Dimorphism of the seed-dispersing organ in a pantropical coastal plant, Scaevola taccada: heterogeneous population structures across islands
Dimorphism of the seed-dispersing organ in a pantropical coastal plant, Scaevola taccada: heterogeneous population structures across islands
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DOI：
10.1007/s11284-014-1164-z
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发表时间：
2014-07-01
影响因子：
2
通讯作者：
Ueda, Keisuke
中科院分区：
文献类型：
--
作者：
Emura, Naoko;Denda, Tetsuo;Ueda, Keisuke
Scaevola taccada的特征在于二型果实，其中一种类型具有软木和果肉（C-变体），另一种类型仅具有果肉（NC-变体）。虽然没有观察到个体内的二态性，但两种变体可以发生在相同的位点。软木浮在海水上，果肉被鸟吃。因此，变种可能有不同的种子传播能力，通过海流和鸟类，分别。本研究旨在确定二型果实的功能特性。首先，通过漂浮试验和测量果实不同部分的比例，分别比较了两种果实变体之间海流和鸟类的潜在种子传播能力。接下来，分析了日本南部岛屿不同基底（海滩，岩石和悬崖）上两种变体的频率。大多数C-变体果实在海水罐中漂浮超过180天，而所有NC-变体果实在大约1周后下沉。NC-变体果实具有比C-变体果实更多的果肉体积和更少的不可消化物质。虽然这两种类型的植物被发现在许多岛屿和所有基板，C-变形占主导地位的海滩，而NC-变形是最常见的悬崖。不同基质上的变异体出现频率可能受其种子传播能力的差异影响。这两种变体在不同基质上的适合度可能不同。这些发现提高了我们对植物扩散适应性的理解。
Scaevola taccada is characterized by dimorphic fruits, with one type having cork and pulp (C-morph) and the other type having only pulp (NC-morph). Although within-individual dimorphism has not been observed, both morphs can occur at the same sites. The cork floats on seawater, and the pulp is eaten by birds. Thus, the morphs may have different seed dispersal abilities, via sea currents and birds, respectively. This study aimed to determine the functional characteristics of the dimorphic fruits. First, the potential seed dispersal ability of sea currents and birds was compared between the two fruits morphs by conducting a floating test and by measuring the proportions of different parts of the fruits, respectively. Next, the frequencies of the two morphs across different substrates (beaches, rocks, and cliffs) in the southern islands around Japan were analyzed. Most C-morph fruits remained floating for more than 180 days in a seawater tank, whereas all NC-morph fruits sank after approximately 1 week. The NC-morph fruits had a more pulp volume and less indigestible material than the C-morph fruits. Although both types of plants were found on many islands and all substrates, the C-morph was dominant on beaches, whereas the NC-morph was most frequent on cliffs. The frequencies of the morphs on different substrates might be influenced by the differences in their seed dispersal abilities. The two morphs may differ in fitness on different substrates. These findings improve our understanding of plant adaptations for dispersal.