GRE阅读高频机经原文：Snowshoeharepopulation

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GRE阅读高频机经原文：Snowshoe hare population　

Snowshoe hare population

The snowshoe hare is one of the northern mammAls that go through periodic cycles of changes in their populations. Over a period of years, their population will increase in numbers and then suddenly crash to very low numbers, only to rise again. Snowshoe hare tend to cycle about once every ten years. The snowshoe hare cycle is one of the best known and fur trappers and traders working in northern Canada first described it. In 1865, traders with the Hudson's Bay Company were flooded by hare pelts brought in by trappers. But, by 1870, only a few hare pelts trickled in. This pattern of high and low abundance of hare pelts repeated itself over and over, roughly every ten years.

Snowshoe hares are a dominant herbivore in northern forest ecosystems. In Alaska and western Canada, their populations cycle over 8 to 11 years. The difference in densities and abundance during the cycle are extreme. Densities as high as 4,000 hares per square kilometer (or 10,000 hares per square mile) have been estimated at the peak (or high point) of the cycle. These populations can "crash" to densities of less than one hare per square kilometer (or 2.6 hares per square mile) within a period of one year. The populations slowly increase to peak densities over the next 6 to 13 years. The densities during peak years, however, are not always the same.

Just what is it that drives the snowshoe hare cycle? This question has puzzled people living in northern areas and scientists for many years. On a broad scale, it may be the 22- year sunspot cycle and its effects on boreal forest weather patterns or forest fires. On a smaller scale, the cycles may be affected by over browsing the food supply, predators, shock disease due to stress, parasites, or a combination of these. The primary theory pertaining to the snowshoe hare population cycle describes the mechanics as a combination of predators and browse (food) availability. During the peak of their cycle, hares eat a large proportion of the shrubs available in their area. They can also kill many of the shrubs in their area by chewing through the outer layer of bark. Over-browsing of shrubs results in a food-shortage that causes malnourishment, starvation, and reduced reproduction. This leads to the start of the population crash or decline. Also, as food supplies decrease, the health of hares declines and makes many individuals more vulnerable to predators and disease. In the western Yukon, scientists believe that the hare cycle is caused by changes in food supply and predation. The declines and increases in the population of hares were influenced by the reproductive rates of adult hares and the survival rates of all ages of hares.

GRE阅读词汇精选之ine结尾的动物

aquiline　adj.鹰的，似鹰的.

asinine　adj.愚笨的

bovine　adj.(似)牛的，迟钝的

canine　adj.犬的，似犬的

elephantine　adj.笨拙的,巨大的

equine　adj.马的,似马的

feline　adj.猫科的

leonine　adj.狮子的

porcine　adj.猪的,似猪的

porcupine　　　n.豪猪,箭猪

serpentine　adj.似蛇般绕曲的，蜿蜒的

ursine　adj.熊的，像熊的

vulpine　adj.狐狸的，狡猾的

lupine　adj　狼的，残忍的，贪吃的

colubrine　adj　无毒蛇的，似蛇的

cervine　adj　鹿的，鹿一样的

GRE词汇精选之格言

adage　n.格言，古训

aphorism　n.格言

dictum　n.格言、声明

gnome　n.地下宝藏的守护神，地精，格言

gnomic　adj.格言的，精辟的

maxim　n.格言，普遍真理

motto　n.座右铭，箴言

precept　n.箴言,格言

epigram　n.警句，讽刺短诗

epigrammatic　adj.警句的

phrase　n.警句，· 乐句，· 短语

还有saying,proverb

GRE阅读精选词汇之几种笑

chortle　v.n.开心地笑

chuckle　v.轻声地笑

guffaw　n.v.哄笑，大笑

simper　v.傻笑、假笑

smirk　v.假笑，得意地笑

snigger　v.n.暗笑，窃笑　(=snicker)

giggle　v.(女孩)咯咯的笑

titter　v.嗤嗤的笑,偷笑

grin　v.露齿而笑

GRE阅读精选词汇之大败,失败,战胜

fiasco　n.大失败，惨败

massacre　n.大屠杀，大败

rout　n.大败，溃败

checkmate　n.(象棋中)被将死时王的位置，完全失败

lurch　n　挫败，大败

washout　n　冲刷，失败

founder　v.(船)沉没，(计划)失败

fizzle　n　咝咝声，失败

flummox　v.使混乱，背诵出错　n.失败

flop　n.　失败　v　笨重的摔

balk　n.障碍,错误,失败

balk　n.障碍,错误,失败　　vt.阻止,突然停止,退缩

bungle　vn拙劣地工作,粗制滥造,失败

confound　v　使混淆,使狼狈,挫败

frustrate　v.挫败，使沮丧

pulverize　v.压成细粉,彻底击败

scalp　n.头皮，· 战利品v.击败

paste　v　狠狠地打，· 击败

abortive　adj.无结果的，· 失败的

crestfallen　adj.挫败的，· 失望的

internecine　adj.内讧的,两败俱伤的

circumvent　v.用计谋战胜，· 规避

landslide　n.山崩，· 压倒性胜利

outfox　v.以机智胜过

outwit　v.以机智胜过

prevail　v.战胜,盛行

surmount　v.克服，· 战胜，· 越过

transcend　v.超越，· 胜过

tie　n.不· 分胜负　v.与成平局

GRE阅读高频机经原文：Snowshoe hare population