Robert P. Adams

Diversification and biogeography of Juniperus (Cupressaceae): variable diversification rates and multiple intercontinental dispersals

• A central aim of biogeography is to understand when and how modern patterns of species diversity and distribution developed. Many plant groups have disjunct distributions within the Northern Hemisphere, but among these very few have been studied that prefer warm semi-arid habitats. • Here we examine the biogeography and diversification history of Juniperus, which occurs in semi-arid habitats through much of the Northern Hemisphere. A phylogeny was generated based on > 10,000 bp of cpDNA for 51 Juniperus species plus many outgroups. Phylogenies based on fewer species were also constructed based on nuclear internal transcribed spacer (nrITS) and combined nrITS/cpDNA data sets to check for congruence. Divergence time-scales and ancestral distributions were further inferred. • Both long dispersal and migration across land bridges probably contributed to the modern range of Juniperus, while long-term climatic changes and the uplift of the Qinghai-Tibetan plateau probably drove its diversification. Diversification apparently slowed down during climate-stable period of the Oligocene, and then speeded up from the Miocene onwards. • Juniperus probably originated in Eurasia, and was a part of the south Eurasian Tethyan vegetation of the Eocene to Oligocene. It reached America once at this time, once in the Miocene and once more recently.

Inhibition of random amplified polymorphic DNAs (RAPDs) by plant polysaccharides

A survey of the inhibition of the amplification of spinach DNA by various plant polysaccharides revealed that neutral polysaccharides (arabinogalactan, dextran, gum guar, gum locust bean, inulin, mannan, and starch) were not inhibitory. In contrast, the acidic polysaccharides (carrageenan, dextran sulfate, gum ghatti, gum karaya, pectin, and xylan)were inhibitory. In the process of preparing random amplified polymorphic DNAs (RAPDs), the loss of large DNA bands appears to be an indicator that the fingerprint pattern has been affected by polysaccharides. The addition of various concentrations of Tween 20, DMSO, or PEG 400 to the PCR reaction mixture resulted in partial restoration of amplification of RAPDs for the acidic polysaccharides. The most effective way to eliminate the effects of polysaccharide inhibition was by diluting the DNA extracts, and thereby diluting the polysaccharide inhibitors.

Systematic Relationships in Juniperus Based on Random Amplified Polymorphic DNAs (RAPDs)

44 taxa of Juniperus were analysed using RAPDs, similarity measures and principal coordinate analyses (PCO). The three sections of Juniperus (sect. Caryocedrus, sect. Juniperus, sect. Sabina) were found to be distinguished by RAPDs. The genus appears to be naturally divided into three major sections with two series (serrate and smooth leaf margins) in J. sect. Sabina. Additional examinations of specific and infraspecific taxa confirms earlier taxonomic work based on leaf terpenoids. Computer software (PCO3D from R.P.A.) for PCO is introduced for the analysis of RAPDs. RAPDs were found to be of taxonomic use ranging from sectional to varietal levels.

Systematics of Juniperus section Juniperus based on leaf essential oils and random amplified polymorphic DNAs (RAPDs)

The composition of the leaf essential oils of all the species of Juniperus in sect. Juniperus (=sect. Oxycedrus) are reported and compared (J. brevifolia, J. cedrus, J. communis, J. c. var. saxatilis, J. c. var. oblonga, J. formosana, J. oxycedrus, J. o. subsp. badia, J. o. subsp. macrocarpa, J. o. subsp. transtagana, J. rigida, J. r. subsp. conferta, J. sibirica, J. taxifolia and J. t. var. lutchuensis). In addition, DNA fingerprinting by RAPDs was utilized. Based on these data, several taxa remained at the same taxonomic level: J. brevifolia, J. cedrus, J. communis, J. c. var. saxatilis, J. formosana, J. oxycedrus, J. rigida, J. r. var. conferta, and J. taxifolia. However, several taxa exhibited considerable differentiation that warranted their recognition at the specific level: J. oblonga M.-Bieb. (=J. communis var. oblonga), J. badia H. Gay (=J. oxycedrus subsp. badia), J. macrocarpa Sibth. and Sm. (=J. oxycedrus subsp. macrocarpa), J. navicularis Gand. (=J. oxycedrus subsp. transtagana), J. sibirica Brugsd. (=J. communis var. saxatilis in part), and J. lutchuensis Koidz. (= J. taxifolia var. lutchuensis).

The leaf essential oils and chemotaxonomy of Juniperus sect. Juniperus

The composition of the leaf essential oils of all ten species of Juniperus in sect. Juniperus (=sect. Oxycedrus) are reported and compared (J. brevifolia, J. cedrus, J. communis, J. conferta, J. formosana,. J. navicularis, J. oblonga, J. oxycedrus, J. rigida, J. sibirica). The oils of these Juniperus are all dominated by monoterpenes (α-pinene, sabinene and limonene). The simplest oil was found in J. cedrus (27 components, endemic to the Canary Islands) and the most complex oil was in J. oblonga (82 components). Quantitative data is presented for 138 compounds found in these ten taxa. The far eastern junipers, J. conferta, J. formosana and J. rigida, appear to form a natural group. Systematic and evolutionary relationships are discussed.

Comparison of free sugars in growing and desiccated plants of Selaginella lepidophylla

Abstract The free sugars are growing and desiccated Selaginella lepidophylla plants were examined. Growing and desiccated plants differed significantly in their percentage of glucose (3.1, 0.2%), sucrose (6.9, 23.1%) and trehalose (89.8, 75.6%). The apparent stoichiometry between the decrease in sucrose and increase in trehalose concentration after rehydration suggests that sucrose serves as the carbon source for trehalose synthesis. A comparison of extraction methods revealed that using “Boileezers” in Soxhlets resulted in sugar degradation ranging from 25 to 75%. Extraction by shaking in 80% ethanol appeared to be the best extraction method.

Statistical character weighting and similarity stability

Terpenoid data from seven species ofJuniperus were used to examine:1) the effect of using different character weights upon the same set of OTU’s; 2) the effect of the organization of the initial data base by populations, individuals, and averages on statistical weights and the resulting classification; and3) the effect of the use of exemplars on statistical weights and similarity measures. Cophenetic correlation and numerical taxonomy, along with certain relationships well documented for these species, were used to examine these questions. Equal weighting of characters, advocated by most numerical taxonomists, gave the most distorted results. Thiswas followed by the 1/coefficient of variation, then the weighting of {ie305-01} and finallyF andF-1 weighting producing the highest fidelity to the known similarities. The use of either all individuals or random individuals appeared to be better than the use of population averages for some OTU’s and individuals for other OTU’s and much better than the use of population averages only. The use of exemplars has small effects, mostly causing the OTU’s to cluster more loosely when exemplars were included in the computation of the statistical weights. The use of equal weighting is discussed and strongly discouraged in numerical taxonomy in favor of statistically derived weights.

Systematics of multi-seeded eastern hemisphere Juniperus based on leaf essential oils and RAPD DNA fingerprinting

Abstract The composition of the leaf essential oils of 15 taxa of the multi-seeded Juniperus in sect. Sabina from the eastern hemisphere are reported and compared ( J . chinensis , J . davurica , J . excelsa , J . excelsa var. polycarpos , J . foetidissima , J . jarkendensis , J . phoenicea , J . procera , J . sabina , J . sabina var. erectopatens , J . semiglobosa , J . seravschanica , J . talassica , J . thurifera , J . turcomanica ). The volatile leaf oil compositions for these Juniperus species are presented. In addition, DNA fingerprinting revealed similar patterns among these species. Based on these data, J . seravschanica is treated as J. turcomanica B. Fedtsch. var. seravschanica (Kom.) R.P. Adams comb . nov ., and J . talassica is recognized as J . semiglobosa var. talassica (Lipinsky) Silba. These data also support the continued recognition of J . jarkendensis Kom. as a distinct species. Juniperus sabina var. erectopatens (Cheng. and L.L. Fu) Y.F. Yu and L.K. Fu was found to be very distinct in both its terpenoids and RAPDs and is recognized as a distinct species, J . erectopatens (Cheng and L.K. Fu) R.P. Adams stat nov. The correct name for the Balochistan, Pakistan juniper is J . turcomanica var. seravschanica (Kom.) R.P. Adams, not J . excelsa or J . excelsa ssp. polycarpos . In addition, the systematic and evolutionary relationships are discussed.

Seasonal variation of terpenoid constituents in natural populations of juniperus pinchotii sudw

Abstract Foliage samples were taken from sixteen trees in eight natural populations of Juniperus pinchotii Sudw. in July and again in January to determine if seasonal variations occur in the volatile terpenoids and if the summer or winter collections would be more variable. Gas/liquid chromatographic analysis revealed that significant differences do occur from summer to winter in the relative composition of the terpenoids. The summer collections were more variable than the winter collections which indicates the desirability of winter sampling when practical.

The circumscription and phylogenetic relationships of Callitropsis and the newly described genus Xanthocyparis (Cupressaceae)

A new species of conifer was recently discovered in northern Vietnam. In a preliminary phylogenetic analysis of morphological data a possible sister species, Chamaecyparis nootkatensis (D. Don) Spach, was identified; however, because of the presumed phylogenetic remoteness of these two species to the remainder of the Cupressaceae, a new genus-Xanthocyparis-was described to accommodate both species. Here an analysis of ITS (nrDNA), matK, and rbcL sequence data in combination with 58 informative morphological characters was aimed at testing the monophyly of the remainder of Chamaecyparis and evaluating the placement and monophyly of Xanthocyparis. Chamaecyparis, minus C. nootkatensis, was resolved as a monophyletic group, remote from Cupressus and Xanthocyparis. Cupressus, Juniperus, and Xanthocyparis formed a very highly supported monophyletic group. However, Cupressus was not monophyletic. Instead the Old World species sampled were resolved sister to a clade containing a monophyletic Juniperus, a monophyletic Xanthocyparis, and a clade of New World Cupressus species. If both species of Xanthocyparis are to be treated as members of the same genus, then due to the principal of priority they will have to be recognized in the genus Callitropsis. Research is continuing to resolve the status of New World and Old World Cupressus.