Michod R E, Long A
Department of Ecology and Evolutionary Biology, University of Arizona, Tucson 85721.
Theor Popul Biol. 1995 Feb;47(1):56-81. doi: 10.1006/tpbi.1995.1003.
In a previous paper we studied the simultaneous, and at times conflicting, needs of coping with DNA damage, efficient cell replication, and the avoidance of cell mortality. These selective factors operated on sexual and asexual haploid and diploid populations that were reproductively isolated from one another. We concluded, in part, that a sexual type of cell could not expand from extreme rarity in populations dominated by asexual haploid and diploid cells. In the present paper we show that it is relatively easy for a rare sexual mutant to expand in a population dominated by asexual haploid cells if some matings occur between sexual and asexual cell types. We also study the persistence of sex in high mortality, high damage environments, in which neither the asexual diploid nor haploid can survive. The diploid cannot survive because its lower birth rate cannot overcome mortality and the haploid cannot survive because its birth rate cannot overcome gene damage. Sex can persist in these punishing environments by tuning the parameters of the sexual cycle, and the fusion and splitting rates, into a specified region, thereby reaping both benefits of damage repair and efficient replication.
在之前的一篇论文中，我们研究了应对DNA损伤、高效细胞复制以及避免细胞死亡这些同时存在且有时相互冲突的需求。这些选择因素作用于彼此生殖隔离的有性和无性单倍体及二倍体群体。我们部分得出结论，在以无性单倍体和二倍体细胞为主的群体中，有性类型的细胞无法从极其稀少的状态扩展。在本文中，我们表明，如果有性和无性细胞类型之间发生一些交配，那么一个罕见的有性突变体在以无性单倍体细胞为主的群体中相对容易扩展。我们还研究了在高死亡率、高损伤环境中性别（有性生殖方式）的持久性，在这种环境下，无性二倍体和单倍体都无法存活。二倍体无法存活是因为其较低的出生率无法克服死亡率，而单倍体无法存活是因为其出生率无法克服基因损伤。通过将有性生殖周期的参数以及融合和分裂速率调整到特定区域，性别（有性生殖方式）可以在这些恶劣环境中持续存在，从而既能获得损伤修复的益处，又能实现高效复制。
