PREDICTING MICROEVOLUTIONARY RESPONSES TO DIRECTIONAL SELECTION ON HERITABLE VARIATION

Microevolution of quantitative traits in the wild can be predicted from a knowledge of selection and genetic parameters. Testing the predictions requires measurement of the offspring of the selected group, a requirement that is difficult to meet. We present the results of a study of Darwin's finches on the Galápagos island of Daphne Major where this requirement is met. The study demonstrates microevolutionary consequences of natural selection.     

The nutritional value of feeding on crops: Diets of vervet monkeys in a humanized landscape

Anthropogenic influences have dramatically altered the environments with which primates interact. In particular, the introduction of anthropogenic food sources to primate groups has implications for feeding behaviour, social behaviour, activity budgets, demography and life history. While the incorporation of anthropogenic foods can be beneficial to primates in a variety of nutritional ways including increased energetic return, they also carry risks associated with proximity to humans, such as risk of being hunted, disease risk and risk of conflict. Given such risks, we initiated a 3‐year study where we sought to understand the underlying nutritional motivations for anthropogenic food resource use by vervet monkeys (Cercopithecus aethiops) in the humanized matrix surrounding the Nabugabo Field Station in central Uganda. Feeding effort, defined as proportion of feeding scans spent on anthropogenic food, was not associated with ripe fruit availability nor with crop availability as determined by phenological monitoring. Likewise, there was no difference in the protein, fibre, or lipid composition of crop food items compared to wild food items. Individuals spent less time feeding overall in months over the 3 years with a higher proportion of time spent feeding on crop foods, suggesting a potential benefit in terms of accessibility (reduction in the proportion of activity budget devoted to feeding).     

Fine root growth and element concentrations of Norway spruce as affected by wood ash and liquid fertilisation

A field experiment to test various management practices of sustainable forestry was conducted in a Swiss spruce forest for two growing seasons. Treatments were a control (C), yearly application of 4000 kg ha^–1 wood ash (A), daily irrigation with a steady state fertilisation as `optimal nutrition` (F) and irrigation with a water control (W). Samples were taken on a 5 × 5 m grid once a year with a soil corer to determine fine root biomass ( 2 mm) and soil pH of the topsoil. A subset of the fine root samples was further analysed for its nutrient composition by CN and ICP-AES analyses. The dynamics of root growth were observed with the aid of ingrowth-cores after 1, 1.5, and 2 years of treatment and the growth pattern was analysed in terms of biomass, tips, forks, length and root diameter of the samples. The A, F and also the W treatment resulted in a significant increase of soil pH in the topsoil. The fine root density increased over the two growing seasons, irrespective of the treatment. The root growth was only slightly different between the treatments with a initially faster growth under the A treatment. The W treatment reduced the number of root tips and forks, and the root length, while the A treatment increased the number of root tips, forks and the root length, but reduced the diameter. The differences between the three harvesting times (March 1999, October 1999, March 2000) of the ingrowth-cores stressed seasonal differences in root growth and the development of quasi `steady state' root dynamics. The root turnover was not changed by the treatments. The elements in the fine roots were strongly affected by the treatments A and F and sometimes by W. Fine root N increased with the F treatment, while C concentrations decreased under the A, F and W treatments. The Ca and Mg concentrations were strongly enhanced by A but also by the F treatment. The K and P concentrations in the fine roots were improved by all three applications. Due to the pH increase Al, Fe and Mn concentrations in the fine roots were decreased by the A and F treatments. S and Zn concentrations showed inconsistent changes over the growing seasons. The results of this study were comparable with those of other studies in Europe and confirm the abilities of the fine roots as indicators of forest nutrition, to some extent more sensitive than the commonly used foliar analysis.     

Fish Growth in Marine Culture Systems: A Challenge for Biotechnology

Aquaculture production is constrained largely by the growth efficiency of the species being produced. Nutritional approaches have played an important part in improving this situation, but, it is argued, the room for further improvement using such established techniques is limited. Alternative ways of improving fish production by utilizing recent biotechnological advances are explored and assessed as to their potential for commercialization in the near future. Transgenic technologies promise a revolution in aquaculture, but it is considered that consumer resistance may delay the use of transgenic fish for food production. An alternative approach could be the breeding of transgenic fodder plants without the amino acid deficiencies of existing alternatives to fish meal in aquaculture diets. The use of probiotics could reduce antibiotic use on fish farms while they might also provide the basis for ``smart' diets, tailored to specific purposes by the inclusion of microorganisms. The selection and genetic engineering of nitrifying and denitrifying bacteria could also pave the way for fully enclosed, recirculating marine culture systems, which would allow control of the environmental variables that currently restrain marine fish culture. Received August 10, 1998; accepted October 8, 1998.     

Effect of the preweaning nutritional state on the cardiac protein profile and functional performance of the rat heart

The aim of the study was to find out whether the changes in nutritional status induced by different litter size during early postnatal development can influence quantitative and qualitative protein remodeling and contractile performance of the myocardium. Male Wistar rats born at the same day were pooled together at 2 days postbirth and assigned by random selection to dams in groups of 4, 8 or 16 rats/litter. The animals were investigated at the age of 4 and 16 weeks. The results revealed that the early postnatal nutritional modification altered weight parameters: whereas lower heart weight persisted in slow-growing rats until 16 weeks, higher body weight of fast-growing rats returned to the control level at the age of 16 weeks. Altered nutritional status influenced also protein remodeling of the myocardium: the concentration of all noncollagenous proteins (fractions of metabolic and contractile proteins) significantly increased in slow-growing rats, on the other hand, the concentration of collagenous proteins (pepsin-soluble and -insoluble fractions) was higher in fast-growing animals. The changes were, however, only transitional: three months after the end of the weaning period most protein changes returned to the control level. However, higher concentration of total blood lipids and triglycerides in fast-growing rats persisted until adulthood. Nutritional changes had, however, only minor effect on ventricular performance. No differences among groups were observed in basal values of the left ventricular pressure, while the maximum pressure attained after an acute ventricular loading and the contractile reserve were significantly decreased in slowgrowing 4 week old rats. The functional consequence of altered nutritional status during weaning was only transitional, in agreement with the transient character of most structural and biochemical markers of myocardial remodeling.     

实验动物新西兰兔适宜营养水平的研究

根据地方饲料资源特点 ,应用计算机软件 ,设计不同的饲料配方 ,并生产相应的颗粒料 ,饲喂 6 0只一级新西兰幼兔、 2 4只繁殖母兔。在饲养管理条件相同的情况下 ,进行动物分组对比试验 ,观察幼兔生长情况、母兔繁殖情况 ,研究新西兰兔不同发育阶段所需的适宜的营养水平。试验按 2× 3因子设计。试验结果 :1、幼兔生长发育的最佳配方 :消化能 11 0 3MJ/kg ,粗蛋白质 15 10 % ,粗脂肪 3 0 4% ,粗纤维 10 2 6 % ,钙 1 34 5 % ,磷0 5 6 %。 2、繁殖母兔的最佳配方 :消化能 10 91MJ/kg ,粗蛋白质 18 17% ,粗脂肪 2 96 % ,粗纤维 10 2 8% ,钙1 47% ,磷 0 5 8%。