AN OVERVIEW OF THE GENUS PYRRHOPAPPUS (ASTERACEAE: LACTUCEAE) WITH EMPHASIS ON CHLOROPLAST DNA RESTRICTION SITE DATA

The genus Pyrrhopappus in recent systematic treatments has comprised five taxa (four species, one with two varieties), which have now been studied anew using morphogeographical and chloroplast DNA restriction site data. Eight populations, representing all of the recognized taxa of Pyrrhopappus, were digested with 17 restriction enzymes. Only three restriction site differences were found from among 750 restriction sites and no length variations were observed. This contrasts with similar studies, using these same enzymes, on the closely related genus Krigia in which 173 mutation sites and 20 length variations were found among the seven species concerned. Nucleotide sequence divergence values among the species of Pyrrhopappus were extremely low (0.0012) compared to much higher values found in the closely related genus Krigia (0.1270). Three species of Pyrrhopappus are herein recognized: two diploids with 2n = 12 chromosomes, P. carolinianus and P. pauciflorus (including P. multicaulis, P. geiseri and P. rothrockii), and a tetraploid (2n = 24), P. grandiflorus. The tetraploid is partially sympatric with both diploids but is readily recognized by its perennial roots, which bear tuber-like enlargements. These three species presumably arose relatively recently, and the DNA data suggest that neither P. pauciflorus nor P. carolinianus gave rise to the tetraploid P. grandiflorus.     

CHLOROPLAST DNA RESTRICTION SITE VARIATION AND THE PHYLOGENY OF COREOPSIS SECTION COREOPSIS (ASTERACEAE)

Restriction site variation in chloroplast DNAs (cpDNAs) of Coreopsis section Coreopsis was employed to assess divergence and phylogenetic relationships among the nine species of the section. A total of fourteen restriction site mutations and one length mutation was detected. Cladistic analysis of the cpDNA data produced a phylogeny that is different in several respects from previous hypotheses. CpDNA mutations divide the section into two groups, with the two perennial species C. auriculata and C. pubescens lacking any derived restriction site changes. The other seven species are united by five synapomorphic restriction site mutations and the one length mutation. These seven species fall into three unresolved clades consisting of 1) the remaining three perennial species, C. grandiflora, C. intermedia, and C. lanceolata; 2) three annual species, C. basalis, C. nuecensoides, and C. nuecensis; and 3) the remaining annual, C. wrightii. The cpDNA data suggest that, although the perennial habit is primitive within the section, the annual species of section Coreopsis have likely not originated from an extant perennial species. The estimated proportion of nucleotide differences per site (given as 100p) for the cpDNAs of species in the section ranges from 0.00 to 0.20, which is comparable to or lower than values reported for other congeneric species. The low level of cpDNA divergence is concordant with other data, including cross compatibility, interfertility and allozymes, in suggesting that species of the section are not highly divergent genetically.     

PHYLOGENETIC IMPLICATIONS OF CHLOROPLAST DNA RESTRICTION SITE VARIATION IN THE MUTISIEAE (ASTERACEAE)

Phylogenetic relationships among 13 species in the tribe Mutisieae and a single species from each of three other tribes in the Asteraceae were assessed by chloroplast DNA restriction site mapping. Initially, 211 restriction site mutations were detected among 16 species using 10 restriction enzymes. Examination of 12 of these species using nine more enzymes revealed 179 additional restriction site mutations. Phylogenetic analyses of restriction site mutations were performed using both Dolio and Wagner parsimony, and the resulting monophyletic groups were statistically tested by the bootstrap method. The phylogenetic trees confirm an ancient evolutionary split in the Asteraceae that was previously suggested by the distribution of a chloroplast DNA inversion. The subtribe Barnadesiinae of the tribe Mutisieae is shown to be the ancestral group within the Asteraceae. The molecular phylogenies also confirm the paraphyly of the Mutisieae and provide statistical support for the monophyly of three of its four currently recognized subtribes (Barnadesiinae, Mutisiinae, and Nassauviinae). The fourth subtribe, Gochnatiinae, is shown to be paraphyletic. Within the subtribes, several closely related generic pairs are identified. Chloroplast DNA sequence divergence among genera of the Asteraceae ranges between 0.7 and 5.4%, which is relatively low in comparison to other angiosperm groups. This suggests that the Asteraceae is either a relatively young family or that its chloroplast DNA has evolved at a slower rate than in other families.     

TRIBAL PLACEMENT OF MARSHALLIA (ASTERACEAE) USING CHLOROPLAST DNA RESTRICTION SITE MAPPING

The examination of morphological traits has failed to resolve the tribal placement of Marshallia. Suggested relationships for this anomalous genus have, at various times, included Eupatorieae, Heliantheae, Vemonieae, and Inuleae. Chloroplast DNA restriction site mapping, using Bamadesiinae (Mutisieae) as the outgroup, revealed 981 restriction site mutations, 332 of which were phylogenetically informative, for 60 genera representing 15 tribes of Asteraceae. Wagner parsimony produced 36 equally parsimonious tress of 729 steps, and Dollo parsimony produced 34 equally parsimonious trees of 759 steps. Monophyletic groups, resulting from the Wagner analysis, were further tested with the bootstrap method. The placement of Marshallia in the Heliantheae-Tageteae-Coreopsideae-Eupatorieae complex was consistent for all trees produced. Tageteae and Coreopsideae form the sister group to paraphyletic Heliantheae, with Marshallia sharing its most recent common ancestor with Galinsoga, Palafoxia, and Bahia. The Eupatorieae form a monophyletic clade that is derived from helianthoid ancestors.     

RESTRICTION FRAGMENT ANALYSIS OF CHLOROPLAST DNA AND THE SYSTEMATICS OF VIGUIERA AND RELATED GENERA (ASTERACEAE: HELIANTHEAE)

Phylogenetic relationships among 31 species representing variously Helianthus, Helianthopsis, Heliomeris, Simsia, Viguiera, and Tithonia were assessed by chloroplast DNA restriction site mapping. A total of 147 mutations including 92 informative ones was detected using 16 restriction enzymes, with an estimated sequence divergence within the group of 1.4%. Parsimony analysis produced a single most parsimonious tree with a length of 161 steps and a consistency index of 0.91. Statistically significant clades, as assessed by the bootstrap method, correspond to a number of taxa recognized previously, including Helianthus (3 species), Helianthopsis (5 species), and several groups within Viguiera, including sect. Maculatae (4 species), the Baja California group (6 species), sect. Paradosa (2 species) and V. dentata (3 samples). However, species of Viguiera collectively form a highly paraphyletic group relative to species of other genera. Helianthus and Helianthopsis were separated into different clades, supporting their recent segregation. Placement of H. porteri in Helianthus rather than Heliomeris was confirmed; the single sample of the latter genus was most similar to the Baja California group of Viguiera. An expected relationship between Simsia (2 species) and one member of Viguiera ser. Grammatoglossae was confirmed (although not with two other putatively related members of Viguiera) and an unexpected relationship between Simsia and Tithonia was suggested. The presence of Mexican taxa as the more basal groups in the tree points toward a possible Mexican origin for Viguiera and related genera. A molecular clock hypothesis is rejected in many pairwise comparisons involving woody taxa with herbaceous ones, although it could not be rejected in most pairwise comparisons involving taxa of similar habit.     

TOPIARY PRUNING AND WEIGHTING REINFORCE AN AFRICAN ORIGIN FOR THE HUMAN MITOCHONDRIAL DNA TREE

A method is presented for removing recent homoplastic events from a phylogenetic tree. This “topiary pruning” method produces a series of progressively modified duplicates of the original set of data, from which more and more of the most recent substitutions have been removed. The edited sets of data have increased amounts of information per remaining taxon, while similar but randomized data sets subjected to topiary pruning do not. The ability of topiary pruning to “unscramble” artificial data sets that have high levels of homoplasy is demonstrated, and is shown to be similar in its effects to the weighting method of Kluge and Farris (1969), although with the additional advantage of reducing the number of taxa to the point where bootstrapping is feasible. Pruning and weighting used together produce closer approximations to the “true” tree than either method used separately. It is further shown that in these artificial data sets midpoint rooting is more likely to be accurate than outgroup rooting. When pruning and weighting are applied to the extensive sets of mitochondrial DNA data of Cann et al. (1987) and Vigilant et al. (1991), trees result that have deep branch points, some of which lead to entirely African branches. In the case of the Vigilant et al. data, the three African branches have bootstrap values between 0.94 and 1.0, and the consensus and bootstrap midpoint roots also have high bootstrap values and occur on these African branches near their junction. An African origin of the human mitochondrial tree is not proved by this approach, particularly since sequences from non-African groups are underrepresented in current data sets, but it is rendered more likely.     

CHLOROPLAST DNA RESTRICTION SITE VARIATION IN THE FERN GENUS PELLAEA: PHYLOGENETIC RELATIONSHIPS OF THE PELLAEA GLABELLA COMPLEX

The cheilanthoid ferns have long resisted efforts to circumscribe well-defined, phylogenetically natural generic and infrageneric groups, presumably because of homoplastic morphologies associated with their xeric habitats. This cladistic analysis of phylogenetically informative chloroplast DNA restriction site data from 14 enzymes and seven taxa in the cheilanthoid genus Pellaea provides new insights into the phylogenetic relationships of the P. glabella complex. It also assesses the congruence of results based on restriction site data at inter- and intraspecific levels in these sexually and apogamously reproducing ferns with those of earlier morphological and isozyme analyses of the same group. Wagner parsimony yielded a single most parsimonious tree of 187 steps and 11% homoplasy, based on a data matrix of 166 restriction sites of which 66 were phylogenetically informative. Phylogenetic analysis based on user-defined stepmatrix character-state weighting of site gains over losses produced an identical single most parsimonious tree. Dollo parsimony yielded two most parsimonious trees, one of which was topologically identical to the Wagner tree. Specific and infraspecific relationships in the P. glabella complex determined by the completely independent restriction site and isozyme data sets are identical. This lends confidence to the ongoing use of restriction site data in a broader study of Pellaea and other cheilanthoid taxa and to the present conclusions that P. atropurpurea is sister to the P. glabella complex, whereas P. breweri, previously considered the closest relative of this complex, is actually more distantly related to it than are the other taxa in this study.     

猪獾和黄鼬mtDNA物理图谱及位点变异性初探

本实验用ＡｐａⅠ,ＢｇｌⅠ,ＢｇｌⅡ,ＣｌａⅠ,ＥｃｏＲⅠ,ＥｃｏＲⅤ,ＨｉｎｄⅢ,ＨｐｅⅠ,ＰｓｔⅠ,ＰｖｕⅠⅡ,ＳａｃⅠ,ＳａｌⅠ等１２种限制性内切酶分析猪獾和黄鼬的ｍｔＤＮＡ限制性片段,并用双酶解法构建限制性内切酶图谱。结合以往积累的资料,我们对哺乳动物ｍｔＤＮＡ限制性位点在远缘物种间的保守性和变异性进行了初步讨论。     

EFFECT OF TAXON SAMPLING,CHARACTER WEIGHTING,AND COMBINED DATA ON THE INTERPRETATION OF RELATIONSHIPS AMONG THE HETEROKONT ALGAE1

Nuclear ribosomal small subunit and chloroplast rbcL sequence data for heterokont algae and potential outgroup taxa were analyzed separately and together using maximum parsimony. A series of taxon sampling and character weighting experiments was performed. Traditional classes (e.g. diatoms, Phaeophyceae, etc.) were monophyletic in most analyses of either data set and in analyses of combined data. Relationships among classes and of heterokont algae to outgroup taxa were sensitive to taxon sampling. Bootstrap (BS) values were not always predictive of stability of nodes in taxon sampling experiments or between analyses of different data sets. Reweighting sites by the rescaled consistency index artificially inflates BS values in the analysis of rbcL data. Inclusion of the third codon position from rbcL enhanced signal despite the superficial appearance of mutational saturation. Incongruence between data sets was largely due to placement of a few problematic taxa, and so data were combined. BS values for the combined analysis were much higher than for analyses of each data set alone, although combining data did not improve support for heterokont monophyly.     

大鼠肝和肝癌DNA及其限制性酶切图谱分析

大鼠肝和肝癌BERH-2 DNA的EcoR Ⅰ,BamH Ⅰ,HindⅢ和Pst Ⅰ,以及EcoR Ⅰ分别与BamH Ⅰ或HindⅢ或Pst Ⅰ组合双酶合切的电泳图谱间无明显差异;双向凝胶电泳重复顺序图谱也近似。在一定实验条件下,大鼠肝癌BERH-2 DNA在凝胶电泳上,除去显示EB荧光主带外,还有呈现阶梯大小的片段。最小片段为270bp,两电泳相邻片段间的长度差约为160bp,并且能与标记的核RNA起杂交反应。对实验结果进行了讨论。     

雪豹线粒体DNA（mtDNA）研究及其分类地位的探讨

本文构建了雪豹和金钱豹的限制性内切酶图谱。通过限制性酶谱的比较,探讨雪豹的属级分类地位。结果表明,两物种的ｍｔＤＮＡ基因组明显趋异,其遗传距离为０．０７５３３,但这种差异根据文献记载,似乎未到属级分化程度,故认为雪豹不应单立为属,而是豹属的一员。但鉴于雪豹在形态、行为、该型和ｍｔＤＮＡ等方面,不同于豹属其他种类,我们认为雪豹应视豹属中的一个有效亚属。     

THE FITNESS OF MANIPULATING PHENOTYPES: IMPLICATIONS FOR STUDIES OF FLUCTUATING ASYMMETRY AND MULTIVARIATE SELECTION

Phenotypic manipulation (or phenotypic engineering) that alters trait distributions provides a way to increase the statistical power of detecting relationships between traits and fitness. Manipulations relying on plastic responses, however, assume a specific relationship between the perturbation and the alteration of the traits when multiple traits are involved. We measured several traits, including condition measured as fluctuating asymmetry, in the ladybird beetle Harmonia axyridis under six different diets to examine how altered environments affected multiple traits and their distributions. Although diet affected fluctuating asymmetry, we found no consistent relationship between degree of asymmetry and other phenotypic measures. As expected, individual traits were altered by our treatments. Contrary to expectation, relationships among traits were not constant among diets. Our results suggest that assumptions about the relationship between condition and trait values, especially fluctuating asymmetry, cannot be made. Further, studies that use manipulated phenotypes to statistically determine the form of selection must first demonstrate that the pattern of the phenotypic correlation matrix is not itself altered by the manipulation. If the phenotypic correlation matrix is not constant, then experimental estimates of selection coefficients may not reflect selection that occurs in the wild.     

关于Miyamayomena simplex和M. angustifolia(Asteraceae)命名人的更正

Miyamayomena simplex和M.angustifolia是陈艺林(Y.L.Chen1986)根据Aster simplex Chang(1935a)和A.angustifolius Chang(1935b)Asteraceae,(Astereae)更名的。后者是A.simplex Willdenow(1809)和A.angustifolius Jacquin(1798)的异物同名,因此不符合国际植物学命名法规第72条款的规定。陈的更名应处理为1986年的新名Miyamayomena simplex Y.L.Chen和M.angustifolia Y.L.Chen。