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Abstract Detail

Mechanisms underlying exceptional plant diversity across eastern Asia

Takahashi, Daiki [1].

Relative contribution of biotic and abiotic drivers for formation of plant diversity in East Asia: A case study of section Heterotropa (genus Asarum; Aristolochiaceae).

East Asia region harbors one of the most diverse temperate floras anywhere in the world and is characterized with high endemism. This diversity is thought to be linked to historical environmental changes associated with the Pleistocene (< 2.6 Mya) climatic oscillations. So, in this region, it has been hypothesized that allopatric speciation could be a major mode of speciation in temperate plants. Although the importance of geographic isolation as a major isolation mechanism in plants has been addressed, recent studies in other regions have implied that biotic factors also promote species diversification. However, many phylogeographic studies conducted in East Asia have only discussed the role of allopatric fragmentation due to geographic and/or climatic events, and few studies have considered other factors as drivers of the diversification. Thus, our knowledge of the diversification process of temperate plants in East Asia remains fragmentary. I focused on section Heterotropa (genus Asarum: Aristolochiaceae), which is endemic to East Asia (mainland China, Taiwan, and Japanese Archipelago) and diversified in this region (including approximately 80 species). Heterotropa shows low dispersal ability with small distribution ranges, implying diversification by geographic events. Yet, this section shows extremely high floral diversity and it has been hypothesized that pollinator mediated selection would be main driver of its diversification. In this study, to reveal how abiotic and biotic factors shaped the diversification of Heterotropa, I conducted phylogenetic analysis using ddRAD-seq and chloroplast genome datasets, estimation of floral traits evolution, and comparison of isolation factors of sister species based on distribution range and floral traits analysis. Phylogenetic analysis showed that Heterotropa firstly diverged into insular and continental clades, which comprise several regional subclades, during the Miocene period, and most speciation events would have occurred during the Pleistocene period. Distribution analysis revealed that most species are distributed allopatrically. These results basically support the hypothesis that the diversification would have been caused by geographic events. In the other hand, evolution rate of floral traits was positively correlated with the speciation rate, and several sister pairs showed floral trait divergence with geographic overlap. These results implied that besides abiotic factors, biotic factors are likely to affect the diversification of Heterotropa. Overall, my study demonstrated that the diversification of Heterotropa would have been triggered by the geographic and climatic events, and subsequent repeated floral trait evolution with and without geographic isolations in the regional lineages.

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1 - Tohoku University, 232-3, Yomogida, Narukoonsen, Osaki, Miyagi, 989-6711, Japan

phylogenetic diversity
East Asia

Presentation Type: Colloquium Presentations
Session: C04, Mechanisms underlying exceptional plant diversity across eastern Asia
Location: /
Date: Tuesday, July 20th, 2021
Time: 11:15 AM(EDT)
Number: C04005
Abstract ID:259
Candidate for Awards:None

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