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Young incipient species provide ideal materials for untangling the process of ecological speciation in the presence of gene flow. The Miscanthus floridulus/sinensis complex exhibits diverse phenotypic and ecological differences despite recent divergence (approximately 1.59 million years ago). To elucidate the process of genetic differentiation during early stages of ecological speciation, we analyzed genomic divergence in the Miscanthus complex using 72 randomly selected genes from a newly assembled transcriptome. In this study, rampant gene flow was detected between species, estimated as M = 3.36 × 10(-9) to 1.20 × 10(-6) , resulting in contradicting phylogenies across loci. Nevertheless, beast analyses revealed the species identity and the effects of extrinsic cohesive forces that counteracted the non-stop introgression. As expected, early in speciation with gene flow, only 3-13 loci were highly diverged; two to five outliers (approximately 2.78-6.94% of the genome) were characterized by strong linkage disequilibrium, and asymmetrically distributed among ecotypes, indicating footprints of diversifying selection. In conclusion, ecological speciation of incipient species of Miscanthus probably followed the parapatric model, whereas allopatric speciation cannot be completely ruled out, especially between the geographically isolated northern and southern M. sinensis, for which no significant gene flow across oceanic barriers was detected. Divergence between local ecotypes in early-stage speciation began at a few genomic regions under the influence of natural selection and divergence hitchhiking that overcame gene flow.

Islands isolated by oceans that act as a geographical barrier for plant migration often possess high species endemism and have been deemed as a natural laboratory for studying species divergence. Fatsia Decne. & Planch. (Araliaceae), with three species, is one of the few plant genera absent in continents while exclusively spanning continental and oceanic islands. The nuclear ribosomal internal transcribed spacer (nrITS) phylogeny uncovered a pattern with reciprocal monophyly of Fatsia oligocarpella Koidz. (Bonin) and Fatsia polycarpa Hayata (Taiwan) vs. paraphyly of Fatsia japonica (Thunb.) Decne. & Planch. (Japan and Ryukyus), suggesting ancestry of the species in Japan and a likely temperate origin; whereas, lack of monophyly of all three allopatrically distributed species at chloroplast DNA (cpDNA) trnL–trnF spacer likely resulted from lineage sorting. In spite of the limited habitats for F. oligocarpella, unexpectedly high genetic variations in this species of oceanic islands were likely attributable to multiple colonizations and recurrent gene introgression. Biogeographical analyses suggested that Fatsia likely diverged via southward colonization in Bonin Islands and Taiwan during the late Pliocene to Pleistocene. Besides, Fatsia species with an allopatric distribution provide a perfect model for testing speciation modes of insular endemics. Nonzero gene flow between species was detected based on MIGRATE and STRUCTURE analyses of DNA sequences and microsatellite fingerprints, suggesting that allopatric speciation is less likely.

Gene flow between species may last a long time in plants. Reticulation inevitably causes difficulties in phylogenetic reconstruction. In this study, we looked into the genetic divergence and phylogeny of 20 Lilium species based on multilocus analyses of 8 genes of chloroplast DNA (cpDNA), the internally transcribed nuclear ribosomal DNA (nrITS) spacer and 20 loci extracted from the expressed sequence tag (EST) libraries of L. longiflorum Thunb. and L. formosanum Wallace. The phylogeny based on the combined data of the maternally inherited cpDNA and nrITS was largely consistent with the taxonomy of Lilium sections. This phylogeny was deemed the hypothetical species tree and uncovered three groups, i.e., Cluster A consisting of 4 taxa from the sections Pseudolirium and Liriotypus, Cluster B consisting of the 4 taxa from the sections Leucolirion, Archelirion and Daurolirion, and Cluster C comprising 10 taxa mostly from the sections Martagon and Sinomartagon. In contrast, systematic inconsistency occurred across the EST loci, with up to 19 genes (95%) displaying tree topologies deviating from the hypothetical species tree. The phylogenetic incongruence was likely attributable to the frequent genetic exchanges between species/sections, as indicated by the high levels of genetic recombination and the IMa analyses with the EST loci. Nevertheless, multilocus analysis could provide complementary information among the loci on the species split and the extent of gene flow between the species. In conclusion, this study not only detected frequent gene flow among Lilium sections that resulted in phylogenetic incongruence but also reconstructed a hypothetical species tree that gave insights into the nature of the complex relationships among Lilium species.

Postglacial climate changes alter geographical distributions and diversity of species. Such ongoing changes often force species to migrate along the latitude/altitude. Altitudinal gradients represent assemblage of environmental, especially climatic, variable factors that influence the plant distributions. Global warming that triggered upward migrations has therefore impacted the alpine plants on an island. In this study, we examined the genetic structure of Juniperus morrisonicola, a dominant alpine species in Taiwan, and inferred historical, demographic dynamics based on multilocus analyses. Lower levels of genetic diversity in north indicated that populations at higher latitudes were vulnerable to climate change, possibly related to historical alpine glaciers. Neither organellar DNA nor nuclear genes displayed geographical subdivisions, indicating that populations were likely interconnected before migrating upward to isolated mountain peaks, providing low possibilities of seed/pollen dispersal across mountain ranges. Bayesian skyline plots suggested steady population growth of J. morrisonicola followed by recent demographic contraction. In contrast, most lower-elevation plants experienced recent demographic expansion as a result of global warming. The endemic alpine conifer may have experienced dramatic climate changes over the alternation of glacial and interglacial periods, as indicated by a trend showing decreasing genetic diversity with the altitudinal gradient, plus a fact of upward migration.

Summary Asian rice, Oryza sativa, consists of two major subspecies, indica and japonica, which are physiologically differentiated and adapted to different latitudes. Genes for photoperiod sensitivity are likely targets of selection along latitude. We examined the footprints of natural and artificial selections for four major genes of the photoperiod pathway, namely PHYTOCHROME B (PhyB), HEADING DATE 1 (Hd1), HEADING DATE 3a (Hd3a), and EARLY HEADING DATE 1 (Ehd1), by investigation of the patterns of nucleotide polymorphisms in cultivated and wild rice. Geographical subdivision between tropical and subtropical O. rufipogon was found for all of the photoperiod genes in plants divided by the Tropic of Cancer (TOC). All of these genes, except for PhyB, were characterized by the existence of clades that split a long time ago and that corresponded to latitudinal subdivisions, and revealed a likely diversifying selection. Ssp. indica showed close affinity to tropical O. rufipogon for all genes, while ssp. japonica, which has a much wider range of distribution, displayed complex patterns of differentiation from O. rufipogon, which reflected various agricultural needs in relation to crop yield. In japonica, all genes, except Hd3a, were genetically differentiated at the TOC, while geographical subdivision occurred at 31°N in Hd3a, probably the result of varying photoperiods. Many other features of the photoperiod genes revealed domestication signatures, which included high linkage disequilibrium (LD) within genes, the occurrence of frequent and recurrent non-functional Hd1 mutants in cultivated rice, crossovers between subtropical and tropical alleles of Hd1, and significant LD between Hd1 and Hd3a in japonica and indica.

Scutellaria austrotaiwanensis is a new species first described in 1997. It is a rare and endemic species in southern Taiwan. In this study, 16 polymorphic microsatellite loci were isolated from Scutellaria austrotaiwanensis using a magnetic bead enrichment method. Several genetic indices, including observed heterozygosity (Ho), expected heterozygosity (He), number of effective alleles (Ne), and polymorphism information content (PIC), were calculated. Deviation of heterozygosity was detected by the fixation index (Fis) and Hardy–Weinberg equilibrium was tested by possibilities (P HWE) using a chi-squared test. Allele numbers ranged from 4 to 8, with observed heterozygosity ranging from 0.611 to 1.000. Five microsatellite markers showed deficient heterozygosity by Fis > 0. No loci exhibited a departure from Hardy–Weinberg equilibrium, possibly due to a stable population. No loci pairs revealed significant linkage disequilibrium. The microsatellite markers reported here should be useful to evaluate the population structure of S. austrotaiwanensis for conservation efforts.

Miscanthus sinensis (Poaceae) is typical of many dominant grasses of East Asia. Due to its characteristics of fast growth and high biomass, Miscanthus, a C4 plant, has been long explored for the potential usage as biofuel. In this study, we described the development of nine microsatellite loci from M. sinensis for genetic studies. These new markers were tested in 25 individuals of five populations in three varieties. The number of alleles ranged from 3 to 8. The expected (H E) and observed (H O) heterozygosities were 0.37–0.78 and 0.05–0.52, respectively. All microsatellite loci are significantly deviated from Hardy–Weinberg expectations likely due to the population structure within samples. Linkage disequilibrium between four loci pairs were observed from the total 36 pairwise comparisons of loci. Cross-species transferability revealed that all loci can be applied to its closely related species, M. floridulus.

Molecular Ecology Resources Editorial Office : 6270 University Blvd, Vancouver,BCV6T1Z4, Canada; International audience; This article documents the addition of 139 microsatellite marker loci and 90 pairs of single-nucleotide polymorphism sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Aglaoctenus lagotis, Costus pulverulentus, Costus scaber, Culex pipiens, Dascyllus marginatus, Lupinus nanus Benth, Phloeomyzus passerini, Podarcis muralis, Rhododendron rubropilosum Hayata var. taiwanalpinum and Zoarces viviparus. These loci were cross-tested on the following species: Culex quinquefasciatus, Rhododendron pseudochrysanthum Hay. ssp. morii (Hay.) Yamazaki and R. pseudochrysanthum Hayata. This article also documents the addition of 48 sequencing primer pairs and 90 allele-specific primers for Engraulis encrasicolus.

Betel nut (Areca nut, Areca catechu L.) is a conspicuous and important cultivated plant of tropical and subtropical habitats throughout Southeast Asia and Oceania. As a significant cultural and social offering, the migration of betel nut associated with human dispersal is an important issue in ethnobotany and anthropology. In this study, we described the development of nine microsatellite loci from A. catechu. The number of alleles per locus ranged from 5 to 15. The expected and observed heterozygosities ranged from 0.71to 0.94 and from 0 to 0.88, respectively. All microsatellite loci, except for AC30, significantly deviated from Hardy–Weinberg equilibrium possibly due to artificially selected cultivation or the existence of excessive null alleles. No linkage disequilibrium was observed from pairwise comparisons of loci, except for AC06 and AC08.

Ludwigia polycarpa is the only species of section Microcarpium occurring north of 37N in the central midwest of the United States. Recently, the loss of wetlands in North America reduced the population number and size of L. polycarpa dramatically. In this study, for the purpose of the conservation of the endangered species, we described eight microsatellite DNA loci. High variabilities enable these molecular markers to assess the population structure. The number of alleles per locus ranged from 8 to 23. The expected (HE) and observed (HO) heterozygosities ranged from 0.86 to 0.96 and 0.00 to 1.00, respectively. Seven of the eight microsatellite loci displayed significant departures from Hardy-Weinberg expectations, likely due to the loss of habitats and the small population size. No linkage disequilibrium was observed in the pairwise com- parisons of loci. The application of these microsatellite loci in L. polycarpa may provide a tool for understanding its demography and population structure.

Miscanthus, a genus of the Poaceae, has attracted biologists' attention because of its high biomass and fast growth, traits that make this grass potentially useful as a biofuel. Miscanthus, is morphologically diverse and widespread across various habitats along altitude and latitude, providing a perfect model for investigating adaptation and speciation. Nevertheless, big genome sizes and rampant gene flow cause challenges in the genomic analysis of species swarms of Miscanthus. Here, we illustrate genetic and genomic analyses of divergence and adaptive differentiation among Miscanthus species. Outlier and linkage disequilibrium analyses are suggested for the identification of genes under diversifying selection.

Suzukia shikikunensis Kudo is an endemic plant in Taiwan and suffers habitat destruction caused by human overexploitation. In this study, we developed 12 microsatellite primer pairs for genetic study. These markers were screened for 24 samples collected from wild populations distributed in Taiwan, and for a sister species S. luchuensis collected from Yonaguni and Lutao Islands. The number of alleles ranged from 5 to 14. The expected (H E) and observed (H O) heterozygosities were 0.65–0.922 and 0–0.625, respectively. All loci were significantly deviated from Hardy–Weinberg equilibrium due to the heterozygote deficiency. These primers amplifying microsatellites in the two species may provide a useful tool for population genetics to establish conservation strategy.

Fatsia polycarpa Hayata (Araliaceae) is an element of evergreen forests at middle elevations in Taiwan, also representing the southern limitation in distribution of the genus. In this study, we described the development of 11 microsatellite loci from F. polycarpa in Taiwan for genetic studies. These new markers were tested in 20 individuals of 5 populations of the woody species. The number of alleles ranged from 9 to 18. The expected (H E ) and observed (H O ) heterozygosities were 0.80–0.95 and 0.10–0.75, respectively. Six of the 11 microsatellite loci are significantly deviated from Hardy–Weinberg expectations likely due to the population structure within samples. No linkage disequilibrium were observed from pairwise comparisons of loci.

Taxus sumatrana (Miq.) de Laub. (Taxaceae) is an endangered conifer with a scattered distribution in central Taiwan. In this study, we described the development of 12 microsatellite loci in T. sumatrana for genetic studies. These new markers were tested in nine individuals of the rare species. The number of alleles ranged from 3 to 13 and expected heterozygosity from 0.627 to 0.948. Eleven of twelve loci are significantly deviated from Hardy–Weinberg expectations due to the heterozygote deficiency.

Background Pinus massoniana, an ecologically and economically important conifer, is widespread across central and southern mainland China and Taiwan. In this study, we tested the central–marginal paradigm that predicts that the marginal populations tend to be less polymorphic than the central ones in their genetic composition, and examined a founders' effect in the island population. Methodology/Principal Findings We examined the phylogeography and population structuring of the P. massoniana based on nucleotide sequences of cpDNA atpB-rbcL intergenic spacer, intron regions of the AdhC2 locus, and microsatellite fingerprints. SAMOVA analysis of nucleotide sequences indicated that most genetic variants resided among geographical regions. High levels of genetic diversity in the marginal populations in the south region, a pattern seemingly contradicting the central–marginal paradigm, and the fixation of private haplotypes in most populations indicate that multiple refugia may have existed over the glacial maxima. STRUCTURE analyses on microsatellites revealed that genetic structure of mainland populations was mediated with recent genetic exchanges mostly via pollen flow, and that the genetic composition in east region was intermixed between south and west regions, a pattern likely shaped by gene introgression and maintenance of ancestral polymorphisms. As expected, the small island population in Taiwan was genetically differentiated from mainland populations. Conclusions/Significance The marginal populations in south region possessed divergent gene pools, suggesting that the past glaciations might have low impacts on these populations at low latitudes. Estimates of ancestral population sizes interestingly reflect a recent expansion in mainland from a rather smaller population, a pattern that seemingly agrees with the pollen record.

PREMISE OF THE STUDY Fifteen microsatellite loci were developed in an endangered species, Amentotaxus formosana, and were tested in an additional three species, A. argotaenia, A. yunnanensis, and A. poilanei, to evaluate the population structure for conservation efforts and reconstruct the phylogeographic patterns of this ancient lineage. METHODS AND RESULTS Polymorphic primer sets were developed from A. formosana; the number of alleles ranged from two to 10, with an observed heterozygosity ranging from 0 to 0.60. All of the loci were found to be interspecifically amplifiable. CONCLUSIONS These polymorphic and transferable loci will be potentially useful for future studies that will focus on identifying distinct genetic units within species and establishing the phylogeographic patterns and the process of speciation among closely related species.

 Premise of the study: Transferable polymorphic microsatellite loci for four skullcaps, Scutellaria indica , S. taiwanensis , S. austrotaiwanensis , and S. playfairii , were developed for future studies of the mating system and population structure of these species. Interspecifi c amplifi cation was also tested in various Scutellaria species.  Methods and Results: Twelve novel polymorphic microsatellite loci were isolated from four S. taiwanensis specimens, and seven are interspecifi cally transferable. Microsatellite loci developed from S. austrotaiwanensis in a previous study were also analyzed in the other three species, and 12 loci were found to be transferable. Allele numbers of the total 24 loci for S. indica , S. taiwanensis , S. playfairii , and S. austrotaiwanensis are two to four, two, two to fiand two to three, respectively, with an expected heterozygosity ranging from 0.114 – 0.661, 0.062 – 0.499, 0.280 – 0.730, and 0.268 – 0.662, respectively. The interspecies transferability of these 24 loci was further tested in another 10 Scutellaria species, including three species native to Taiwan. Seventeen loci were found to be interspecifi cally amplifi able, especially among the Taiwan native species.  Conclusions: These highly polymorphic and transferable loci will be useful for future studies of the mating system of closely related Scutellaria species.

Recovering the genetic divergence between species is one of the major interests in the evolutionary biology. It requires accurate estimation of the neutral substitution rates. Arabidopsis thaliana, the first whole-genome sequenced plant, and its out-crossing relatives provide an ideal model for examining the split between sister species. In the study, rates of molecular evolution at markers frequently used for systematics and population genetics, including 14 nuclear genes spanning most chromosomes, three noncoding regions of chloroplast genome, and one intron of mitochondrial genome, between A. thaliana and four relatives were estimated. No deviation from neutrality was detected in the genes examined. Based on the known divergence between A. thaliana and its sisters about 8.0–17.6 MYA, evolutionary rates of the eighteen genes were estimated. Accordingly, the ratio of rates of synonymous substitutions among mitochondrial, chloroplast and nuclear genes was calculated with an average and 95% confidence interval of 1 (0.25–1.75): 15.77 (7.48–114.09): 74.79 (36.27–534.61). Molecular evolutionary rates of nuclear genes varied, with a range of 0.383–0.856 × 10− 8 for synonymous substitutions per site per year and 0.036–0.081 × 10− 9 for nonsynonymous substitutions per site per year. Compared with orthologs in Populus, a long life-span tree, genes in Arabidopsis evolved faster in an order of magnitude at the gene level, agreeing with a generation time hypothesis. The estimated substitution rates of these genes can be used as a reference for molecular dating.

 Premise of the study: Miscanthus , a nonfood plant with high potential as a biofuel, has been used in Europe and the United States. The selection of a cultivar with high biomass, photosynthetic effi ciency, and stress resistance from wild populations has become an important issue. New genic microsatellite markers will aid the assessment of genetic diversity for different strains.  Methods and Results: Twelve polymorphic microsatellite markers derived from the transcriptome of Miscanthus sinensis fo. glaber were identifi ed and screened on 80 individuals of M. sinensis . The number of alleles per locus ranged from 6 to 12, and the mean expected heterozygosity was 0.75. Cross-taxa transferability revealed that all loci can be applied to all varieties of M . sinensis , as well as the closely related species M. fl .  Conclusions: These new genic microsatellite markers are useful for characterizing different traits in breeding programs or to select genes useful for biofuel.

Summary •Outcrossing Arabidopsis species that diverged from their inbreeding relative Arabidopsis thaliana 5 million yr ago and display a biogeographical pattern of interspecific sympatry vs intraspecific allopatry provides an ideal model for studying impacts of gene introgression and polyploidization on species diversification. •Flow cytometry analyses detected ploidy polymorphisms of 2× and 4× in Arabidopsis lyrata ssp. kamchatica of Taiwan. Genomic divergence between species/subspecies was estimated based on 98 randomly chosen nuclear genes. Multilocus analyses revealed a mosaic genome in diploid A. l. kamchatica composed of Arabidopsis halleri-like and A. lyrata-like alleles. •Coalescent analyses suggest that the segregation of ancestral polymorphisms alone cannot explain the high inconsistency between gene trees across loci, and that gene introgression via diploid A. l. kamchatica likely distorts the molecular phylogenies of Arabidopsis species. However, not all genes migrated across species freely. Gene ontology analyses suggested that some nonmigrating genes were constrained by natural selection. •High levels of estimated ancestral polymorphisms between A. halleri and A. lyrata suggest that gene flow between these species has not completely ceased since their initial isolation. Polymorphism data of extant populations also imply recent gene flow between the species. Our study reveals that interspecific gene flow affects the genome evolution in Arabidopsis.