Carotenoid availability affects the development of a colour-based mate preference and the sensory bias to which it is genetically linked

Regardless of their origins, mate preferences should, in theory, be shaped by their benefits in a mating context. Here we show that the female preference for carotenoid colouration in guppies (Poecilia reticulata) exhibits a phenotypically plastic response to carotenoid availability, confirming a key prediction of sexual selection theory. Earlier work indicated that this mate preference is genetically linked to, and may be derived from, a sensory bias that occurs in both sexes: attraction to orange objects. The original function of this sensory bias is unknown, but it may help guppies find orange-coloured fruits in the rainforest streams of Trinidad. We show that the sensory bias also exhibits a phenotypically plastic response to carotenoid availability, but only in females. The sex-specificity of this reaction norm argues against the hypothesis that it evolved in a foraging context. We infer instead that the sensory bias has been modified as a correlated effect of selection on the mate preference. These results provide a new type of support for the hypothesis that mate preferences for sexual characters evolve in response to the benefits of mate choice--the alternatives being that such preferences evolve entirely in a non-mating context or in response to the costs of mating.

Caribbean AIDS Explosion examined

Examines the factors causing the spread of AIDS in the Caribbean. Other issues raised at a conference on February 25, 2000; Estimated number of infected women; Statistics presented at the conference.(AU)

Evaluation of a sexuality education program for young adolescents in Jamaica

Despite their increasing numbers, few of the sexuallity education and pregnancy preventative programs in developing countries have been evaluated. This study, conducted in 1995-1997, assesses the impact of a school-based sexuality education program, the Grade 7 Project, on 945 Jamaican seventh graders (aged 11-14) and their initiation of sexual activity and the use of contraception at first intercourse, as well as the knowledge and attitudes that influence their behaviors. Using a quasi-experimental design, the study measured the effects of the Grade 7 Project when the nine-month intervention was completed (short term) and one year after that (long term). Multivariate logistic regression analysis indicated that the project had no effect on initiation of sexual activity, but it had a positive short-term impact on use of contraception at first intercourse (P=.08); adolescents in the intervention group were more than twice as likely to use contraception. The project also had a positive short-term influence on several aspects of the adolescents' knowledge of and attitudes about sexuality and pregnancy. The modest impact of the Grade 7 project is encouraging, as school-based sexuality education programs of limited duration rarely have a long-term impact. Moreover, competing socioeconomic and cultural forces in Jamaica encourage early sexuality and parenthood among adolescents. The use of more participatory teaching methods and smaller class sizes might strengthen the Grade 7 Project and enhance its impact (AU)

Percepcion del riesgo, comportamientos riesgosos y seroprevalencia del VIH en trabajadoras sexuales de Georgetown, Guyana / HIV risk perception, risk behavior, and seroprevalence among female commercial sex workers in Georgetown, Guyana

A study of 108 female sex workers engaged in prostitution in Georgetown, Guyana, was made in April 1993. Based on interviews and procurement of blood samples, the study investigated relationships between HIV seroprevalences and AIDS knowledge, risk behaviors, client characteristics, and condom use. Street-walkers-as distinct from sex workers in bars, hotels and Port Georgetown-tended to charge less, be worse off socioeconomically, and have clients who were similiarly disadvantaged; they were therefore classified as belonging to a "lower" socioeconomic stratum, while the other workers were classified as belonging to a "higher" stratum. The overall HIV seroprevalence found among the sex workers was 25 percent (95 percent CI: 17-33 percent). But the 50 subjects in the lower stratum had a relatively high seroprevalence (42 percent, as compared to 10 percent among those in the higher stratum), accounting for 21 of the 27 HIV-seropositive subjects. Reported patterns of client origins (Guyanese or foreign), worker willingness to have sex without a condom, and condom use by clients differed by stratum. Participants in the higher stratum were more disposed to having sex without a condom. The workers' knowledge of what causes AIDS and how HIV is transmitted was low in both strata; substantial numbers of workers said they had contracted a sexually transmitted disease within the past two years or were users of illicit drugs. Condom use is reportedly less common among among Guyanese than foreign clients, suggesting a greater risk of contracting HIV from Guyanese clients or infecting Guyanese clients with it. The HIV seroprevalence among those reporting more than five clients per week was statistically greater among those reporting fewer. HIV seropsitivity was relatively high among the 12 workers whosaid they used cocaine. Overall, the findings supported the view that interventions targeted at female sex workers and their clients should be strengthened-more specifically, that concerted efforts should be made to intensify condom promotion, distribution, and social marketing; to improve STD services that provide treatment and counseling for female sex workers; and to increase educational activities among the workers' Guyanese clients (AU)

Sexuality and the secondary school: some observations on coed and single-sex environments

Identifies some issues relating to adolescent sexual development and the current functioning of secondary schools in Barbados. Analyses data gathered from a survey which indicates that 1) the coeducational experience is likely to lead to antagonistic and even aggressive attitudes towards the opposite sex at school; 2) the difficulties students face as adolescents even outside of the school context should be attempted to be alleviated by the schools; and 3) both staff and students are concerned by the occurrence or suspected occurrence of improper sexual behaviour on the part of some teachers. Suggests that these issues need to be addressed so that undesirable and counterproductive influences can be eliminated and schools assisted to have a more positive and constructive impact on the sexual development and adjustment of their students(AU)