Research interests
My central focus is to understand how plant species originated, evolved, and interacted with biotic and abiotic factors in tropical and subtropical forests. Below I have a brief introduction to my research directions.
(1) Plant DNA barcoding and community phylogenetics in forest plots from local to regional, and to global scale
Nancai’s previous work has focused on DNA barcode, which consists of a standardized short sequence of DNA between 400 and 800 base pairs long that in theory can be easily isolated and characterized for all species on the planet. We sampled, sequenced, and employed matK, rbcL and psbA-trnH to generate a multi-locus barcode for a subtropical forest dynamics plot: 183 species in a 20-ha plot at Dinghushan (DHS) National Nature Reserve, South China. We compared the published results from one subtropical forest plot (LFDP in Puerto Rico, 143 species) and two tropical forest plots (BCI in Panama, 296 species; and NRS in French Guiana, 254 species) to evaluate the universality and species correct discrimination of the proposed DNA barcodes in these four forest plots. Rates of sequencing success for each region in subtropics and tropics were: rbcL (95.1%, 93%), psbA-trnH (94.6%, 91.5%), and matK (79.7%, 68.5%), respectively, which confirmed the rate of recovery for matK region can be improved, at least in subtropics. The combination of matK+rbcL showed high discrimination in geographically restricted regions few congeners than in taxonomic groups. The three-locus barcode (matK+rbcL+psbA-trnH) resulted in a high rate of correct species identification both in subtropics (90%) and in tropics (84%).
Using DNA barcoding method rather than the traditional online software (such as Phylomatic) , we have reconstructed a better-resolved community phylogeny in a subtropical CTFS forest plot (Dinghushan) in South China, with similar findings in other studies conducted in BCI, Panama and in Luquillo, Puerto Rico. Compared to the two-locus barcode (rbcL+matK , and rbcL+psbA-trnH), the supermatrix of three barcode loci discriminated most of closed related taxa and generated a better-resolved community phylogeny utilizing an unconstraint approach in the DHS plot, providing a first case that a subtropical forest plot with similarly limited taxon sampling with fewer orders and families could also provide significant congruence to the overall angiosperm phylogeny.
These sequence data of numerous species in various forest plots obtained from DNA barcodes can be incorporated into the online database (such as BOLD and GenBank), which becomes a new bioliteracy and works as an efficient way to preserve current biodiversity.
See Pei 2012 (a and b) for examples of this work.
(2) Community ecology of subtropical forests from a phylogenetic perspective
Elucidating the ecological mechanisms underlying community assembly in subtropical forests remains a central challenge for ecologists. The assembly of species into communities can be due to interspecific differences in habitat associations, and there is increasing evidence that these associations may have an underlying phylogenetic structure in contemporary terrestrial communities. In other words, by examining the degree to which closely related species prefer similar habitats and the degree to which they co-occur, ecologists are able to infer the mechanisms underlying community assembly. Here we implement this approach in a diverse subtropical tree community in China using a long-term forest dynamics plot and a molecular phylogeny generated from three DNA barcode loci. We find that there is phylogenetic signal in plant-habitat associations (i.e. closely related species tend to prefer similar habitats) and that patterns of co-occurrence within habitats are typically non-random with respect to phylogeny. In particular, we found phylogenetic clustering in valley and low-slope habitats in this forest, indicating a filtering of lineages plays a dominant role in structuring communities in these habitats and we found evidence of phylogenetic overdispersion in high-slope, ridge-top and high-gully habitats, indicating that distantly related species tended to co-occur in these high elevation habitats and that lineage filtering is less important in structuring these communities. Thus we infer that non-neutral niche-based processes acting upon evolutionarily conserved habitat preferences explain the assembly of local scale communities in the forest studied.
I am now extending this work to subtropical forests where large trait datasets and molecular phylogenies are to be generated to determine when and why functional similarity and evolutionary relatedness influence community assembly from local to regional scales.
See Pei 2011a, and Pei et al. 2011 (a and b) for examples of this work.
(3) Flowering phenology and pollination biology of tropical and subtropical plant species
Selection favoring avoidance of stigma clogging, pollen discounting, self-fertilization, and other negative effects of self-pollination can produce intricate patterns of intra- and interfloral dichogamy in plants bearing numerous flowers. Studies of the floral biology of the more common and representative tropical Araliaceae have been somewhat narrow in scope. Observations are often limited to just a few individuals or populations per species, and typically only to portions of extended flowering seasons. Consequently, data on floral visitors to tropical araliads are also limited. We reported an extensive study of the relationships among dichogamy, floral sex allocation (pollen-to-ovule ratios), nectar production, floral visitors, mating system, and fruit set in natural populations of Schefflera heptaphylla (Araliaceae), a widespread paleotropical secondary forest tree that produced thousands of flowers in a blooming season. The result showed that protandrous dichogamy and the three phased synchronous flowering in S. heptaphylla effectively avoided selfing, promoted out-crossing, and lead to efficient pollination in a tropical secondary forest tree. Such results extend our knowledge of the phenomenon of synchronized protandry and hermaphroditism in plant kingdom.
See Pei et al. 2011c for example of this work.
(4) Floristic study of seed plants in Chinese forest plots
Large scale permanent plots (LSPP) work as important platform for long-term research on biodiversity, community phylogenetics and evolution, and ecosystem function in forests. I selected four Chinese forest dynamics plots representing four climatic types of Chinese vegetation (Xishuangbanna in tropics, Dinghushan in southern subtropics, Gutianshan in middle subtropics, and Changbaishan in temperate zone) to analyze the areal-types of seed plants at the level of family, genus, and species, according to the approach of Wu (1991) and Wu et al. (2003, 2006). The results showed that Xishuangbanna was characteristic of the margin of tropical flora, Dinghushan was characteristic of the transition from tropical flora to subtropical flora, Gutianshan being characteristic of typical subtropical flora, and Changbaishan being characteristic of temperate zone. These results were consistent with previous findings in Chinese forests, exhibiting distinctly geographic distribution of Chinese genera along altitude gradient, which indicated that the comparatively floristic analysis of multi-region, benefiting from the LSPP platform sharing original data, was testified to be feasible and effective.
See Pei 2011b for example of this work.
(5) Urban forest ecology
Nowadays, my research group mainly focus on urban forests and their ecosystem functions around the Pearl River Delta, which possesses a huge population with about 50 million and has been listed as World's biggest cities merging into 'mega-regions' by UN report recently.
More details coming soon.
(1) Plant DNA barcoding and community phylogenetics in forest plots from local to regional, and to global scale
Nancai’s previous work has focused on DNA barcode, which consists of a standardized short sequence of DNA between 400 and 800 base pairs long that in theory can be easily isolated and characterized for all species on the planet. We sampled, sequenced, and employed matK, rbcL and psbA-trnH to generate a multi-locus barcode for a subtropical forest dynamics plot: 183 species in a 20-ha plot at Dinghushan (DHS) National Nature Reserve, South China. We compared the published results from one subtropical forest plot (LFDP in Puerto Rico, 143 species) and two tropical forest plots (BCI in Panama, 296 species; and NRS in French Guiana, 254 species) to evaluate the universality and species correct discrimination of the proposed DNA barcodes in these four forest plots. Rates of sequencing success for each region in subtropics and tropics were: rbcL (95.1%, 93%), psbA-trnH (94.6%, 91.5%), and matK (79.7%, 68.5%), respectively, which confirmed the rate of recovery for matK region can be improved, at least in subtropics. The combination of matK+rbcL showed high discrimination in geographically restricted regions few congeners than in taxonomic groups. The three-locus barcode (matK+rbcL+psbA-trnH) resulted in a high rate of correct species identification both in subtropics (90%) and in tropics (84%).
Using DNA barcoding method rather than the traditional online software (such as Phylomatic) , we have reconstructed a better-resolved community phylogeny in a subtropical CTFS forest plot (Dinghushan) in South China, with similar findings in other studies conducted in BCI, Panama and in Luquillo, Puerto Rico. Compared to the two-locus barcode (rbcL+matK , and rbcL+psbA-trnH), the supermatrix of three barcode loci discriminated most of closed related taxa and generated a better-resolved community phylogeny utilizing an unconstraint approach in the DHS plot, providing a first case that a subtropical forest plot with similarly limited taxon sampling with fewer orders and families could also provide significant congruence to the overall angiosperm phylogeny.
These sequence data of numerous species in various forest plots obtained from DNA barcodes can be incorporated into the online database (such as BOLD and GenBank), which becomes a new bioliteracy and works as an efficient way to preserve current biodiversity.
See Pei 2012 (a and b) for examples of this work.
(2) Community ecology of subtropical forests from a phylogenetic perspective
Elucidating the ecological mechanisms underlying community assembly in subtropical forests remains a central challenge for ecologists. The assembly of species into communities can be due to interspecific differences in habitat associations, and there is increasing evidence that these associations may have an underlying phylogenetic structure in contemporary terrestrial communities. In other words, by examining the degree to which closely related species prefer similar habitats and the degree to which they co-occur, ecologists are able to infer the mechanisms underlying community assembly. Here we implement this approach in a diverse subtropical tree community in China using a long-term forest dynamics plot and a molecular phylogeny generated from three DNA barcode loci. We find that there is phylogenetic signal in plant-habitat associations (i.e. closely related species tend to prefer similar habitats) and that patterns of co-occurrence within habitats are typically non-random with respect to phylogeny. In particular, we found phylogenetic clustering in valley and low-slope habitats in this forest, indicating a filtering of lineages plays a dominant role in structuring communities in these habitats and we found evidence of phylogenetic overdispersion in high-slope, ridge-top and high-gully habitats, indicating that distantly related species tended to co-occur in these high elevation habitats and that lineage filtering is less important in structuring these communities. Thus we infer that non-neutral niche-based processes acting upon evolutionarily conserved habitat preferences explain the assembly of local scale communities in the forest studied.
I am now extending this work to subtropical forests where large trait datasets and molecular phylogenies are to be generated to determine when and why functional similarity and evolutionary relatedness influence community assembly from local to regional scales.
See Pei 2011a, and Pei et al. 2011 (a and b) for examples of this work.
(3) Flowering phenology and pollination biology of tropical and subtropical plant species
Selection favoring avoidance of stigma clogging, pollen discounting, self-fertilization, and other negative effects of self-pollination can produce intricate patterns of intra- and interfloral dichogamy in plants bearing numerous flowers. Studies of the floral biology of the more common and representative tropical Araliaceae have been somewhat narrow in scope. Observations are often limited to just a few individuals or populations per species, and typically only to portions of extended flowering seasons. Consequently, data on floral visitors to tropical araliads are also limited. We reported an extensive study of the relationships among dichogamy, floral sex allocation (pollen-to-ovule ratios), nectar production, floral visitors, mating system, and fruit set in natural populations of Schefflera heptaphylla (Araliaceae), a widespread paleotropical secondary forest tree that produced thousands of flowers in a blooming season. The result showed that protandrous dichogamy and the three phased synchronous flowering in S. heptaphylla effectively avoided selfing, promoted out-crossing, and lead to efficient pollination in a tropical secondary forest tree. Such results extend our knowledge of the phenomenon of synchronized protandry and hermaphroditism in plant kingdom.
See Pei et al. 2011c for example of this work.
(4) Floristic study of seed plants in Chinese forest plots
Large scale permanent plots (LSPP) work as important platform for long-term research on biodiversity, community phylogenetics and evolution, and ecosystem function in forests. I selected four Chinese forest dynamics plots representing four climatic types of Chinese vegetation (Xishuangbanna in tropics, Dinghushan in southern subtropics, Gutianshan in middle subtropics, and Changbaishan in temperate zone) to analyze the areal-types of seed plants at the level of family, genus, and species, according to the approach of Wu (1991) and Wu et al. (2003, 2006). The results showed that Xishuangbanna was characteristic of the margin of tropical flora, Dinghushan was characteristic of the transition from tropical flora to subtropical flora, Gutianshan being characteristic of typical subtropical flora, and Changbaishan being characteristic of temperate zone. These results were consistent with previous findings in Chinese forests, exhibiting distinctly geographic distribution of Chinese genera along altitude gradient, which indicated that the comparatively floristic analysis of multi-region, benefiting from the LSPP platform sharing original data, was testified to be feasible and effective.
See Pei 2011b for example of this work.
(5) Urban forest ecology
Nowadays, my research group mainly focus on urban forests and their ecosystem functions around the Pearl River Delta, which possesses a huge population with about 50 million and has been listed as World's biggest cities merging into 'mega-regions' by UN report recently.
More details coming soon.