Speciation of <i>Viola albida</i> var. <i>takahashii</i> based on both artificial and natural hybridization between <i>V. albida</i> var. <i>albida</i> and <i>V. albida</i> var. <i>chaerophylloides</i>

Abstract

The study aims are to examine the characteristics of artificial and natural hybrids between &lt;i&gt;Viola albida&lt;/i&gt; var. &lt;i&gt;albida&lt;/i&gt; (= &lt;i&gt;albida&lt;/i&gt;, from below) and &lt;i&gt;V. albida&lt;/i&gt; var. &lt;i&gt;chaerophylloides&lt;/i&gt; (= &lt;i&gt;chaerophylloides&lt;/i&gt;, from below), and to confirm if hybrids could be fertile and make populations in their native habitats. The 1st filial (= F&lt;sub&gt;1&lt;/sub&gt;, from below) leaf shape produced by artificial crossing between &lt;i&gt;albida&lt;/i&gt; and &lt;i&gt;chaerophylloides&lt;/i&gt; was the same as that of &lt;i&gt;V. albida&lt;/i&gt; var. &lt;i&gt;takahashii&lt;/i&gt; (= &lt;i&gt;takahashii&lt;/i&gt;, from below), and F&lt;sub&gt;1&lt;/sub&gt; bore also both chasmogamous and cleistogamous flowers. F&lt;sub&gt;1&lt;/sub&gt; seed number was 9.6 per cleistogamous pods, which was remarkably less than the average of 38.2 for &lt;i&gt;albida&lt;/i&gt; and &lt;i&gt;chaerophylloides&lt;/i&gt;, but the germination rate was all similar. The leaf type of self-crossed 2nd offsprings (= F&lt;sub&gt;2&lt;/sub&gt;, from below) showed all leaf types found in the &lt;i&gt;Viola albida&lt;/i&gt; complex, but the ratio of &lt;i&gt;chaerophylloides&lt;/i&gt; leaf type was relatively low. Individuals whose F&lt;sub&gt;2&lt;/sub&gt; leaf type was restored to &lt;i&gt;albida&lt;/i&gt; produced an average of 31.4 seeds per capsule, meaning that fertility was restored. On the other hand, individuals of F&lt;sub&gt;2&lt;/sub&gt; &lt;i&gt;takahashii&lt;/i&gt; leaf type come to fruition a low average of 10.4 seeds per capsule, which is similar to that of &lt;i&gt;takahashii&lt;/i&gt;. The results of crossbreeding experiment, where is their native habitats, were similar to that of laboratory. Both &lt;i&gt;albida&lt;/i&gt; and &lt;i&gt;chaerophylloids&lt;/i&gt; in Mt. Bulmyeong distribute extensively, but &lt;i&gt;takahashii&lt;/i&gt; make a small population only in places where &lt;i&gt;albida&lt;/i&gt; and &lt;i&gt;chaerophylloides&lt;/i&gt; grow together. Summarizing the above results is suggesting that the speciation of &lt;i&gt;takahashii&lt;/i&gt; was done by hybrid between &lt;i&gt;albida&lt;/i&gt; and &lt;i&gt;chaerophylloides&lt;/i&gt;, and these have been maintained with relatively small population by cleistogamous capsules.