Biochemical Systematics and Ecology

Published by Elsevier
Online ISSN: 0305-1978
Publications
Hypothetical cladogram of the tribe Trypetini based on morphology. Numbers refer to the characters listed in the text (also illustrated on the left). (A) Lateral view of distiphallus * Montiludia nemorivaga Ito; (B) Lateral view of distiphallus * Acidiella longipennis Hendel; (C) Ventral view of aculeus * Paratrypeta yavoscutata Han & Wang; (D) Caudal view of male epandrial complex (cercus removed) * A. longipennis; (E) Ventral view of female postabdomen/lateral view of aculeus * Paramyiolia nigricornis (Doane).
Trypetine relationships inferred from the single most parsimonious tree. Numbers indicate bootstrap P values (P ) higher than 50% (500 replications). Statistics for the most parsimonious tree: length"1332, CI"0.4565, HI"0.5435, RI"0.3901, RC"0.1780.
Article
Monophyly and intratribal relationships of the tribe Trypetini were tested using mitochondrial 16S ribosomal RNA gene from 16 species of Trypetini, six tephritid outgroups, and two non-tephritid outgroups. The number of aligned sites was 1279 bp, but 1165 bp were used for analysis after excluding sites with missing data or gaps. Among these 1165 sites, 447 sites were variable and 305 were informative for parsimony analysis. Phylogenetic information was extracted from this data set using neighbor-joining and maximum parsimony methods and compared to a phylogenetic hypothesis proposed from the morphological literature. My molecular data suggest: (1) monophyly of the tribe Trypetini; (2) monophyly of the Chetostoma group; (3) monophyly of the Trypeta group; and (4) non-monophyletic nature of the previous concept of Hemilea. I suggest that more sensitive genetic markers with less A+T bias are needed to bring about finer resolution within the tribe Trypetini, and additional tephritid lineages should be sampled to identify the sister-group relationship of the tribe Trypetini.
 
Graphic representation of the study area and the collecting sites (*) for each species of Hypostomus. H. aff. commersonii: Downstream Segredo Dam (25847 0 /52808 0 ), 2 specimens; Iratim River (26803 0 /51853 0 ), 3 specimens. H. derbyi: Downstream Segredo Dam, 8 specimens; Upstream Segredo Dam, 3 specimens; Iratim River, 1 specimen; Downstream Areia Dam (26800 0 /51836 0 ), 2 specimens. H. myersi: Downstream Segredo Dam, 4 specimens; Iratim River, 6 specimens; Downstream Areia Dam, 5 specimens.
Isozyme patterns of alcohol dehydrogenase (ADH), glucose 1-dehydrogenase (GCDH), phosphoglucomutase (PGM), and superoxide dismutase (SOD) in heart (h), liver (l) and muscle (m) tissues of three species of Hypostomus: H. commersonii (Hc), H. derbyi (Hd), and H. myersi (Hm). The genetic patterns are represented by the most common allele at each locus for each species.
Tissue expression of acid phosphatase isozyme (ACP) and NADP-dependent malate dehydrogenase (MDHP) in heart (h), liver (l) and muscle (m) tissues of three species of Hypostomus: H. commersonii (Hc), H. derbyi (Hd), and H. myersi (Hm). The genetic patterns are represented by the most common allele at each locus for each species.
Isozyme patterns of aspartate transaminase (ATA), peroxidase (PER), glucose 6-phosphate dehydrogenase (G6PDH), and glucose 6-phosphate isomerase (GPI) in heart (h), liver (l) and muscle (m) tissues of three species of Hypostomus: H. commersonii (Hc), H. derbyi (Hd), and H. myersi (Hm). The genetic patterns are represented by the most common allele at each locus for each species.
Isozyme patterns of glycerol 3-phosphate dehydrogenase (G3PDH), isocitrate dehydrogenase (ICDH), l -lactate dehydrogenase (LDH),and malate dehydrogenase (MDH) in heart (h), liver (l) and muscle (m) tissues of three species of Hypostomus : H. commersonii (Hc), H. derbyi (Hd), and H. myersi (Hm) . The genetic patterns are represented by the most common allele at each locus for each species. 
Article
The expression patterns of 14 enzymatic systems in skeletal muscle, liver and heart tissues of three species of Hypostomus from the Iguaçu River basin (Brazil) were investigated. Although the patterns were similar for the three species, different tissues showed differential expressions, and the data showed that differential tissue expressions of isoperoxidases may be due to preferential combination or association of polypeptide subunits. The detected patterns for SOD isozymes showed that the quaternary structures of these enzymes were in disagreement with the subunit number reported for the majority of other vertebrate groups. Tissue-specific restriction on heterotetramer formation also were described in LDH and MDHP isozymes. Thus, these tissue-specific gene expression character in the species of Hypostomus have the greatest potential to be recognized and applied in systematic studies among species of Hypostomus.
 
Article
Polymorphism at 11 enzyme loci was used to compare the four evergreen oak species of the Mediterranean Basin and to establish their taxonomical relationships. As a comparison, two evergreen oak species from Tibet, located in the primary distribution area of evergreen oaks, were analysed at the same loci. Cladistic analyses led to the separation of a cluster of four species, namely the three Mediterranean Q. ilex, Q. coccifera and Q. alnifolia and the Tibetan Q. aquifolioides. The other Tibetan species, Q. semicarpifolia, and Q. suber, from the Western Mediterranean Basin, were very distinct genetically from the four other species. These results were not consistent with previous taxonomical treatment, based on morphology alone, which classified Q. ilex and Q. coccifera in "ilex group" (=subgenus Sclerophyllodrys O. Schwartz), and the other four species in "cerris group" (subgenus Cerris, according to Schwartz). Allozyme variation has thus provided useful information to clarify the taxonomy of evergreen oaks.
 
Article
The anamorph determination of Cordyceps sinensis remains problematic due to the lack of clear links between the sexual and conidial forms of the fungus. In this study, we applied molecular approaches to analyze the genetic variation of Cordyceps sinensis and its allies to identify the anamorph-teleomorph connection. The sequences of the internal transcribed spacers (ITS1 and ITS2) and 5.8S ribosomal RNA gene of Cordyceps sinensis (teleomorph) collected from Qingzang plateau (altitude over 4000m), Tibet and several related asexual conidial forms were determined. The sequence comparison showed that Cordyceps sinensis was most closely related to Hirsutella sinensis, and was clearly divergent from Paecilomyces sinensis, Stachybotrys sp. or Tolypocladium sp.; distance values, estimated according to Kimura two-parameter models between Cordyceps sinensis and Hirsutella sinensis, were extremely low (<0.02), whereas distance values between Cordyceps sinensis and Paecilomyces sinensis, Stachybotrys sp. and Tolypocladium sp. were 0.34, 0.21 and 0.25, respectively. Taken together, Hirsutella sinensis and Cordyceps sinensis are the different stages of the life cycle stages of the same organism. Hirsutella sinensis is therefore the anamorph of Cordyceps sinensis, rather than Paecilomyces sinensis or other species. The possible reasons as to why different taxa can be obtained when culturing Cordyceps sinensis are also discussed.
 
Article
9'Z-(3S,5R,6R,3'S,5'R,6'S)-Neoxanthin reisolated from spinach (Spinacea oleracea) and characterized by HPLC, VIS, MS, and 2D (1)H NMR, has been submitted to photoinduced stereomutation in the presence of iodine or diphenyl diselenide at conditions not involving isomerization of the allenic bond. The six individual geometrical isomers, all-E,9Z,9'Z,13Z,13'Z,15Z and three minor di-Z-isomers, presumably 9,9'-di-Z,9',13-di-Z and 9',13'-di-Z, present in the equilibrium mixture have been characterized by HPLC, VIS data, 1H NMR and reversibility tests. Judged by the quantitative composition of the equilibrium mixture the naturally occurring 9'Z-isomer is thermodynamically less stable than the all-E-isomer. The availability of these isomers facilitates future search in natural sources. 9'Z-(6R90% of total neoxanthin in spinach and broccoli (Brassica oleracea var. italica), consistent with previous findings of its abundance in chloroplasts. all-E90% of total violaxanthin in the same sources. It is postulated that a neoxanthin Delta9'-isomerase is present and involved in the biosynthesis of abscisic acid in higher plants. Allenic S-isomers are of interest as postulated biosynthetic precursors of R-allenes. All-E-(6S)- and 9'Z-(6S)-neoxanthin were available as semi-synthetic model compounds. The allenic (6S)-diastereomers could not be detected in spinach or broccoli.
 
Article
DNA sequence and morphological data were analyzed for specimens of twenty-five species of acanthomorph fishes and two specimens representing the outgroups Aulopiformes and Myctophiformes. A 572 base-pair (bp) segment of the 12S ribosomal mitochondrial gene, 1112 bp from three regions of the 28S ribosomal nuclear gene, and 38 morphological transformation series were analyzed under the criterion of maximum parsimony. The total evidence analysis resulted in a set of four most parsimonious trees. Relationships common to all trees are largely congruent with the hypothesis articulated by Johnson and Patterson (1993. Bull. Mar. Sci. 52, 554-626).
 
Article
The composition of the essential oils of Thymus pulegioides L. plants growing wild in Vilnius district (Lithuania) with "ester", lemon and carvacrol (phenol) odours were collected in one location and investigated by GC, GC/MS and IR-spectroscopy. The essential oils with lemon and carvacrol odour belong to corresponding known citral-geraniol and carvacrol chemotypes. The essential oil of plants with "ester" odour containing 50-70% of alpha-terpenyl acetate belong to alpha-terpenyl acetate chemotype, which was not noticed earlier in Thymus pulegioides L. species.
 
Article
The presence and identity of very long chain polyunsaturated fatty acids from three freshwater crustacean species, Bathynella natans, B. baicalensis and Baicalobathynella magna from Lake Baikal and caves of central Europe were determined by means of liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization (LC-MS with APCI). LC-MS with APCI enabled the identification of more than 50 very long chain polyunsaturated fatty acids. These acids were described in the crustaceans for the first time, predominantly 26:5n6, 28:7n6, 30:7n3 and 40:7n6. A hypothesis for the biosynthesis of these acids is proposed.
 
Article
Using enzyme electrophoresis and nematocyst analysis, the sympatrically occurring "light" and "dark" color morphs of the sea anemone Anthopleura orientalis from the Sea of Japan were shown to be two valid species. The "light" morph was identified as A. orientalis (Averintsev, 1967 Issledovaniya fauny morei: Vyp. 5 (13). Nanka, Leningrad, pp. 62-77), while the "dark" morph was designated as Anthopleura sp. The analysis of 21 isozyme loci revealed high value of Nei's genetic distance (D=1.284) between the two species, which are indistinguishable in their external morphology. The mean values of observed and expected heterozygosities for A. orientalis and Anthopleura sp. are high (H(o)=0.252+/-0.061, H(e)=0.250+/-0.061 and H(o)=0.327+/-0.052, H(e)=0.351+/-0.054, respectively). The species differ significantly in the size of spirocysts and nematocysts, among which the atrichs from acrorhagi and the basitrichs from actinopharynx contribute most to the observed difference. Strong qualitative difference is revealed between distributions of nematocysts in mesenteric filaments of the two sea anemone species studied. The possible conspecificity of Anthopleura sp. with Anthopleura artemisia (Dana, 1848) is discussed and the conclusion made that these are two separate species.
 
Article
Allozyme analyses were performed to determine patterns of genetic variation and phylogenetic relationships within the genus Notropis in southern Mexico. Products of 28 gene loci were resolved in 24 geographic samples belonging to four putative species. These species represent the southern limit of the Cyprinidae in North America. Five loci were found monomorphic and 11 were diagnostic among species when the outgroup, Phoxinus phoxinus, was not taken into account. Four groups were identified, but these do not correspond perfectly to the four nominal species. Notropis sallaei was identified by allozyme analyses being the most basal among southern Mexican Notropis and the most genetically divergent. Notropis imeldae, was also diagnosed on the basis of allozymic variation, however a population sample representing the Balsas drainage was genetically divergent and is considered as an undescribed new species (N. n. sp.). No genetic differences were found between the samples of N. boucardi and N. moralesi. Therefore, we recommend that N. moralesi should be considered as a junior synonym of N. boucardi. A broad geographic sampling strategy was employed across all the distribution range of N. boucardi representing rivers from three different drainages, which cover both Mexican slopes. The slight divergence found among the headwater populations of N. boucardi permitted us to predict a model of paleohydrographic relationships of these three drainages. Two alternative hypotheses are postulated to explain the current distribution pattern of populations of N. boucardi in southern Mexico.
 
Article
The cyanogenic polymorphism in Trifolium repens is caused by the variation in two genes, the interaction of which produces four distinct cyanotypes. Along the Atlantic coasts of Bretagne, T. repens is sometimes found in populations mixed with the related species Trifolium occidentale, although the latter species usually occurs only in a narrow fringe along the coast, whereas T. repens is a more inland species. No plants of T. occidentale have ever been reported to have linamarase activity. Indeed, of 763 T. occidentale plants studied, none contained linamarase activity. However, the variation in the proportion of cyanotypes in T. repens was enormous, even between sites less than 2km apart. Our results confirm the presumption that T. repens and T. occidentale are indeed separate species. Both the fact that T. occidentale plants never contain linamarase activity, and the difference in proportion of plants with cyanoglucosides in mixed stands show that gene flow between the species must be rare. These dissimilar distributions strongly indicate that cyanotypic frequencies in adjacent and mixed populations of the very closely related species T. occidentale and T. repens are regulated by different mechanisms
 
Article
Plains zebras (Equus quagga antiquorum) occur in few large, but many small, isolated populations in KwaZulu-Natal. Problems identified in small populations include reduced striping patterns on hind quarters, smaller size, elevated mortality rates and high number of still-births. Inbreeding may be implicated. Population viability analysis (PVA) was conducted with a computer model (VORTEX), and DNA and allozyme analyses were conducted to test the findings of the model. Using standard methods, DNA (PCR-RAPD) and allozyme diversity was assessed in blood samples from 72 plains zebra from four KwaZulu-Natal Nature Conservation Services (KZN-NCS) protected areas: Umfolozi Game Reserve (UGR), Albert Falls (AFNR), Vernon Crookes (VCNR) and Harold Johnson (HJNR) Nature Reserves. Populations of the latter three, small-sized (9-110 individuals) populations were seeded from the same source population (UGR: current population of 2000) during the past 25 years. Information from PCR-RAPD and allozyme analyses were compared with each other as well as to that predicted by population genetic modelling (using VORTEX). Allozyme heterozygosities were consistently high in all populations (12.1-12.9%), with no observable losses associated with reduced population size. On the other hand, percentage loss of polymorphism (20-39%) calculated from the PCR-RAPD study appeared to be positively correlated with the loss of heterozygosity predicted by population viability analysis (PVA), and negatively correlated with population size. On the basis of the above results, a policy of translocation was advocated for small, intensely managed populations of zebras, whereby a harem should be translocated every five years for a population size of nine (HJNR), while for a population size of 110 (VCNR) translocations should take place every 15 years if heterozygosity is to be maintained at more than 90% within each population over 100 years.
 
Article
The two common southern African mice species (Mastomys coucha and M. natalensis) are morphologically almost identical, making field identification impossible at present. Specimens from two localities were collected and tissue and blood samples taken. The habitat type of each locality was studied, and a distribution map compiled. A definite correlation between biome-type and species range was found to be present. Three isozyme markers were identified: glucose phosphate isomerase in liver, and two general (non-specific) protein coding loci in muscle. In addition, we also identified species characteristic haemoglobin components in both species. This is the first study to report genetic variation within, and differentiation between these species. Our results are of medical importance because Mastomys coucha carries bubonic plague and M. natalensis carries Lassa Fever.
 
Article
The leaf essential oil of Wollemia nobilis (Wollemi Pine) has been investigated and compared with other members of the family Araucariaceae. All araucaroids examined yielded steam volatile oils in low yields. The oil from Wollemia nobilis was composed mainly of (+)-16-kaurene (60%), together with alpha-pinene (9%) and germacrene-D (8%). Oils from Agathis species endemic to Australia were high in monoterpenes, in contrast to those isolated from extra-Australian species. The major constituents of A. atropurpurea oil were phyllocladene (13%) and 16-kaurene (19%), followed by alpha-pinene (8%) and delta-cadinene (9%). A. microstachya yielded oil in which alpha-pinene (18%) was the major component; the only other components in excess of 5% were myrcene (7%), bicyclogermacrene (6%) and delta-cadinene (6%). A. robusta oil contained spathulenol (37%) and rimuene (6%). Approximately 40% of the oil was unidentified sesquiterpenes. A. australis oil contained 16-kaurene (37%), sclarene (5%) and an unidentified oxygenated diterpene K (12%) as major components; the only other compound in excess of 5% was germacrene-D (9%). 5,15-Rosadiene (60%), and 16-kaurene (7%) were the major constituents of A. macrophylla oil. A. moorei oil was rich in sesquiterpenes, but the only compounds in excess of 5% were allo-aromadendrene (6%), germacrene-D, delta-cadinene (10%), an unidentified sesquiterpene (12%) and 16-kaurene (6%). In A. ovata oil the most significant compounds were caryophyllene oxide (15%) and phyllocladene (39%). Araucaria angustifolia contained germacrene-D (9%) and the diterpenes hibaene (30%) and phyllocladene (20%) as major components of its essential oil. Oils of A. bidwillii, A. columnaris and A. cunninghamii were all low in mono- and sesquiterpenes and high in diterpenes. In the first, hibaene (76%) was the major constituent; the second contained hibaene (9%), sclarene (6%), luxuriadiene (13-epi-dolabradiene)(23%) and two unidentified diterpene hydrocarbons (B) (33%) and (E) (10%). In the last, 16-kaurene (53%) was the most significant component followed by hibaene (29%). A. heterophylla was unusual in that over half the oil was made up of the monoterpenoid alpha-pinene (52%), with phyllocladene (32%) being the only other compound of significance. alpha-Pinene (18%) was a significant component of A. hunsteinii oil; sclarene (11%) and germacrene-D (5%) were the only other compounds present in concentrations of more than 5%. A. luxurians oil was composed of 5,15-rosadiene (20%) and luxuriadiene (13-epi-dolabradiene) (66%), previously unreported from natural sources. The major components of A. montana were phyllocladene (61%) and 16-kaurene (23%). Sclarene (20%), luxuriadiene (19%) and the unidentified diterpene hydrocarbons (B) (25%) and (E) (10%) were the most important constituents of A. muelleri oil. A. scopulorum contained large amounts of 16-alpha-phyllocladanol (41%) as well as luxuridiene (10%) and delta-cadinene and alpha-copaene, both at 6%.
 
Article
Present study The pungent numbing agents of Ctenium aromaticum are present in a 1-2 cm region where roots join the base of stems and in the seed head, but not in roots or leaves. Components of methanolic soxhlet extract of the base of stems were fractionated by prep TLC (Si gel, hexane : acetone 2 : 1). Numbing activity was found in two closezones (Rf 0.70 and 0.75) detectable with phosphomolybdic acid reagent. The prep TLC fractions were further fractionated by prep HPLC (isocratic acetonitrile : water 1 : 1, 260 nm) to obtain three cleanly separated metabolites identified as N-(1-isobutyl)-2(E),4(E)-decadienamide, (pellitorine, MW 223), N-(1-isobutyl)-2(E),4(E),8-decatrieneamide (isoaffinin, M" 221) and N-(1-isobutyl)-2(E),4(E),8,11-dodecatetraenamide, M" 247, by mass spectral MW and H-, COSY, HMBC and HMQCNMR. Spectral properties were identical to those reported for these isobutylamides (Bohlmann et al., 1974; Zdero et al., 1988). All expected proton-proton and proton-carbon correlations were observed for the three compounds. Coupling constants were consistent with a trans, trans 2,4-diene system in all three amides. Chemical shifts for the isolated double bond in two of the three amides overlapped, precluding cis-trans assignment. Spectrally pure dodecadienamide caused numbing action on the gums and tongue; pure pellitorine is known to be tasteless but to produce a numbing sensation (Jacobson and Crosby, 1971). Isoaffinin was not tested.
 
Article
1. Subject and sourceIn order to continue our chemosystematic studies of the genus DictyotaLamouroux, Dictyotales, Phaeophyta (Cavalcanti et al., 1998a and referencesquoted therein) we examined D. menstrualis (Hoyt) Schnetter, Ho¨rnig & Weber-Peukert collected at Enseada do Forno, Bu´ zios, Rio de Janeiro State, Brazil (22845
 
Article
The objective of this study was to determine whether differences in toxicity between Tall larkspur (Delphinium barbeyi) and Duncecap larkspur (D. occidentale) were genetically inherent within the species, or due to environmental influences unique to the different regions where they grow. There was no difference in the concentration of the toxic alkaloids between the two species when grown in common gardens. However, both species had higher concentration of toxic alkaloids when grown in the southern Rocky Mountain region which is characterized by summer monsoonal thunderstorms, compared to summer drought in the north. In a unique occurrence where Duncecap larkspur grew beside Tall larkspur, toxic alkaloids were very low in Duncecap larkspur, but total alkaloid concentration was often higher than in Tall larkspur.
 
Article
New records are reported for a Hemipteran (Largus rufipennis) and a Coleopteran (Chauliognathus fallax) feeding on Senecio brasiliensis (Asteraceae) and sequestering pyrrolizidine alkaloids (PAs). Both insects are warningly colored and rejected by predators.
 
Article
Alkaloids retamine, anagyrine, lupanine, 17-oxoretamine, 12-alpha-hydroxylupanine were detected, along with four others unidentified compounds in the aerial parts of Genista ephedroides D.C.
 
Article
The leaves of Eupatorium semialatum were investigated for the occurrence of pyrrolizidine alkaloids. Although this type of alkaloids generally occurs in the Eupatorieae, only unusual non-toxic pyrrolizidines of the tussilagin type were identified. All compounds are methyl esters of the corresponding beta-amino acids.
 
Article
To elucidate the potential of electrophoretic analysis for understanding relationships among microhylid frogs in Papua New Guinea, an allozyme analysis was conducted. A total of 119 individuals from nine species of Cophixalus, two species of Sphenophryne and one species of Barygenys, all of which belong to the family Microhylidae, were studied. Fourteen enzymes extracted from skeletal muscles and livers were analyzed by starch-gel electrophoresis. These enzymes were encoded by genes at 20 loci. There were 2-15 phenotypes produced by 2-12 alleles at these loci. The mean proportion of heterozygous loci per individual, mean proportion of polymorphic loci per population, and mean number of alleles per locus in 12 species were 6.1%, 17.1% and 1.17a on average, respectively. The NJ and ML trees constructed from Nei's genetic distances showed that the genus Sphenophryne can be distinguished biochemically from Cophixalus and Barygenys, and that the species groups of Cophixalus, which are similar in external morphology, can be divided biochemically into several species.
 
Article
An electrophoretic genetic analysis utilising starch gel electrophoresis was employed to assess clonality in endangered Zieria baeuerlenii populations distributed over an area of less than a kilometre square in Nowra (NSW). Eleven enzymes systems encoded by 19 loci (41 alleles) when assayed to estimate levels of genetic diversity within and among populations, revealed moderate levels of genetic diversity. Despite finding seven loci being fixed at a particular locus, 20 unique multilocus genotypes/clones restricted to a particular population were detected within a sample of 179 ramets collected from throughout the range of the species. The probability of finding any clone produced by sexual reproduction is <0.0025 and is further supported by the fact that reproduction appears to be exclusively by vegetative spread and there is virtually no pollen viability and seed production. The lack of seed set in this area may be due to additional factors inhibiting sexual reproduction. Overall, such genetic studies play a crucial role in devising conservation and management strategies for rare and endangered taxa.
 
Article
Starch gel electrophoresis was employed to survey the allozyme polymorphism and phylogenetic relationships among 35 populations covering six closely related Western Australian endemic Pterostylis species (series Grandiflorae); viz P. rogersii, P. aspera, P. angusta, P. hamiltonii, P. scabra and P. aff. alata. The aim of this study was to determine intraspecific and interspecific genetic diversity and species relationships based on allozyme analysis. The frequencies of 56 alleles at 12 enzyme systems coded by 15 loci were determined along with a mean intraspecific genetic identity value. Allozyme markers clearly discriminated populations belonging to different species. Nei's genetic distance/identity co-efficient was used to measure the level of genetic differentiation among populations and species. Based on these values, a dendrogram was constructed which revealed that all the populations clustered into groups corresponding to the respective species. Gene diversity analysis among all the species revealed total genetic diversity H(t) of 0.23 with co-efficient of gene differentiation 10% (G(st)=0.10). Mean genetic variability (H(e)=0.136, P=40%) was also higher than for other outbreeding plant species. Mean genetic identity coefficient of populations of all species was 0.859 which increased to 0.877 upon exclusion of P. aff. alata, indicating a high degree of similarity among all species except P. aff. alata which segregated distinctively from the rest. Overall, the investigation provided independent support for the morphological segregation of these taxa.
 
Article
The role of electrophoretic data is discussed as it applies to plant taxonomy and systematic studies. Nei's (Am. Nat. 106 (1972) 283-292; Genetics 89 (1978) 583-590) genetic distances calculated for a large number of populations, species and genera were taken from published data. The relation between Nei's genetic identity measures and taxonomic rank (populations, species and genera) are shown graphically. The graphs obtained in this way (from 3021 pairs of plant taxa) differ substantially from previous graphs published by Thorpe (Ann. Rev. Ecol. Syst. 13 (1982) 139-168; in: G.S. Oxford, D. Rollinson (Eds.), Protein Polymorphism: Adaptive and Taxonomic Significance, Academic Press, London, 1983, pp. 131-152) and Thorpe and Solé-Cava (Zool. Scripta 23 (1994) 3-18). These authors suggested that the divergence between the different taxonomic ranks is roughly similar across a wide range of taxa. The latter was based on values for 2664 (Thorpe, 1982) and 8060 (Thorpe, 1983) pairs of animal and plant taxa, but the plant data contributed little to the total. For any given taxonomic rank, we found that plants are genetically more closely related than animals (possibly with the exception of birds). This result is important because the empirical relationships of genetic distance measures, to different levels of taxonomic separation, is often used for distinguishing and identifying cryptic or sibling species where conventional methods are unable to resolve systematic problems.
 
Article
Phylogenetic relationships between Encephalartos altensteinii Lehmann, E. arenarius R.A. Dyer, E. horridus (Jacquin) Lehmann, E. latifrons Lehmann, E. lehmannii Lehmann, E. longifolius (Jacquin) Lehmann, E. princeps R.A. Dyer and E. trispinosus (Hooker) R.A. Dyer were studied, using E. ferox Bertoloni f. as outgroup. Three continuous and one discontinuous buffer systems were used and gene products of 14 enzyme coding loci were examined by horizontal starch gel-electrophoresis. Genetic variation was studied in a cultivated population of E. lehmannii and the average heterozygosity value for this population is 13.5%, which falls within the range reported for other cycad species. Fixed allele differences between the species studied was not found at any of the loci studied, which suggest that these species are closely related. DNA sequence analysis of rbcL and ITS 1 & 2 genes (1428 and 895 basepairs, respectively) confirmed the close genetic relationships between these taxa. According to ITS and rbcL sequences E. altensteinii and E. princeps are sibling taxa which form a sister group to E. arenarius, E. horridus, E. latifrons, E. lehmannii, E. longifolius, and E. trispinosus. The genetic distances between both groups were 0.12-0.47% for ITS and 0.08-0.16% for rbcL DNA. The results indicate recent (probably pleistocenic) speciation for this group of cycads, and the relationships are discussed with reference to affinities based on morphology and distribution.
 
Article
The phenyl pyrone, aloenin was positively identified in 16 species in a greater chemotaxonomic study on 380 species of Aloe. A large number of species have previously been suggested to be related on the basis of their macromorphological characters. The leaf exudate composition of the 16 species are presented together with a summary of the salient morphological characters. The possible taxonomic relationships between aloenin producing species, not previously thought to be associated with one another are discussed and illustrates the need to explore additional characters of taxonomic value in this large genus of ca. 420 species where no natural classification system exists.
 
Article
Aloe arborescens is a large, multi-stemmed shrub. It is used as hedge plants to protect agricultural fields or stock and as horticultural plants in gardens. In natural habitats it is one of the very common Aloe species along the Indian Ocean coast of southern Africa, from the Cape, in the south, to Zimbabwe and Malawi in the north. Secondary phenolic metabolites such as barbaloin (Rf 0.31-0.35), aloeresin (Rf 0.25-0.3) and aloenin (Rf 0.51-0.55) have been found to be distributed in the succulent leaves of Aloe arborescens in a peripheral defense strategy. The youngest leaves have the highest content. The terminal third of each leaf has the highest content and the basal third, the lowest. Along the leaf margins, on the top third and adaxial side, the content is the highest and in the base third, the lowest along the leaf center on the abaxial side. Similar relative amounts of these three secondary phenolic metabolites were found in the different leaf locations. The leaf orientation may affect the total content of these three phenols but not their relative amounts in the different parts of the leaves. It is possible that the more often the plant parts are damaged by consumption by animals such as elephants, kudu or insects, the greater the increase of their phenolic metabolites. This increase may reduce or prevent further consumption when the content of the metabolites reaches a certain level. The plants then have a chance to renew themselves.
 
Article
A chemotaxonomic survey of 380 species of Aloe indicated the presence of the anthrone isomers aloin A and B together with the aloinoside isomers and microdontin A and B in 36 (10%) species of Aloe. This group, referred to as the microdontin chemotype, is thus characterised by a combination of exudate compounds and not merely a single phytochemical marker, implying taxonomic significance of leaf exudate compounds. The 36 representatives of the group occupy disparate taxonomic positions in the largely artificial hierarchy of the present classification system. Although many of the species have previously been considered as related (based on macromorphology only), a large number of species have not been associated with one another before. The chemical profiles and leaf exudate compositions of the species are presented, followed by a brief summary of the morphological diversity. Whilst conceding the possibility of convergent evolution, the geographical distribution of the species and thoughts on possible relationships between the taxa are discussed.
 
Article
Evidence is presented to suggest the hybrid origin of Aloe broomii, with the one putative parent belonging to Aloe series Purpurascentes and the other a member of Aloe series Anguialoe. A chemotaxonomic and morphological assessment is presented for both infrageneric groups and their hypothesised hybrid. Four of the species belonging to the series Purpurascentes display a characteristic leaf exudate profile containing the chemotaxonomic marker microstigmin. Aloe gariepensis and A. succotrina lack the diagnostic leaf exudate compounds. The distinct morphological apomorphies for Aloe section Anguialoe are supported on the chemical level reinforcing the monophyly of this group.
 
Article
Formylated phloroglucinol compounds (FPCs) in Eucalyptus leaves are important determinants of feeding in marsupial folivores and have a wide range of other biological actions. We conducted a survey of the occurrence of formylated phloroglucinol compounds (euglobals, macrocarpals and sideroxylonals) in acetone-petrol extracts of 41 species of Eucalyptus from among seven informal subgenera growing on the East Coast of Australia. We used electrospray ionisation, Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTMS) to search crude extracts of eucalypt leaves for molecular weights characteristic of FPC compounds. We found masses characteristic of reported FPCs in 27 of the 41 species examined. The most frequently identified group of compounds was the sideroxylonals. Notable was the lack of known FPCs in the informal subgenus Monocalyptus.
 
Top-cited authors
Robert P. Adams
  • Baylor University
Renée J Grayer
  • Royal Botanic Gardens, Kew
David s. Seigler
  • University of Illinois, Urbana-Champaign
Geoffrey C Kite
  • Royal Botanic Gardens, Kew
B.-E. Van Wyk
  • University of Johannesburg