QTL Mapping of Reproductive Isolation in Louisiana Irises

[00:74 . 159]阿诺德生殖隔离的进化在物种形成过程中是至关重要的，因为它是基因流动的停止，最终使不同的谱系走上不同的进化道路，成为新的物种。物种形成和生殖隔离是如何发生的取决于赋予隔离的基因的数量以及合子前后生殖障碍的相对重要性。确定相关基因的数量和大小也可以阐明物种形成所需的自然选择的时间和强度。我们将研究路易斯安那鸢尾花生殖隔离的遗传基础，鸢尾花是近一个世纪以来生态、遗传和进化研究的焦点。构建鸢尾和短尾鸢尾生殖隔离机制的QTL （quantitative trait loci）图谱。我们的分析将找到对交配前和交配后繁殖障碍表达影响最大的qtl。与预交配障碍相关的特征包括花的差异，导致大黄蜂优先访问短叶菊和蜂鸟优先访问富尔瓦菊（如开花时间、花的颜色、花蜜引导形状、花蜜糖浓度）。与交配后障碍相关的性状包括：(i)配子竞争（即，同株花粉管生长得更快，因此比来自交替物种的花粉管更有效地使胚珠受精）和（ii）两种杂交形成的花粉可育性。

0074159ArnoldThe evolution of reproductive isolation is critically important in the speciation process, because it is cessation of gene flow that definitively places diverging lineages onto separate evolutionary paths towards becoming new species. How speciation and reproductive isolation occur depends on the number of genes conferring isolation and the relative importance of pre- vs. post-zygotic reproductive barriers. Identifying the number and magnitude of genes involved can also elucidate both the time and strength of natural selection needed for speciation.We will study the genetic basis of reproductive isolation in the Louisiana Irises, a species complex has been a focus of ecological, genetic and evolutionary studies for almost a century. We will construct a QTL (quantitative trait loci) map of reproductive isolating mechanisms separating two species, Iris fulva and I. brevicaulis. Our analysis will locate QTLs that have the largest effect on the expression of both pre-mating and post-mating barriers to reproduction. The traits associated with the pre-mating barriers include floral differences that cause bumblebees to preferentially visit I. brevicaulis and hummingbirds to preferentially visit I. fulva (e.g., flowering time, flower color, nectar guide shape, nectar sugar concentration). The traits associated with post-mating barriers include (i) gamete competition (i.e., conspecific pollen tubes grow more quickly and thus fertilize ovules more efficiently than do pollen tubes from the alternate species) and (ii) pollen fertility of hybrids formed between the two species.