Van Putten Wilhelmus F, Biere Arjen, Van Damme Jos M M
Department of Plant Population Biology, Netherlands Institute of Ecology, NIOO-KNAW, P.O. Box 40, NL-6666 ZG Heteren, The Netherlands.
Evolution. 2003 Apr;57(4):766-76.
We studied intraspecific competition and assortative mating between strains of the anther smut fungus Microbotryum violaceum from two of its host species, Silene latifolia and S. dioica. Specifically, we investigated whether strains from allopatric host populations have higher competitive ability on their native host species and show positive assortative mating. In general, strains isolated from S. latifolia outcompeted strains isolated from S. dioica on both host species, but in female hosts, heterotypic dikaryons (i.e., dikaryons composed of a haploid strain originating from S. latifolia and a haploid strain originating from S. dioica) were most successful in competition. Furthermore, the latency period was significantly shorter for heterokaryons that contained at least one strain originating from S. latifolia, compared to heterokaryons that only contained strains originating from S. dioica. The frequencies of conjugations between strains originating from S. latifolia were much higher than conjugation frequencies between strains originating from S. dioica. A significant positive correlation was detected between the relative success of strains in competition and in conjugation, suggesting that success of a strain in competition might be partly determined by its swiftness of mating. In addition, reciprocal differences within heterotypic crosses revealed a significant effect of fungal mating type, with mating type a1 being the main determinant of mating pace. The observed differences in infection success, conjugation rate, and latency period in favor of strains from S. latifolia relative to strains from S. dioica on both host species are discussed in an evolutionary context of opportunities for the maintenance of differentiation between different formae speciales upon secondary contact.
我们研究了来自两种寄主植物——宽叶蝇子草（Silene latifolia）和 dioica 蝇子草（S. dioica）的花药黑粉菌（Microbotryum violaceum）菌株之间的种内竞争和选型交配。具体而言，我们调查了来自异域寄主种群的菌株在其原生寄主物种上是否具有更高的竞争能力，并表现出正选型交配。总体而言，从宽叶蝇子草分离出的菌株在两种寄主植物上都比从 dioica 蝇子草分离出的菌株更具竞争力，但在雌性寄主中，异型双核体（即由源自宽叶蝇子草的单倍体菌株和源自 dioica 蝇子草的单倍体菌株组成的双核体）在竞争中最为成功。此外，与仅包含源自 dioica 蝇子草菌株的异核体相比，包含至少一个源自宽叶蝇子草菌株的异核体的潜伏期明显更短。源自宽叶蝇子草的菌株之间的结合频率远高于源自 dioica 蝇子草的菌株之间的结合频率。在菌株竞争和结合的相对成功率之间检测到显著的正相关，这表明菌株在竞争中的成功可能部分取决于其交配速度。此外，异型杂交中的相互差异揭示了真菌交配型的显著影响，交配型 a1 是交配速度的主要决定因素。在二次接触时不同专化型之间维持分化的机会的进化背景下，讨论了在两种寄主植物上观察到的有利于宽叶蝇子草菌株相对于 dioica 蝇子草菌株的感染成功率、结合率和潜伏期的差异。
