Abstract
East Asia is characterized by high levels of species diversity and endemism. However, the biogeographic patterns and processes of endemic epiphytic plants within East Asia are still poorly known. In this study, we used eleven plastid and one nuclear DNA sequences to infer the historical biogeography of Holcoglossum Schltr. (Orchidaceae), an eastern Asian endemic genus. Phylogenetic analyses strongly support Holcoglossum as monophyletic, and contains three major clades (TC, HC and AC). Our results suggest that the most recent common ancestor of Holcoglossum occurred in Palaeotropical region in the late Miocene (6.29 Ma). Within Asian mainland, three dispersal and one vicariant events were hypothesized to explain the expansion of Holcoglossum from Palaeotropical region to Sino-Himalayan and Sino-Japanese region. These events occurred in the latest Miocene to middle Pleistocene, which may be associated with the uplift of the southeastern Tibetan Plateau and intensification of East Asia monsoon around that period. A disjunct distribution between Asian mainland and Taiwan was inferred in the latest Pliocene-early Pleistocene, which supports the close floristic affinity between Taiwan and Asian mainland. This study contributes to our knowledge on the historical biogeography of endemic epiphytic plants in East Asia.
Highlights
East Asia is well-known for its vascular plant diversity and endemic (Qian et al, 2005)
The phylogenetic result based on combined chloroplast and nuclear data strongly supported Holcoglossum as monophyletic, which included three clades, i.e., tropical clade (TC), HC, and TC, which is consistent with Xiang et al (2012) and Li et al (2019)
Holcoglossum naglandensis and H. himalaicum among TC are sisters in this study and Xiang et al (2012), while H. naglandensis is close to H. amesianum and H. himalaicum is close to H. wangii due to different DNA sequences
Summary
East Asia is well-known for its vascular plant diversity and endemic (Qian et al, 2005). Understanding the historical origins and processes of the plant richness of East Asia has been of major interest for ecologists and biogeographers. East Asia is suggested as both a “Cradle” and a “Museum” for vascular plants since the Cretaceous (e.g., Wu and Wu, 1998; Wen, 1999; Jiang et al, 2019). During the glacial periods of Quaternary, East Asia acted as refugia for vascular plants’ survival and evolution, especially for more recent divergent lineages (Tiffney, 1985; Ying, 2001; Qiu et al, 2011; Chen et al, 2018). The biogeographic patterns and processes of endemic epiphytic plants in East Asia are still poorly known
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