Since the mid-1800's,Adelaide's mammal diversity has fallen by more than a quarter,New York City has lost nearly half of its native plants,and at least 25 species of butterflies have disappeared from Rome.Our concrete jungles can be hard on wildlife,but there are plants and animals that survive-even thrive-in them.
从19世纪中叶起 阿德莱德的物种数量下降了超过1/4，纽约近半数本土植物已不见踪影，至少25种蝴蝶也消失在罗马城内，我们的水泥城墙让野生动物受尽折磨，不过 也有一些动植物能在其中生存 甚至壮大。
Some lucky species happen to be naturally suited to cities.For instance,English ivy and rock pigeons climb and roost on vertical structures like trees and cliffs anyway,so brick walls and sky-high ledges are fine substitutes.And omnivorous raccoons thrive on an endless buffet of everything from corn chips to cockroaches,helping them live ten times more densely in cities than in woodland habitats.
Natural flexibility can also help animals cope with the streeses of metropolitan living:coyotes that colonize cities often become more nocturnal to minimize their encounters with humans.Most species can't adopt an urban lifestyle so easily.But over several generations,genetic change can help some populations evolve into city slicker.
New York City's white-footed mice are one example:DNA sequencing suggests that these urban dweller's genes differ from their country cousins'in more than 30 significant ways.We don't yet know exactly what effects these changes have,but we know they've shown up in genes involved in fighting disease and processing toxins,traits that likely help mice survive in crowded landscapes.
We usually think of evolution as a slow process,so evolving fast enough to keep up with urbanization may seem like a tall order.But when a big challenge spring up suddenly.an uncommon trait that helps individuals cope can become the genetic norm surpringingly fast expecially in speedy breeders because those without it may not get a chance to reproduce.
For example after factories dumped thousands of tons of toxic PCBS into the Hudson River in the mid-twentieth century.it took just just six decades for 99 percent of the local tomcod to evolve a protective mutation that blocks the toxin from entering their cells.And in Montpelier,France,it's taken fewer than 12 years for urban weeds to start producing a larger proportion of heavy seeds,boosting their odds of settling in a patch of nearby soil instead of crash-landing on concrete.
例如 21世纪中期 当工厂向哈得孙河排放数千吨，有毒PCB后，当地99%的鳕鱼仅花了60年，就进化出能阻止有毒物质进入细胞的保护性变异，在法国蒙彼利埃 市区内的野草不到12年内就开始长出，大多较沉的种子，显著提高种子落在附近土壤 而非混凝圭土的几率。
As urban and rural populations diverge genetically and geographically,there's even a chance that some species could split in two.This doesn't mean that cities are a boon for biodiversity,but they aren't biological dead zones either-they're more like accidental laboratories where the limits of life's adjustability are being tested...and tasted.
城市郊区种群在基因和地理上渐行渐远，甚至一些物种可能分为两种，这不是说城市有利于生物多样性，亦非城市是生物的“死区”，它更像是充江满偶然的实验室 生物极限适应性在其中，不断被探索 品味。