PREFERENCE HIERARCHIES AND THE ORIGIN OF GEOGRAPHIC SPECIALIZATION IN HOST USE IN SWALLOWTAIL BUTTERFLIES

Four allopatric populations of the widely distributed western anise swallowtail butterfly, Papilio zelicaon, use different plant genera as hosts, but simultaneous choice experiments showed that these populations have diverged only slightly in oviposition preference. Of the four populations—two from southeastern Washington State, one from coastal southwestern Washington State, and one from central California—three use hosts that are not available to any of the others. Although variation for the degree of preference for particular plant species occurred within and among populations, all four populations ranked hosts in the same overall order. Monophagy on a local, low-ranking host outside the range of high-ranking hosts did not necessarily lead to the loss of preference for those high-ranking hosts, thereby indicating that the high-ranking hosts would still be accepted, and in some cases even preferred, if a population encountered them again. Hence, the overall preference hierarchy among P. zelicaon populations appears to be evolutionarily conservative. Analyses of differences among families within the California population indicated that increased preference for some hosts is inversely correlated, whereas preference for other hosts may be uncorrelated. Positive correlations may also occur but were not observed among the plant species tested. Overall, the results indicate local monophagy on different plant species in P. zelicaon has not involved major reorganizations in the preference hierarchy of ovipositing females, even in populations that may have fed on a low-ranking host for many generations. Instead, small increases in preference for local hosts have occurred within an evolutionarily conservative preference hierarchy.     

HOST SPECIALIZATION DIFFERENTIATES CRYPTIC SPECIES OF FEATHER-FEEDING LICE

Parasite species with differentiated host-specific populations provide a natural opportunity to explore factors involved in parasite diversification. Columbicola macrourae is a species of ectoparasitic feather louse currently recognized from 15 species of New World pigeons and doves. Mitochondrial sequences reveal five divergent haplotype clusters within C. macrourae , suggesting cryptic species. Each cluster is relatively host specific, with only one or a few hosts. We conducted a reciprocal transfer experiment with two of these lineages to test whether host use has an adaptive component. Our results demonstrate that the fitness of each lineage is considerably higher on its native host than on the novel host suggesting that one or more selective agents favor host specialization by the different lineages. In addition, we were able to morphologically separate individual lice from the two experimental lineages using discriminant function analysis. Furthermore, differences in the size of these louse lineages match differences in the size of their respective hosts, paralleling the strong correlation between parasite and host body size across the genus Columbicola . Together, these results suggest that selection in this cryptic species complex reflects selection across the whole genus, and that this selection, in part, contributes to the maintenance of host specialization.     

CELL‐CELL INTERACTION IN THE EUKARYOTE‐PROKARYOTE MODEL OF THE MICROALGAE CHLORELLA VULGARIS AND THE BACTERIUM AZOSPIRILLUM BRASILENSE IMMOBILIZED IN POLYMER BEADS1

Cell‐cell interaction in the eukaryote‐prokaryote model of the unicellular, freshwater microalga Chlorella vulgaris Beij. and the plant growth‐promoting bacterium Azospirillum brasilense, when jointly immobilized in small polymer alginate beads, was evaluated by quantitative fluorescence in situ hybridization (FISH) combined with SEM. This step revealed significant changes, with an increase in the populations of both partners, cluster (mixed colonies) mode of colonization of the bead by the two microorganisms, increase in the size of microalgae‐bacterial clusters, movement of the motile bacteria cells toward the immotile microalgae cells within solid matrix, and formation of firm structures among the bacteria, microalgae cells, and the inert matrix that creates a biofilm. This biofilm was sufficiently strong to keep the two species attached to each other, even after eliminating the alginate support. This study showed that the common structural phenotypic interaction of Azospirillum with roots of higher plants, via fibrils and sheath material, is also formed and maintained during the interaction of this bacterium with the surface of rootless single‐cell microalgae.     

PATTERNS IN HOST RANGE FOR TWO STRAINS OF AMOEBOPHRYA (DINOPHYTA) INFECTING THECATE DINOFLAGELLATES: AMOEBOPHYRA SPP. EX ALEXANDRIUM AFFINE AND EX GONYAULAX POLYGRAMMA1

The endoparasitic dinoflagellate Amoebophrya ceratii (Koeppen) Cachon uses a number of its free‐living relatives as hosts and may represent a species complex composed of several host‐specific parasites. Two thecate host–parasite systems [Amoebophrya spp. ex Alexandrium affine (Inoue and Fukuyo) Balech and ex Gonyaulax polygramma Stein], were used to test the hypothesis that two strains of Amoebophrya have a high degree of host specificity. To test this hypothesis, a series of cross‐infection experiments were conducted, with 10 thecate and three athecate dinoflagellate species as potential hosts. Surprisingly, the two strains of Amoebophrya lacked host specificity and had wider host ranges than previously recognized. Among the host species tested, Amoebophrya sp. ex Alexandrium affine was capable of infecting only species of genus Alexandrium (Alexandrium affine, Alexandrium catenella, and Alexandrium tamarense), while the parasite from Gonyaulax polygramma infected species covering five genera (Alexandrium, Gonyaulax, Prorocentrum, Heterocapsa, and Scripsiella). In the context of previous reports, these results suggest that host specificity of Amoebophrya strains varies from extremely species‐specific to rather unspecific, with specificity being stronger for strains isolated from athecate hosts. Information on host specificity of Amoebophrya strains provided here will be helpful in assessing the possibility of using these parasites as biological control agents for harmful algal blooms, as well as in defining species of Amoebophrya in the future.     

GENERAL-PURPOSE GENOTYPES FOR HOST SPECIES UTILIZATION IN A NEMATODE PARASITE OF DROSOPHILA

The nematode Howardula aoronymphium parasitizes several species of mushroom-feeding Drosophila. A survey of isofemale strains of H. aoronymphium and a 25-generation selection experiment revealed that this species does not comprise host races, and that it harbors little heritable variation for adaptation to specific hosts No tradeoffs in performance on the different host species were evident. General-purpose genotypes, which can utilize all host species, characterize H. aoronymphium. An important feature of the natural history of these nematodes—correlated epidemiology across host species—is postulated to be both a cause and a consequence of the evolution of general-purpose genotypes in this species.     

大头茶族的范围及族内属的界限

广义大头茶族几乎包括了整个山茶亚科的属,分群的界限不够明确,易于造成混乱,经过研究,作者所持的是狭义大头茶族的概念。考察这一族包括Polyspora, Gordonia和Laplacea三个属形态特征上的差异和洲际分布的事实,这三个属虽然有共同的祖先,但由于演化上的歧异,仍应作为独立的属看待。在划分属的界限上,苞被分化与否和花部其他形态的差异具有最重要的意义,花粉表面纹饰的差异也可作为一种依据。Polyspora种群划分也被讨论。     

ENDOPHYTIC ALGAE OF CHONDRUS CRISPUS (RHODOPHYTA). III. HOST SPECIFICITY1

Susceptibility of rhodophycean macroalgae to infection by the green endophytes, Acrochaete operculata Correa & Nielsen and A. heteroclada Correct & Nielsen was studied. Cross-infection experiments showed that A. operculata is host specific and developed only in sporophytic fronds of Chondrus crispus Stackh. and Iridaea cordata (Turn.) Bory. Although A. operculata penetrated equally the multilamellar outer cell wall of sporophytic and gametophytic fronds of C. crispus, subsequent development was arrested in the gametophytic fronds. Susceptibility of the sporophytic phase of C. crispus was detected early in the development of the host, at a discoid stage that is structurally distinct from the adult fronds. The evidence strongly suggests that host specificity in A. operculata is determined by cell-wall composition of the hosts, likely the carrageenan fraction. In contrast, A. heteroclada was not host specific, infecting all offered hosts, including carrageenophytes and agarophytes. Germination occurred on the surface of the hosts and led to the development of an epiphytic stage. Subsequent penetration in many cases involved total displacement of cortical tissue in the infected frond.     

ENTRY OF A CHLORELLA-VIRUS INTO ITS HOST CELL1

The endosymbiotic Chlorella sp. (Chlorophyceae) of Paramecium bursaria (Ciliata) can be infected by a double-stranded DNA-containing virus (Chlorella-virus) that has a phagelike entry mechanism. Electron micrographs show that soon after attachment of the virus to the algal cell wall, a hole is formed through which the viral DNA enters the alga. Biochemical studies on a European Chlorella-virus system suggest that digestion of the algal cell wall is caused by glycolytic enzymes, one of which was identified as a β-d -glucosidase. Enzymes are bound to the virus capsid and are activated only after or by the attachment of the virus to its cognate alga or to preparations of the algal cell wall. Common features of viral cell wall-digesting enzymes and algal autolysins are discussed.     

HOST-INDUCED ASSORTATIVE MATING IN HOST RACES OF THE LARCH BUDMOTH

Abstract The likelihood of sympatric speciation is enhanced when assortative mating is a by‐product of adaptation to different habitats. Pleiotropy of this kind is recognized as important in parasites that use their hosts as a long‐range cue for finding mates, but is generally assumed to have limited applicability for most other organisms. In the larch budmoth, Zeiraphera diniana (Lepidoptera: Tortricidae), sympatric host races feed on larch or pine. Zeiraphera diniana females attract males (call) by releasing host‐independent long‐range pheromones. Pheromone composition differs strongly between host races, but we show in an experimental field study that cross‐attraction can occur at a rate of 0.03–0.38. Cross‐attraction to larch females increases when they call from neighborhoods (8‐m radius) rich in pine or from pine trees. Cross‐attraction to pine females similarly increases when calling from neighborhoods rich in larch, but there is no significant effect of calling substrate. Males, as well as females, of this species preferentially alight on their own host, and in neighborhoods where their own host is common. This effect of tree species and host neighborhood on assortative mating is therefore due, at least in part, to the numbers of males of each host race present within approximately 200 m² surrounding the female. This proximity effect is enhanced by the clumped distributions of the hosts themselves. Host chemistry might also affect pheromone production and/or response directly, but we have evidence neither for nor against this. This work provides empirical evidence that host adaptation has a pleiotropic effect on assortative mating in a species with host‐independent long‐range mating signals. Sympatric speciation via pleiotropy between ecological traits and assortative mating may thus be more common than generally supposed: Clumped resource distributions and habitat choice by adults are widespread.     

寄生蜂寄主选择行为研究进展

寄生蜂是膜翅目昆虫中的重要类群,在自然界种类多,数量大。据文献报道全世界膜翅目昆虫大约有10万种”’,其中许多种类与农林害虫长期保持一定的制约关系,在害虫防治中占有重要地位。由于大量使用化学农药导致害虫的抗药性增加,利用天敌昆虫来防治害虫越来越显示出其重要性和优越性。但是,直到近20年来,寄生蜂的寄生行为才受到重视,并给予了广泛的、深入的研究”－‘’严格地讲,寄生蜂应该称为拟寄生蜂,它与通常所说的寄生昆虫像虱子、臭虫等有明显不同,主要区别在于：1．寄生仅仅发生在未成熟阶段,而成虫阶段营自由生活;2．寄…     

INVOLVEMENT OF INDOLE‐3‐ACETIC ACID PRODUCED BY THE GROWTH‐PROMOTING BACTERIUM AZOSPIRILLUM SPP. IN PROMOTING GROWTH OF CHLORELLA VULGARIS1

Involvement of indole‐3‐acetic acid (IAA), produced by the microalgae‐growth‐promoting bacteria Azospirillum brasilens and A. lipoferum, in promoting growth of the microalga Chlorella vulgaris Beij. was studied. Four wildtype strains of Azospirillum and their IAA‐deficient mutants were co‐immobilized with C. vulgaris in alginate beads. Cultures were grown in synthetic growth medium supplemented with tryptophan. Growth promotion of microalgae and production of exogenous IAA by Azospirillum spp. were monitored. All wildtype Azospirillum spp. produced significant but varying amounts of IAA, while their mutant forms produced significantly less. The results demonstrated a significant growth promotion in Chlorella cultures when immobilized with the four wildtype strains of Azospirillum, while very low or no enhanced growth was induced by the four IAA‐deficient mutants, compared to when C. vulgaris is immobilized alone. A complementation experiment, where an IAA‐attenuated mutant (A. brasilense SpM7918) was supplemented with IAA produced by its parental wildtype strain (A. brasilense Sp6), restored growth promotion in the microalgae‐mutant culture.     

ROLE OF EVOLVED HOST BREADTH IN THE INITIAL EMERGENCE OF AN RNA VIRUS

Understanding how evolution promotes pathogen emergence would aid disease management, and prediction of future host shifts. Increased pathogen infectiousness of different hosts may occur through direct selection, or fortuitously via indirect selection. However, it is unclear which type of selection tends to produce host breadth promoting pathogen emergence. We predicted that direct selection for host breadth should foster emergence by causing higher population growth on new hosts, lower among‐population variance in growth on new hosts, and lower population variance in growth across new hosts. We tested the predictions using experimentally evolved vesicular stomatitis virus populations, containing groups of host‐use specialists, directly selected generalists, and indirectly selected generalists. In novel‐host challenges, viruses directly selected for generalism showed relatively higher or equivalent host growth, lower among‐population variance in host growth, and lower population variance in growth across hosts. Thus, two of three outcomes supported our prediction that directly selected host breadth should favor host colonization. Also, we observed that indirectly selected generalists were advantaged over specialist viruses, indicating that fortuitous changes in host breadth may also promote emergence. We discuss evolution of phenotypic plasticity versus environmental robustness in viruses, virus avoidance of extinction, and surveillance of pathogen niche breadth to predict future likelihood of emergence.     

一株极端环境光合细菌的生理特性研究

从山西运城盐厂解化池分离获得一株嗜盐嗜碱细菌,编号为Y。其纯培养物经形态学、生理生化特性和DNA G+C含量等特征分析,结果表明,该菌株可在盐度ρ(NaCl)/gL-1为160和pH9.0碱性条件下生长。单细胞为杆状,大小为0.4-0.8×0.9-1.5μm。二分裂繁殖。革兰氏阴性。光合内膜为片层堆积并与细胞质膜相连,但并不与细胞质膜平行。细胞含有细菌叶绿素a,液体培养物呈玫瑰红色。Y菌株不仅可将硫化物氧化为元素硫沉积于细胞外,也可光同化多种有机物,并具有固氮和产H2特性。DNA中 G+C含量为61.6%。根据以上鉴定特征及相关资料,Y菌株应归于嗜盐红螺菌属(Halorhodospira)。但其生长所依赖的盐度、pH、细胞内色素成分及鞭毛着生方式与该属正式承认的3个种有明显的不同。该菌株独特的生理生化特性,对于极端环境微生物的资源开发和利用有重要的理论意义和应用价值。     

EXTRACELLULAR LYSIS OF THE BLUEGREEN ALGA PHORMIDIUM LURIDUM BY BDELLOVIBRIO BACTERIOVORUS1

When either cells of the bacterium, Bdellovibrio bacteriovorus (Stolp & Starr), strain 15143, or a heat-resistant lytic factor derived from these cells is added to viable cultures of Phormidium luridum var. olivacea Boresch all the algal cells underwent gradual lysis. This effect was obtained with a mean initial bdellovibrio:algal cell ratio of 7.5:1. When P. luridum was mixed with the bdellovibrio cultures the algal chlorophyll content showed an 8-fold decrease. Concomitantly, this interspecies interaction caused, a 75% inhibition of algal photosynthesis after-4 h. Heat, treatment of the B. bacteriovorus culture supernatant fluid increased its ability to inhibit photosynthesis approximately 14%. Light, microscopy showed pale granules and intracellular spaces to form in the P. luridum within 16 h after adding the bdellovibrio lytic factor. Subsequent morphological changes included the development of large intracellular spaces, intercellular spaces, spheroplast formation and finally Complete lysis of the algal cells.     

蚜茧蜂产卵对寄主龄期的选择与其对蚜虫种群影响大小的计算机模拟研究

利用苦苣菜蚜-苦苣菜蚜茧蜂混合种群系统模拟模型,通过改变种群参数、初始虫量和温度条件,探讨了蚜茧蜂产卵选择寄主龄期特性对整个种群系统行为的影响,并比较了这一特性与蜂产卵量两者的相对重要性。结果表明,蜂产卵对寄主龄期选择特性的改变可明显改变其对蚜虫种群增长影响的程度,当产卵选择特性改变,产卵量在多数情况下必须要大幅度直至成倍的增减,才能补偿其对蚜虫种群的控制作用。不过,当蜂产卵嗜好三龄、二龄、四龄若蚜时(这在蚜茧蜂中较普遍),其作用和产卵无选择性时基本相似。     

藏药的历史及研究进展

藏族是分布于我国青藏高原的一个古老民族。藏医药学的文字记载始于1300多年前。八世纪以后流传下来的藏医药文献很多,本文就其中6种进行论述,着重指出：①对藏药正品的考证来说,十七八世纪之交时桑杰嘉措主编的《蓝琉璃》和与之配套的彩色药物挂图是很好的资料。②丹增彭措著的《晶珠本草》成书年代宜暂作1743士9年,而不是目前一些文献流行的1840年或1800年。③丹增再传弟子蒙古人绛贝多杰著藏文本草《正确认药图鉴》,约半数附图注汉文药名,此书能反映当时蒙医使用藏药名的实际情况。但不是全部藏药,且导致后世汉译与英译古藏医药文献时对藏药名的误译,但其正文中引用许多藏医药名著对该药的生境、形态等描述而为《晶珠本草》未记载的,对考证藏药仍有重要作用。本文还就七十年代两种藏药方剂405个,统计出现20次以上的最常用藏药50种,列表供参考。此外还介绍近30年来对藏药的调查开发情况。文末附参考文献121篇。     

ROLE OF GLUTAMATE DEHYDROGENASE AND GLUTAMINE SYNTHETASE IN CHLORELLA VULGARIS DURING ASSIMILATION OF AMMONIUM WHEN JOINTLY IMMOBILIZED WITH THE MICROALGAE‐GROWTH‐PROMOTING BACTERIUM AZOSPIRILLUM BRASILENSE1

Enzymatic activities of glutamate dehydrogenase (GDH) and glutamine synthetase (GS) participating in the nitrogen metabolism and related ammonium absorption were assayed after the microalga Chlorella vulgaris Beij. was jointly immobilized with the microalgae‐growth‐promoting bacterium Azospirillum brasilense. At initial concentrations of 3, 6, and 10 mg · L^?1 NH₄⁺, joint immobilization enhances growth of C. vulgaris but does not affect ammonium absorption capacity of the microalga. However, at 8 mg · L^?1 NH₄⁺, joint immobilization enhanced ammonium absorption by the microalga without affecting the growth of the microalgal population. Correlations between absorption of ammonium per cell and per culture showed direct (negative and positive) linear correlations between these parameters and microalga populations at 3, 6, and 10 mg · L^?1 NH₄⁺, but not at 8 mg · L^?1 NH₄⁺, where the highest absorption of ammonium occurred. In all cultures, immobilized and jointly immobilized, having the four initial ammonium concentrations, enzymatic activities of Chlorella are affected by A. brasilense. Regardless of the initial concentration of ammonium, GS activity in C. vulgaris was always higher when jointly immobilized and determined on a per‐cell basis. When jointly immobilized, only at an initial concentration of 8 mg · L^?1 NH₄⁺ was GDH activity per cell higher.     

SPECIES OF ANTITHAMNION (RHODOPHYCEAE,CERAMIACEAE) OCCURRING ON THE SOUTHEAST AFRICAN COAST (NATAL)1

Three species of Antithamnion Naegeli were previously known from Natal, all reported since 1984. A more thorough collection of the flora in recent months has revealed that there are nine species in Natal, four of which are newly described. Vegetative characteristics are emphasized in this study of the taxonomy of Antithamnion, the most important being (1) size of axial cells, (2) form of whorl-branchlets, (3) size of whorl-branchlet basal cells, (4) size and shape of whorl-branchlet terminal cells, (5) size and position of gland cells, (6) primary or secondary derivation of indeterminate lateral branches, and (7) the relationship of primary indeterminate branches, if present, to normal arrangement of whorl-branchlets. Two closely related species, A. diminuatum Wollaston and A. eliseae sp. nov. have been grown in laboratory culture allowing for testing of stability and reliability of vegetative characteristics for use in taxonomic studies. Conclusions are that these criteria can be effectively used for these purposes. In addition to A. eliseae, A. nematocladellum, A. pterocladellum and A. adenocladellum also are described as new species. A tropical species previously known from the Caribbean and Red Seas, A. Iherminieri Nasr, a species previously recorded from Japan, A. secundum Itono, a species previously known from California and Japan, A hubbsii Dawson, and two species from Australia, A. diminuatum Wollaston and A. divergens (J. Agardh) J. Agardh, are also described from Natal.     

SPECIES OF ANTITHAMNION (RHODOPHYCEAE,CERAMIACEAE) OCCURRING ON THE SOUTHEAST AFRICAN COAST (NATAL)1

Three species of Antithamnion Naegeli were previously known from Natal, all reported since 1984. A more thorough collection of the flora in recent months has revealed that there are nine species in Natal, four of which are newly described. Vegetative characteristics are emphasized in this study of the taxonomy of Antithamnion, the most important being (1) size of axial cells, (2) form of whorl-branchlets, (3) size of whorl-branchlet basal cells, (4) size and shape of whorl-branchlet terminal cells, (5) size and position of gland cells, (6) primary or secondary derivation of indeterminate lateral branches, and (7) the relationship of primary indeterminate branches, if present, to normal arrangement of whorl-branchlets. Two closely related species, A. diminuatum Wollaston and A. eliseae sp. nov. have been grown in laboratory culture allowing for testing of stability and reliability of vegetative characteristics for use in taxonomic studies. Conclusions are that these criteria can be effectively used for these purposes. In addition to A. eliseae, A. nematocladellum, A. pterocladellum and A. adenocladellum also are described as new species. A tropical species previously known from the Caribbean and Red Seas, A. lherminieri Nasr, a species previously recorded from Japan, A. secundum Itono, a species previously known from California and Japan, A hubbsii Dawson, and two species from Australia, A. diminuatum Wollaston and A. divergens (J. Agardh) J. Agardh, are also described from Natal.     

大蚜科系统发育及与寄主植物关系演变的研究(同翅目:蚜虫类)(英文)

本文根据大蚜科２０个代表属的２６个形态学及生态学特征对大蚜科系统发育及与寄主植物演变关系进行了研究。确认了传统的长足大蚜亚科及长跗蚜亚科为单系群,传统的大蚜亚科为多系群。建议保留传统的三个亚科,即长足大蚜亚科、长跗蚜亚科和大蚜亚科。在长足大蚜亚科中重新进行了族的划分,即长足大蚜亚科包括长足大蚜族、细长大蚜族和钝喙大蚜族。另外,推测大蚜科祖先共同的原始寄主植物为阔叶林,而非针叶林或其它类植物。