- 2018年05月08日12:48 来源：小站整理
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更新世绝大多数动、植物属种与 2012 年的物种相似。显著特征为气候变冷、有冰期与间冰期的明显交替。人类也在这一时期出现。更新世的植物开始同现代的植物相似,被子植物特别是落叶的种类在温和的和较冷的区域中迅速繁殖。那时,猛犸、骆驼、马、巨型河狸、狼和短面熊等适应寒冷气候的动物,在整个冰期都生活在亚洲、欧洲和美洲大陆。更新世晚期,距今约 2 万年前,现代人类经白令海峡进入美洲。
Pleistocene rewilding is the advocacy ofthe reintroduction of descendants of Pleistocene megafauna, or their closeecological equivalents. An extension of the conservation practice of rewilding,which involves reintroducing species to areas where they became extinct inrecent history (hundreds of years ago or less).
Toward the end of the Pleistocene era(roughly 13,000 to 10,000 years ago), nearly all megafauna of South, Central,North America and Europe dwindled toward extinction. With the loss of largeherbivores and predator species, niches important for ecosystem functioningwere left unoccupied. In the words of the biologist Tim Flannery, "eversince the extinction of the megafauna 13,000 years ago, the continent has had aseriously unbalanced fauna". This means, for example, that the managers ofnational parks in North America have to resort to culling to keep thepopulation of ungulates under control.
Paul S. Martin (originator of thePleistocene overkill hypothesis) states that present ecological communities inNorth America do not function appropriately in the absence of megafauna,because much of the native flora and fauna evolved under the influence of largemammals.
Test Point – 官方真题Official22L3
So here’s the biologists’idea. Take aselect group of animals, megafauna from places like Africa and Asia, andintroduce them into other ecosystems similar to their current homes, beginningin the United States. They call their plan Pleistocene rewilding.
Now, the advocates of Pleistocene rewildingcite two main goals. One is to help prevent the extinction of some endangeredmegafauna by providing new refuges, new habitats for them. The other is torestore some of the evolutionary and ecological potential that has been lost inNorth America. What do I mean by restore evolutionary potential? Well as youknow the evolution of any species is largely influenced by its interactionswith other species. So during the Pleistocene epoch... let’s take the now extinctAmerican cheetah, for instance. We believe it played a pivotal role in theevolution of the pronghorn antelope, the antelope’s amazing speed, to be exact,because natural selection would favor those antelope that could outrun acheetah. When the American cheetahs disappeared, their influence on theevolution of pronghorn and presumably on other prey animals stopped. So it isconceivable that the pronghorn antelope would have continued to evolve, getfaster maybe, if the cheetahs were still around. That’s what’s meant byevolutionary potential. Importing African cheetahs to the western United Statescould, in theory, put the pronghorn back onto its ...uh, natural evolutionarytrajectory according to these biologists.