关键词: 选择性败育, 适合度, 结实结籽格局, 进化生态学

Abstract:

Selective abortion in seed plants means selective abortion of developing fruits/seeds based on pollen source, order of pollination, location of fruits on plant, number of developing seeds, or some combination of these. In species with linearly arranged ovules, such as occurs in members of Fabaceae, embryos at the peduncular, stigmatic, or both ends of the fruit can be selectively aborted. Position of fruit within the inflorescence also has a marked effect on abortion. Selective abortion has been documented in many species of Fabaceae, Brassicaceae and Boraginaceae. The primary factor causing selective abortion of fruit and/or seeds is resource limitation. Competition for limited maternal resources occurs among fruits and seeds. Thus, those that are initiated first and have the faster rate of growth can capture more maternal resources and thus are less likely to be aborted than those that are initiated later.+++Genetically correlated factors also can result in selective abortion. In some species, fruits from cross-pollinated flowers tend to have more seeds that are more likely to mature than fruits from self-pollinated flowers. Methods used to investigate selective abortion include 1) removing a fraction of the ovules at an early stage, 2) hand-thinning some young fruits or flowers, and 3) using molecule techniques of RAPD and isoenzyme analyses. Selective abortion can increase offspring quality. Progenies that are selectively matured have higher vigor, germinate to higher percentages, produce more leaves, inflorescences and flowers, and mature more seeds than those that are randomly matured. Aborting some seeds also can reduce wing load (ratio of fruit weight to fruit surface area), improve dispersal distance, and decrease sibling rivalry. Thus, selectively aborting some selfed and/or inferior genotype fruits/seeds increases the fitness of the maternal plant, its offspring, or both. Therefore, research on selective abortion is important to understanding patterns of fruit-set and/or seed-set and its evolutionary pattern and mechanism in angiosperms.+++We review recent advances in selective abortion research in angiosperms, with emphasis on 1) patterns of selective abortion; 2) factors affecting selective abortion; 3) evolutionary, ecological significance of selective abortion; and 4) primary methods used to investigate selective abortion. We also discuss prospects for further research.

Key words: selective abortion, fitness, pattern of fruit-set and/or seed-set, evolutionary ecology