Timing is everything: Dichogamy and pollen germinability underlie variation in autonomous selfing among populations.
Timing is everything: Dichogamy and pollen germinability underlie variation in autonomous selfing among populations.
复制标题
时机就是一切：雌雄异株和花粉发芽能力是种群间自主自交变异的基础。
DOI：
10.1002/ajb2.1025
复制
发表时间：
2018
影响因子：
3
通讯作者：
L. Galloway
中科院分区：
文献类型：
--
作者：
M. Koski;Li‐Yaung Kuo;K. Niedermaier;L. Galloway
研究前提
多花性状的进化往往是从异交到自交的转变的基础。这些性状可以影响自交的能力，以及自交发生的时间，这反过来又影响自交的成本。在自主自交中表现出变异的物种提供了一个机会来剖析导致交配系统变异的表型变化。
方法
在一个共同的花园里，我们测量了雌雄异熟和herkogamy在24个人口的先雄混合交配草本风铃草美洲，并与这些自主坐果（自治）。然后，我们测量了高自主性和低自主性人群中自花粉沉积和果实生产的时间，并确定了整个花发育过程中花粉萌发能力是否有助于自主性的变化。
关键成果
更迅速地过渡到女性阶段的人口显示升高的自主自交，但herkogamy与自主自交无关。在高度自治的群体中，自交发生得更快，这是因为在雌性阶段早期，自花花粉沉积量更大。花粉萌发率在低自主权的人口保持恒定的整个花的发展，但在高自主权的人口增加开花后，最高的女性阶段的发病。
结论
减少雌雄异熟，提高自花花粉沉积，和较高的花粉萌发后期的男性阶段有助于更早的自交和更大的自交。这些特征在种群中各不相同，可能反映了过去对交配系统的选择。虽然延迟自交承担更少的健身成本，早期自交的进化可能是有利的，如果自花粉可用性降低花发育。
PREMISE OF THE STUDY
The evolution of multiple floral traits often underlies the transition from outcrossing to selfing. Such traits can influence the ability to self, and the timing at which selfing occurs, which in turn affects the costs of selfing. Species that display variation in autonomous selfing provide an opportunity to dissect the phenotypic changes that contribute to variability in the mating system.
METHODS
In a common garden, we measured dichogamy and herkogamy in 24 populations of the protandrous mixed-mating herb Campanula americana, and related these to autonomous fruit set (autonomy). We then measured the timing of self-pollen deposition and fruit production in populations with high and low autonomy, and determined whether pollen germinability across floral development contributes to variation in autonomy.
KEY RESULTS
Populations that transitioned more rapidly to female phase displayed elevated autonomous selfing, but herkogamy was unassociated with autonomous selfing. Selfing occurred more rapidly in highly autonomous populations because of greater self-pollen deposition early in female phase. Pollen germinability in low-autonomy populations remained constant across floral development, but in high-autonomy populations it increased after floral anthesis and was highest near the onset of female phase.
CONCLUSIONS
Reduced dichogamy, elevated self-pollen deposition, and higher pollen germination late in male phase contribute to both earlier selfing and greater selfing. These traits vary among populations, likely reflecting past selection on the mating system. While delayed selfing bears fewer fitness costs, the evolution of earlier selfing may be favored if self-pollen availability decreases over floral development.