Papers by Rosabelle Samuel
Ceylon Journal of Science, Jun 21, 2022
Molecular Phylogenetics and Evolution, Oct 1, 2018
Australian Systematic Botany
Nine new species in Australian Nicotiana section Suaveolentes are described, including N. clarkso... more Nine new species in Australian Nicotiana section Suaveolentes are described, including N. clarksonii M.W.Chase & Christenh., N. erytheia M.W.Chase & Christenh., N. latifolia M.W.Chase & Christenh., N. latzii M.W.Chase, R.W.Jobson & Christenh., N. gibbosa M.W.Chase, D.D.Andrew & J.J.Bruhl, N. olens M.W.Chase & Christenh., N. praecipitis M.W.Chase & K.Durham, N. karara M.W.Chase & Christenh. and N. bungonia M.W.Chase & Taseski. Some have been known from herbarium specimens for a long time, but their distinction from other species concepts was unsuspected until DNA studies showed their divergent nature. Others are known from one or only a few new localities. All are morphologically and genetically distinct from their close relatives. Increased sampling of populations in our molecular studies has led us to the conclusion that the widespread, recently described species N. insecticida is a species complex, comprising as many as six genetically distinct taxa, one of which includes material...
Journal of the National Science Foundation of Sri Lanka, 2020
Family Anacardiaceae comprises 70 genera and approximately 985 species distributed worldwide. Sri... more Family Anacardiaceae comprises 70 genera and approximately 985 species distributed worldwide. Sri Lanka harbours 19 species in seven genera, among these 15 are endemics. This study focuses on regionally restricted endemics and native Anacardiaceae species, which have not been investigated before at molecular and cytological level. Nuclear rDNA ITS and plastid matK regions were sequenced for ten species, having nine endemics and one native, and incorporated into the existing sequence data for phylogenetic analyses. The topologies resulting from maximum parsimony, maximum likelihood and Bayesian inference are congruent. Family Anacardiaceae forms a monophyletic group having monophyletic subfamily Anacardioideae and paraphyletic subfamily Spondioideae. Tribes Anacardieae, Semecarpeae and Rhoeae form subclades within the major clade of Anacardioideae. All the endemic species occupy correct position in the molecular phylogeny as per the existing classifi cation except for Campnosperma zeylanica, which shows a close relationship to members of the subfamily Spondioideae. The position of non-native species Trichoscypha acuminata also remains unclear. Chromosome counts and karyograms were constructed for fi ve endemic species. The chromosome numbers incorporated in the tree range from 2n = 28-58. Species of tribe Rhoeae have the lowest chromosome number (2n = 24, 28, 30) while species of tribe Semecarpeae have the higher numbers (2n = 50, 52, 58). Chromosome numbers mapped on the phylogeny shows that dysploidy had played a role in the evolution of the species of the family Anacardiaceae in Sri Lanka.
Ceylon Journal of Science, 2019
Plectranthus hadiensis is an important medicinal plant in Sri Lanka. It was considered a separate... more Plectranthus hadiensis is an important medicinal plant in Sri Lanka. It was considered a separate species, P. zeylanicus, endemic to the island until its inclusion, as P. hadiensis var. tomentosus, together with morphs from southern Africa in the revised species concept of P. hadiensis. However, there are morphological, chemical, and therapeutic differences between the African and Sri Lankan morphs. We used eight molecular markers in a phylogenetic study to clarify the species concept of P. hadiensis and to investigate whether it should include the Sri Lankan morph. We examined the position of the two P. hadiensis morphs in relation to eight other Plectranthus species. The maximum likelihood tree revealed three clades: a weakly supported clade including P. calycinus, P. glabratus, P. fruticosus, and P. malabaricus; a highly supported clade including P. amboinicus and African and Sri Lankan specimens of P. hadiensis; and a highly supported clade formed by P. barbatus, P. caninus, and P. hadiensis var. tomentosus. The African P. hadiensis specimens form a highly supported subclade sister to a subclade containing the Sri Lankan P. hadiensis, suggesting that the subclades correspond to either two sister species or two subspecies. We propose that they are more likely to be sister species given the differences in morphology, chemistry, and chromosome number.
Botanical Journal of the Linnean Society, 2017
Phylogenetic and molecular clock analyses were performed including all genera except one (Pseudom... more Phylogenetic and molecular clock analyses were performed including all genera except one (Pseudomonotes) for the three subfamilies of Dipterocarpaceae. We also included representatives of Sarcolaenaceae and Cistaceae with Bixaceae as the ultimate outgroup. Three plastid regions (six markers), partial rbcL, trnK-matK-trnK (partial trnK intron including complete matK) and trnT-trnL-trnF (partial trnT, complete trnT-trnL intergenic spacer, complete trnL, complete trnL-trnF intergenic spacer and partial trnF), were analysed. We also investigated additional accessions for genome size and chromosome numbers. Our phylogenetic results differ in three important respects from previous interpretations of morphological characters, as reflected in recent classifications. First, our analyses strongly support assignment of Pakaraimaea (subfamily Pakaraimaeoideae) to Cistaceae. Second, the morphological concepts of Dipterocarpeae and Shoreeae in subfamily Dipterocarpoideae are not supported because Dipterocarpus is sister to Dryobalanops plus tribe Shoreeae. Our analysis revealed four clades: (1) Dipterocarpus; (2) Dryobalanops, for which tribal assignment has been contentious; (3) genera of Shoreeae; and (4) the remaining genera of Dipterocarpeae. Third, Shorea is not monophyletic. Monotoideae are weakly supported as sister to Dipterocarpoideae; Sarcolaenaceae (endemic to Madagascar) are sister to this pair. Divergence in extant Dipterocarpoideae occurred c. 55 Mya. Genome sizes for all accessions examined are small (0.3264-0.6724 pg), and the additional chromosome numbers we collected fit into the patterns previously observed for Dipterocarpaceae.
Phytotaxa, 2016
A taxonomic revision of Bromeliaceae subfam. Tillandsioideae is presented based on a multi-locus ... more A taxonomic revision of Bromeliaceae subfam. Tillandsioideae is presented based on a multi-locus DNA sequence phylogeny (viz., plastid DNA loci rpoB-trnC-petN, trnK-matK-trnK, and ycf1, and the nuclear DNA gene PHYC) and new or re-evaluated morphology (e.g., leaf, inflorescence, sepal, petal, ovary, stigma, stamen, pollen, ovule, and seed morphology). This enables the circumscription of monophyletic units using synapomorphic combinations of diagnostic morphological characters. Stigma morphology has proven to be indicative for super-specific taxa in Tillandsioideae. One new stigma type and several subtypes of previously described stigmas were found. The four tribes proposed earlier are mostly confirmed, but Catopsideae replaces the formerly used name Pogospermeae for the monotypic tribe of Catopsis. In addition, the two new subtribes Cipuropsidinae and Vrieseinae are proposed within tribe Vrieseeae. Several new genera are established to render taxonomic units monophyletic and morphol...
Caryologia, 1992
Nuclear DNA contents were measured in eight species of Peperomia (2n=22, 33, 44, 66). Formaldehyd... more Nuclear DNA contents were measured in eight species of Peperomia (2n=22, 33, 44, 66). Formaldehyde fixations show more reliable results than those with acetic alcohol. The diploid species vary significantly in chromosome size and DNA-content. Increasing chromosome length is directly correlated with increased DNA-amounts/chromosome in all the species except in triploid P. metallica. Polyploid species have increased DNA-values.
Botanical Journal of the Linnean Society, Jan 25, 2019
In this review article, we provide an overview of the status of research on Old World Ebenaceae w... more In this review article, we provide an overview of the status of research on Old World Ebenaceae with an emphasis on the large genus Diospyros. The well-supported phylogenetic tree obtained from nucleotide sequences of multiple regions of plastid genome gave clear insights into the subfamilial classification of Ebenaceae. It supported inclusion of previously recognized genera such as Cargillia, Gunisanthus, Maba, Macreightia and Tetraclis in Diospyros. Endemic Diospyros spp. of New Caledonia have multiple origins. One of these clades has c. 21 species that are morphologically distinct and occupy different ecological niches, but they exhibit low genetic variation, leading to a lack of phylogenetic resolution. Analyses of whole plastid genome sequences did not greatly increase resolution or support for results of our previous plastid analyses. Geographical clustering of the individuals against a background of lower sequence divergence of the whole plastid genome could be due to transfer of plastid genomes during hybridization and introgression following secondary contact. However, > 8400 filtered single nucleotide polymorphisms (SNPs) from restriction site associated DNA sequencing (RADseq) confirmed species circumscriptions for this clade and produced well-supported phylogenetic relationships, pointing to an early regional clustering among populations and species. This supported allopatric speciation with respect to macrohabitat (i.e. climatic conditions) having had a role in the initial differentiation in the group. A later, more rapid radiation involved divergence with respect to microhabitat (e.g. soil preference). Although chromosome counts indicate that Diospyros spp. are consistently diploids with 2n = 30, extensive variation in genome size has been observed, which is due to an increase of repeat elements, including LTR/gypsy. In Ebenaceae, pollen is heterogeneous, and palynological synapomorphies are traced at different taxonomic levels. Several new Diospyros spp. have recently been identified and documented from India, Thailand, China, Africa and New Caledonia. Taxonomic revisions have been completed for the Australian species, and synonyms are reported for some New Caledonian Diospyros spp.
Annals of Botany, Dec 12, 2018
Plant Systematics and Evolution
Five species of Annona and one species from Artabotrys, Cananga, Polyalthia, and Rollinia were in... more Five species of Annona and one species from Artabotrys, Cananga, Polyalthia, and Rollinia were investigated in regard to 11 different allozyme loci. Preliminary studies on small population samples of Annona suggest genetic uniformity in three species and variability within and between populations in two other species. The allotetraploid origin of A. glabra is clearly shown by its hybrid enzyme bands. The genetic distance between five Annona species partly corresponds with their morphological relationships; only A. muricata appears more separated than is suggested by morphology. A comparison of the five genera demonstrates close relationship between Annona and Rollinia. Two enzyme loci are identical within all taxa investigated and possibly may serve as a genetic marker for the family. 14 28 A. montana MACF. 14 WM 3-23890 (HBV) A. muricata L. 2 14 WM 4-23890 (Sri Lanka) A. reticulata L. 2 14 WM 5-23890 (Brazil, HBV) Artabotrys hexapetala (L. f.) BHANDARI 16 WM 6-23890 (HBV) Cananga odorata (LAM.) 16 HOOK. ill. & THOMS. WM 7-23890 (HBV) Polyalthia suberosa (RoxB.) 18 BENTH. & HOOK. WM 8-23890 (Cuba/HBV) Rollinia m u c o s a (JAcQ.) BAILL.
Phytotaxa, 2017
Sri Lanka is a country with unique landscapes and positioning. Its land profile varies from coast... more Sri Lanka is a country with unique landscapes and positioning. Its land profile varies from coastal areas through lowland hills to central montane region, and the climatic zones governed by seasonal monsoons results in a significantly high biodiversity. Sri Lanka together with Western Ghats is a biodiversity hot spot among the 35 regions known worldwide. Sri Lanka harbors 3154 species of which 894 are endemics belonging to different angiosperm families. The orchid flora of the country, with 189 known species including 55 endemics is one that contributes very much for this high endemism. However 70.6% are currently listed as nationally threatened species during National Red listing in 2012. The present study was conducted to investigate the current status and occurrence of species of the family Orchidaceae within and outside the conservation areas including few unexplored/ undocumented regions in the country. Field visits were carried out mainly focusing on the flower...
Cytogenetics and cell genetics
Plant Systematics and Evolution, 1989
Chromosome numbers for 26 different species of the genera Piper, Peperomia and Pothomorphe (Piper... more Chromosome numbers for 26 different species of the genera Piper, Peperomia and Pothomorphe (Piperaceae) are reported. The basic chromosome numbers are 2 n = 26, x= 13 (Piper, Pothomorphe) and 2n= 22, x= 11 (Peperomia), polyploid series are characteristic for Piper and Peperomia. Piper has the smallest chromosomes and prochromosomal interphase nuclei, Peperomia the largest ones and mostly reticulate to euchromatic nuclei. Pothomorphe is intermediate in both characters. The karyomorphological differences between Pothomorphe and Piper underline their generic separation. Interspecific size variation of chromosomes occurs in Piper and Peperomia. Infraspecific polyploidy was observed in Piper betle. C-banding reveals different patterns of heterochromatin (hc) distribution be
Plant Systematics and Evolution, 1999
ABSTRACT RAPDs were employed as genetic markers to detect interspecific hybridization between the... more ABSTRACT RAPDs were employed as genetic markers to detect interspecific hybridization between the closely related oak speciesQuercus robur andQ. petraea. Fourteen primers were used in order to check the genetic status (pure or hybrid) of individuals classified morphologically. Among the 147 PCR fragments obtained 11 appear to be species-specific. In the phenotypically intermediate individuals different combinations of these species-specific bands were obtained. The patterns in these putative hybrids were not additive, which may be either the result of repeated backcrossing and introgression between the two species or of heterozygosity within the parental species. The results of the RAPD study are consistent with morphological analyses and allozyme data obtained for theGot-2 locus. Thus the RAPD markers used in this study may provide a powerful genetic tool for the identification of hybrids and the discrimination between the two pure species.
Botanica Acta, 1997
The PCR-amplified atp8/rbcl spacer region of ten Cyrtandra species and representatives of the gen... more The PCR-amplified atp8/rbcl spacer region of ten Cyrtandra species and representatives of the genera Didymocarpus, Didissandra. and Monophyllaea was sequenced and used for phylogenetic analyses. In Cyrtandra 83 variable positions were found over a length of 890bp. The data suggest that the Samoan species included in our study originated by at least two independent colonization events, while for the Hawaiian species the situation is not clear yet. With respect to generic relationships, Monophyllaea shows considerable divergence (9.9%) from the remaining taxa and thus is used as outgroup. Didymocarpus is most closely related to Cyrtandra, their genetic divergence (2.2%) being only slightly higher than the average distance within Cyrtandra (1.9%). The promoter regions for the arp8 and r6cl genes, which have been described from Rubiaceae. were identified and found to be located at homologous positions. Of the two arpB promoters found in Rubiaceae only the distal one appears functional, the proximal promoter has been eroded by mutations and is disrupted in Didissandra by a 14bp insertion.
Botanica Acta, 1995
AGROVOC Terms QUERCUS ROBUR, QUERCUS CERRIS, QUERCUS PETRAEA, QUERCUS PUBESCENS, ALLOZYMES, GENET... more AGROVOC Terms QUERCUS ROBUR, QUERCUS CERRIS, QUERCUS PETRAEA, QUERCUS PUBESCENS, ALLOZYMES, GENETIC CORRELATION, HYBRIDIZATION, ELECTROPHORESIS, PLANT POPULATION, AUSTRIA, QUERCUS ROBUR, QUERCUS ...
Plant Systematics and Evolution, 2002
Genetic variation in 42 populations throughout the range of Biscutella laevigata L. (Brassicaceae... more Genetic variation in 42 populations throughout the range of Biscutella laevigata L. (Brassicaceae), a morphologically variable central European species, has been investigated by enzyme electrophoresis with three loci (Amy1, Amy2, and Gpi2). Genetic identities and the Fitch-Margoliash tree suggest differentiation into four regional groups: 1) a northwestern diploid group (northern France and northern Germany), 2) a northeastern diploid group (southern Germany, Upper Austria, northern Lower Austria, Poland, and Romania), 3) a central diploid group in southern Lower Austria corresponding to subspecies austriaca, and 4) a southern tetraploid group in Alpine areas of France, Germany, Switzerland, Austria, Italy, and Slovenia corresponding to subspecies laevigata. Geographically isolated diploid relic populations that are genetically depauperate are found in the NW and NE diploid groups. On the other hand, the diploid relic subspecies austriaca from the NE Prealps and Alps is highly variable. Subspecies laevigata appears to be a genetical autotetraploid with multiple origins involving several diploid progenitors (the NW diploids, subspecies austriaca and B. prealpina).
Kew Bulletin, 1987
... J. Exp. Zool. 9: 715-749. Jose, J. (1981). Karyomorphological studies on Piper attenuatum Ham... more ... J. Exp. Zool. 9: 715-749. Jose, J. (1981). Karyomorphological studies on Piper attenuatum Ham. A new record. Curr. Sci. 50: 646-647. &amp;amp; Sharma, AK (1985). Structure and behaviour of chromosomes in Piper and Peperomia (family Piperaceae). Cytologia 50: 301-310. ...
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Papers by Rosabelle Samuel