Natural selection and quantitative genetics of life-history traits in Western women: A twin study

Whether contemporary human populations are still evolving as a result of natural selection has been hotly debated. For natural selection to cause evolutionary change in a trait, variation in the trait must be correlated with fitness and be genetically heritable and there must be no genetic constraints to evolution. These conditions have rarely been tested in human populations. In this study, data from a large twin cohort were used to assess whether selection Will cause a change among women in contemporary Western population for three life-history traits: age at menarche, age at first reproduction, and age at menopause. We control for temporal variation in fecundity (the baby boom phenomenon) and differences between women in educational background and religious affiliation. University-educated women have 35% lower fitness than those with less than seven years education, and Roman Catholic women have about 20% higher fitness than those of other religions. Although these differences were significant, education and religion only accounted for 2% and 1% of variance in fitness, respectively. Using structural equation modeling, we reveal significant genetic influences for all three life-history traits, with heritability estimates of 0.50, 0.23, and 0.45, respectively. However, strong genetic covariation with reproductive fitness could only be demonstrated for age at first reproduction, with much weaker covariation for age at menopause and no significant covariation for age at menarche. Selection may, therefore, lead to the evolution of earlier age at first reproduction in this population. We also estimate substantial heritable variation in fitness itself, with approximately 39% of the variance attributable to additive genetic effects, the remainder consisting of unique environmental effects and small effects from education and religion. We discuss mechanisms that could be maintaining such a high heritability for fitness. Most likely is that selection is now acting on different traits from which it did in pre-industrial human populations.

Genetic and environmental contributions to educational attainment in Australia

The genetic and environmental contributions to educational attainment in Australia are examined using a multiple regression model drawn from the medical research literature. Data from a large sample of Australian twins are analysed. The findings indicate that at least as much as 50 percent and perhaps as much as 65 percent of the variance in educational attainments can be attributed to genetic endowments. It is suggested that only around 25 percent of the variance in educational attainments may be due to environmental factors, though this contribution is shown to be around 40 percent when adjustments for measurement error and assortative mating are made. The high fraction of the observed variation in educational attainments due to genetic differences is consistent with results reported by Heath et al. (Heath, A.C., Berg, K., Eaves, L.J., Solaas, M.H., Corey, L.A., Sundet, J., Magnus, P., Nance, W.E., 1985. Education policy and the heritability of educational attainment. Nature 314(6013), 734-736.), Tambs et al. (Tambs, K., Sundet, J.M., Magnus, P., Berg, K., 1989. Genetic and environmental contributions to the covariance between occupational status, educational attainment and IQ: a study of twins. Behavior Genetics 19(2), 209-222.), Vogler and Fulker (Vogler, G.P., Fulker, D.W., 1983. Familial resemblance for educational attainment. Behavior Generics 13(4), 341-354.) and Behrman and Taubman (Behrman, J., Taubman, P., 1989. Is schooling mostly in the genes? Nature-nurture decomposition using data on relatives. Journal of Political Economy 97(6), 1425-1446.), suggesting that the finding is robust. (C) 2001 Elsevier Science Ltd. All rights reserved.

What constitutes success in telehealth?

Before telehealth applications can be judged, there must be some general understanding about what constitutes success. At first sight it seems that defining success in a telehealth application should be relatively easy: a successful application is one that produces high-quality care at low cost. However, the calculation of cost requires some care, since it depends on assuming a particular financial perspective (the patient's, the health-care provider's, or society's) and is meaningless without a statement of the workload being handled. Other factors include the context in which the service is being delivered. Ultimately, the political imperative may override any rational judgement of success.

The point-of-referral barrier - a factor in the success of telehealth

A feasibility study was carried out to test the hypothesis that, for an effective telehealth service, a full-time coordinator is required to act as a single point of contact for consultation requests. By shifting the responsibility for telepaediatrics from the referrer to the provider, the telehealth process becomes equally (or more) attractive as the conventional alternative. Preliminary results showed that, within six months, telepaediatric activity increased to an average of 8 h per month. Not only did certain health services become more accessible to children and their families in remote areas of Queensland, but significant savings were also made. At least 12 patient transfers were avoided to and from the tertiary facility, with an estimated minimum saving of $18,000 to the health-care provider.

Development of educational policy and early intervention for learning difficulties in Australia: In the case of Queensland

This paper aims to describe the historical outline and current development of the educational policy for students with learning difficulties in Australia, focusing especially on the state of Queensland. In order to develop educational policy of learning difficulities at the state level, the concept of learning difficulities had been discussed until the middle of the 1970's. Receiving the submissions which argued strongly against a diagnostically-oriented definition of learning disabilities, the Select Comittee concluded that there was much conceptual confusion regarding the definition and cause of learining difficulties that might take many years to resolve. Despite that it was recongnised that action was needed to assist children by looking at their "total learning environmerit", and recommended the development of an educational policy for students with learning difficulties. During 1980's, support teachers for students with learning difficulties were employed in many schools. Scince the early 1980's support teachers have been making their efforts in regular classrooms rather than in the resource rooms. Their roles have been to help students with learning difficulties using effective and specific skills, and to consult with the regular classroom teacher in solving the problems related to learning difficulties in regular classes. Currently, the support system for students with learning difficulties has been employed to organize a more systematic and broader approach in Queensland based on the accountability of schools. In the context of enphasizing literacy and numeracy, a systematic whole school approach and particular programs, such as the Year 2 Diagnostic Net and Reading Recovery, have been introduced into the educational system for early identification and early intervention.

Factors influencing paternity success in Antechinus agilis: last-male sperm precedence, timing of mating and genetic compatibility

We describe the patterns of paternity success from laboratory mating experiments conducted in Antechinus agilis, a small size dimorphic carnivorous marsupial (males are larger than females). A previous study found last-male sperm precedence in this species, but they were unable to sample complete Utters, and did not take male size and relatedness into account. We tested whether last-male sperm precedence regardless of male size still holds for complete litters. We explored the relationship between male mating order, male size, timing of mating and relatedness on paternity success. Females were mated with two males of different size with either the large or the small male first, with 1 day rest between the matings. Matings continued for 6 h. in these controlled conditions male size did not have a strong effect on paternity success, but mating order did. Males mating second sired 69.5% of the offspring. Within first mated males, males that mated closer to ovulation sired more offspring, To a lesser degree, variation appeared also to be caused by differences in genetic compatibility of the female and the male, where high levels of allele-sharing resulted in lower paternity success.

Mating aggregations and mating success in the flower thrips, Frankliniella schultzei (Thysanoptera: Thripidae), and a possible role for pheromones

Aggregations of Frankliniella schultzei males were observed on the corollas of Hibiscus rosasinensis and Gossypium hirsutum flowers in southeast Queensland. Aggregations were seen only on the upper surfaces of corollas but may have occurred on other flower parts, which were hidden from view. Conspecific females entered aggregations and a small proportion of them mated [18% (n = 163), H. rosasinensis; 30% (n = 181), G. hirsutum]. Most females (87 and 72%, respectively) that did not mate in aggregations walked to other flower parts. Behavior was difficult to observe on these parts, but mating was sometimes observed there. The number of females that landed within aggregations on the upper surfaces of both H. rosasinensis and G. hirsutum corollas was highly correlated with the number of males (r = 0.88, r = 0.93, respectively; P < 0.001). Significantly more mating pairs were observed in high-density aggregations (mean +/- SE, 1.10 +/- 0.22 and 4.44 +/- 0.48, respectively) than in low-density aggregations (0.37 +/- 0.11 and 1.67 +/- 0.29, respectively) (P < 0.05) on flowers of both species. More F. schultzei females were attracted to sticky traps baited with live conspecific males set among flowering Ipomoea indica (mean +/- SE, 8.83 +/- 0.32) and G. hirsutum (10.90 +/- 0.79) plants than to control traps (0.10 +/- 0.05 and 0.70 +/- 0.25, respectively)( P < 0.05), presumably in response to male-produced pheromones. Significantly more females were attracted to traps with high male densities than to traps with low densities. We found no statistical evidence that aggregation size influenced mating success (proportion males that mated). Mating success, however, should be evaluated with respect to mating on all flower parts and not just the upper surfaces of corollas. The results of this study constitute the first behavioral evidence for an attractant sex pheromone in thrips.

Can medical education be fun as well as educational?

Today's challenge to medical educators is to provide continuing education that supports excellence in clinical practice while finding new approaches to make learning more stimulating, motivating, and entertaining. At our hospital we are experimenting with innovative teaching techniques, incorporating games and debate, which encapsulate core concepts of the theory of adult learning: active participation by learners, application of knowledge, informal presentation, and feedback(1).