Ecology and the evolution of biphasic life cycles
Ecology and the evolution of biphasic life cycles
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DOI：
10.1086/303241
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发表时间：
1999-09-01
影响因子：
2.9
通讯作者：
Otto, SP
中科院分区：
文献类型：
--
作者：
Hughes, JS;Otto, SP
有性真核生物经历单倍体和二倍体核期的交替。在一些生物体中，单倍体和二倍体阶段都经历了体细胞发育，并作为独立的实体存在。尽管最近受到了关注，但这种双相生命周期演变和持续的机制仍然不清楚。一种很少受到理论关注的解释是，单倍体-二倍体生物可能通过两个倍性阶段的生态位分化更有效地利用它们的环境。即使在成虫形态相似的同构物种中，成虫阶段或幼虫之间的微小差异也可能起到重要的生态作用，有助于维持单倍体-二倍体。我们为生命周期的进化开发了一个遗传模型，该模型包含了密度依赖的生长。我们发现，单倍体和二倍体阶段之间的生态差异可以在广泛的条件下导致双相生活史的进化和维持。Gracilaria gracilis是一种世代同构的单倍体-二倍体红藻，其种群人口统计数据的参数估计被用来证明，即使成虫之间只有轻微的形态差异，单倍体-二倍体的生态学解释也是可信的。
Sexual eukaryotes undergo an alternation between haploid and diploid nuclear phases. In some organisms, both the haploid and diploid phases undergo somatic development and exist as independent entities. Despite recent attention, the mechanisms by which such biphasic life cycles evolve and persist remain obscure. One explanation that has received little theoretical attention is that haploid-diploid organisms may exploit their environments more efficiently through niche differentiation of the two ploidy phases. Even in isomorphic species, in which adults are morphologically similar, slight differences in the adult phase or among juveniles may play an important ecological role and help maintain haploid-diploidy. We develop a genetic model for the evolution of life cycles that incorporates density-dependent growth. We find that ecological differences between haploid and diploid phases can lead to the evolution and maintenance of biphasic life cycles under a broad range of conditions. Parameter estimates derived from demographic data on a population of Gracilaria gracilis, a haploid-diploid red alga with an isomorphic alternation of generations, are used to demonstrate that an ecological explanation for haploid-diploidy is plausible even when there are only slight morphological differences among adults.