BET-HEDGING GERMINATION OF DESERT ANNUALS - BEYOND THE 1ST YEAR
BET-HEDGING GERMINATION OF DESERT ANNUALS - BEYOND THE 1ST YEAR
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DOI：
10.1086/285550
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发表时间：
1993-09-01
影响因子：
2.9
通讯作者：
PHILIPPI, T
中科院分区：
文献类型：
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作者：
PHILIPPI, T
沙漠一年生植物种子的长期休眠被认为是对环境不确定性的适应。发芽时间持续数年可以减少基因型适应性的逐年变化。先前的研究表明，对于许多物种来说，并非所有有活力的种子都会在第一年的一组条件下发芽，但休眠种子随后的命运尚未经过测试。在这项研究中，对来自亚利桑那州波特尔的六种冬季一年生植物的种子进行了发芽实验。第一年在良好条件下未发芽的种子在随后的几年中在相同条件下会发芽。然而，前两年的发芽率与剩余可存活种子的比率并不相等，这是理论上的最佳行为，而且物种之间的发芽分布差异很大。在一年的发芽条件恶劣之后，在良好条件下的发芽也因物种而异。发芽行为取决于年龄，对土壤样本中未知年龄的种子进行发芽试验可能会给出误导性的结果。这些结果表明，种子休眠是一种对冲赌注的形式，但对跨年份发芽最佳分布的选择可能很弱。
Prolonged seed dormancy in desert annuals is thought to be an adaptation to environmental uncertainty. Germination spread over several years could reduce the year-to-year variation in the fitness of a genotype. Previous work has demonstrated that, for a number of species, not all viable seeds germinate under one set of conditions in the first year, but the subsequent fate of the dormant seeds has not been tested. In this study, germination experiments were performed on seeds of six species of winter annuals from Portal, Arizona. Seeds that do not germinate under good conditions in the first year germinate under the same conditions in subsuquent years. However, germination fractions in the first 2 yr are not equal fractions of remaining viable seeds, which is the theoretical optimal behavior, and the germination distributions differ greatly among species. Germination under good conditions following a year of bad conditions for germination also differs among species. Germination behavior is age-dependent, and germination trials conducted on seeds of unknown ages from soil samples may give misleading results. These results indicate that seed dormancy acts as a form of bet hedging but that selection for an optimal distribution of germination across years may be weak.