It is a common assumption that species' ranges are limited by their physiological tolerances to climatic factors, Biotic factors, such as competition, are rarely considered. We investigated the distributions of Ulex minor and U. gallii at three spatial scales from geographic ranges to individual heaths -to examine whether the species are negatively associated, as predicted by the hypothesis that ihe ranges of the species are limited by competition with each other. Distribution maps for the British Isles and France (100-400 km^ survey units) show the two species have largely separated, but slightly overlapping ranges. A region of range overlap on the heaths of Dorset, southern England was mapped using 4 ha survey squares. There was strong negative association between the species, and the heaths could be divided into zones where one species was dominant. There was some indication of edaphic differences between the V. m/Ro/--dominated zones and the V. gallii zones. The few heaths where the species co-occurred were surveyed using 4 m^ quadrats placed along transects. Usually one species was widespread over the heath, while the other occurred in patches. The species were strongly negatively associated in all transects. Therefore, the two species showed strong negative associations at three mapping scales. Apparent co-occurrences detected at one spatial scale largely disappeared when species were mapped at finer scales, emphasising the fractal nature of distributions. This provides evidence that the distributions of the two species are not independent and that they cannot coexist, and therefore that their ranges are limited by competition. Over their ranges, competitive superiority is probably determined by the climate. At the range boundaries in the region of overlap, climate is not important, but other physical factors such as edaphic conditions may determine the outcome of competition.J. M. Bullock (jmbul@ceh.ae.uk). R.

Our aim was to determine if antenatal hypoxia was associated with liver dysfunction and coagulation abnormalities in small-for-gestational-age (SGA) infants. Sixteen SGA infants, median gestational age 30 (range 26–32) weeks, who consecutively had had umbilical artery Doppler studies in the week before delivery, were compared to appropriate-for-gestational-age (AGA) controls, who were each matched to an SGA infant for gestational age. The median international normalised ratio (INR) was significantly higher (1.9 vs. 1.3, p < 0.001) and the neutrophil (p = 0.003) and platelet counts (p < 0.001), alkaline phosphatase (p < 0.001) and albumin (p < 0.02) levels significantly lower in the SGA compared to the AGA group. The umbilical artery pulsatility index (PI) was elevated, indicating antenatal hypoxia, in all but 1 of the SGA infants. Multiple linear regression analysis demonstrated that the INR was significantly related to the umbilical artery PI independent of the other variables (p = 0.0002, R² = 0.71). These results suggest that the coagulopathy seen in preterm SGA infants might at least be partially explained by antenatal hypoxia affecting the liver and hence vitamin K-dependent coagulation.

It is a common assumption that species' ranges are limited by their physiological tolerances to climatic factors, Biotic factors, such as competition, are rarely considered. We investigated the distributions of Ulex minor and U. gallii at three spatial scales from geographic ranges to individual heaths ‐ to examine whether the species are negatively associated, as predicted by the hypothesis that the ranges of the species are limited by competition with each other. Distribution maps for the British Isles and France (100 400 km2 survey units) show the two species have largely separated, but slightly overlapping ranges. A region of range overlap on the heaths of Dorset, southern England was mapped using 4 ha survey squares. There was strong negative association between the species, and the heaths could be divided into zones where one species was dominant. There was some indication of edaphic differences between the U. minor‐dominated zones and the U. gallii zones. The few heaths where the species co‐occurred were surveyed using 4 m2 quadrats placed along transects. Usually one species was widespread over the heath, while the other occurred in patches. The species were strongly negatively associated in all transects. Therefore, the two species showed strong negative associations at three mapping scales. Apparent co‐occurrences detected at one spatial scale largely disappeared when species were mapped at finer scales, emphasising the fractal nature of distributions. This provides evidence that the distributions of the two species are not independent and that they cannot coexist, and therefore that their ranges are limited by competition. Over their ranges, competitive superiority is probably determined by the climate. At the range boundaries in the region of overlap, climate is not important, but other physical factors such as edaphic conditions may determine the outcome of competition.