Jenn Che Wang

Allozyme Variation and the Genetic Structure of Populations of Trochodendron aralioides, a Monotypic and Narrow Geographic Genus

Trochodendron aralioides Siebold & Zucc., a primitive angiosperm that is insect-pollinated, has wind-dispersed seeds and grows only in eastern Asia. Nineteen populations were analyzed, including 16 from Taiwan, two from the main islands of Japan and one from Iriomote Island in the Ryukyu Islands. Genetic variability (0.133) at the species level was more similar to that of a narrow geographic species than an endemic species. Based on genotype frequencies, mating within populations was non-random (FIs=0.065) and there was significant genetic differentiation (FST=0.164) among populations. Genetic diversity was largely within, rather than among, populations (Hs=0.132, 85.14%). Bisexual flowers of T. aralioides exhibit synchronized dimorphism. The protogynous and protandrous morphs are self-incompatible, which probably promotes outcrossing and contributes to the high levels of heterozygosity within populations. Using a maximum likelihood tree, populations of T. aralioides were separated into two distinct clusters: Japan and Taiwan/ Iriomote Island. Populations of T. aralioides on Iriomote Island and in northern Taiwan exhibited a high degree of genetic similarity. The isolation-by-distance model does not fit populations in Taiwan, but suitably describes the relationship between populations of T. aralioides in Japan and Taiwan.

The First National Vegetation Inventory in Taiwan

This article describes the successful implementation and preliminary results of the first national vegetation inventory in Taiwan. This project which aimed to establish national criteria for vegetation classification, map island-wide forest vegetation at a scale of 1: 5000 and establish a vegetation data management system was launched in 2003. More than 3000 permanent plots (20 m×20 m) were set up throughout Taiwan, and 792 articles on vegetation of Taiwan were located to acquire vegetation data. Vegetation types were identified according to the physiognomic appearances in aerial photographs. The national vegetation classification system was constructed by referring to field observations, vegetation data, and currently available vegetation classification schemes. This project was finalized in 2008. Up to 67% of native vascular plant species in Taiwan were recorded, and 59% of the total area of Taiwan was mapped in this project. Preliminary vegetation analyses identified 9 major vegetation types and their diagnostic species, constant species and dominant species. The Taiwan Vegetation Information was established and has performed the functions of data management for the current project since 2003. The latest version of the Taiwan Vegetation Classification System was released in 2007. The achievement and experiences of the current project have paved the way for the successful implementation of subsequent large-scale surveys in Taiwan.

Molecular Evidence for Genetic Heterogeneity and the Hybrid Origin of Acrorumohra subreflexipinna from Taiwan

Abstract Acrorumohra subreflexipinna, an endemic fern of Taiwan, has been suspected to be a hybrid species. The aims of this study were to detect possible multiple origins of this species, determine the genetic variation in different populations, and clarify their lineages. One nuclear and three organellar DNA fragments were sequenced to determine parentage of this putative hybrid and to examine genetic differentiation among populations. Sequence data support the conclusion that A. subreflexipinna arose from the hybridization of A. hasseltii and A. diffracta, and the hybridization was uni-directional, i.e., based on the assumption of maternal inheritance in organellar DNA, the former was its maternal species while the latter was its paternal source. A convincing interpretation is that the female gametes of A. hasseltii gametophyte could be fertilized by the male gametes from apogamous A. diffracta. Unique nuclear alleles present in different populations of A. subreflexipinna and A. hasseltii demonstrated that hybridization occurred many times independently. The nuclear haplotypes present in A. subreflexipinna were subsets of those found in the parental species, and A. subreflexipinna always had lower haplotype diversity than A. hasseltii at sympatric sites. Our results show that any genetic variation of A. subreflexipinna came from its parents and that it maintains this significant genetic variability because of recurrent hybridization.

Bidens identification using the noncoding regions of chloroplast genome and nuclear ribosomal DNA

Bidens pilosa L. is a plant producing barbed fruits which, due to its method of seed dispersal, is commonly found during forensic investigations. In Taiwan there are three varieties of the species, radiata, minor and pilosa. Fragments of these three varieties are difficult to differentiate by traditional morphological characteristics and until now little is known of their genetic composition. To discover genetic polymorphisms among these varieties, five loci within the nuclear and chloroplast genomes were screened. A total of 161 specimens were used in this study comprising different geographical populations. Seven samples of Bidens biternata were included as an out-group control. DNA fragments of all samples at the trnL intron and trnL-trnF IGS loci of the chloroplast genome, internal transcribed spacer (ITS1 and ITS2) and the 5.8S of nuclear ribosomal DNA (nrDNA) were amplified and sequenced. There were 3, 4, 20, 12 and 9 sequence types at these five loci, respectively. The sequence types for any locus of trnL intron, ITS1, ITS2 and 5.8S were found to be useful markers to identify Bidens biternata and B. pilosa. The resulting 84 haplotypes at the 5 loci could differentiate the var. radiata from the varieties of B. pilosa with only the exception of 1 type. The genetic polymorphisms can be used when comparing botanical remains to identify the variety of B. pilosa present at a crime scene.

Contrasting demographic patterns of Ceriops tagal (Rhizophoraceae) populations in the South China Sea

Demographic history and dispersal ability are significant factors in determining the genetic composition of a population.Inthisstudy,weexaminedthephylogeographicpatternsofCeriopstagalfromtheHainanIslandandtheGulfof ThailandintheSouthChinaSea,wherethereareabundantmangrovespecies.NucleotidevariationsintwochloroplastDNA spacers were compared with trace Ceriops propagule dispersal routes and demographic history. An analysis of Templeton, Crandall and Sings (TCS) parsimonious networks and population demographics suggests that the Ceriops population graduallyexpandedfromthenorthernpartsoftheSouthChinaSeatothesouth-westernpopulationsintheGulfofThailand. Such phylogeographic inferences reflect a postglacial southward shift in the mangrove genetic diversity centre and a connection between the demographic dynamics and the coastal range expansion caused by the sea-level rise in the Pleistocene. Therefore, the phylogeographic pattern and historical demography of mangrove species were affected by glaciations during the Pleistocene such as temperate biota.

Classification of the High-Mountain Coniferous Forests in Taiwan

Vegetation of boreal coniferous forests has been extensively studied in many areas of northern Eurasia and North America, but similar forests in the high mountains of subtropical and tropical eastern Asia have been poorly documented so far. This paper, focusing on such forests, is the first phytosociological study at a national scale in Taiwan. The relevés from the National Vegetation Diversity Inventory and Mapping Project database were used to define vegetation types of the high-mountain coniferous forests and to characterize their distribution in Taiwan. Environmental variables such as aspect, elevation, soil rockiness and slope were related to species composition. Cluster analysis was used to classify vegetation plots and establish groups that were interpreted as nine associations belonging to two alliances. The alliance Juniperion squamatae represents woodlands and forests scattered in the subalpine belt, in which Juniperus squamata dominates the canopy and subalpine meadow species occur in the understorey. The Abieti kawakamii-Tsugion formosanae alliance includes forests dominated by Abies kawakamii and Tsuga chinensis var. formosana with shade-tolerant herb species in the upper montane belt. In addition to regional vegetation description, an identification key for the studied forests was developed based on the classification tree technique.

Disentangling the effects of isolation-by-distance and isolation-by-environment on genetic differentiation among Rhododendron lineages in the subgenus Tsutsusi

Ecological speciation has long been noted as a central topic in the field of evolutionary biology, and investigation into the relative importance of ecological and geographical factors is becoming increasingly emphasized. We surveyed genetic variation of 277 samples from 25 populations of nine Rhododendron species within Tsutsusi subgenus in Taiwan using simple sequence repeats of expressed sequence tags. Bayesian clustering revealed four genetic lineages: (1) the Rhododendron simsii, Rhododendron kanehirai, and Rhododendron nakaharae lineage (lineage 1); (2) the Rhododendron longiperulatum, Rhododendron breviperulatum, and Rhododendron noriakianum lineage (lineage 2); (3) the Rhododendron rubropilosum lineage (lineage 3); and (4) the Rhododendron oldhamii lineage (lineage 4). Asymmetric introgressions were found from lineage 3 into lineages 1 and 2 (introgressed lineages). Genetic admixture of non-R. oldhamii species was also revealed by a neighbor-joining tree. Variation partitioning showed that environment explained much larger portions of genetic variation than geography between non-introgressed lineages (i.e., between R. oldhamii and other lineages). However, the Mantel and partial Mantel tests and the multiple matrix regression with randomization found that isolation-by-distance played a more important role than isolation-by-environment (IBE) in contributing to genetic variation in most between lineage comparisons. Nevertheless, strong IBE was found when compared between non-introgressed lineages of R. oldhamii and R. rubropilosum, suggesting post-speciation ecological divergence. Several environmental variables, including annual mean temperature, aspect, isothermality, seasonal precipitation, slope, and soil pH, could be important ecological drivers involved in reproductive isolation between R. oldhamii and non-R. oldhamii species within the Tsutsusi subgenus.

Camellia kissi Wallich (Theaceae): A Newly Recorded Tree from Taiwan

【Summary】 During our botanical exploration of the mountains of Chihpen, Taitung County in September 2005, we collected an unknown Camellia which was subsequently identified as Camellia kissi Wallich, a species widely distributed from the Himalayas to South China. The newly recorded species is easily distinguished from its congeners in Taiwan by the pyriform capsules. In the present article, a description, line drawing, photos taken in the wild, and a key to the species of Camellia section Paracamellia in Taiwan are provided. The conservation status for C. kissi is also evaluated.

Asarum pubitessellatum, sp. nov. (sect. Heterotropa, Aristolochiaceae) from Taiwan based on morphological and palynological evidence

BackgroundRecently, we discovered an unknown Asarum from Taiwan which is closely related to A. crassisepalum S.F. Huang, T.H. Hsieh and T.C. Huang and A. taipingshanianum S.F. Huang, T.H. Hsieh and T.C. Huang by sharing a thick leaf blade, spreading perianth-lobes and a conical to cylindrical perianth-tube. We compared it with other related species and identified this plant as a new species.ResultsThis new species differs distinctly from the above two related species by having larger plant body, shortened rhizomes and an inner surface of the perianth-tube that is covered with numerous simple trichomes (vs. glandular trichomes). The pollen tectum in this new species is perforate, which differs from the incomplete reticulate with small supratectate granules in A. crassisepalum and the compact rugulate with small supratectate granules in A. taipingshanianum. Furthermore, these three species are geographically separated from one another.ConclusionsAsarum pubitessellatum C.T. Lu & J.C. Wang, a new species is described and illustrated. The trichomes on the inner surface of the perianth-tube and pollen micromorphology were the valuable characters in the low-level classification of Heterotropa species in Taiwan.

Molecular genetic and biochemical evidence for adaptive evolution of leaf abaxial epicuticular wax crystals in the genus Lithocarpus (Fagaceae)

BackgroundLeaf epicuticular wax is an important functional trait for physiological regulation and pathogen defense. This study tests how selective pressure may have forced the trait of leaf abaxial epicuticular wax crystals (LAEWC) and whether the presence/absence of LAEWC is associated with other ecophysiological traits. Scanning Electron Microscopy was conducted to check for LAEWC in different Lithocarpus species. Four wax biosynthesis related genes, including two wax backbone genes ECERIFERUM 1 (CER1) and CER3, one regulatory gene CER7 and one transport gene CER5, were cloned and sequenced. Ecophysiological measurements of secondary metabolites, photosynthesis, water usage efficiency, and nutrition indices were also determined. Evolutionary hypotheses of leaf wax character transition associated with the evolution of those ecophysiological traits as well as species evolution were tested by maximum likelihood.ResultsEight of 14 studied Lithocarpus species have obvious LAEWC appearing with various types of trichomes. Measurements of ecophysiological traits show no direct correlations with the presence/absence of LAEWC. However, the content of phenolic acids is significantly associated with the gene evolution of the wax biosynthetic backbone gene CER1, which was detected to be positively selected when LAEWC was gained during the late-Miocene-to-Pliocene period.ConclusionsChanges of landmass and vegetation type accelerated the diversification of tropical and subtropical forest trees and certain herbivores during the late Miocene. As phenolic acids were long thought to be associated with defense against herbivories, co-occurrence of LAEWC and phenolic acids may suggest that LAEWC might be an adaptive defensive mechanism in Lithocarpus.