Host plant trichomes and the advantage of being big: progeny size variation of the pipevine swallowtail

1. Plants possess numerous traits that confer resistance against insect herbivores, and herbivores, in turn, can evolve traits to ameliorate the effectiveness of these traits. The pipevine swallowtail, Battus philenor, is an extreme specialist on plants in the genus Aristolochia. The only host plant available to the California population of B. philenor is A. californica. Aristolochia californica is distinct from most other B. philenor host plants in that it is pubescent. 2. The progeny of B. philenor are larger in California compared with populations examined in Texas. Size differences persist throughout larval development. 3. Regardless of maternal host plant, population differences in progeny size persist, and crosses between California (large progeny) and Texas (small progeny) B. philenor populations resulted in offspring producing intermediate sized progeny, indicating a heritable component to progeny size variation. 4. California neonate caterpillars more easily overcame the trichomes of A. californica compared with Texas neonates. When trichomes were removed from A. californica, time to feeding establishment was reduced for caterpillars from both populations. Texas caterpillars established feeding sites on A. californica with trichomes removed, in the same time required to establish feeding on their non‐pubescent host plant, A. erecta. 5. This study shows that plant trichomes might impose selection pressure on progeny size.     

SEASONAL PRODUCTIVITY OF TWO RED ALGAE IN A CENTRAL CALIFORNIA KELP FOREST1

The in situ productivity of Botryocladia pseudodichotoma (Farl.) Kyl. and Rhodymenia californica var. californica Kyl., two common understory macrophytes in Macrocystis pyrifera (L.) C. Ag. forests, was determined once per month for one year. Gross productivity for B. pseudodichotoma was highest in October (1.23 mgC · g dry wt.^?1· h^?1), but rates were generally greater in spring and lower in summer. Respiration was variable throughout the year, especially in proportion to gross productivity. Gross productivity for R. californica var. californica was also highest in October (4.62 mgC · g dry wt.^?1· h^?1), and lowest in summer. Respiration was highly variable throughout the year. Deep (11 m) populations o/B. pseudodichotoma had 50% higher productivity than shallow (3 m) populations when incubated in shallow water, and 45% higher productivity when incubated in deep water. Populations of B. pseudodichotoma growing in shade at 3 m had 77% higher productivity than populations growing in sun at the same depth when incubated in a sun exposed location at 3 m. Respiration of the shade-adapted plants was only one-half that of the sun-adapted plants. In comparison with similar studies in other sub-tidal communities, net productivity of these two understory red algae is somewhat lower. Lack of strong seasonal productivity patterns and the highly variable underwater light regime suggests that understory algae may be adapted for rapid growth during short periods of high light, regardless of the time of year.     

EVOLUTION OF UNISEXUALITY IN THE HAWAIIAN FLORA: A TEST OF MICROEVOLUTIONARY THEORY

The evolution of separate sexes as a means of avoiding self-fertilization requires the controversial coexistence of large inbreeding depression and high selfing rate in the ancestral hermaphrodite population. Fitness components of adult females and hermaphrodites in nature, of their open-pollinated progeny, and of experimental selfs and outcrosses onto hermaphrodites were compared in endemic Hawaiian Bidens sandvicensis, all of whose known populations are gynodioecious, consisting of a mixture of females and hermaphrodites. Multilocus selfing rates of hermaphrodites were also estimated, and sex morph ratio monitored over four seasons in three populations of B. sandvicensis and one population of gynodioecious B. cervicata. Total mean inbreeding depression in seed set (in the glasshouse), germination rate (in an open-air nursery on Kauai), and first year survivorship and fecundity in the field were estimated as 0.94 (SE 0.04), and occurred primarily in drought months. Lower survivorship and fecundity of selfs were partially explained by their consistently smaller size. Open-pollinated seed of females had significantly lower germination rate, proportion flowering, and fecundity than outcrossed progeny of hermaphrodites, suggesting moderate biparental inbreeding in females and a lack of any non-outcrossing advantage to progeny of females. In all fitness components, open-pollinated progeny of hermaphrodites were inferior to those of females and to outcrosses, and in most components were superior to selfs. Total performance of open-pollinated progeny of females relative to those of hermaphrodites was calculated as 2.3 (SE = 0.4), but since inflorescences of females also set 20% to 50% more seed than those of hermaphrodites, their total relative ovule success was estimated as 3.2 (SE = 0.5). If inheritance of male sterility is nuclear, this superiority is sufficient to maintain females in frequencies over 20% in populations, whose actual frequencies ranged from 14% to 33%. In four populations, selfing rates of hermaphrodites, assayed in seedlings, were 0.50, 0.45, 0.25, and 0.30, but since substantial inbreeding depression occurred prior to germination, the mean selfing rate of hermaphrodite ovules exceeded 0.57. Female frequencies were significantly higher in the two populations with higher hermaphrodite selfing rate. These results suggest that inbreeding depression can exert a profound influence on the mating system of self-compatible plants on Hawaii and perhaps other oceanic islands, and can be sufficiently strong to electively favor the elimination of the male function.     

Differential Parasitism of Native and Introduced Snails: Replacement of a Parasite Fauna

The role of parasites in a marine invasion was assessed by first examining regional patterns of trematode parasitism in the introduced Japanese mud snail, Batillaria cumingi (= B. attramentaria), in nearly all of its introduced range along the Pacific Coast of North America. Only one parasite species, which was itself a non-native species, Cercaria batillariae was recovered. Its prevalence ranged from 3 to 86%. Trematode diversity and prevalence in B. cumingi and a native sympatric mud snail, Cerithidea californica, were also compared in Bolinas Lagoon, California. Prevalence of larval trematodes infecting snails as first intermediate hosts was not significantly different (14% in B. cumingi vs 15% in C. californica). However, while the non-native snail was parasitized only by one introduced trematode species, the native snail was parasitized by 10 native trematode species. Furthermore, only the native, C. californica, was infected as a second intermediate host, by Acanthoparyphium spinulosum(78% prevalence). Given the high host specificity of trematodes for first intermediate hosts, in marshes where B. cumingi is competitively excluding C. californica, 10 or more native trematodes will also become locally extinct.     

Feedbacks of Soil Inoculum of Mycorrhizal Fungi Altered by N Deposition on the Growth of a Native Shrub and an Invasive Annual Grass

Anthropogenic nitrogen (N) deposition causes shifts in vegetation types as well as species composition of arbuscular mycorrhizal (AM) fungi and other soil microorganisms. A greenhouse experiment was done to determine whether there are feedbacks between N-altered soil inoculum and growth of a dominant native shrub and an invasive grass species in southern California. The region is experiencing large-scale loss of Artemisia californica shrublands and replacement by invasive annual grasses under N deposition. Artemisia californica and Bromus madritensis ssp. rubens were grown with soil inoculum from experimental plots in a low N deposition site that had (1) N-fertilized and (2) unfertilized soil used for inoculum, as well as (3) high-N soil inoculum from a site exposed to atmospheric N deposition for four decades. All treatments plus a nonmycorrhizal control were given two levels of N fertilizer solution. A. californica biomass was reduced by each of the three inocula compared to uninoculated controls under at least one of the two N fertilizer solutions. The␣inoculum from the N-deposition site caused the greatest growth depressions. By contrast, B.␣madritensis biomass increased with each of the three inocula under at least one, or both, of the N solutions. The different growth responses of the two plant species may be related to the types of AM fungal colonization. B. madritensis was mainly colonized by a fine mycorrhizal endophyte, while A. californica had primarily coarse endophytes. Furthermore, A. californica had a high level of septate, nonmycorrhizal root endophytes, while B. madritensis overall had low levels of these endophytes. The negative biomass response of A. californica seedlings to high N-deposition inoculum may in part explain its decline; a microbially-mediated negative feedback may occur in this system that causes poor␣seedling growth and establishment of A.␣californica in sites subject to N deposition and B. madritensis invasion.     

Competitive displacement and predation between introduced and native mud snails

Experimental field and laboratory studies indicate that Cerithidea californica, a native mud snail, is restricted to only a portion of its normal habitat range in San Francisco Bay as a result of direct interactions with an introduced ecological equivalent, Ilyanassa obsoleta. The native snail typically inhabits marsh pans, tidal creeks and mudflats in estuaries along the Pacific coast. However, in San Francisco Bay it is confined to pans for most of the year, while the non-native snail inhabits the creeks and mudflats. Experiments and field monitoring demonstrate that this abnormal distribution pattern is caused by 1) interference competition for space in the form of an adult-adult behavioral avoidance by C. californica in the presence of invading I. obsoleta, and 2) predation by I. obsoleta on the eggs and juveniles of C. californica. The competitive exclusion of C. californica by I. obsoleta has not led to the extinction of the native snail because of the existence of a refuge for C. californica in pan habitats, beyond the physiological tolerances of I. obsoleta. As a consequence of the seasonal migrations of both species and changes in abiotic factors along the habitat gradient, repeated competitive displacements, rather than a one-time competitive exclusion, are observed between these two species. This is the first documented case of the competitive displacement of an endemic marine intertidal species by an introduced ecological equivalent.     

A time series and geographical analysis of population dynamics of the red-backed vole in Hokkaido,Japan

Summary A time series and geographical analysis of the long term (25-years and 16-years) census data of the red-backed vole, Clethrionomys rufocanus bedfordiae, populations in Hokkaido, Japan was carried out. Eighty seven populations from all over Hokkaido were grouped into the following 4 types according to their flucturation patterns: type A: low density-constant type; type B: medium density-gradual increase type; type C: medium density-wavy change type; type D: high density-large amplitude type. The border between type B and type C was not clear. Although the distribution of the fluctuation types did not show any geographical cline, the high density type (type D) occurred in limited areas where the winter was severe and spring came later and almost all the populations in the Oshima peninsula were the low density type (type A). The most common type of population in Hokkaido, type C, greatly fluctuated from year to year with the maximum density level/the minimum one being over 10. The periodicity of the peak years was not statistically significant, although peaks often occurred at 3 or 4 year intervals. The population grew from spring to autumn in almost all years so that the pattern of the seasonal change was qualitatively constant. The population density levels in spring were not significantly different between peak years and others, while those in autumn were greatly different between them, so that the population growth rates from spring to autumn were variable from year to year. This differential pattern was also found between high and low density areas.     

Flavonoid Pigments in Rice Leaves and the Isolation of Glucotricin

The distribution of flavonoid pigments in the leaves of indica and japonica type rice plants was studied by paper chromatographic and electrophoretic techniques. A fluorescent flavoniod compound prominent in the leaves of indica was isolated in a crystalline form and identified as glucotricin (tricin-7-β-glucoside), the structure of which was characterized by Kuwatsuka in 1962.     

苎麻疫霉有性生殖导致菌落形态和生长速率在无性后代持续变异的研究*

研究了苎麻疫霉（PhytophthoraboehmeriaeSawada）菌株JS-5自交S1代单卵孢株的菌落形态和生长速率在其单游动孢子无性系后代的遗传与变异。结果表明,亲本菌株JS-5的菌落形态和生长速率在连续4代单游动孢子无性系后代稳定遗传,而该菌株的自交S1代的约2／3单卵孢株的上述性状在其单拘无性后代中发生分离,且上述性状的分离在无性单孢后代中至少可连续保持3～4代。本研究结果提示,苎麻疫霉有性生殖导致上述性状的变异,除有性生殖过程中的基因重组外,有性生殖还诱导产生了一种新的机制参与上述性状遗传与变异的调控。本研究还观察到供试菌株及其后代所产生的游动孢子绝大多数细胞内只含有1个细胞核,表明上述机制与异核现象无关。有性生殖导致生物学性状在随后的无性后代中发生持续变异可能是苎麻疫霉生物学性状遗传多样性的重要机制之一。     

不同群体马尾松核型分化式样

<正> 马尾松(Pinus massoniana Lamb.)是我国分布最广,数量最多的一个树种。近年来对马尾松核型做了不少研究,但结果不尽一致。究其原因:一是取材产地和方法不同,有从单株上取材,有从多株混合种子作试材;二是取材产地局限。马尾松分布南自广西南部,东至福建东北部,西到四川东部大相岭东坡,北达安徽大别山以南及陕西汉水流域以南,沿海长江中下游分布在海拔700米以下,在西部地区可达海拔1500米以上。在这样广     

IS ORGANELLE DNA STRICTLY MATERNALLY INHERITED? POWER ANALYSIS OF A BINOMIAL DISTRIBUTION

Although numerous exceptions are well known, organelle DNA is often exclusively or predominantly maternally inherited. In such cases, maternal inheritance is often documented by the study of progeny derived from crosses between parents with distinguishable organelle genotypes. These studies generally detect a single type of progeny, those containing organelles derived from only one of the parents; no progeny containing organelles derived either from the opposite parent or from both parents are found. However, in most cases the number of progeny examined is quite small. I present a simple binomial model of organelle inheritance to determine the power of such experiments to distinguish between the hypothesis of strict maternal inheritance and a more complex hypothesis involving the presence of both organelle types within a progeny array. Extremely large sample sizes of progeny are required to distinguish these two hypotheses with reasonable confidence when organelle transmission is not strictly maternal. As a result, studies involving simple progeny testing may be misleading. Larger samples, more complex breeding designs, or more sensitive molecular methods are required to document adequately strict maternal inheritance of organelles.     

Grazing intensity influences the strength of an associational refuge on temperate reefs

Recent studies have emphasized the role of positive interactions in ecological communities, but few have addressed how positive interactions are mediated by abiotic stress and biotic interactions. Here, I investigate the effect of a facilitator species on the abundance of macroalgae over a gradient of herbivory. Grazing by sea urchins can be intense on temperate reefs along the California coast, with benthic macroalgae growing exclusively in physical refuges and interspersed within colonies of the strawberry anemone, Corynactis californica. Field experiments indicated that the net effect of C. californica on turf algae was strongly nonlinear over a gradient in density of sea urchins. At low intensities of urchin grazing, the anemone and macroalgae competed for space, with algae capable of overgrowing C. californica. At intermediate grazing intensities, C. californica provided a refuge for turf algae but not for juvenile kelp. Neither turf algae nor kelp benefited from the presence of C. californica at the highest levels of grazing intensity, as sea urchins consumed nearly all macroalgae. The hump-shaped effect observed for C. californica contrasts with the prevailing view in ecological theory that positive interactions are more common in harsh environmental conditions. The results reported here qualify this view and underscore the need to evaluate positive interactions over a range of abiotic stress and consumer pressure.     

Aerobic growth and toxigenicity ofClostridium botulinum types A and B

Clostridium botulinum types A and B cultured in association with avian skin flora, had similar growth patterns under both aerobic and anaerobic conditions. The selective “C. botulinum isolation” (CBI) medium was found to be especially useful for the recovery and quantitation of small numbers of type A or type B organisms from the mixed cultures. Enzyme immunoassay in conjunction with conventional mouse biossay provided a practical means for the quantitation of toxigenicity ofC. botulinum in avian skin cultures. The amount of toxin produced by type A was always higher than that produced by type B strains. The aerobically incubated type A or type B cultures appeared to be less toxigenic than cultures incubated anaerobically.     

Co-Occlusion and Persistence of a Baculovirus Mutant Lacking the Polyhedrin Gene

A co-occlusion process was evaluated as a commercially and ecologically acceptable strategy for the development of genetically improved baculovirus insecticides. Coinfection of Spodoptera frugiperda (IPLB-SF-21) tissue culture cells with Autographa californica nuclear polyhedrosis virus (AcMNPV) and an AcMNPV mutant (Ac-E10) lacking the polyhedrin gene resulted in occlusion of both virus types within polyhedra. The amount of occluded Ac-E10 virions in progeny polyhedra populations during serial passage in Trichoplusia ni larvae was evaluated. Maintenance of the mutant in progeny polyhedra required polyhedra inocula containing equal numbers of the two virus types at a high dose. A significant reduction in occluded mutant nucleocapsids occurs with inoculum levels below a 100% lethal dose. At inoculum levels below a 30% lethal dose, the majority of fourth-instar larvae were infected with only one type of virus. The commercial application and ecological advantages of the co-occlusion process are discussed.     

Patterned Arrays of Intramembranous Particles in the Bristle Cilia of Three Different Species of Euplotes1

Freeze-fractured cells of three marine species of Euplctes (E. crassus, E. raikovi, and E. rariseta) show bristle cilia with patterned arrays of intramembranous particles. Such arrays are essentially of three types, in different positions along the bristle shaft. One array is located near the bristle base and shows a plate-like shape. It appears in a close spatial correspondence with the lasiosome network, which is a structure consisting of interconnected electron-dense bodies lying in between the peripheral axonemal doublets and the bristle membrane. The second type of array, apparently typical of only E. raikovi, consists of eight to ten longitudinal rows of particles that occupy most of the intermediate portion of the bristle. The third type of array appears differently shaped in different species and occurs at the bristle apex.     

gerud1.0: a computer program for the reconstruction of parental genotypes from progeny arrays using multilocus DNA data

We have no standard computer algorithm for the reconstruction of parental genotypes from the data generated by molecular studies of progeny arrays. Here I present a computer program that uses the multilocus genotypes of parents and offspring to reconstruct the genotypes of unknown parents contributing gametes to a progeny array for which one parent is known a priori. A second program performs simulations to assess the reliability of the algorithm under various scenarios. These programs will aid scientists engaged in parentage analyses, particularly in species with large clutches.     

Isolation and structural determination of 13 flavonoid glycosides in Hibiscus esculentus (okra)

Eleven flavonol glycosides and two anthocyanins, only one of which was previously identified, were isolated from the flower petals of okra, Hibiscus esculentus L. On the basis of chromatographic, spectral, and degradative evidence, the following structural assignments were made: quercetin 4′-glucoside, quercetin 7-glucoside, quercetin 5-glucoside, quercetin 3-diglucoside, quercetin 4′-diglucoside, quercetin 3-triglucoside, quercetin 5-rhamnoglucoside, gossypetin 8-glucoside, gossypetin 8-rhamnoglucoside, gossypetin 3-glucosido-8-rhamnoglucoside, cyanidin 4′-glucoside, and cyanidin 3-glucosido-4′ glucoside. Some evidence was obtained of a pentahy-droxy, monomethoxy-flavone glycoside. The total flavonoid content in the red portion of the petal was 0.48% of fresh weight; that in the white portion was 2.51%. The two anthocyanins comprised 28.5% of the flavonoid content of the red flower but only a trace of the content of the white.     

A CHEMOSYSTEMATIC STUDY OF SELECTED TAXA OF CAPSICUM

Six taxa of Capsicum were chosen for a comparative chemosystematic study. A “key” individual from each taxon was selected for intensive chemical investigation. Thirteen flavonoids were isolated from leaf material and characterized by paper chromatography and absorption spectroscopy. The C-glycosylflavones vitexin and isovitexin, and orientin and iso-orientin, as well as O-glycosides of the flavones apigenin, luteolin, and chrysoeriol, were isolated from the key individuals. Chromatographic analysis of collections from various regions of South America, Central America, and Mexico showed in general that flavonoid variability is more common in cultivated taxa than in wild. Three groups of Capsicum were recognized and the main systematic conclusions were: (1) The white-flowered taxa in Group I, C. baccatum var. baccatum and C. baccatum var. pendulum, have identical flavonoids, corroborating previous conclusions that they are one species. The absence of chrysoeriol in this group separates it from Groups II and III. (2) The purple-to-white-flowered C. eximium var. eximium and C. eximium var. lomenlosum, Group II, have a complex flavonoid chemistry which appears to link Groups I and III. (3) Two purple-flowered species, C. cardenasii and C. pubescens, Group III, are chemically distinct from the other taxa examined.     

Anaerobic transformation of quercetin-3-glucoside by bacteria from the human intestinal tract

From human feces two phenotypically different types of bacteria were isolated on quercetin-3-glucoside as carbon and energy source. Isolates of one type were identified as strains of Enterococcus casseliflavus. They utilized the sugar moiety of the glycoside, but did not degrade the aglycon further. The sugar moiety (4 mM) was fermented to 5.5 ± 2.1 mM formate, 2.1 ± 0.7 mM acetate, 1.6 ± 0.3 mM l-lactate, and 1.3 ± 0.4 mM ethanol. The second type of isolate was identified as Eubacterium ramulus. This organism was capable of degrading the aromatic ring system. Growing cultures of Eubacterium ramulus converted 5 mM quercetin-3-glucoside to 1.7 ± 0.6 mM 3,4-dihydroxyphenylacetic acid, 7.6 ± 1.0 mM acetate, and 4.0 ± 0.4 mM butyrate. Molecular hydrogen, 3,4-dihydroxybenzaldehyde, and ethanol were detected in small amounts. Phloroglucinol was a transient intermediate in the breakdown of quercetin-3-glucoside. Eubacterium ramulus did not grow on the aglycon quercetin or the ring-fission intermediate phloroglucinol, but cleaved the flavonoid ring system when glucose was present as a cosubstrate. The most probable number of quercetin-3-glucoside-degrading bacteria determined in nine human fecal samples was 10⁷–10⁹/g dry mass. Isolates from these experiments were all identified as Eubacterium ramulus. Received: 9 July 1998 / Accepted: 10 November 1998     

Enteroviral aseptic meningitis in Japan, 1981-1991. A report of the National Epidemiological Surveillance of Infectious Agents in Japan.

In Japan, aseptic meningitis cases due to enterovirus infections increase every summer in various degrees with an incidence peak usually in July. During the past 11 years from 1981 through 1991, a total of 8,595 enterovirus isolations from aseptic meningitis cases were reported from 54 participating laboratories. Eight enterovirus types caused large epidemics; more than 100 isolations of each type from aseptic meningitis cases were reported for every epidemic year of the respective type. They were coxsackievirus (C) types B3 and B5, echovirus (E) types 4, 6, 7, 9, 18 and 30. Among these, the highest meningitis-associating frequency was reported for E30, representing 82.6% of the total isolations reported for the type during this period, followed by E4, 71.1%. The frequencies of E9, E7, E6 and CB5 were in a range from 54.5% to 44.4%, while that of E18 was 37.7% and that of CB3 21.0%. During the epidemics, enterovirus-associated meningitis was most frequently reported among children of 4-7 years of age. High frequencies were also shown in infants less than 1-year of age in some types. A total of 4,240 enteroviruses were isolated from cerebrospinal fluid of aseptic meningitis cases, representing 49.3% of the cases with enterovirus isolation.