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The evolution of sexually monomorphic (i.e. mutual) ornamentation has attracted growing attention as a 'blind-spot' in evolutionary biology. The popular consensus is that female ornaments are subject to the same modes of sexual selection as males: intrasexual competition and mate choice. However, it remains unclear how these forces interact within and between sexes, or whether they fully capture selection on female traits. One possibility is that the 'armament-ornament' model - which proposes that traits used primarily in male-male contests are also co-opted by females as indicators of male quality - can be extended to explain signal evolution in both sexes. We examine this idea by testing the function of acoustic signals in two species of duetting antbirds. Behavioural observations and playback experiments suggest that male and female songs function primarily as armaments in competitive interactions. Removal experiments reveal that song is also a classic ornament used by unpaired males and females to advertise for mates. These results indicate that 'armament-ornament' processes may operate in reciprocal format, potentially explaining widespread mutual ornamentation in species with elevated intrasexual competition for resources. In addition, given that songs mediate competition between species outside the breeding season, our findings suggest that processes shaping monomorphic ornaments extend beyond the traditional definitions of sexual selection and are best understood in the broader framework of social selection.

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Sexual selection is thought to counteract natural selection on the grounds that secondary sexual traits are inherently costly and evolve at the expense of naturally selected traits. It is therefore commonly predicted that increased sexual selection is associated with decreased physiological tolerance or ecological plasticity. Using phylogenetic comparative methods, we test this prediction by exploring relationships between traits assumed to be sexually selected (plumage dichromatism and song structure) and traits assumed to be naturally selected (altitudinal range and habitat range) in a diverse family of tropical birds. Contrary to expectations, we find that taxa with higher levels of dichromatism, and lower song pitch, occupy a wider variety of habitats and elevations. In other words, indices of sexual selection are positively related to two standard measures of ecological generalism. One interpretation of this pattern is that sexual selection combines synergistically with natural selection, thereby increasing physiological tolerance or the propensity to adapt to novel environments. An alternative possibility is that ecological generalism increases population density, which in turn promotes sexual selection in the form of greater competition for mates. Overall, our results suggest that a synergism between natural selection and sexual selection may be widespread, but the processes underlying this pattern remain to be investigated.

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In the first molecular study of a member of the threatened avian family, Mesitornithidae, we used nine polymorphic microsatellite loci to elucidate parentage, patterns of within-group kinship and occurrence of extra-group paternity in the subdesert mesite Monias benschi, of southwest Madagascar. We found this cooperatively breeding species to have a very fluid mating system. There was evidence of genetic monogamy and polygynandry: of the nine groups with multiple offspring, six contained one breeding pair with unrelated helpers and three contained multiple male and female breeders with related helpers. Although patterns of within-group kinship varied, there was a strong positive relationship between group size and relatedness, suggesting that groups form by natal philopatry. There was also a strong positive correlation between within-sex and between-sex relatedness, indicating that unlike most cooperatively breeding birds, philopatry involved both sexes. In contrast to predictions of kin selection and reproductive skew models, all monogamous groups contained unrelated individuals, while two of the three polygynandrous groups were families. Moreover, although between-group variation in seasonal reproductive success was related to within-group female relatedness, relatedness among males and between the sexes had no bearing on a group's reproductive output. While kin selection may underlie helping behaviour in females, factors such as direct long-term fitness benefits of group living probably determine helping in males. Of the 14 offspring produced by fully sampled groups, at least two were sired by males from neighbouring groups: one by a breeding male and one by a nonbreeding male, suggesting that males may augment their reproductive success through extra-group paternity.

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We report experimental observation of an inverse Doppler shift, in which the frequency of a wave is increased on reflection from a receding boundary. This counterintuitive effect has been produced by reflecting a wave from a moving discontinuity in an electrical transmission line. Doppler shifts produced by this system can be varied in a reproducible manner by electronic control of the transmission line and are typically five orders of magnitude greater than those produced by solid objects with kinematic velocities. Potential applications include the development of tunable and multifrequency radiation sources.

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To investigate the relative importance of paternity defences in the European robin we used behavioural observations, simulated intrusions and temporary male removal experiments. Given that paired males did not increase their mate attendance, copulation rate or territory size during the female's fertile period, the most frequently quoted paternity assurance strategies in birds were absent. However, males with fertile females sang and patrolled their territories more regularly, suggesting that territorial motivation and vigilance were elevated when the risk of cuckoldry was greatest. In addition, there was a significant effect of breeding period on response to simulated intrusions: residents approached and attacked freeze-dried mounts more readily in the fertile period. During 90-min removals of the pair male in the fertile period, neighbours trespassed more frequently relative to prefertile and fertile period controls and appeared to seek copulations with unattended females. When replaced on their territories, males immediately increased both song rate and patrolling rate in comparison with controls. We propose that male robins sing to signal their presence, and increase their territorial vigilance and aggression in the fertile period to protect paternity. Copyright 2000 The Association for the Study of Animal Behaviour.

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Sperm competition in sex-role reversed, polyandrous jacanas is intense because females copulate with multiple male mates before laying each clutch. These males may be unable to attempt to maximize their share of copulations by mate guarding or forcing copulations. Instead, males in polyandrous harems may compete for sexual access to the female by giving a call, termed the 'yell', to attract her. Male bronze-winged jacanas, Metopidius indicus, yelled at higher rates in larger harems, and when the female was further from the yeller or on a comate's territory. Half of all yells were given at mating platforms where all copulations occurred. Males that received the clutch yelled at lower rates during the incubation and chick care periods. Yells attracted the female when she was far from the yeller or with a comate. When the yell of a polyandrous male was broadcast from his territory, the female was more likely to fly to his territory during playback than during control periods. Within polyandrous harems the males that yelled at the highest rates received the most copulations, and three out of four females gave clutches to the male that gave the longest and most frequent yells, so females may have used yells to assess male quality. Intrusions by females, but not males, increased during yell playbacks, and tended to be more frequent on the territories of males with high yell rates. Females may therefore respond to their mates' yells because yells may attract female intruders which may attempt to take over the territory. Copyright 1999 The Association for the Study of Animal Behaviour.

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After severe head injury, many children continue to experience major cognitive and behavioural problems and consequent educational difficulties, even after good physical recovery. Forty three children referred to the regional multidisciplinary head injury rehabilitation team are described. The clinical outcome at a median interval of 13 months after injury showed that 18 (42%) had persistent neurological impairment and 15 (35%) had an identified need for special educational support. Thirty seven children were further assessed for psychiatric morbidity, cognitive impairment, and classroom performance. Rutter behavioural questionnaires were sent to parents and teachers of head injured index cases and classmate controls matched for age and sex. Index parents scored their children significantly worse in both 'health' and 'habits' and more cases than controls had scores suggesting a psychiatric disorder. Teachers scored index cases significantly worse for five of the traits questioned, but discriminated cases from controls less decisively than parents. Index cases were significantly disadvantaged on teachers' assessments of classroom skills and performance. A need for improved support and training of staff who teach head injured children was identified.

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Nic Seddon reflects on what the future holds for personnel staff in the NHS. His main concerns are the effects of the white paper, employment in the 1990s and the Single European Market.

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A communications aid for the severely handicapped is described. The aid is primarily intended to be mounted on an electric wheelchair and to be powered from the chair's battery. It may be operated by any two-switch input system or by more elaborate controls such as joy-sticks. The central unit of the aid is a purpose-built 8085 microcomputer, the operating program and data tables being sorted in a 2 kbyte EPROM. The input control is used to drive a cursor around an 8 X 8 letter board array, the selected alphanumeric character being output to a liquid crystal display. Up to 64 messages, each of no more than 15 characters, can be composed and stored by the user and recalled as required. The messages are stored in a 2 kbyte CMOS memory and are retained when the aid is switched off. It is a simple matter to increase the number of stored messages. The aid was designed with the needs of a particular 15 year old, athetoid child in mind and the results of his tests of the aid will be briefly discussed.

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