Grant B S, Wiseman L L
Department of Biology, College of William and Mary, Williamsburg, VA 23187-8795, USA.
J Hered. 2002 Mar-Apr;93(2):86-90. doi: 10.1093/jhered/93.2.86.
Industrial melanism in peppered moths has been studied most intensively in Britain. The first melanic phenotype (effectively solid black) was recorded near Manchester in 1848. By 1895 about 98% of the specimens near Manchester were melanic, and this once rare phenotype had spread across regions of the country blackened by industrial soot. In rural, unpolluted regions, well away from industrial centers, the pale phenotype (peppered with white and black scales) remained the predominant form. During the latter half of the 20th century, following legislation designed to improve air quality, melanics began to decline in frequency and are now rare where once they had been common. Similar evolutionary changes have occurred elsewhere, but records from outside Britain are fragmentary. We have extended previous surveys of American peppered moth populations and present a composite picture of the recent decline in melanism in northern industrial states-Michigan and Pennsylvania-where melanic phenotypes decreased from more than 90% in 1959 to 6% by 2001. We contrast these changes to the near absence of melanism in a southern state-Virginia-during that same period. As in Britain, the decline in melanism in American peppered moths followed clean air legislation.
在英国，对桦尺蛾的工业黑化现象进行了最为深入的研究。1848年，在曼彻斯特附近首次记录到了第一种黑化表型（实际上是纯黑色）。到1895年，曼彻斯特附近约98%的标本都是黑化的，这种曾经罕见的表型已经蔓延到了该国被工业烟尘熏黑的地区。在远离工业中心的农村未受污染地区，浅色表型（带有白色和黑色鳞片）仍然是主要形式。在20世纪后半叶，随着旨在改善空气质量的立法的实施，黑化桦尺蛾的频率开始下降，现在在它们曾经常见之处已很罕见。类似的进化变化在其他地方也有发生，但英国以外地区的记录并不完整。我们扩展了之前对美国桦尺蛾种群的调查，并呈现了一幅近期北方工业州——密歇根州和宾夕法尼亚州——黑化现象下降的综合图景，在这些地方，黑化表型从1959年的90%以上降至2001年的6%。我们将这些变化与同一时期南方弗吉尼亚州几乎不存在黑化现象的情况进行对比。与英国一样，美国桦尺蛾黑化现象的下降也是在清洁空气立法之后出现的。
