Dissertation Research: Viability Selection at Three Early Life Stages of the Tropical Tree, Platypodium elegans

[902041]许多植物，尤其是树木，在它们的受精花中会有相当大比例的败育。虽然这种败育可以发生在果实发育的任何阶段，但实质性的败育通常发生在果实成熟期的很晚阶段。许多理论都被用来解释这一现象，但人们对堕胎的实际过程知之甚少。特别是，通常不知道流产的果实是否代表受精胚珠的随机样本，或者流产是否代表具有特定谱系的种子的死亡，例如，自花授粉后发育的果实。扁桃是一种后期果实败育率较高的热带乔木。先进的DNA技术将用于比较该物种的流产果实、未流产果实和已建立的幼苗，以证明自然选择是否对具有特定谱系或基因组成的幼苗起作用。这项研究将极大地促进我们对植物育种系统的理解，并将提供对自然选择在植物生命周期早期阶段所起作用的更好理解。这项研究的结果还可以预测热带森林破碎化对秀丽隐杆线虫等树木成功繁殖能力的影响。

9902041Hamrick & HuffordMany plant species, especially trees, abort relatively large proportions of their fertilized flowers. Although such abortion can occur at any stage of fruit development, often substantial abortion occurs very late in the fruit maturation period. Many theories have been developed to explain this phenomena, but very little is known about the actual abortion process. In particular, it is generally not known whether the fruits that are aborted represent a random sample of the fertilized ovules or whether abortion represents the mortality of seeds with specific pedigrees, e.g., fruits developing after self-pollination. Platypodium elegans is a tropical tree with relatively high late fruit abortion. Advanced DNA technologies will be used to compare aborted fruits, non-aborted fruits, and established seedlings of this species to document whether natural selection is acting to select seedlings with specific pedigrees or genetic compositions.This study will greatly advance our understanding of plant breeding systems and will provide greater understanding of the role natural selection plays in the early stages of plant life cycles. The results of this research may also allow predictions of the effect of tropical forest fragmentation on the ability of trees like P. elegans to successfully reproduce.