On the phylogeny and diversity of the microsoroid ferns (Polypodiaceae)

Microsoroid ferns (Microsoroideae) are the third largest subfamily of the Polypodiaceae, containing ca. 180 species (PPG I, 2016) and found mainly in tropical and subtropical Asia, Australasia, the Pacific Islands, Madagascar, and tropical Africa. The relationships between groups of this subfamily have long been controversial, especially the delimitation of the genus Microsorum, which, based on current understanding, is not a monophyletic entity. By using mostly DNA sequence data, as well as the micro-morphological information (spore ornamentation), the focus of this thesis is to clarify the delimitation of each genus and subgroup within Microsoroideae, in order to improve our understanding of the diversity of the subfamily. In the first and second study, molecular data was used to infer the phylogenetic relationships of microsoroid ferns. The results of the first study confirmed the placement of the Java Fern (Leptochilus pteropus), the common plant used in aquaria, in the monophyletic Leptochilus, with L. macrophyllus as the most basal branch. The second study shows that five tribes should be recognized within Microsoroideae, containing ca. 11 genera/groups with 205-225 species total. The previous Microsorum s.l. is divided into six clades in two tribes, Microsoreae and Lecanoptereae. By integrating molecular and micro-morphological data in the third study, more information is provided regarding possible classification, especially in tribe Microsoreae, indicating that there are two potentially new genera that need to be further confirmed. Most species of the six subfamilies of Polypodiaceae are epiphytic. Microsoreae is, in this respect, exceptional with a relatively low percentage of epiphytes. Therefore, in the fourth study, I explored the evolution of the substrate preference of the microsoroid ferns by combining the data of divergence time estimation based on fossils, trying to answer the questions “why” and “when”. The results show that the evolution of substrate preference has possibly been influenced by climate fluctuations and the colonization of new geographic regions during the Oligocene-Miocene periods.

Grantor dc:publisher

Helsingin yliopisto

Year dc:date.issued

2022

Author dc:creator

• Chen, Chi-Chuan

• plant biology

Statement dc:rights

• Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.
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Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/10138/346274

OAI record oai:identifier

https://helda.helsinki.fi/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Ahelda.helsinki.fi%3A10138%2F346274