Nakahara Toru, Fukano Yuya, Hirota Shun K, Yahara Tetsukazu
Graduate School of Systems Life Sciences Kyushu University Fukuoka Japan.
Graduate School of Agricultural and Life Sciences The University of Tokyo Tokyo Japan.
Ecol Evol. 2017 Dec 20;8(2):1159-1170. doi: 10.1002/ece3.3722. eCollection 2018 Jan.
In wind-pollinated plants, male-biased sex allocation is often positively associated with plant size and height. However, effects of size (biomass or reproductive investment) and height were not separated in most previous studies. Here, using experimental populations of monoecious plants, we examined (1) how male and female reproductive investments (MRI and FRI) change with biomass and height, (2) how MRI and height affect male reproductive success (MRS) and pollen dispersal, and (3) how height affects seed production. Pollen dispersal kernel and selection gradients on MRS were estimated by 2,102 seeds using six microsatellite markers. First, MRI increased with height, but FRI did not, suggesting that sex allocation is more male-biased with increasing plant height. On the other hand, both MRI and FRI increased with biomass but often more greatly for FRI, and consequently, sex allocation was often female-biased with biomass. Second, MRS increased with both height and MRI, the latter having the same or larger effect on MRS. Estimated pollen dispersal kernel was fat-tailed, with the maximum distance between mates tending to increase with MRI but not with height. Third, the number of seeds did not increase with height. Those findings showed that the male-biased sex allocation in taller plants of is explained by a direct effect of height on MRS.
在风媒传粉植物中，雄性偏向的性别分配通常与植株大小和高度呈正相关。然而，在大多数先前的研究中，大小（生物量或繁殖投入）和高度的影响并未分开。在此，我们利用雌雄同株植物的实验种群，研究了：（1）雄性和雌性繁殖投入（MRI和FRI）如何随生物量和高度变化；（2）MRI和高度如何影响雄性繁殖成功率（MRS）和花粉传播；（3）高度如何影响种子产量。使用六个微卫星标记，通过2102粒种子估计了MRS的花粉传播核和选择梯度。首先，MRI随高度增加，但FRI没有，这表明随着植株高度增加，性别分配更偏向雄性。另一方面，MRI和FRI都随生物量增加，但FRI通常增加得更多，因此，性别分配在生物量方面通常偏向雌性。其次，MRS随高度和MRI增加，后者对MRS的影响相同或更大。估计的花粉传播核是肥尾的，配偶之间的最大距离倾向于随MRI增加而增加，但不随高度增加。第三，种子数量不随高度增加。这些发现表明，较高植株中雄性偏向的性别分配是由高度对MRS的直接影响所解释的。
