Department of Biology, Indiana University, Bloomington, IN, 47405, USA.
New Phytol. 2019 Nov;224(3):1075-1079. doi: 10.1111/nph.15868. Epub 2019 May 26.
It has long been known that more pollen grains often arrive on stigmas than there are ovules to fertilize, resulting in pollen competition. Moreover, this competition among pollen grains (gametophytes) depends, in part, on their extensive haploid gene expression. Here I review how this leads to a variety of phenomena in dioecious plants of interest to evolutionary biologists. For example, pollen competition can lead to extreme female-biased sex ratios. In addition, gene expression by individual pollen grains can slow mutation accumulation and degeneration of the Y chromosome. Lastly, I review work on how the haploid selection resulting from pollen competition has been proposed to influence which alleles are linked to the Y chromosome, and some recent empirical evidence in support of this theory.
长期以来，人们已经知道，落在柱头上的花粉粒往往比能够受精的胚珠多，从而导致花粉竞争。此外，花粉粒（配子体）之间的这种竞争部分取决于它们广泛的单倍体基因表达。在这里，我回顾了这在进化生物学家感兴趣的雌雄异株植物中如何导致各种现象。例如，花粉竞争可导致极端的雌性偏性性别比。此外，单个花粉粒的基因表达可以减缓突变的积累和 Y 染色体的退化。最后，我回顾了关于花粉竞争导致的单倍体选择如何影响与 Y 染色体相连的等位基因的工作，以及一些支持该理论的最新实证证据。
