As ecosystems change and deserts expand, food production diminishes, water sources dry up and populations are pressured to move to more hospitable areas.
随着生态系统发生变化，沙漠面积不断扩大，粮食生产日渐减少，水源枯竭，人口也不得不迁移，搬到更适宜居住的地区。
Digital ecosystems-the platforms around which populations focus online communications-can vary wildly between countries and within a single country.
数字生态系统——环绕于在线交流人群周围的平台——在国家与国家，甚至一个国家之内都有很大不同。
With captive breeding and luck, new populations of tortoises could be released on Pinta and Floreana Islands in five to 10 years, helping to restore their lost ecosystems, Dr. Cayot said.
卡洛特博士认为，经过悉心哺育，再加上一些运气，新象龟群体有望在五至十年后放还到平塔岛和弗罗里安那岛，帮助重建那里已经消失的生态系统。
With captive breeding and luck, new populations of tortoises could be released on Pinta and Floreana Islands in five to 10 years, helping to restore their lost ecosystems, Dr. Cayot said.
卡洛特博士认为，经过悉心哺育，再加上一些运气，新象龟群体有望在五至十年后放还到平塔岛和弗罗里安那岛，帮助重建那里已经消失的生态系统。
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