Importance of dispersal routes that minimize open-ocean movement to the genetic structure of island populations.

Islands present a unique scenario in conservation biology, offering refuge yet imposing limitations on insular populations. The Kimberley region of northwestern Australia has more than 2500 islands that have recently come into focus as substantial conservation resources. It is therefore of great interest for managers to understand the driving forces of genetic structure of species within these island archipelagos. We used the ubiquitous bar-shouldered skink (Ctenotus inornatus) as a model species to represent the influence of landscape factors on genetic structure across the Kimberley islands. On 41 islands and 4 mainland locations in a remote area of Australia, we genotyped individuals across 18 nuclear (microsatellite) markers. Measures of genetic differentiation and diversity were used in two complementary analyses. We used circuit theory and Mantel tests to examine the influence of the landscape matrix on population connectivity and linear regression and model selection based on Akaike's information criterion to investigate landscape controls on genetic diversity. Genetic differentiation between islands was best predicted with circuit-theory models that accounted for the large difference in resistance to dispersal between land and ocean. In contrast, straight-line distances were unrelated to either resistance distances or genetic differentiation. Instead, connectivity was determined by island-hopping routes that allow organisms to minimize the distance of difficult ocean passages. Island populations of C. inornatus retained varying degrees of genetic diversity (NA = 1.83 - 7.39), but it was greatest on islands closer to the mainland, in terms of resistance-distance units. In contrast, genetic diversity was unrelated to island size. Our results highlight the potential for islands to contribute to both theoretical and applied conservation, provide strong evidence of the driving forces of population structure within undisturbed landscapes, and identify the islands most valuable for conservation based on their contributions to gene flow and genetic diversity.

Cortisol and testosterone levels on a weekend and a work day in three mountain villages in the Selska Valley of northwest Slovenia.

BACKGROUND: In contemporary western populations, a week commonly involves 5 days of paid work (work days) and two non-working days (weekend). Work days are usually perceived as being more stressful than non-work days and this hypothesis has been tested in several studies, most of which selected subjects with jobs that are perceived to have high stress. AIM: The study measured salivary cortisol and testosterone on a work day and a weekend in a community-based sample of people going about their everyday lives and tested the hypothesis that hormone levels will be higher on a work day. SUBJECTS AND METHODS: Slovenian alpine villagers (30 females and 25 males) were sampled without reference to their occupation. Each individual was measured on two occasions, a day on a weekend and a work day as they went about their usual activities in the afternoon. RESULTS: Cortisol (mean = 3.32 ng ml(-1), range 0.4-27.9) and testosterone (mean = 121 pg ml(-1), range 17-424) values were similar to other populations. Neither the age of subjects nor the time in the afternoon of sample collection were associated with hormone concentrations. On each day of collection, cortisol and testosterone values were correlated for each sex, with the estimate of the correlation coefficient ranging from 0.57 to 0.88. For females, testosterone values were higher on the weekend than the work day (102 pg ml(-1) and 60 pg ml(-1), respectively) but not for males (mean across both days 134 pg ml(-1)). Independent of this effect, the presence of a spouse or other adult in the house was significantly associated with lower testosterone levels in both sexes. Husband and wife testosterone values are correlated on the weekend (r = 0.67, p = 0.02) but not on the work day. Mean cortisol values for the weekend and work day were not different and there was no correlation between levels on these two days. CONCLUSIONS: These results, although based upon a small sample size, reveal potential relationships between testosterone, work-rest activities, and the presence-absence of a social partner that warrant further investigation.

Variation in epinephrine and cortisol excretion rates associated with behavior in an Australian Aboriginal community.

Urinary epinephrine and cortisol hormone output in a remote Australian Aboriginal community was on average about twice as high in those individuals measured on a Thursday or Friday as those measured at the beginning of the next week (Monday or Tuesday). Diastolic blood pressure was about 6 mm Hg higher in the Thursday-Friday group, but the difference in mean systolic blood pressure between the day groups does not reach statistical significance. These physiological differences are associated with a marked dichotomy in behavior in the two time periods: on the first 2 days, virtually all adults were involved in intense gambling activity for large stakes, but this was not a feature of the latter period. This behavior pattern occurs on a regular weekly basis. If substantiated by longitudinal studies, this phenomenon may provide an additional link between human behavior and a poor health profile mediated via the physiological consequences of high stress hormone output.

Patterns of cortisol and adrenaline variation in Australian aboriginal communities of the Kimberley region.

Urinary cortisol and adrenaline excretion rates were measured in three Australian Aboriginal communities in the Kimberley region in the north-west of the country. The three communities, Derby, Kalumburu and Kupungarri, differ in size and remoteness and some lifestyle parameters. Cortisol excretion rate is associated with age and urine flow rate, but there is no association with smoking or the consumption of alcohol. All three communities show very high cortisol excretion rates compared to a sample of UK (Oxford) residents and there are also differences between the three communities. Adrenaline excretion rate also shows associations with age and urine flow rate, but not with smoking. Aboriginal people in the Kimberley region excrete adrenaline at a slightly higher rate than that found in Oxford, which itself is high by world standards. There are no marked differences between communities in their adrenaline excretion rates. Alcohol drinkers in Derby, where alcohol is freely available, have higher adrenaline output than non-drinkers.

A GENETIC PERSPECTIVE OF MAMMALIAN VARIATION AND EVOLUTION IN THE INDONESIAN ARCHIPELAGO: BIOGEOGRAPHIC CORRELATES IN THE FRUIT BAT GENUS CYNOPTERUS.

This study investigated allozyme and morphometric variability within the genus Cynopterus, with particular emphasis on C. nusatenggara, which is endemic to Wallacea, the area encompassing the Oriental-Australian biogeographic interface. The genetic distances between Cynopterus species are small by mammalian standards and suggest that this genus has undergone a recent series of speciation events. The genetic distance between populations of C. nusatenggara is strongly correlated with both the contemporary sea-crossing distance between islands and the estimated sea crossing at the time of the last Pleistocene glacial maximum, 18,000 b.p. This observation, together with low levels of population substructure within islands as shown by F-statistics, indicates that the sea is a primary and formidable barrier to gene exchange. The genetic distance and the great-circle geographical distance between the populations of C. nusatenggara are not correlated, although a principal-coordinates analysis of genetic distance reveals relationships between the populations that are similar to their geographical arrangement. A strong negative correlation exists between the level of heterozygosity within island populations of C. nusatenggara and the minimum sea-crossing distance to the nearest large source population. This is interpreted as reflecting an isolation effect of the sea, leading to reduced heterozygosity in populations that have larger sea barriers between them and the large source islands. Independently of this, heterozygosity is negatively associated with longitude, which in turn is associated with systematic changes in the environment such as a gradual decline in rainfall from west to east. The association between heterozygosity and longitude is interpreted as reflecting an association between genetic and environmental variance and supports the niche-width theory of genetic variance. Morphometric variability did not show any of the main effects demonstrated in the genetic data. Furthermore, there was no evidence that, at the level of individuals, genetic and morphometric variability were associated.

Consanguinity, gestational period and anthropometric measurements at birth in Pakistan.

The effects of consanguinity on gestational period and anthropometric measurements at birth were assessed in a group of 662 babies delivered in Lahore, Pakistan. Regression analysis revealed consanguinity-related declines in birthweight, recumbent length, head circumference and chest girth and in gestational period. Considered in combination with a recent report from the region linking inbreeding effects to neonatal and childhood mortality, the data suggest that the widely favoured practice among Pakistanis, at home and abroad, of marriage between close relatives may be a contributory factor in their comparatively unfavourable health profile.

Marital distance and child variability.

The effects of marital distance on the mean and variance of child stature and weight were investigated using the British National Child Development Study data. Children of large marital distance unions had mean values as predicted from mid-parent values and did not exhibit a hybrid vigour effect. However, they did show reduced levels of variability and this effect was most marked at 16 years, although it was also present at 7 and 11 years of age. These results are discussed in terms of large marital distance being associated with high heterozygosity levels, because of geographic variation in gene frequencies.

Consanguinity, spousal age at marriage and fertility in seven Pakistani Punjab cities.

A retrospective study was conducted on spousal age at marriage, time to first birth and total pregnancies in the populations of seven cities in the Pakistani province of Punjab. Consanguineous marriages were strongly favoured with coefficients of inbreeding (F) for the present generation ranging from 0.0236 to 0.0286. Male and female ages at marriage were younger in consanguineous unions and spousal age differences smaller than in their non-consanguineous counterparts. Time elapsed from marriage to first birth tended to be longer in consanguineous unions but, in general, they had more pregnancies. As consanguinity has been shown to be associated with increased ante- and postnatal mortality in these communities, reproductive compensation provides a credible explanation for the apparent enhanced fertility with inbreeding. However, the data equally could be interpreted in terms of greater reproductive span and/or biosocial compatibility of the consanguineous unions.

Consanguinity related prenatal and postnatal mortality of the populations of seven Pakistani Punjab cities.

A retrospective study was conducted on prenatal and postnatal mortality among the populations of seven cities in the Pakistani province of Punjab. Consanguineous marriages were strongly favoured and the coefficients of inbreeding (F) for the present generation in each locality ranged from 0.0236 to 0.0286. There was a highly significant relationship between the degree of inbreeding and mortality, with most consanguinity related deaths reported in the neonatal, infantile, and childhood periods. The findings strongly suggest that consanguinity may play a major role in the high rates of postnatal mortality observed in Pakistani communities now resident in the United Kingdom.

Variability in stature growth.

An analysis of longitudinal data shows that there are marked changes in the variability of stature and stature velocity during growth in stature, as measured by the coefficient of variation. Variability in stature velocity tends to rise after birth but from age 2 years it gradually declines until the end of adolescence, once variation in the timing of adolescence is taken into account. Comparison of velocity variation in an affluent western society (UK) with velocity variation in two poorer societies (India and Thailand) shows the former to be systematically smaller.

Patterns in the within-population variability of stature and weight.

An analysis has been undertaken of the comparative magnitudes of the within-population variability in stature and body weight as reported in the recent literature. The distributions of the variability have been investigated for patterns related to latitude, altitude, 'affluence' and the mean value of the measurements. It is shown that differences in stature variability are substantially explained by differences in mean stature only. This however, is not the case with weight variability where, in addition to the mean, there is evidence of independent effects of affluence, altitude, and especially latitude. In most populations the weight of females is more variable than that of males. This is considered to be due to their greater amounts of fat, and differing levels of fat may also explain much of the geographical patterns in weight variability.

Genetic and morphometric variances in three human populations.

Data from three human populations were used to investigate the putative relationship between genetic and morphological variances. There was no evidence to support the hypothesis that individuals heterozygous at a small number of marker loci are more often near the mean for anthropometric characters than are homozygotes. In one population (Otmoor), apparent support for the hypothesis was due to the confounding factors of correlations between anthropometric traits and population subdivision. It is unlikely that such relationships can be detected by intrapopulation comparisons because of the low association between measured and total heterozygosity.

Changes in total and free concentrations of steroid hormones in the plasma of women throughout pregnancy: effects of medroxyprogesterone acetate in the first trimester.

The total (protein-bound plus free) and free concentrations of progesterone, oestradiol-17 beta and cortisol were measured serially throughout pregnancy in the plasma of two groups of women whose pregnancies went to term. Group A (n = 53) experienced an uneventful low-risk pregnancy with a spontaneous abortion rate of 8.6%. Women in group B (n = 22) were treated orally with medroxyprogesterone acetate (MPA; 80-120 mg daily) until 18 weeks gestation for threatened abortion within the first 6 weeks of pregnancy. In both groups of women the proportion of each hormone circulating in the free or unbound form remained constant despite the overall increases with occurred in total circulating hormone concentrations as pregnancy progressed. The steroid hormonal profiles in the first half of pregnancy were similar in both groups of women. However, from weeks 20 to 40 total and free progesterone concentrations were significantly (P less than 0.05 in each case) higher in group B compared with group A. Conversely, total and free oestradiol-17 beta concentrations were lower (P less than 0.005 and P less than 0.01 respectively) in group B. At this stage it is not known if these differences were attributable to the administration of MPA to women in group B or to altered placental steroidogenesis as a result of earlier uterine bleeding.

Histamine sensitivity influences reactivity to allergens.

The ability to mount an IgE response to allergens is a prerequisite for the development of positive allergen skin tests, and this is reflected to some extent by the observation that allergen-responsive subjects tend to have higher total serum IgE concentrations. To determine whether histamine sensitivity also contributes to allergen responsiveness, 893 subjects in a rural community were prick tested with 14 allergens and tenfold dilutions of histamine phosphate beginning at 1 mg/ml-1. IgE was measured in a subset of 400 subjects. Three-way contingency table analysis confirmed previous reports of an association between allergen responsiveness and IgE (p less than 0.001) and also demonstrated that allergen responsiveness is associated with sensitivity to histamine (p less than 0.001). This association is independent of IgE so that the additive effect of IgE and histamine sensitivity allows more nearly accurate prediction of allergen responsiveness than either measurement alone.

An association between cutaneous sensitivity to histamine and HLA phenotype.

Four hundred and twenty randomly chosen subjects from a normal population were HLA typed and tested for cutaneous sensitivity to histamine by prick testing with 5 concentrations of histamine (10(-3), 10(-2), 10(-1), 1, 10 mg X ml-1). Positive responses to 10(-1) mg X ml-1 histamine occurred in 41% of the subjects, and particularly those with HLA-B7 (55%) (p less than 0.005). It is concluded that genes within the major histocompatibility complex influence cutaneous responses to histamine.

An electrophoretic investigation of the binding of 3-14C coumarin to rat serum proteins.

The binding of coumarin to serum proteins of the rat has been demonstrated. Of the total bound coumarin (37% of injected dose), 36% was bound to slow and fast oc1 globulins, 11% to the post albumins, 10% to globulin and 9% to albumin.