed in FID within- and between-years. As predicted by theory, females adjusted their behaviour to state by decreasing their FID with season and age. Decomposing these population patterns into within- and between-individual effects showed that the state-dependent change in FID was driven by individual plasticity in FID and that bolder females were more plastic than shyer females. This study shows that nest defence behaviour differs consistently among individuals and is adjusted to individual state in a direction predicted by adaptive personality theory

A phase II study of paclitaxel in heavily pretreated patients with small-cell lung cancer.

The purpose of the study was to delineate the efficacy and toxicity of paclitaxel (Taxol, Bristol Myers Squibb) in the treatment of drug resistant small-cell lung cancer (SCLC). Patients with SCLC relapsing within 3 months of cytotoxic therapy received paclitaxel 175 mg m(-2) intravenously over 3 h every 3 weeks. The dose of paclitaxel was adjusted to the toxicity encountered in the previous cycle. Of 24 patients entered into the study, 24 and 21 were assessable for response and toxicity respectively. There were two early deaths and two toxic deaths. No complete and seven partial responses (29%) (95%CI 12-51%) were observed and five patients had disease stabilization. The median survival (n = 21) was 100 days. Life-threatening toxicity occurred in four patients; in others (non)-haematological toxicity was manageable. Paclitaxel is active in drug-resistant SCLC. Further investigation in combination with other active agents in this poor prognosis group is appropriate

Experimentally quantifying the effect of nest-site depth on the predation risk and breeding success of Blue Tits

Predation is a key factor in the nesting preferences of birds. Studies indicate that cavity-breeding birds prefer deeper nest sites, possibly because they are more safe from predation. We studied the Blue Tit (Cyanistes caeruleus), a cavity-breeding passerine, to test (1) whether nest-site depth affects breeding success and (2) whether potential effects of nest-site depth on breeding success are related to predation risk. We performed 2 experiments to separate effects of nest-box depth from potential effects of the quality of the breeding pair. In the first (free-choice) experiment, Blue Tits competed for scarce deep nest boxes that were provided well before nest-box choice, enabling an association between nest-box quality and bird quality. In the second (forced-choice) experiment, we randomly altered nest-box depth after Blue Tits had chosen a nest box, thus disconnecting the association between nest-box quality and bird quality. We found no evidence that the occurrence of signs of predation was related to nest-box depth. However, we did find clear positive effects of nest-box depth (1) on clutch size and hatching success throughout the study area and (2) on fledging success, the number of fledglings, and the overall probability of nest success, specifically in parts of the study area with high predation. We found no indication of independent effects of parental quality on breeding success. Parents also seemed to perceive the shallower boxes as more risky; in shallower boxes, nest thickness was decreased, irrespective of the local predation pressure during the free-choice experiment. Parents nesting in shallow boxes may have had lower breeding success because of (1) increased actual (but undetected) predation and (2) reduced reproductive investment by parents, based on the latter's experience with predation or an evolutionary response to past predation risk