Climatic seasonality, resource bottlenecks, and abundance of rainforest birds: implications for global climate change

We demonstrate that within-year climatic variability, particularly rainfall seasonality, is the most significant variable explaining spatial patterns of bird abundance in Australian tropical rainforest. The likely mechanism causing this pattern is a resource bottleneck (insects, nectar, and fruit) during the dry season that limits the population size of many species. The patterns support both the diversity–climatic–stability hypothesis and the species–energy hypothesis but clearly show that seasonality in energy availability may be a more significant factor than annual totals or means. An index of dry season severity is proposed that quantifies the combined effect of the degree of dryness and the duration of the dry season. We suggest that the predicted increases in seasonality due to global climate change could produce significant declines in bird abundance, further exacerbating the impacts of decreased range size, increased fragmentation, and decreased population size likely to occur as a result of increasing temperature. We suggest that increasing climatic seasonality due to global climate change has the potential to have significant negative impacts on tropical biodiversity.     

An RFLP for probe 26-6 that is useful in linkage diagnosis for adult polycystic kidney disease

A previously unreported RFLP for probe 26-6, at 1.2-kb, has been recorded in two families after Southern blotting, where it has been useful in establishing phase. This allele is not detected in the polymerase chain reaction (PCR) assay for 26-6 where individuals are typed only as E₂.     

An unreported RFLP for probe 218 EP6 that is useful in linkage analysis of adult polycystic kidney disease

Probe 218 EP6 is known to recognise two restriction fragment length polymorphisms (RFLPs) after digestion of genomic DNA withPvuII. We report a rare allele that segregates in Mendelian fashion, in a family where adult polycystic kidney disease was being tracked using linked polymorphisms.     

The physical characteristics of the members during the International Biomedical Expedition to the Antarctic

Twelve male medical scientists formed the International Biomedical Expedition to the Antarctic (IBEA). Their physical characteristics and maximum oxygen uptakes (VO2max) were measured in association with three series of thermal tolerance tests in Sydney, twice before and once after going to the Antarctic. In the Antarctic they lived in tents and spent 15 days travelling by motor toboggan. Their body mass (BM) and skinfold thickness (SFT) were measured four times during the 69 days the expedition spent in the field. The characteristics of the group were (ranges): age 26-52 years, height 1680-1889 mm, BM 58.5-103.4 kg, fatness 16-34% BM and VO2max 33-49 ml X kg-1 X min-1. In the Antarctic 9 men lost between 0.7 and 5.5 kg (mean 2.7 kg) of BM with a decrease in SFT, whilst 2 men increased BM by 1.2 and 1.9 kg without change in SFT. One man retired early from the expedition. BM and SFT were regained and physical fitness lost during the return voyage to Australia. Consequently there was no difference in average SFT between the pre- and post-Antarctic laboratory tests, but BM was greater after the Antarctic implying gains in fat free mass. VO2max was lower in the final laboratory tests than in the tests before Antarctica.     

Record performances at the Boston Marathon: Biometeorological factors

Air temperature and relative humidity have long been suspected of affecting the performance of marathon runners. Though these factors are important in their extremes, we show that other factors are even more indicative of race performances. Performances of the top 3 finishers in the last 30 Boston Marathons were correlated with hourly meteorological data for each race day. These 90 individual performances were classified as: record breaking performances (31), average performances (35), and unusually slow performances (24). The factors that help predict record breaking and unusually slow performances are: (i) wet bulb temperature, (ii) percent sky cover, and (iii) presence or absence of a light precipitation. Record breaking performances are characterized by a wet bulb temperature of <7.8°C, and 100% sky cover. A light drizzle is also conducive to better performances. On the other hand, unusually low performances are accompanied by a wet bulb temperature of >7.8°C, and a sky cover of 50% or less. No light, precipitation was recorded on any of the unusually slow race days. A graphic analysis clearly shows these relationships to exist. In addition, a multiple regression analysis confirms the importance of these variables. The authors advise that these are reliable predictors; however, when considering marathon races held in various geographical regions and differing climatic regimes, the exact numerical thresholds used here may not apply.