Sexual dimorphism in amphipods: the role of male posterior gnathopods revealed in Gammarus pulex

In the mate-guarding amphipod, Gammarus pulex, the enlarged male posterior gnathopods have been variously suggested to function to grasp and subdue the female, to be used as weapons in fights between males, to signal to the female the male presence and stimulate moult accelaration, egg development or egg extrusion. These hypotheses were tested in a series of experiments, the results of which reveal an unexpected function. Ablation of the posterior gnathopods of males showed that they were neither necessary for, nor advantageous in, establishment and/ or maintenance of precopula mate guarding, with or without competition with intact males. Furthermore, these appendages do not function to advance female moult, or stimulate egg development or extrusion. However, only males with intact posterior gnathopods were able to copulate. We also show that females require a full copulation of several bouts to extrude eggs. We conclude that the function of the posterior gnathopods is to facilitate copulation and suggest future studies focus on the selective pressures acting on copulating males.

Sexual cannibalism and mate choice

Sexual cannibalism, where a female kills and consumes a courting male, represents an extreme form of sexual conflict and has been proposed as a mechanism of mate choice. We evaluate the evidence for mate choice through premating sexual cannibalism via mate rejection, other indirect mechanisms of mate 'choice' and choice in postmating sexual cannibalism. We highlight a paucity of investigations, particularly of field studies, and note gaps in our knowledge. There is empirical support for the size-dependent sexual cannibalism predicted by mate choice through premating sexual cannibalism. This may represent mate choice operating on absolute male size but it could be a by-product of female foraging behaviour and greater vulnerability of relatively smaller males. Thus, indirect mate choice is as plausible an explanation of size-dependent sexual cannibalism as is direct mate choice based on discrimination of male traits. Direct female choice, mediated through premating sexual cannibalism, has yet to be demonstrated. We suggest a framework for distinguishing direct and indirect choice and note an absence of information on which to test it. There is evidence for sequential mate choice in postmating sexual cannibalism, but the nature or basis of the female's discriminatory behaviour remains unclear. Costs and long-term fitness benefits of the putative mate choice have been largely ignored. Reversed sexual cannibalism, in which the male eats the female, presumably occurs when the gain from food is high and potential gain from mating low and probably has little to do with mate choice. (c) 2005 The Association for the Study of Animal Behaviour Published by Elsevier Ltd. All rights reserved.

Restorative Justice as a Response to Sexual Offending – Addressing the Failings of Current Punitive Approaches

This article explores the use of restorative justice as a response to sexual crime. The management of high risk sex offenders, particularly in the community post-release, has been a key focus of contemporary popular and political debates on sexual offending. Many offenders fail to come to the attention of the criminal justice system. For those that do, there is the almost blanket application of recent control in the community measures such as sex offender registries and community notification which have failed to prevent reoffending. The response by the media and the public to the presence of sex offenders in the community may also impede offender rehabilitation. The use of punishment alone via formal criminal justice is, therefore, an inadequate deterrent for sexual crimes. Although controversial, this article advocates the use of restorative practices with sexual crime as a proactive, holistic response to the problem and ultimately as a more effective means of reducing the incidence of sexual offences and sex offender recidivism.

The L Pack: Addressing the Sexual Health Needs of Young Lesbians

Concerns about the sexual health of women who identify as other than heterosexual have been highlighted in numerous research reports, yet access to information, advice and services remains limited within Northern Ireland. In response to this, a group of young women have produced a sexual health resource (‘‘The L Pack’’) specifically for those who identify as lesbian or bisexual. This article discusses the issue of lesbian sexual health and the rationale for the production of The L Pack. Drawing upon discussions with the young women involved and the various partners, it outlines the participatory process of producing information for young women by young women, the meaning and value of this and the nature of learning for all involved. Illustrating feminist and related principles through practice examples, the article outlines how the project moved from a focus on individual learning to one where the young women involved gained the knowledge, skills and confidence to take their learning to their peers and others.

Sexual size dimorphism and reproductive investment by female spiders: A comparative analysis

We investigate the association between female reproductive investment, absolute size, and sexual size dimorphism in spiders to test the predictions of the fecundity-advantage hypothesis. The relationships between absolute size and sexual size dimorphism and aspects of female reproductive output are examined in comparative analyses using phylogenetically independent contrasts. We provide support for the idea that allometry for sexual dimorphism is the result of variation in female size more so than male size. Regression analyses suggest selection for increased fecundity in females. We argue that fecundity selection provides the only general explanation for the evolution of sexual size dimorphism in spiders.