Genetic Variation and Genetic Structure of Two Closely Related Dipterocarp Species, Dryobalanops aromatica C.F. Gaertn. and D. beccarii Dyer

Abstract

Large-scale genetic structure revealed in tree populations in SE Asia, as well as in many temperate forests, has been shaped by climatic fluctuation in the late Pleistocene, most importantly by that in the last glacial period. In a comparative study of the phylogeographic patterns of two closely related dipterocarp species, Dryobalanops aromatica C.F.Gaertn. and D. beccarii Dyer, we investigated how changes in land area associated with changes in climate affected large-scale genetic structure. We examined the genetic variation of D. aromatica, collected from nine populations throughout the Sundaic region, and of D. beccarii, collected from 16 populations mainly in Borneo, using seven polymorphic microsatellite markers. The two species were clearly distinguishable in the STRUCTURE analysis, although hybridisation probably occurred in sympatric populations and also in several other populations. The D. aromatica populations were divided into two main groups by the STRUCTURE analysis: Malay–Sumatra and Borneo. Mixing of the Sumatra and Borneo clusters occurred on the Malay Peninsula, supporting the hypothesis that tropical rainforests expanded over a dried Sunda Shelf during the last glacial period. The two main genetic clusters might have been formed by repeated cycles of fluctuation in land area. The D. beccarii populations in Borneo were divided into four geographically distinct groups: western Sarawak, central inland Sarawak, central coastal Sarawak and Sabah. The population on the Malay Peninsula (Gunung Panti) was an admixture of the four Bornean clusters. This suggests that this population is a relic of the recent range expansion of D. beccarii during the last glacial period.

Genetic structure of the endemicDipterocarpus condorensisrevealed by microsatellite markers

“…Previous studies mainly focused on morphological and ecological characteristics ( Nghia 2005 ; Bien and Huong 2011 ). In our study, D. condorensis maintained relatively low genetic diversity ( N A = 2.4, H O = 0.296 and H E = 0.324) compared with previously published studies for some other species, such as S. leprosula ( Ng et al 2004 ), S. robusta ( Pandey and Geburek 2009 ), D. aromatica ( Harada et al 2018 ), and D. dyeri ( Tam et al 2020 ). However, our results showed a similar level of genetic diversity found previously in several studies, P. malaanonan ( Abasolo et al 2009 ), Shorea javanica ( Rachmat et al 2012 ), D. alatus ( Tam et al 2014 ) and H. odorata ( Trang et al 2014 ).…”

“…To date, genetic research on D. condorensis has been limited. However, previous studies have shown high genetic variability in some dipterocarp species, such as Shorea leprosula ( Ng et al 2004 ), S. robusta ( Pandey and Geburek 2009 ), Dryobalanops aromatica ( Harada et al 2018 ) and Dipterocarpus dyeri ( Tam et al 2020 ), reflecting the life history traits and mating system. Several threatened dipterocarps have low genetic variability, such as Parashorea malaanonan ( Abasolo et al 2009 ), Dipterocarpus alatus ( Tam et al 2014 ) and Hopea odorata ( Trang et al 2014 ) suggesting the loss and fragmentation of habitats.…”

Genetic variation of Anisoptera costata Korth in Tan Phu tropical forest, Dinh Quan district, Dong Nai province

“…Kỹ thuật Microsatellite (SSR -simple sequence repeats) là một trong những công cụ được sử dụng phổ biến cho việc đánh giá đa dạng di truyền ở thực vật và kỹ thuật này có tiềm năng, liên quan đến đa hình cao và tính kế thừa đồng trội trong genome, và lợi thế cho việc nghiên cứu di truyền các loại cây quý hiếm. Trên thế giới, kỹ thuật Microsatellite được ứng dụng phổ biến cho các nghiên cứu về đa dạng di truyền đối với một số loài cây họ Dầu (Rachmat et al, 2012;Trang et al, 2014;Harada et al, 2018;Vu et al, 2019).…”

Genetic Variation and Evolutionary History of the Threatened Dipterocarpus turbinatus C.F.Gaertn. Detected Using Microsatellites

“…Due to their distribution across all genomes, their polymorphism, and their reproducibility [17], microsatellite markers, i.e., simple sequence repeats (SSRs), have been widely used to investigate genetic diversity, population structure, gene flow, and mating systems in plants [18,19]. For the purpose of species conservation and management [20][21][22][23][24], nuclear microsatellites have been used in studies of genetic diversity focusing on certain dipterocarp species, such as Dryobalanops lanceolata in Sarawak, Malaysia [25], Shorea curtisii in Sarangor, Malaysia [26], and Dipterocarpus tempehes in Sarawak, Malaysia [27]. The exploration of genetic variability within and among populations of D. turbinatus is of crucial importance for species conservation, management, and restoration.…”