POPULATION DYNAMIC CONSEQUENCES AND EVOLUTION OF SEED TRAITS OF HETEROSPERMA PINNATUM (ASTERACEAE)
POPULATION DYNAMIC CONSEQUENCES AND EVOLUTION OF SEED TRAITS OF HETEROSPERMA PINNATUM (ASTERACEAE)
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DOI：
10.1002/j.1537-2197.1995.tb12646.x
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发表时间：
1995-03
影响因子：
3
通讯作者：
D. L. Venable;E. Dyreson;E. Morales
中科院分区：
文献类型：
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作者：
D. L. Venable;E. Dyreson;E. Morales
对羽状异型种子瘦果形态变异的研究进行了综述。没有年度种子银行。瘦果大小，幼苗大小，或幼苗生长速度的不同形态没有生态相关的差异。位于头部中央的瘦果在秋季瘦果生产和雨季开始（5月至7月）之间的时期较早地失去休眠。这导致中央瘦果相对较早出现。有芒的中央瘦果也有更大的粘性。在墨西哥中部的自然种群播种到瘦果的出现，生存和繁殖力进行了测量。当恶劣的条件导致很少的种子存活下来繁殖时，优势往往会流向更“保守”的外围瘦果。温室实验表明，一个强大的遗传成分，以确定瘦果比例内和种群之间和各种遗传相关性。具芒瘦果比例高的种群往往被发现在植被类型中，它们可能是短暂的。高比例的中央瘦果往往被发现在网站很少雨季前降水。这些模式被解释为选择传播和年内发芽的时间。
We summarize research on variation in achene morphology ofHeterosperma pinnatum.Each flowering head has a broad range of achene morphologies. There is no between‐year seed bank. There are no ecologically relevant differences in achene size, seedling size, or seedling growth rates of the different morphs. Achenes located centrally in the heads lose dormancy earlier during the period between autumn achene production and the onset (May‐July) of the rainy season. This results in relatively more early emergence of central achenes. Awned central achenes also have greater adhesive dispersibility. Emergence, survival, and fecundity were measured for achenes sown into natural populations in central Mexico. When harsh conditions result in few seeds surviving to reproduce, the advantage tends to go to the more “conservative” peripheral achenes. Greenhouse experiments show a strong genetic component to the determination of achene proportions within and among populations and a variety of genetic correlations. Populations with a high proportion of awned achenes tend to be found in vegetation types where they are likely to be ephemeral. A high proportion of central achenes tend to be found in sites with little pre‐rainy season precipitation. These patterns are interpreted in terms of selection for dispersal and the within‐year timing of germination.