Jimenez Ana Gabriela, Cooper-Mullin Clara, Calhoon Elisabeth A, Williams Joseph B
Department of Evolution, Ecology and Organismal Biology, Ohio State University, 318 W. 12th Ave., Columbus, OH, 43210, USA,
J Comp Physiol B. 2014 Jul;184(5):545-61. doi: 10.1007/s00360-014-0825-0. Epub 2014 Mar 27.
Animal life-history traits fall within limited ecological space with animals that have high reproductive rates having short lives, a continuum referred to as a "slow-fast" life-history axis. Animals of the same body mass at the slow end of the life-history continuum are characterized by low annual reproductive output and low mortality rate, such as is found in many tropical birds, whereas at the fast end, rates of reproduction and mortality are high, as in temperate birds. These differences in life-history traits are thought to result from trade-offs between investment in reproduction or self-maintenance as mediated by the biotic and abiotic environment. Thus, tropical and temperate birds provide a unique system to examine physiological consequences of life-history trade-offs at opposing ends of the "pace of life" spectrum. We have explored the implications of these trade-offs at several levels of physiological organization including whole-animal, organ systems, and cells. Tropical birds tend to have higher survival, slower growth, lower rates of whole-animal basal metabolic rate and peak metabolic rate, and smaller metabolically active organs compared with temperate birds. At the cellular level, primary dermal fibroblasts from tropical birds tend to have lower cellular metabolic rates and appear to be more resistant to oxidative cell stress than those of temperate birds. However, at the subcellular level, lipid peroxidation rates, a measure of the ability of lipid molecules within the cell membranes to thwart the propagation of oxidative damage, appear not to be different between tropical and temperate species. Nevertheless, lipids in mitochondrial membranes of tropical birds tend to have increased concentrations of plasmalogens (phospholipids with antioxidant properties), and decreased concentrations of cardiolipin (a complex phospholipid in the electron transport chain) compared with temperate birds.
动物的生活史特征处于有限的生态空间内，繁殖率高的动物寿命较短，这一连续体被称为“慢-快”生活史轴。在生活史连续体慢端、体重相同的动物，其特征是年繁殖产出低、死亡率低，许多热带鸟类就是如此；而在快端，繁殖率和死亡率都很高，比如温带鸟类。这些生活史特征的差异被认为是由生物和非生物环境介导的繁殖投资或自我维持之间的权衡所致。因此，热带和温带鸟类提供了一个独特的系统，用于研究在“生活节奏”谱两端的生活史权衡所带来的生理后果。我们已经在包括整个动物、器官系统和细胞在内的几个生理组织层面探讨了这些权衡的影响。与温带鸟类相比，热带鸟类往往具有更高的存活率、更慢的生长速度、更低的全动物基础代谢率和峰值代谢率，以及更小的代谢活跃器官。在细胞层面，热带鸟类的原代表皮成纤维细胞往往具有较低的细胞代谢率，并且似乎比温带鸟类的细胞对氧化细胞应激更具抗性。然而，在亚细胞层面，脂质过氧化率（衡量细胞膜内脂质分子阻止氧化损伤传播能力的指标）在热带和温带物种之间似乎没有差异。尽管如此，与温带鸟类相比，热带鸟类线粒体膜中的脂质往往具有更高浓度的缩醛磷脂（具有抗氧化特性的磷脂）和更低浓度的心磷脂（电子传递链中的一种复合磷脂）。
