Wetherington Jeffrey D, Weeks Stephen C, Kotora Karen E, Vrijenhoek Robert C
Center for Theoretical and Applied Genetics, Cook College, Rutgers University, P.O. Box 231, New Brunswick, NJ, 08903.
Evolution. 1989 May;43(3):635-645. doi: 10.1111/j.1558-5646.1989.tb04258.x.
The frozen-niche-variation model was proposed to account for the coexistence of genetically related clones in naturally occurring unisexual populations. This model is based on two assumptions: 1) ecologically different clones have multiple independent origins from sexual ancestors; and 2) the population of sexual ancestors contains genetic variability for ecologically relevant traits. To test these assumptions, we produced 14 new "hemiclones" (nonrecombining haploid genotypes) of fish (Poeciliopsis: Poeciliidae). Our ability to synthesize many new hemiclones demonstrates the feasibility of multiple independent origins of nonrecombining genotypes. A substantial proportion (10-50%) of the phenotypic variation among hemiclones in size at birth, juvenile growth rate, and fecundity had a genetic basis. Thus, we conclude that multiple origins can give rise to an assemblage of genetically distinct hemiclones, each with a unique combination of life-history traits. Additionally, a comparative analysis of two natural hemiclones revealed that the synthetic strains represent a broad field of variation from which natural hemiclones can be selected.
冷冻生态位变异模型被提出来解释自然存在的单性种群中基因相关克隆的共存现象。该模型基于两个假设：1）生态上不同的克隆有多个来自有性祖先的独立起源；2）有性祖先种群包含与生态相关性状的遗传变异性。为了检验这些假设，我们培育了14个新的鱼类（食蚊鱼属：花鳉科）“半克隆体”（非重组单倍体基因型）。我们合成许多新半克隆体的能力证明了非重组基因型多个独立起源的可行性。半克隆体在出生时大小、幼体生长速率和繁殖力方面的表型变异中有很大一部分（10%-50%）具有遗传基础。因此，我们得出结论，多个起源可以产生一组基因不同的半克隆体，每个半克隆体都有独特的生活史特征组合。此外，对两个天然半克隆体的比较分析表明，合成菌株代表了一个广泛的变异范围，从中可以选择天然半克隆体。
