Bradshaw H D, Otto K G, Frewen B E, McKay J K, Schemske D W
College of Forest Resources, University of Washington, Seattle, Washington 98195, USA.
Genetics. 1998 May;149(1):367-82. doi: 10.1093/genetics/149.1.367.
Conspicuous differences in floral morphology are partly responsible for reproductive isolation between two sympatric species of monkeyflower because of their effect on visitation of the flowers by different pollinators. Mimulus lewisii flowers are visited primarily by bumblebees, whereas M. cardinalis flowers are visited mostly by hummingbirds. The genetic control of 12 morphological differences between the flowers of M. lewisii and M. cardinalis was explored in a large linkage mapping population of F2 plants n = 465 to provide an accurate estimate of the number and magnitude of effect of quantitative trait loci (QTLs) governing each character. Between one and six QTLs were identified for each trait. Most (9/12) traits appear to be controlled in part by at least one major QTL explaining >/=25% of the total phenotypic variance. This implies that either single genes of individually large effect or linked clusters of genes with a large cumulative effect can play a role in the evolution of reproductive isolation and speciation.
花形态上的显著差异在一定程度上导致了两种同域分布的猴面花物种之间的生殖隔离,因为这些差异会影响不同传粉者对花朵的访问。刘易斯猴面花(Mimulus lewisii)的花朵主要由大黄蜂传粉,而深红猴面花(M. cardinalis)的花朵大多由蜂鸟传粉。在一个由465株F2植株组成的大型连锁图谱群体中,研究了刘易斯猴面花和深红猴面花花之间12种形态差异的遗传控制,以准确估计控制每个性状的数量性状位点(QTL)的数量和效应大小。每个性状鉴定出1到6个QTL。大多数(9/12)性状似乎至少部分受一个主要QTL控制,该QTL解释了总表型变异的25%以上。这意味着,要么是单个效应大的基因,要么是具有大的累积效应的连锁基因簇,都可能在生殖隔离和物种形成的进化中发挥作用。