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 <i>Viola albida</i> var. <i>albida</i> (= <i>albida</i>, from below) and <i>V. albida</i> var. <i>chaerophylloides</i> (= <i>chaerophylloides</i>, from below), and to confirm if hybrids could be fertile and make populations in their native habitats. The 1st filial (= F₁, from below) leaf shape produced by artificial crossing between <i>albida</i> and <i>chaerophylloides</i> was the same as that of <i>V. albida</i> var. <i>takahashii</i> (= <i>takahashii</i>, from below), and F₁ bore also both chasmogamous and cleistogamous flowers. F₁ seed number was 9.6 per cleistogamous pods, which was remarkably less than the average of 38.2 for <i>albida</i> and <i>chaerophylloides</i>, but the germination rate was all similar. The leaf type of self-crossed 2nd offsprings (= F₂, from below) showed all leaf types found in the <i>Viola albida</i> complex, but the ratio of <i>chaerophylloides</i> leaf type was relatively low. Individuals whose F₂ leaf type was restored to <i>albida</i> produced an average of 31.4 seeds per capsule, meaning that fertility was restored. On the other hand, individuals of F₂ <i>takahashii</i> leaf type come to fruition a low average of 10.4 seeds per capsule, which is similar to that of <i>takahashii</i>. The results of crossbreeding experiment, where is their native habitats, were similar to that of laboratory. Both <i>albida</i> and <i>chaerophylloids</i> in Mt. Bulmyeong distribute extensively, but <i>takahashii</i> make a small population only in places where <i>albida</i> and <i>chaerophylloides</i> grow together. Summarizing the above results is suggesting that the speciation of <i>takahashii</i> was done by hybrid between <i>albida</i> and <i>chaerophylloides</i>, and these have been maintained with relatively small population by cleistogamous capsules.