Mating Patterns and Inbreeding Depression in Dimorphic Populations of Eichhornia paniculata (Pontederiaceae)

一年生水生凤眼莲的9306473个Kohn自然居群通常含有两个易于识别的遗传形态，其自交率平均分别为0.8%和0.2%。我们将利用这些种群来评估最近的几个理论预测，这些预测对于理解近亲繁殖衰退和交配系统变化的进化动力学至关重要。我们将测量特定形态的自交受精和雄性异交成功的水平，以获得这些自然种群中特定形态的配子传递的完整信息。这将提供一些关于增加自交率的花形态如何影响配子传递的其他方面的初步信息。我们将评估特定形态的近亲繁殖抑制，看看控制交配系统的基因是否与导致近亲繁殖抑制的合适等位基因不平衡。在最近的许多理论模型下，这种关联是可以预期的，并且可以改变基于近亲交配抑郁的群体平均水平的预期。然而，在两性植物的任何自然种群中，交配和适应等位基因之间的联系尚未被证明。我们将对10多年前首次研究的人群的形态频率进行重新采样，以获得关于形态比率随时间变化的稳定性的信息。以前在这些人群中传播的衡量标准提供了一个预期，即随着自体比率的降低，变异的频率会迅速下降。如果变种频率没有改变，我们对传播和生存能力的测量应该会揭示维持交配系统多态的因素。如果自交率较低的变种在下降，我们将获得一个异常有据可查的例子，说明自然选择在人类时间尺度上的进化。这一结果将对促进混合交配系统稳定或不稳定的因素以及自然种群近亲繁殖衰退的动态提供有用的见解。

9306473 Kohn Natural populations of the emergent-aquatic annual Eichhornia paniculata often contain two readily identifiable genetic morphs whose rates of self fertilization average 0.8 and 0.2, respectively. We will take advantage of these populations to evaluate several recent theoretical predications of critical importance for understanding the evolutionary dynamics of inbreeding depression and mating system change. We will measure morph-specific levels of self fertilization and male outcrossing success to obtain complete information on morph-specific gamete transmission in these natural populations. This will provide some of the first information on how a floral morphology that increases the selfing rate affects other aspects of gamete transmission. We will evaluate morph-specific inbreeding depression to see if genes that control the mating system are in disequilibrium with fitness alleles responsible for inbreeding depression. Such associations are expected under many recent theoretical models and can alter expectations based on population mean levels of inbreeding depression. However, associations between mating and fitness alleles have not as yet been demonstrated in any natural population of hermaphroditic plants. We will resample morph frequencies in populations first examined over 10 years ago to gain information on the stability of morph ratios over time. Previous measures of transmission in these populations provided an expectation of rapid decline in the frequency of the morph with the lower selfing rate. If morph frequencies have not changed, our measures of transmission and viability should shed light on factors maintaining mating system polymorphism. If the morph with the lower selfing rate is in decline, we will gain an unusually well-documented example of evolution by natural selection over a human time scale. The results will provide useful insights into factors promoting stability or instability of mixed mating systems and t he dynamics of inbreeding depression in natural populations.***