Latest Papers from the Royal Society Journals

Please find below the summaries of papers in Biology Letters, Proceedings B and Proceedings A that are due to be published this week on FirstCite®, the Royal Society's new rapid online publication service.

BIOLOGY LETTERS

Female choice of young sperm in a genetically monogamous bird by Dr RH Wagner, Dr F Helfenstein and Dr E Danchin

In the black-legged kittiwake Rissa tridactyla, a monogamous seabird, most females ejected their mates' sperm following copulations that were performed many days before egg-laying. Females that suffered hatching failure were those that retained sperm that had become old by the time of laying. Furthermore, chicks that hatched from eggs fertilised by old sperm were in poor condition relative to those fertilised by young sperm. These findings support the 'young sperm' hypothesis which predicts that females choose fresh sperm to avoid reproductive failure, and are the first to show intra-male sperm choice by females in any animal species.Contact: Dr Richard Wagner, Konrad Lorenz Institute for Comparative Behavioural Research, Austrian Academy of Sciences, Savoyenstrasses 1a, A-1160 Vienna, Austria

Constraints on muscular performance: trade-offs between power output and fatigue-resistance by Dr RS Wilson and Dr RS James

The physical performance of vertebrates is believed to be constrained by a trade-off between speed and endurance capacity. Individual differences in the ratio of fast, powerful muscle fibres to the slow more fatigue-resistant fibres is considered to underlie this performance constraint. However, most studies have found no evidence of this trade-off when tested at the whole-animal level. We investigated the existence of this trade-off at the whole-muscle level, the presumed site of this physiological conflict, by examining inter-individual variation in mouse muscle performance. We found several measures of maximum power output and force production of the muscles were negatively correlated with fatigue resistance, indicating a functional conflict between these performance parameters. We suggest this performance conflict has imposed an important constraint on the evolution of vertebrate physical performance.

PROCEEDINGS B (Biological sciences)

A model of pollen-mediated gene flow for oilseed rape by Dr PJ Walklate, Dr JCR Hunt, Dr HL Higson and Dr J Sweet

The development of genetically modified (GM) oilseed rape has precipitated the need to assess and regulate the risk of pollen mediated gene flow (ie contamination of non-GM varieties due to cross-fertilisation with GM pollen, dispersed by wind and insect activity). This paper presents a mathematical model of these processes to obtain new insight into the factors that determine gene flow. It is shown that the isolation distance, needed to regulate gene flow, is proportional to the area of GM cultivation and is most effective for protecting self-fertile non-GM crops, but is ineffective for protecting male-sterile non-GM crops.

Ancient lakes as evolutionary reservoirs: Evidence from the thalassoid gastropods of Lake Tanganyika by Dr AB Wilson, Dr M Glaubrecht and Professor A Meyer

What factors are responsible for the distribution of biological diversity? The ancient lakes of Africa have attracted considerable scientific interest due to phenomenal rates of speciation in their endemic fishes and are commonly regarded as biodiversity hotspots. The gastropod snails of Africa's Lake Tanganyika are also extremely diverse, but their evolutionary origins have remained in doubt. Using molecular phylogenetic methods to derive an evolutionary clock, we have found that the present-day genetic and morphological diversity of these snails stems from at least four major lineages that predate the formation of the lake by as much as 40 million years. While these lakes have clearly been important for the generation of new species, our study demonstrates that these long-lived inland seas have also been important evolutionary reservoirs, conserving biodiversity that has been eroded in more ephemeral surrounding habitats.

The limits of elaboration: curved allometries reveal the constraints on mandible size in stag beetles by Dr RJ Knell, Dr JC Pomfret and Dr JL Tomkins

What limits the size of a stag beetle's mandibles? These beetles use their huge mandibles in combat with other males over access to mates, and the beetle with the larger mandibles will usually win the fight and mate with the disputed female. In this paper we show that the ultimate size of the mandibles is probably limited by competition over resources such as protein between the rapidly growing mandibles and the beetle's other body parts in the pupa. One implication of this is that the large size of many stag beetles has evolved simply to enable them to grow larger mandibles.

Complex biogeographic history of a Holarctic passerine by Dr SV Drovetski, Professor RM Zink, Professor S Rohwer, Dr IV Fadeev, Dr IV Fadeev, Dr YV Nesterov, Dr I Karagodin and Dr Y Red'kin

Winter wrens have an unforgettable song, consisting of an eerie, long series of descending notes. Ornithologists had recognized that there are two song types in North America, and that the one in eastern North America is more similar to that in Europe. We sequenced mitochondrial DNA to test whether the Winter Wren was genetically a single species, or if in fact there were genetic differences that paralleled song types. We found that the species includes six deeply divergent groups: Western Nearctic, Eastern Nearctic, Eastern Asia, Central Asia, Caucasus, and Europe, representing a remarkable example of cryptic vicariant speciation that has been overlooked.

Motor mechanisms of a vocal mimic: implications for birdsong production by Dr SA Zollinger and Dr RA Suthers

How does a vocal mimic copy the song of another species? We show that when mockingbirds imitate the songs of cardinals, cowbirds or canaries, they use the same vocal mechanism for producing the song as used by the tutor species. If the mockingbird's production mechanism differed from that of the model then the song also differed. By identifying the parts of song most difficult for the mockingbird to copy we can gain an insight into the physical and physiological limitations on song production and how different species have become vocal specialists in different ways.

To age or not to age by Dr PD Sozou and Dr RM Seymour

Wouldn't it be better not to age? From a Darwinian evolutionary perspective it would seem so, and yet animals do age. To address this puzzle, evolutionary biologists have proposed that there is a trade off, with vitality in later life sacrificed in return for increased fertility when young. We examine this theory using mathematical analysis. Contrary to received wisdom, we find that such a trade off does not inevitably lead to ageing. Biologists therefore have further work to do to explain why ageing is so universal.

The mathematics of motion camouflage by Professor PA Glendinning

Insects such as dragonflies adopt a curious stealth strategy - motion camouflage - in territorial disputes. The aggressor moves so that it appears to be stationary when observed by the (moving) target, neglecting the change of size as it approaches. It does this by moving so as to stay on the line connecting the target with a fixed reference point, so it always appears as though at the reference point. In this paper the precise mathematical equations which determine paths under this strategy are given. Solutions are compared to those of classical pursuit paths, and the problem of chaotic pursuit is also described. Motion camouflage turns out to be an extremely efficient way of approaching a target.

Natural interspecific and intraspecific horizontal transfer of parthenogenesis-inducing Wolbachia in Trichogramma wasps by Dr ME Huigens, Dr RP De Almeida, Dr PAH Boons, Dr RF Luck and Dr R Stouthamer

The bacterium Wolbachia resides in the eggs of many insects. It is currently much studied because it can manipulate insect reproduction. Minute Trichogramma wasps normally reproduce sexually but female wasps infected with the bacterium can produce daughters without having sex (asexual reproduction). Wolbachia was known to be transmitted from mother to daughter but we show that the bacterium - and consequently asexual reproduction - is infectious within and between wasp species. Uninfected wasps can acquire an infection when they share a food source with infected wasps. Our results provide a better understanding of the evolutionary pathways of Wolbachia infections.

Remarkable iridescence in the hindwings of the damselfly Neurobasis chinensis (Linnaeus) (Zygoptera: Calopterygidae) by Dr P Vukusic, Dr RJ Wootton and Professor JR Sambles

Manipulating the passage of light is possible using materials comprising minute structures. These so-called nanostructures exist in many naturally occurring systems like butterflies and beetles, resulting in bright eye-catching iridescent colour. In the extraordinary damselfly studied here, we show that a multilayer structure combines with dark pigment, producing hind-wings that are astonishingly bright green on their top surface, yet simultaneously dark brown on their bottom surface. Optically this is bizarre and rather complicated to achieve for a single membrane of wing. We solve the riddle of how it is done and describe the way the insect uses it to full effect.

Phylogenetic position of the Pentastomida and (pan)crustacean relationships by Dr DV Lavrov, Dr WM Brown and Dr JL Boore

Pentastomids, or tongue worms, are an obscure group of parasitic animals with unique morphology and uncertain phylogenetic affinities. To clarify the phylogenetic position of this group we sequenced complete mitochondrial genomes of the pentastomid Armillifer armillatus and four representatives of diverse crustacean lineages. The mitochondrial gene arrangement data demonstrate unambiguously that Pentastomida is a group of modified crustaceans and reveal an unexpected interrelationship among crustacean lineages. Since pentastomid-like animals appear virtually simultaneously with crown-group crustaceans in the fossil record, these results suggest either an extremely fast rate of morphological evolution of pentastomids or morphological convergence between extinct and extant taxa.

PROCEEDINGS A (Mathematical, Physical & Engineering Sciences)

A three-phase tesselation: solution and effective properties by Dr RV Craster and Professor YV Obnosov

In this paper we have studied the effective properties (the average resistance, say) of a model three phase structure in electrostatics; the structure is constructed from diamond shaped inclusions. Such model systems are useful in a wide range of areas in applied physics, electrostatics, porous media and heat transfer. We show that a special problem is explicitly solvable, and we solve it. The effective resistivities and conductivities are found and then compared to simpler asymptotic and approximate results.

The motion of a vortex near two circular cylinders by Professor ER Johnson and Dr NR McDonald

Eddies in the ocean are concentrated regions of rapidly rotating flow within a relatively quiescent background - geophysical vortices - and their motion is strongly influenced by the shape of the ocean floor. This paper presents a simple analytical model for vortex motion near islands, replacing the vortices by point singularities. Numerical integrations for finite area vortices demonstrate the accuracy of the point singularity model. The significance of these results lies in the power of the simple theory to predict the highly nonlinear motion of these intense flows which so greatly affect heat flow, pollutant transport and local currents.

Slow damping of internal waves in a stably stratified fluid by Dr KF Gurski, Dr R Kollar and Professor RL Pego

It is a problem that has long puzzled fluid dynamicists: How long does it take the waves in a container of fluid to settle? To date there is no complete mathematical analysis; the air/liquid/wall contact line and surface tension complicate things. But for ``supercritical'' fluids at high pressure (important in several industrial processes, such as decaffeination of coffee), the sharp distinction between liquid and vapour disappears. Viscosity can be expected to damp internal waves with a characteristic exponential relaxation time associated with the slowest decaying mode of the system. This work proves that, surprisingly, there is no slowest decaying mode in such stratified fluids.

The Newtonian limit of space-times describing uniformly accelerated particles by Dr R Lazkoz and Dr JAV Kroon

The Newtonian theory of Gravity and Einstein's theory of Gravity both describe the universal attraction between bodies. Although Einstein's theory supersedes Newton theory, the latter still has an appropriate domain of applicability in which its predictions remain accurate. Although the link between both theories is fairly well understood, the connection between solutions to each theory is not that clear. Establishing this connection is of extreme importance as -quite paradoxically- almost all the measurements of the gravitational properties of diverse systems are made using Newtonian models and notions. In the present work we consider the only explicitly known class of solutions to Einstein's theory which describe moving particles. The conditions under which they have a Newtonian analogue are considered, and their properties studied.