Department of Zoology, Tel Aviv University, Tel Aviv, Israel.
Biol Rev Camb Philos Soc. 2011 May;86(2):531-41. doi: 10.1111/j.1469-185X.2010.00168.x. Epub 2010 Nov 11.
Geographical and temporal variations in body size are common phenomena among organisms and may evolve within a few years. We argue that body size acts much like a barometer, fluctuating in parallel with changes in the relevant key predictor(s), and that geographical and temporal changes in body size are actually manifestations of the same drivers. Frequently, the principal predictors of body size are food availability during the period of growth and ambient temperature, which often affects food availability. Food availability depends on net primary productivity that, in turn, is determined by climate and weather (mainly temperature and precipitation), and these depend mainly on solar radiation and other solar activities. When the above predictors are related to latitude the changes have often been interpreted as conforming to Bergmann's rule, but in many cases such interpretations should be viewed with caution due to the interrelationships among various environmental predictors. Recent temporal changes in body size have often been related to global warming. However, in many cases the above key predictors are not related to either latitude and/or year, and it is the task of the researcher to determine which particular environmental predictor is the one that determines food availability and, in turn, body size. The chance of discerning a significant change in body size depends to a large extent on sample size (specimens/year). The most recent changes in body size are probably phenotypic, but there are some cases in which they are partly genetic.
生物体的体型存在地理和时间上的变化是常见现象，并且可能在几年内发生演变。我们认为，体型就像晴雨表一样，与相关关键预测因子（predictor）的变化平行波动，体型的地理和时间变化实际上是同一驱动因素的表现。通常，体型的主要预测因子是生长期间的食物可获得性和环境温度，而环境温度往往会影响食物的可获得性。食物的可获得性取决于净初级生产力，而净初级生产力又取决于气候和天气（主要是温度和降水），这些又主要取决于太阳辐射和其他太阳活动。当上述预测因子与纬度有关时，这些变化通常被解释为符合伯格曼法则，但在许多情况下，由于各种环境预测因子之间存在相互关系，这种解释应该谨慎看待。近年来体型的变化通常与全球变暖有关。然而，在许多情况下，上述关键预测因子与纬度和/或年份都没有关系，研究人员的任务是确定哪个特定的环境预测因子决定了食物的可获得性，进而决定了体型。能否发现体型的显著变化在很大程度上取决于样本量（标本/年）。最近的体型变化可能是表型的，但在某些情况下，它们部分是遗传的。
