beetle测天气变化那个。 这篇我没看文章，就第三段扫了10秒……直接做的题，时间来不及了 题目1. 就是beetle 和 pollen 比较的那个， 我选的 beetle 更quickly那一项，那一项挺长的，大概就是 beetles which requires same environment as plants react to environment more quick than do these plants。 2. 这篇文章的primary purpose？ 我选的解释为什么一个科学方法会如此受科学家们的favor 3. 第三段还是第几段，反正是最后一段，问此段的作用？ 我选的再illustrate几个beetle 的attribute。
阅读第四篇是beetle的那个，这篇没时间做了，实在是啥都没看清，不好意思了。。。就记得问题有主旨题，一个细节题问beetle为什么比pollen更靠谱，这题我确定我选错了，原文中有contaminated by long-distant wind-啥的 pollen，应该是选花粉被污染那个选项，LZ悲剧地不认识contaminate，纠结了很久。。。
WHY BEETLES ARE GOOD ENVIRONMENTAL PROXIES Beetle fossils are commonly preserved as disarticulated skeletal fragments (fig. 2) in organic sediments such as clays, peats, sands and silts (Porch & Elias, 2000).
Beetles preserve well due to their robust nature and structural details can often be distinguished allowing them to be identified to species level. In most cases identification has revealed fossilised beetles to be extant species indicating a great degree of morphological（形态学的） constancy throughout the Quaternary（地质学第四季）. This constancy includes that of key characters, such as genitalia（生殖器）, used in the identification of species. As morphology does not appear to have evolved it is generally assumed that the physiological（生理学的） requirements of beetles have also remained constant.
Evidence to support this assumption exists in the fact that the composition of beetle communities has, like morphology, remained relatively constant throughout the Quaternary and that host-specific phytophagus species can be sometimes be found in association with macrofossils of their host plant. Due to this observed constancy and the ectothermic nature of beetles – and thus their reliance on environmental conditions – beetle fossils can therefore make excellent indicators of pale environment.
HISTORY OF FOSSIL BEETLE PALEOENVIRONMENTAL RECONSTRUCTIONS The first climate and environmental reconstruction using beetle fossils was published by Coope. Since this time beetle fossils have been increasingly used for reconstructing past environments and the associated climate. Initially this work was restricted to the United Kingdom but soon spread to continental Europe and North America . Since then the number of studies utilizing beetle remains to reconstruct the pale environment has continued to increase, primarily in the Northern Hemisphere, but also in South America and recently there has been discussion of the potential for this research in Australia. In 2002 the first New Zealand study using beetle fossils to reconstruct pale climate and pale environment was completed proving that this technique is usable in New Zealand and laying the groundwork for this study.
While the use of beetle fossils for pale climatic and pale environmental reconstruction has increased over the last four decades it is still little used when compared to other biological proxies, and in New Zealand palaeo environmental analysis is dominated by palynology even though the flora of New Zealand is temperature-tolerant making quantification of palaeo climate difficult. Other methods of environmental and climatic reconstruction used in New Zealand are tree rings, phytoliths, aerosolic quartz influx, glacial equilibrium-line estimates, speleothems and diatoms
ADVANTAGES OF FOSSIL BEETLES OVER OTHER BIOLOGICAL PROXIES Fossil beetle analysis has a number of advantages over other biological proxies such as pollen. Beetles are the most diverse group of organisms filling a large range of ecological roles and habitats from deserts to rainforests to the littoral（海滨的） zone. Beetles, and insects in general, respond rapidly to environmental change by dispersal（分散）, rather than undergoing speciation, and fossils are generally identifiable to species level in contrast to New Zealand palynological studies where some genera contain species with different ecological requirements, but with indistinguishable pollen.
Predatory and scavenging beetles are able to take advantage of recently modified areas (along with pioneer plant species) before the trees and shrubs with similar climatic requirements. Trees and shrubs can therefore lag behind the actual period of climatic change and the resultant spread of beetles. This ability to rapidly respond to climatic change has also revealed short-term climate fluctuations that are not observed in the pollen record. Beetles fossils also avoid the problem of contamination of the local pollen rain (and hence local climate signal) by long-distance wind dispersed pollen
Until the development of the Mutual Climatic Range (MCR) by Atkinson et. al. (1987) studies using beetle fossils were, like palynology, predominantly qualitative in nature. MCR is a method of quantifying paleoclimateand has further increased the usefulness of beetle fossils in reconstructing the past climate of the Quaternary. This quantitative method has enabled studies of beetle fossils to be compared to, or combined with, other proxy(有代表性的) data to provide a more complete paleo climatic and paleo environmental reconstruction.
MCR uses the modern distribution of a species found within a fossil beetle assemblage to construct a climate envelope for that species. This is based on the observation that the contemporary distribution of a beetle species is seen to measure its climatic tolerances. Only predators and scavengers are used to calculate MCR as the distribution of some herbivorous species may be limited by the range of a host plant rather than by direct climatic influences. The climate envelopes of all applicable species in the assemblage are overlapped to find the mutual intersection of the climatic ranges. This provides a quantitative measure of the paleoclimate at the time of the assemblage deposition. While providing a quantitative measure of temperature MCR has been found to underestimate maximum temperatures (TMAX) and overestimate minimum temperatures (TMIN) in extremely cold environments. TMIN can also be underestimated in areas with milder winters. However these errors can be corrected for using regression equations. Currently these equations have been calibrated for Europe and North American sites. The recent work by Marra(2002) has also formulated a method of establishing quantitative measures of paleoclimate for the smaller datasets normally extracted from New Zealand sites. Herbivorous beetle species, while excluded from MCR analysis due to their potential relationship to host-plants, are extremely useful in paleoenvironmental reconstruction. Some phytophagus beetle species, such as some scolytids (bark beetles), are restricted in their distribution to certain species of trees. When discovered in a fossil assemblage these beetle species therefore indicate that the required host-plant was present at the study site at the time of deposition. The application of phytophagus beetle fossils for this purpose is possible in a New Zealand context as previously shown by Marra.
PROJECT OUTLINE This project will use fossil beetle analysis to examine the faunal changes in fossil beetle assemblages through several glacial-interglacial cycles. At the very least, the peat and mud units associated with the warm phases will allow the examination of beetle migration and relative environmental conditions through several of these cycles.
This would be the first beetle record extending beyond one glacial cycle in the Southern Hemisphere and, when the work is complete, one of the best beetle records in the world. The work will involve the field collection of samples along chronological transects from the raised beach terraces along the coast of Westland . Analysis of the fossil beetle material will hopefully allow the environmental and reconstruction of the past climate from each site. This research will further the development of the use of fossil beetles as high-resolution paleoclimatic and paleoenvironmental indicators in New Zealand and will, in theory, provide quantitative measures of the geologically recent climate of the West Coast of the South Island. Furthermore the fossil evidence collected will provide biogeographical information on migration and distribution of the New Zealand beetle fauna in the Quaternary. In addition this study will provide the beginnings of a database of information on fossil beetles that can be used to aid future environmental reconstructions enabling the development of a clearer overall picture of the Quaternary climate and environment of New Zealand. 作者: 张学友 时间: 2012-1-1 17:42
挺你作者: anjjule 时间: 2012-1-1 17:49
顶作者: 泾渭不凡 时间: 2012-1-1 18:49
考古帝归来~作者: xingruiming 时间: 2012-1-2 15:01
考古帝终于回来了！！！！作者: niniz1990 时间: 2012-1-14 21:02
UP~~~