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

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/

Sea buckthorn berries <i>Hippophae rhamnoides</i> L. predict size and composition of a great tit population <i>Parus major</i> L.

In seasonal environments variation in food abundance in the non-breeding season is thought to affect songbird population dynamics. In a unique tit-sea buckthorn berry system we can estimate the berry abundance and both the tit consumption and population dynamics. Six hundred nest boxes were available to great and blue tits Cyanistes caeruleus for breeding in spring and roosting in winter. We followed the dynamics including the recapture histories of individually marked great tits from 2008 to 2014. In each year we estimated 1) the winter sea buckthorn berry availability, 2) an index of berry consumption in December based on the colour of the faeces of roosting birds, 3) the number of breeding great and blue tits, 4) both recapture probability and the return rate of the great tits and 5) immigration rates. December berry abundance positively predicted the number of breeding pairs of both species in the subsequent season and great tit return rates in the second half of the winter. There was support for a sex specific berry effect on the adult return rate in the great tit: female return rate was associated less strongly to berry abundance than male return rate. This skewed the sex ratio of the local breeders in the following breeding season. Intriguingly, annual berry consumption in December was not related to berry abundance, and individuals consuming more berries tended to have slightly lower return rates. Reproductive rate was not related to berry abundance. There was hardly support for a relation between immigration rates of first year breeders and berry abundance. Taken together these results imply that berry stock not only affected population size but also the population composition through sex specific exchange with the surroundings. Since population density covaried with berry abundance, density dependent effects provide an alternative explanation for the patterns observed

Analyzing hierarchical multi-view MRI data with StaPLR: an application to Alzheimer's disease classification

Multivariate analysis of psychological dat

Cloaking and Holography Experiments Using Immersive Boundary Conditions

ISSN:2331-701

Probing Tectonic Topography in the Aftermath of Continental Convergence in Central Europe

Continental topography is at the interface of processes taking place at depth in the Earth,at its surface,and above it.Topography influences society, not only in terms of slow processes of landscape change and earthquakes,but also in terms of how it affects climate.The Pannonian Basin–Carpathian Orogen System in Central and Eastern Europe represents a key natural laboratory for the development of a new generation of models for ongoing orogeny and its effect on continental topography development (Figure 1).This system comprises some of the best documented sedimentary basins in the world,located within the Alpine orogenic belt, at the transition between the western European lithosphere and the East European Craton. It includes one of the most active seismic zones in Europe,with intermediate depth (50–220 km) mantle earthquakes of significant magnitude occurring in a geographically restricted area in the Vrancea zone of southeastern Romania

Visual ecology of aphids – a critical review on the role of colours in host finding

We review the rich literature on behavioural responses of aphids (Hemiptera: Aphididae) to stimuli of different colours. Only in one species there are adequate physiological data on spectral sensitivity to explain behaviour crisply in mechanistic terms. Because of the great interest in aphid responses to coloured targets from an evolutionary, ecological and applied perspective, there is a substantial need to expand these studies to more species of aphids, and to quantify spectral properties of stimuli rigorously. We show that aphid responses to colours, at least for some species, are likely based on a specific colour opponency mechanism, with positive input from the green domain of the spectrum and negative input from the blue and/or UV region. We further demonstrate that the usual yellow preference of aphids encountered in field experiments is not a true colour preference but involves additional brightness effects. We discuss the implications for agriculture and sensory ecology, with special respect to the recent debate on autumn leaf colouration. We illustrate that recent evolutionary theories concerning aphid–tree interactions imply far-reaching assumptions on aphid responses to colours that are not likely to hold. Finally we also discuss the implications for developing and optimising strategies of aphid control and monitoring

Versterken van de positie van de school in de regio

Samen met studenten werken aan een betere toekomst voor de regio. Dat is regioleren. Ondernemers, overheden en maatschappelijke organisaties bepalen de agenda en werken samen met onderwijs en onderzoek aan oplossingen. Waar liggen de uitdagingen? Voor de instellingen is het een belangrijke uitdaging om aansluiting te vinden bij de regio. Hoe verander je van een onderwijsinstelling in een regionaal kenniscentrum? Hoe wordt je een volwaardige partner in een kenniswerkplaats? Een tweede belangrijke uitdaging ligt in de koppeling van het leren in de regio aan de lerende regio. In het programma Regionale Transitie is deze taak bij de kenniswerkplaatsen gelegd. De kenniswerkplaats is gebaseerd op een gezamenlijke regionale kennisagenda van overheid, ondernemers, maatschappelijke organisaties, onderwijs en onderzoek

Clinical course of cone dystrophy caused by mutations in the RPGR gene

Contains fulltext : 97720.pdf (publisher's version ) (Closed access)BACKGROUND: Mutations in the RPGR gene predominantly cause rod photoreceptor disorders with a large variability in clinical course. In this report, we describe two families with mutations in this gene and cone involvement. METHODS: We investigated an X-linked cone dystrophy family (1) with 25 affected males, 25 female carriers, and 21 non-carriers, as well as a small family (2) with one affected and one unaffected male. The RPGR gene was analyzed by direct sequencing. All medical records were evaluated, and all available data on visual acuity, color vision testing, ophthalmoscopy, fundus photography, fundus autofluorescence, Goldmann perimetry, SD-OCT, dark adaptation, and full-field electroretinography (ERG) were registered. Cumulative risks of visual loss were studied with Kaplan-Meier product-limit survival analysis. RESULTS: Both families had a frameshift mutation in ORF15 of the RPGR gene; family 1 had p.Ser1107ValfsX4, and family 2 had p.His1100GlnfsX10. Mean follow up was 13 years (SD 10). Virtually all affected males showed reduced photopic and normal scotopic responses on ERG. Fifty percent of the patients had a visual acuity of <0.5 at age 35 years (SE 2.2), and 75% of the patients was legally blind at age 60 years (SE 2.3). Female carriers showed no signs of ocular involvement. CONCLUSIONS: This report describes the clinical course and visual prognosis in two families with cone dystrophy due to RPGR mutations in the 3' terminal region of ORF15. Remarkable features were the consistent, late-onset phenotype, the severe visual outcome, and the non-expression in female carriers. Expression of RPGR mutations in this particular region appears to be relatively homogeneous and predisposed to cones