Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia
Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia.
Proc Natl Acad Sci U S A. 2021 Aug 24;118(34). doi: 10.1073/pnas.2104942118.
Metabolism should drive demography by determining the rates of both biological work and resource demand. Long-standing "rules" for how metabolism should covary with demography permeate biology, from predicting the impacts of climate change to managing fisheries. Evidence for these rules is almost exclusively indirect and in the form of among-species comparisons, while direct evidence is exceptionally rare. In a manipulative field experiment on a sessile marine invertebrate, we created experimental populations that varied in population size (density) and metabolic rate, but not body size. We then tested key theoretical predictions regarding relationships between metabolism and demography by parameterizing population models with lifetime performance data from our field experiment. We found that populations with higher metabolisms had greater intrinsic rates of increase and lower carrying capacities, in qualitative accordance with classic theory. We also found important departures from theory-in particular, carrying capacity declined less steeply than predicted, such that energy use at equilibrium increased with metabolic rate, violating the long-standing axiom of energy equivalence. Theory holds that energy equivalence emerges because resource supply is assumed to be independent of metabolic rate. We find this assumption to be violated under real-world conditions, with potentially far-reaching consequences for the management of biological systems.
新陈代谢应该通过决定生物工作和资源需求的速度来驱动人口统计学。长期以来，关于新陈代谢应该如何与人口统计学相关的“规则”渗透到生物学中，从预测气候变化的影响到管理渔业。这些规则的证据几乎完全是间接的，并且是以种间比较的形式出现的，而直接证据则极为罕见。在一项针对固着海洋无脊椎动物的操纵性野外实验中，我们创建了实验种群，这些种群在种群大小（密度）和代谢率方面存在差异，但体型不变。然后，我们通过使用野外实验的终生表现数据来为种群模型参数化，测试了关于新陈代谢和人口统计学之间关系的关键理论预测。我们发现，代谢率较高的种群具有更高的内在增长率和更低的承载能力，这与经典理论定性一致。我们还发现了与理论的重要偏离——特别是，承载能力的下降不及预测的那么陡峭，因此，在平衡状态下的能量使用随着代谢率的增加而增加，违反了长期以来的能量等效公理。理论认为，能量等效性的出现是因为资源供应被假定与代谢率无关。我们发现，在现实条件下，这一假设被违反了，这可能对生物系统的管理产生深远的影响。
