Laboratory of Ecological and Evolutionary Dynamics, Department of Biosciences, University of Helsinki, Finland.
Biol Rev Camb Philos Soc. 2011 Aug;86(3):717-32. doi: 10.1111/j.1469-185X.2010.00167.x. Epub 2010 Nov 14.
The group selection debate of the 1960s made it clear that evolution does not necessarily increase population performance. Individuals can be selected to have traits that diminish a common good and make population persistence difficult. At the extreme, the discrepancy between levels of selection is predicted to make traits evolve towards values at which a population can no longer persist (evolutionary suicide). Dispersal and prospecting are prime examples of traits that have a strong influence on population persistence under environmental and demographic stochasticity. Theory predicts that an 'optimal' dispersal strategy from a population point of view can differ considerably from that produced by individual-level selection. Because dispersal is frequently risky or otherwise costly, individuals are often predicted to disperse less than would be ideal for population performance (persistence or size). We define this discrepancy as 'inertia' and examine current knowledge of its occurrence and effects on population dynamics in nature. We argue that inertia is potentially widespread but that a framework is currently lacking for predicting precisely the extent to which it has a real influence on population persistence. The opposite of inertia, 'hypermobility' (more dispersal by individuals than would maximize population performance) remains a possibility: it is known that highest dispersal rates do not lead to best expected population performance, and examples of such high dispersal evolving exist at least in the theoretical literature. We also show, by considering prospecting behaviour, that similar issues arise in species with advanced cognitive and learning abilities. Individual prospecting strategies and the information acquired during dispersal are known to influence the decisions and therefore the fate of individuals and, as a corollary, populations. Again, the willingness of individuals to sample environments might evolve to levels that are not optimal for populations. This conflict can take intriguing forms. For example, better cognitive abilities of individuals may not always lead to better population-level performance. Simulation studies have found that 'blind' dispersal can lead to better connected metapopulations than cognitively more advanced habitat choice rules: the latter can lead to too many individuals sticking to nearby safe habitat. The study of the mismatch between individual and population fitness should not be a mere intellectual exercise. Population managers typically need to take a population-level view of performance, which may necessitate human intervention if it differs from what is selected for. We conclude that our knowledge of inertia and hypermobility would advance faster if theoretical studies--without much additional effort--quantified the population consequences of the evolving traits and compared this with hypothetical (not selectively favoured) dispersal rules, and if empirical studies were similarly conducted with the differing levels of selection in mind.
群体选择争论在 20 世纪 60 年代就已经明确指出，进化不一定会提高种群表现。个体可以被选择具有减少共同利益的特征，并使种群的持续存在变得困难。在极端情况下，选择水平之间的差异预计会导致特征朝着种群无法再持续存在的价值方向进化（进化自杀）。扩散和勘探是受环境和人口随机性影响下对种群持续存在有强烈影响的特征的主要例子。理论预测，从种群的角度来看，一种“最佳”的扩散策略可能与个体水平选择产生的策略有很大的不同。由于扩散通常是有风险的或其他代价高昂的，因此通常预测个体的扩散量将少于种群表现（持久性或规模）的理想水平。我们将这种差异定义为“惰性”，并研究其在自然界中对种群动态的发生和影响的现有知识。我们认为，惰性可能很普遍，但目前缺乏一个框架来准确预测它对种群持续存在的实际影响程度。惰性的相反，“超流动性”（个体的扩散比最大化种群表现所需的更多）仍然是一种可能性：已知最高的扩散率并不导致最佳预期的种群表现，并且在理论文献中至少存在这种高扩散进化的例子。通过考虑勘探行为，我们还表明，具有先进认知和学习能力的物种也会出现类似的问题。个体勘探策略和在扩散过程中获得的信息已知会影响个体的决策，从而影响个体和种群的命运。同样，个体采样环境的意愿可能会进化到对种群不利的水平。这种冲突可能会呈现出有趣的形式。例如，个体更好的认知能力并不总是会导致更好的种群水平表现。模拟研究发现，盲目扩散可以导致比认知上更先进的栖息地选择规则更好的连接的复合种群：后者可能导致太多个体坚持附近的安全栖息地。个体和种群适应性之间不匹配的研究不应仅仅是一种智力练习。种群管理者通常需要从种群水平的角度来看待性能，如果与所选内容不同，可能需要人为干预。我们得出的结论是，如果理论研究在不增加太多工作量的情况下量化进化特征的种群后果，并将其与假设（未受选择青睐）的扩散规则进行比较，并且如果实证研究也考虑到不同的选择水平，那么我们对惰性和超流动性的认识将更快地提高。
