Ranta E, Tesar D, Alaja S, Kaitala V
Department of Ecology and Systematics, University of Helsinki, Finland.
Evolution. 2000 Feb;54(1):145-50. doi: 10.1111/j.0014-3820.2000.tb00015.x.
A persistent question in the evolution of life histories is the fitness trade-off between reproducing only once (semelparity) in a lifetime or reproducing repeated times in different seasons (iteroparity). The problem can be formulated into a research agenda by assuming that one reproductive strategy is resident (has already evolved) and by asking whether invasion (evolution) of an alternative reproductive strategy is possible. For a spatially nonstructured system, Bulmer (1994) derived the relationship v + PA < 1 (PA is adult survival; vbS and bS are offspring numbers for iteroparous and semelparous breeding strategies, respectively) at which semelparous population cannot be invaded by an iteroparous mutant. When the inequality is changed to v + PA > 1, invasion of a semelparous mutant is not possible. From the inequalities, it is easy to see that possibilities for evolutionary establishment of a novel reproductive strategy are rather narrow. We extended the evolutionary scenario into a spatially structured system with dispersal linkage among the subunits. In this domain, a rare reproductive strategy can easily invade a population dominated by a resident reproductive strategy. The parameter space enabling invasion is far more generous with spatially structured evolutionary scenarios than in a spatially nonstructured system.
在生活史的进化过程中，一个长期存在的问题是一生中只繁殖一次（单次生殖）与在不同季节重复繁殖（多次生殖）之间的适应性权衡。通过假设一种生殖策略是常住的（已经进化），并询问另一种生殖策略的入侵（进化）是否可能，可以将这个问题转化为一个研究议程。对于一个空间非结构化系统，布尔默（1994年）推导出了v + PA < 1的关系（PA是成体存活率；vbS和bS分别是多次生殖和单次生殖繁殖策略的后代数量），在这种情况下，单次生殖种群不会被多次生殖突变体入侵。当不等式变为v + PA > 1时，单次生殖突变体的入侵是不可能的。从这些不等式中很容易看出，一种新的生殖策略在进化上确立的可能性相当小。我们将进化情景扩展到一个空间结构化系统，其中各亚单位之间存在扩散联系。在这个领域，一种罕见的生殖策略很容易入侵由常住生殖策略主导的种群。与空间非结构化系统相比，空间结构化进化情景下允许入侵的参数空间要大得多。
