Walters Richard John, Hassall Mark
Center for Ecology, Evolution, and Conservation, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom.
Am Nat. 2006 Apr;167(4):510-23. doi: 10.1086/501029. Epub 2006 Mar 14.
The majority of ectotherms mature at a larger size at lower rearing temperatures. Although this temperature-size rule is well established, a general explanation for this phenomenon has remained elusive. In this article, we address the problem by exploring the proximate and ultimate reasons for why a temperate grasshopper, Chorthippus brunneus, is an exception to the temperature-size rule. Using a complete set of life-history data to parameterize an established life-history model, we show that it is optimal for this species to mature at a larger size at higher temperatures. We also show that plasticity in adult size is determined by the relative difference between the minimum temperature thresholds for growth and development rates. The mechanism relates to aspects of the biophysical model of van der Have and de Jong. Ectotherms that obey the temperature-size rule are identified as having a higher temperature threshold for development rate than for growth rate; exceptions are identified as having a lower temperature threshold for development rate than for growth rate. The latter scenario may arise broadly in two ways. These are discussed in reference to the thermal biology of temperate grasshoppers and ectotherms in general.
大多数变温动物在较低的饲养温度下成熟时体型更大。尽管这种温度-体型规则已得到充分确立，但对这一现象的普遍解释仍然难以捉摸。在本文中，我们通过探究一种温带蝗虫——褐牧草蝗为何是温度-体型规则的例外的直接和根本原因来解决这个问题。我们使用一整套生活史数据对一个已确立的生活史模型进行参数化，结果表明，对该物种来说，在较高温度下以更大体型成熟是最优的。我们还表明，成虫体型的可塑性由生长和发育速率的最低温度阈值之间的相对差异决定。该机制与范德哈夫和德容的生物物理模型的某些方面相关。遵循温度-体型规则的变温动物被确定为发育速率的温度阈值高于生长速率的温度阈值；例外情况则被确定为发育速率的温度阈值低于生长速率的温度阈值。后一种情况可能大致以两种方式出现。本文将结合温带蝗虫及一般变温动物的热生物学对这两种方式进行讨论。
