van Treuren R, Bijlsma R, Ouborg N J, van Delden W
Department of Genetics, University of Groningen, Kerklaan 30, 9751 NN, Haren, The Netherlands.
Department of Plant Population Biology, Netherlands Institute of Ecology, P.O. Box 40, 6666 ZG, Heteren, The Netherlands.
Evolution. 1993 Dec;47(6):1669-1680. doi: 10.1111/j.1558-5646.1993.tb01259.x.
The effects of self-fertilization, within-population crosses (WPC) and between-population crosses (BPC) on progeny fitness were investigated in the greenhouse for Scabiosa columbaria populations of varying size. Plants grown from field collected seeds were hand pollinated to produce selfed, WPC, and BPC progeny. The performance of these progenies was examined throughout the entire life cycle. The different pollination treatments did not significantly affect germination, seedling-to-adult survival, flowering percentage and the number of flower heads. But severe inbreeding depression was demonstrated for biomass production, root development, adult survival, and seed set. Additionally, multiplicative fitness functions were calculated to compare relative fitnesses for progeny. On average, WPC progeny showed a more than 4-fold, and BPC progeny an almost 10-fold, advantage over selfed progeny, indicating that S. columbaria is highly susceptible to inbreeding. No clear relationship was found between population size and level of inbreeding depression, suggesting that the genetic load has not yet been reduced substantially in the small populations. A significant positive correlation was found between plant dry weight and total fitness. In two out of six populations, the differences between the effects of the pollination treatments on dry weight increased significantly when seedlings were grown under competitive conditions. This result is interpreted as an enhancement of inbreeding depression under these conditions. It is argued that improvement of the genetic exchange between populations may lower the probability of population extinction.
在温室中，针对不同规模的蓝盆花种群，研究了自交、种群内杂交（WPC）和种群间杂交（BPC）对后代适合度的影响。用从野外采集的种子培育的植株进行人工授粉，以产生自交、WPC和BPC后代。在整个生命周期中对这些后代的表现进行了检查。不同的授粉处理对发芽率、从幼苗到成株的存活率、开花百分比和花头数量没有显著影响。但在生物量生产、根系发育、成株存活率和结实率方面表现出严重的近交衰退。此外，计算了乘法适合度函数以比较后代的相对适合度。平均而言，WPC后代比自交后代表现出超过4倍的优势，BPC后代比自交后代表现出近10倍的优势，这表明蓝盆花极易受到近亲繁殖的影响。未发现种群大小与近交衰退程度之间存在明确关系，这表明在小种群中遗传负荷尚未大幅降低。发现植株干重与总适合度之间存在显著正相关。在六个种群中的两个种群中，当幼苗在竞争条件下生长时，授粉处理对干重的影响差异显著增加。这一结果被解释为在这些条件下近交衰退加剧。有人认为，改善种群间的基因交换可能会降低种群灭绝的概率。
