Evidence for maternally inherited factors favouring male homosexuality and promoting female fecundity by Dr F Corna, Dr A Camperio-Ciani and Dr C Capiluppi
Genetic causes of male homosexuality are often the argument of inflamed discussion. A strong opposition to the genetic explanation is the Darwinian paradox; in fact a genetic factor that reduces reproductive success should progressively disappear from the population. The authors here argue genetic factors could partially explain male homosexuality, and propose a paradox solution: genetic factors favouring homosexuality in males could increase fecundity in females, recovering the loss of fitness. They suggest these factors should be partly bound to the X chromosome, because male homosexuality, associated with increased female fecundity was found only in maternal line and not in paternal line of homosexuals.
Contact: Dr Francesca Corna, Department of General Psychology, University of Padova, Via Venezia 8, PADOVA, 351000, Italy
Sperm whale behaviour indicates the use of rapid echolocation click buzzes 'creaks' in prey capture by Dr PJO Miller, Dr MP Johnson and Dr PL Tyack
Sperm whales produce long series of clicks interspersed with buzzes called "creaks" while foraging at depth. Using sound, depth and orientation-recording tags attached to 23 sperm whales using suction cups, we found they consistently produced creaks preferentially at maximum dive depths, increased body manoeuvring during creaks, and remained at depth longer when creak rates were higher. These results clearly indicate that sperm whales produce click buzzes during prey capture, as do bats which are a million times smaller. As creaks indicate feeding events, acoustic tracking may be used to monitor the health of sperm whales in increasingly human-impacted oceanic ecosystems.
Contact: Dr Patrick Miller, Sea Mammal Research Unit, University of St Andrews
Sexual selection, natural selection and the evolution of dimorphic coloration and ornamentation in agamid lizards by Dr DM Stuart-Fox and Dr TJ Ord
Conspicuous coloration and ornamentation in males are thought to result from sexual selection. However, these 'showy' traits can also incur increased predation risk. We examined the trade-off between sexual selection and natural selection in dragon lizards. Our results reveal that in species occupying closed habitats, both sexes are ornamented and males are more conspicuously coloured than females. In contrast, species occupying open habitats tend to be less ornamented and males tend to be conspicuously coloured only on body regions that can be concealed from predators. Natural selection from predators therefore constrains the evolution of sexually selected traits in dragon lizards.
Contact: Dr Terry Ord, Department of Biology, Indiana University, 1001 East 3rd Street, Jordan Hall 142, BLOOMINGTON, IN 47405, USA
A temporal analysis shows major histocompatibility complex loci in the Scandinavian wolf population are consistent with neutral evolution by Dr JM Seddon and Professor H Ellegren
The major histocompatibility complex (MHC) has an integral role in the immune system and the high levels of variability found among its genes may be of particular importance for the health of populations. We examined the level of diversity at three MHC class II loci in the wolf population of Scandinavia, a population naturally recolonised with a genetic contribution from as few as three founders, and in four neighbouring wolf populations. The bottlenecks and fragmentation noted in wolf populations in Europe have resulted in a lack of selective forces that would otherwise be expected to maintain high level of variation.
Contact: Dr Jennifer Seddon, School of Veterinary Science, University of Queensland, St Lucia QLD 4072, Australia
Quantitative evolutionary genomics: differential gene expression and male reproductive success in Drosophila melanogaster by Dr JM Drnevich, Mrs. MM Reedy, Ms. EA Ruedi, Dr. S Rodriguez-Zas and Dr KA Hughes
We have identified several genes associated with variation in male reproductive success (ie ability to sire offspring when in competition with other males). We measured the expression level of over 14,000 genes in the fruit fly and identified 27 that were strongly associated with differences in male reproductive success. One of these genes is known to cause pesticide resistance, and our results suggest that there is a cost to resistance in terms of decreased male success. Genes involved in oxidative stress resistance, energy acquisition and energy storage also are important for male reproductive success.
Contact: Dr Jenny Drnevich, School of Integrative Biology, University of Illinois, 515 Morrill Hall, URBANA, IL 61801, United States
Generation cycles in Indonesian lady beetle populations may occur as a result of cannibalism by Dr K Nakamura, Dr N Hasan, Dr I Abbas, Professor HCJ Godfray FRS and Dr MB Bonsall
Cannibalism can cause cycles in population numbers of Indonesian lady beetles. We show using a mathematical model and data analysis of a long-term study (over 20 years) how cannibalism may drive the Indonesian lady beetle populations. Particular types of dynamics: generation cycles have been observed in several different field and laboratory populations. These particular cycles are shown to occur in our Indonesian lady beetle populations and are consistent with the natural history of the beetles which are highly cannibalistic. This is one of the very few studies to show generation cycles due to cannibalism in a natural population.
Contact: Dr Mike Bonsall, Department of Biology and NERC Centre for Population Biology, Imperial College at Silwood Park, Ascot, BERKSHIRE, SL5 7PY
Strategic growth decisions in helper cichlids by Dr D Heg, Dr N Bender and Dr IM Hamilton
Subordinates of the Lake Tanganyika cichlid Neolamprologus pulcher help raise the young of dominant breeders. However, these helpers live under the ever-present danger of being evicted from the group, particularly when helpers and breeders are of similar size. We show in a controlled laboratory experiment that helpers reduce this risk of eviction by maintaining a 'safe size difference' with the breeders: they grow slowly when helping small-sized breeders and grow quickly when helping large-sized breeders. We discuss whether this effect is due to helper growth 'restraint' or whether breeders actively interfere with the growth rate of their helpers. Contact: Dr Dik Heg, Behavioural Ecology, Zoological Institute, University of Bern, Wohlenstrasse 50a, HINTERKAPPELEN, CH-3032, Switzerland
Proceedings of The Royal Society A: Mathematical, Physical and Engineering Sciences
Predictions of microtorsional experiments by micropolar plasticity by Dr P Grammenoudis and Dr C Tsakmakis
There are some experimental works which provide compelling arguments for the presence of length scale effects in the constitutive laws governing the response of plastically deformable materials. These experiments are referred to specimens with lateral dimensions of a few micrometer. Size effects cannot be captured adequately with classical theories which are formulated locally. Thus, length scale effects may be addressed by introducing some nonlocality aspects. A particular type of a nonlocal theory is the micropolar model. Capabilities of this model are discussed in the paper with reference to experimental results.
Contact: Dr Charalampos Tsakmakis, Technische Universitat Darmstadt, Institut fur Mechanik, Hochschulstrasse 1, 64289, DARMSTADT, Germany
Osmosis in small pores: a molecular dynamics study of the mechanism of solvent transport by Dr KS KIM, Dr IS Davis, Dr PA Macpherson, Professor TJ Pedley FRS and Professor A Hill
This work is a study of the movement of fluids (like water) through molecular-sized channels by osmosis. Using a Molecular Dynamics simulation, fluid molecules and a pore are modelled on a computer and set in motion according to the laws of dynamics. The results indicate that osmosis in such pores is a complex phenomenon involving both viscosity and diffusion, where the contribution of each is determined by the geometry of the pore - a new finding. Such channels actually exist in cells of animals and plants and there is current interest in making membranes containing artificial channels for desalination and filtration.
Contact: Professor AE Hill, Physiological Laboratory, Cambridge University, Downing Site, CAMBRIDGE, CB2 3EG