big questions in ecology and evolution apr 2009

[...]... reduction in their rate of egg laying as they age.39 Individually marked large herbivorous mammals such as bighorn sheep, ibex, and red deer all show relatively clear evidence of increases in age-dependent mortality in 10 Big Questions in Ecology and Evolution the wild.40 Spectacular examples of rapid increases in mortality following reproduction, such as that seen in annual plants, many insects, several... consideration of evolution, and almost all evolutionary questions have significant ecological components In essence, this book is intended as an introduction to several key ideas in ecology and evolution However, it introduces readers to these subjects not in the traditional way, but through posing a range of fundamental questions, and discussing the plausibility of solutions that have been offered These questions. .. without ageing, individuals are at continual risk of death (and infertility) from a variety of agents including accidents, predation, and disease What this means is that even in the absence of ageing, the probability of an individual living to a given point of time declines as the time interval increases Clearly, there is no guarantee that the occasional parent that happens to survive extrinsic challenges... in Ecology and Evolution line and general maintenance of the somatic cells The theory works on the assumption that somatic maintenance (such as DNA repair and the use of antioxidants to mop up ROS) is a metabolically costly activity involving both physical infrastructure and running costs, and that resources invested in general maintenance and repair are not available for development and reproduction... of mutations with late-acting deleterious effects, so 16 Big Questions in Ecology and Evolution they can begin to express their effects in occasional old individuals, causing death in old age Medawar’s theory of mutation accumulation does not refer to the accumulation of mutations within an individual during its lifetime, only that mutations that can cause harmful effects in late life are not as effectively... approach— fundamental ecological and evolutionary concepts are introduced only as and when they are needed to explain the question at hand Asking big questions and examining solutions have their challenges from an educational perspective—concepts need to be built up Nevertheless, it is our hope that by introducing the science in this way, our readers will immediately feel involved Who does not want to... probability of being killed by extrinsic factors, because there is no fitness advantage in keeping an organism going for any longer than it would naturally live Hence, if these evolutionary explanations were broadly correct, then one potential prediction might be that ageing would be slower (and longevity longer), the lower the level of extrinsic 20 Big Questions in Ecology and Evolution hazard.5 In contrast,... theory 3: ageing and the individual When considering the early ideas of Wallace, one also thinks of Charles Darwin, who had a remarkable track record of being right Darwin’s notebooks contain the unanswered Why Do We Age? 15 question ‘Why is life short?’79 (thereby incidentally echoing the sentiments of his grandfather Erasmus in The Temple of Nature: ‘How short the span of life’), indicating that he... maintained in the laboratory.18 A fascinating botanical example of genetically-mediated variation in age of senescence comes from the work of Richard Law and colleagues,19 who took seeds from populations of the meadow grass Poa annua growing in two different conditions: lowdensity populations (including the disturbed derelict site in Liverpool, UK, shown in Fig 1.5) and high-density populations (including... Law and colleagues19 involved sowing the seeds of the grass Poa annua collected from a range of low-density and high-density sites and rearing them in a common environment The offspring of plants growing in the low-density sites showed rather different growth forms and, months later, died significantly earlier than the offspring of plants growing in high-density sites Experiments such as these indicate . x0 y0 w0 h0" alt="" Big Questions in Ecology and Evolution This page intentionally left blank Big Questions in Ecology and Evolution THOMAS N. SHERRATT DAVID M. WILKINSON 1 3 Great Clarendon. ecological and evolutionary concepts are introduced only as and when they are needed to explain the question at hand. Asking big questions and examining solutions have their challenges from. proofreading. Many other colleagues, too numerous to mention individually, helped in answering questions and providing clarifi - cations. As ever, all inaccuracies and misconceptions remain our