Floral Biology, Reproductive Strategies, and Cluster Analyses of Selected Calamoids of Sarawak (Arecaceae)

Win Seng, Ng (2025) Floral Biology, Reproductive Strategies, and Cluster Analyses of Selected Calamoids of Sarawak (Arecaceae). PhD thesis, Universiti Malaysia Sarawak.

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Abstract

The Calamoids are from the subfamily Calamoideae and account for one-fifth of Arecaceae, the palm family. The floral biology and breeding strategies in the tribe Calameae of Calamoideae is still relatively unknown despite its importance that supports a billion-dollar industry in rattan products. This study aims to investigate the floral biology and breeding strategies of three members of Calameae, Calamus lobbianus, Calamus pygmaeus, and Salacca vermicularis. The data on floral biology, floral visitors, and floral availability were collected and analysed. The Nectar availability was investigated by further measurement of nectar concentration and volume. Pollination studies were conducted to investigate the breeding mechanisms. Seed dispersal study was further conducted on S. vermicularis via camera trapping. Investigation on the population genomics of C. pygmaeus was conducted to elucidate on the asexual propagation as a viable breeding strategy by performing single nucleotide polymorphisms and insertion deletion analyses. For both species of Calamus, anthesis started in the early morning for pistillate and staminate plants, ended by late noon (staminate plants) but lasted till the next day in pistillate plants. Although both species appeared to be aseasonal in flowering, C. lobbianus exhibited a male-biased population while C. pygmaeus did not exhibit any sex bias. Nectar was observed to be extruded from the base of the petals of the staminate flowers and sterile male flowers of the pistillate plants of C. lobbianus. The concentration and volume of the nectar of the staminate flower and sterile male flower of C. lobbianus peaked at c. 11% and 9 µl around 1100 (Day 1) and c. 13% and 8 µl around 0930 (Day 1) respectively but only appeared as a layer of glistening exudate in C. pygmaeus. Floral scent was not detected in any of the inflorescences of both species. Several insect visitors were observed to be the primary visitors of both Calamus species which include two species of Tetragonula, a species of Liostenogaster sp., andiv Stenodyneriellus sp. Experiments on breeding mechanism of C. lobbianus and C. pygmaeus indicate that both species are most likely apomictic. Anthesis in staminate flowers of S. vermicularis began around noon and persisted until early morning on the second day whilst anthesis in pistillate flowers began around evening and took up to 40 hours to fully bloom. Floral scent was present throughout anthesis for staminate and pistillate plants. Apomixis is not present in this species. Several insect visitors were observed, namely Heterotrigona (Apidae) sp. as well as members of Curculionidae, Sciaridae, Formicidae, and Acaridae. Three species of visitors are likely the dispersal agents of S. vermicularis, namely Hystrix sp. (Hystricidae: Hystricinae), Tragulus sp. (Tragulidae), and Lariscus insignis (Sciuridae: Callosciurinae). A mongoose (Herspetidae) was observed foraging nearby. Phylogenetic analysis and DAPC analysis concluded that the C. pygmaeus found to consist of genetic clones forming genets with distinct genetic makeup among subpopulations.

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