Hörandl Elvira
Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, A-1030 Vienna, Austria.
Int J Plant Sci. 2008 Dec;169(9):1219-1228. doi: 10.1086/591980.
Uniparental reproduction has often been regarded as advantageous for colonization. In pseudogamous a pomicts, reproduction via single individuals requires self-pollination and consequently self-compatibility (SC) for production of viable seeds. SC and reproductive fitness have been studied in diploid and polyploid taxa of the Ranunculus auricomus complex via pollinator exclusion tests, assessment of seed set, and germination rates. Reproductive fitness of sexuals exceeds that of apomicts and of F(1) hybrids but may fluctuate more strongly between years than is the case in apomicts. Diploid sexual taxa and also their F(1) hybrids are completely self-incompatible (SI). Auto-polyploid sexual cytotypes are also predominantly SI, which may have restricted their range expansion. The observed breakdown of SI in the rather widespread allohexaploid apomicts may be explained by initial partial SC inherited from semi-self-compatible ancestors and strong selection for SC genotypes. It is concluded that higher reproductive fitness of sexuals may help to maintain sexual populations when cross-pollination is available, whereas SC in apomicts may be advantageous in temporally and spatially unstable environments and also for colonization events. Results suggest that SC in connection with pseudogamous apomixis is an important factor for the observed distribution pattern of geographical parthenogenesis.
单亲生殖通常被认为有利于种群拓殖。在假配生殖的无融合生殖体中，单个个体的繁殖需要自花授粉，因此需要自交亲和性（SC）才能产生有活力的种子。通过传粉者排除试验、结实率评估和发芽率评估，对毛茛复合体的二倍体和多倍体类群中的自交亲和性和繁殖适合度进行了研究。有性生殖体的繁殖适合度超过无融合生殖体和F(1)杂种，但与无融合生殖体相比，其年际间波动可能更大。二倍体有性类群及其F(1)杂种完全自交不亲和（SI）。同源多倍体有性细胞型也主要是自交不亲和的，这可能限制了它们的范围扩展。在分布相当广泛的异源六倍体无融合生殖体中观察到的自交不亲和性的破坏，可能是由于从半自交亲和祖先遗传而来的初始部分自交亲和性以及对自交亲和基因型的强烈选择所致。得出的结论是，当有异花授粉时，有性生殖体较高的繁殖适合度可能有助于维持有性种群，而无融合生殖体中的自交亲和性在时间和空间不稳定的环境以及种群拓殖事件中可能具有优势。结果表明，与假配生殖的无融合生殖相关的自交亲和性是观察到的地理孤雌生殖分布模式的一个重要因素。
