Selection for outbreeding in Varroa parasitising resistant honey bee (Apis mellifera) colonies

Parasitism is expected to select for counter‐adaptations in the host: driving a coevolutionary arms race. However, human interference between honey bees (Apis mellifera) and Varroa mites removes the effect of natural selection and restricts the evolution of host counter‐adaptations. With full‐sibling mating common among Varroa, this can rapidly select for virulent, highly inbred, Varroa populations. We investigated how the evolution of host resistance could affect the infesting population of Varroa mites. We screened a Varroa‐resistant honey bee population near Toulouse, France, for a Varroa resistance trait: the inhibition of Varroa's reproduction in drone pupae. We then genotyped Varroa which had co‐infested a cell using microsatellites. Across all resistant honey bee colonies, Varroa's reproductive success was significantly higher in co‐infested cells but the distribution of Varroa between singly and multiply infested cells was not different from random. While there was a trend for increased reproductive success when Varroa of differing haplotypes co‐infested a cell, this was not significant. This suggests local mate competition, through the presence of another Varroa foundress in a pupal cell, may be enough to help Varroa overcome host resistance traits; with a critical mass of infesting Varroa overwhelming host resistance. However, the fitness trade‐offs associated with preferentially co‐infesting cells may be too high for Varroa to evolve a mechanism to identify already‐infested cells. The increased reproductive success of Varroa when co‐infesting resistant pupal cells may act as a release valve on the selective pressure for the evolution of counter resistance traits: helping to maintain a stable host–parasite relationship.     

Inconsistent detection of extinction debts using different methods

The extinction debt, delayed species extinctions following landscape degradation, is a widely discussed concept. But a consensus about the prevalence of extinctions debts is hindered by a multiplicity of methods and a lack of comparisons among habitats. We applied three contrasting species–area relationship methods to test for plant community extinction debts in three habitats which had different degradation histories over the last century: calcareous grassland, heathland and woodland. These methods differ in their data requirements, with the first two using information on past and current habitat area alongside current species richness, whilst the last method also requires data on past species richness. The most data‐intensive, and hence arguably most reliable method, identified extinction debts across all habitats for specialist species, whilst the other methods did not. All methods detected an extinction debt in calcareous grassland, which had undergone the most severe degradation. We conclude that some methods failed to detect an extinction debt, particularly in habitats that have undergone moderate degradation. Data on past species numbers are required for the most reliable method; as such data are rare, extinction debts may be under‐reported.     

A reconsideration of Gallicolumba (Aves: Columbidae) relationships using fresh source material reveals pseudogenes,chimeras, and a novel phylogenetic hypothesis

Phylogenetic analyses of nuclear and mitochondrial DNA sequences were used to test a recent phylogenetic hypothesis for the avian genus Gallicolumba that relied heavily on preserved museum study skins for DNA samples. Our comparisons show that several published gene sequences represent pseudogenes or chimeras of multiple taxa, and these sequences had an adverse influence on phylogeny estimation. A new phylogenetic hypothesis strongly supports the monophyly of Philippine bleeding-hearts, the monophyly of Gallicolumba sensu stricto, and places Leucosarcia as part of an Australasian radiation rather than sister to Alopecoenas. These findings clarify Gallicolumba biogeography and also highlight the need for greater caution in the use of suboptimal source material in molecular systematic studies.     

Science,Uncertainty, and Values in Ecological Restoration: A Case Study in Structured Decision‐Making and Adaptive Management

This article demonstrates a structured and collaborative approach to decision‐making in the context of adaptive management experiments, using a case study involving the restoration of a hydrological regime in a regulated river in western Canada. It provides a framework based on principles of decision analysis for structuring difficult multi‐attribute decisions and building the trust and technical capacity needed to implement them. Participants included ecologists and fisheries biologists, government regulators, electric utility employees, and representatives of aboriginal communities. The case study demonstrates a values‐based approach to implementing adaptive management that addresses some of the long‐standing difficulties associated with integrating adaptive management into restoration decisions. It highlights practical methods for incorporating participants' values concerned with learning, cultural quality, and stewardship as part of developing a decision‐making and monitoring framework for restoration initiatives. It also provides an example of how to implement principles of meaningful consultation in a restoration context, with emphasis on ensuring that all voices and concerns are heard and meaningfully incorporated. Participants have adopted the framework as a model to guide future collaborative decision‐making processes involving Aboriginal communities, regulatory agencies, and other parties.     

Working with living krill – the people and the places

The fascination of Antarctic scientists with Antarctic krill and their capabilities has a long and varied history, and prompted many scientists to maintain and manipulate krill under laboratory conditions. Starting in the Discovery era with Mackintosh at the King Edward Point labs on South Georgia, 1930, scientists have collected krill from sailing vessels, small boats, inflatable zodiacs and large ice-breaking vessels. Krill have been maintained in small and large jars, deep rectangular tanks, large round tanks and in flow-through and recycling systems. They have been maintained both on board research vessels and in laboratories, in flowing seawater systems at ambient conditions and in temperature-controlled environmental rooms. A few researchers have transported living krill back to their home laboratories, for example tropical laboratories in Japan (Murano) and Australia (Ikeda), temperate laboratories (Nicol) in Australia, a northern European laboratory in Germany (Marschall) and a sunny maritime laboratory in California (Ross and Quetin). The goals have been varied: short-term experiments to understand in situ physiological rates, long-term experiments to test the effects of manipulations or controlled changes in environmental conditions, and behavioral responses. We take you on a brief historical tour as we trace the lineage of modern day research on living Antarctic krill.     

Pulsed magnetohydrodynamic blood flow in a rigid vessel under physiological pressure gradient

Blood flow in a steady magnetic field has been of great interest over recent years. Many researchers have examined the effects of magnetic fields on velocity profiles and arterial pressure, and major studies have focused on steady or sinusoidal flows. In this paper, we present a solution for pulsed magnetohydrodynamic blood flow with a somewhat realistic physiological pressure wave obtained using a Windkessel lumped model. A pressure gradient is derived along a rigid vessel placed at the output of a compliant module which receives the ventricle outflow. Then, velocity profile and flow rate expressions are derived in the rigid vessel in the presence of a steady transverse magnetic field. As expected, results showed flow retardation and flattening. The adaptability of our solution approach allowed a comparison with previously addressed flow cases and calculations presented a good coherence with those well established solutions.     

Preservation and Paleoenvironmental Significance of a Footprinted Surface on the Sandai Plain,Lake Bogoria,Kenya Rift Valley

An exhumed late Pleistocene land surface on the deltaic Sandai Plain north of Lake Bogoria, Kenya, preserves traces of bovids, suids, birds, and at least one hominid. The host sediments (Loboi Silts) are reddish brown, poorly bedded siltstones, mudstones and silty sandstones that were probably deposited in a shallow closed-basin lake. Most of the prints were impressed on exposed, moist lake-marginal mudflats. Print distribution is patchy due to a complex interaction between biogenic and sedimentological factors. The preservation of a single hominid track provides a fortuitous addition to the sparse hominid track record in East Africa. Field, petrographic, and mineralogical analyses of the fossil substrate were undertaken to determine how the footprinted surface was preserved. Comparison with modern lake-marginal processes suggests that the prints were initially stabilized by desiccation, soil-crusting, and organic films, followed by cementation of the surface sediments by calcite and analcime, with minor authigenic clay minerals and Fe-Mn-oxihydroxides. The zeolites formed by reaction of detrital silicates with saline, alkaline groundwater; calcite was precipitated from dilute runoff and fresher groundwaters. Cementation likely occurred during a prolonged period of relatively low, stable lake level. Following cementation, the surface was buried by Holocene lake sediments, then recently exhumed.