VARIABILITY IN TEMPERATURE AND HISTORICAL PATTERNS IN REPRODUCTION IN THE FUCUS DISTICHUS COMPLEX (HETEROKONTOPHYTA; PHAEOPHYCEAE): IMPLICATIONS FOR SPECIATION AND THE COLLECTION OF HERBARIUM SPECIMENS1

Natural and anthropogenic‐induced fluctuations in temperature can have profound effects on an organism's reproduction. The potential of herbarium collections for detecting changes in the timing of reproduction associated with interannual fluctuations in temperature from 1905 to 2003 was assessed in several taxa in the Fucus distichus (L.) emend. Powell complex from northern New England. Data were also used to evaluate whether air and/or sea temperature and North Atlantic Oscillation indices can cause overlap in the reproductive seasonalities of these taxa, a potential mechanism that prevents speciation. For all taxa, there was much variability in reproductive seasonalities among years. Discerning potential correlations with air or sea temperature was difficult because of a suspected bias to collect reproductive specimens at times when most of the population was nonreproductive. Nevertheless, there was a trend for seawater temperature to explain aseasonal reproduction for some taxa. Moreover, the existing archive (1895–2003) shows that the reproductive seasons of these taxa often overlap, and we suggest that interannual variability in temperature may often inhibit speciation. Suggestions also include archive of both reproductive and vegetative materials as well as coordinated sampling in critical biogeographic regions. No one investigator or institution can accomplish this, but phycological societies could organize and sustain such efforts.     

THE STRUCTURE AND REPRODUCTION OF GLAPHYRYMENIA PUSTULOSA

Norris , R. E. (U. Minnesota, Minneapolis.) The structure and reproduction of Glaphyrymenia pustulosa. Amer. Jour. Bot. 48(3): 262–268. Illus. 1961.—Specimens of Glaphyrymenia pustulosa, a red alga from Australia that has seldom been found, were collected recently. The specimens were examined particularly with respect to development of the vegetative tissues and the formation of the female reproductive apparatus and gonimoblast. The vegetative structure is primitive in the Kallymeniaceae and structural characteristics are present that are similar to the Cryptonemiaceae and Dumontiaceae. The female reproductive system has a monocarpogonial carpogonial branch apparatus and an auxiliary cell that is borne on a separate system that does not have a carpogonial branch. After fertilization, stages in the development of the gonimoblast are similar to those of Kallymenia and Pugelia.     

THEORY OF MAST REPRODUCTION IN PLANTS: STORAGE-SIZE DEPENDENT STRATEGY

The amount of available resource can be considered to restrict mast seeding behavior in plants, regardless of the cause of masting itself. The reproductive strategy of a plant that has stopped growing, but continues to maintain a constant size, is based on the allocation of assimilated resources between reproduction and storage. If both plant death and population growth rates are constant, the plant strategy is dependent only on its own storage size. Conditions for the evolution of mast reproduction were analyzed under both constant and varying environments, from the view point of storage-size dependent strategy, which is influenced by three parameters: the advantage coefficient of mast seeding, β; the cost coefficient of delayed seeding, γ; and the assimilation rate, P. The model indicated that: (1) mast seeding evolves only with a greater than linear increase in reproductive success with effort (β > 1) under both constant and varying environments; (2) in mast seeding, a critical storage size, S_c*, occurs, above which plants utilize all storage for reproduction; (3) in a constant environment, S_c* increases with increasing β and P and/or decreasing γ; (4) concomitant with (3), an intermasting period, τ, also increases with increasing β and decreasing 7, but is independent of P; (5) in a varying environment, S_c* and the average of τ increase with increasing variance of the assimilation rate, P; and (6) concomitant with (5), the intermasting period has a certain probability distribution. In addition, reproductive synchrony within the population and the relationship between mast seeding and species diversity are discussed.     

SOME FACTORS AFFECTING SEXUAL REPRODUCTION OF APHANOMYCES EUTEICHES

Papavizas , G. C, and C. B. Davey . (USDA, ARS, Crops Res. Div., Beltsville, Maryland.) Some factors affecting sexual reproduction of Aphanomyces euteiches. Amer. Jour. Bot. 47(10) : 884–889. Illus. 1960.—Oospores of Aphanomyces euteiches Drechsler were consistently formed in abundance on a medium (SM–2) consisting of mineral salts, D-glucose, thioglycolic acid, Difco “Special Agar-Noble,” and a mixture of amino acids added in proportions found in powdered yeast extract. The isolates of A. euteiches studied differed in their nutritional requirements for sexual reproduction. Isolates 4 and 7 formed oospores abundantly on SM–1 which was smiliar to SM–2 except that DL-glutamic acid was substituted for the amino acid mixture. Isolate 572 did not form oospores on medium SM–1 except when DL-methionine was substituted for thioglycolic acid. Sexual reproduction of isolates 4 and 7 was observed at a wider concentration range of reduced-sulfur-containing compounds than that of isolate 572. Sexual reproduction of the 3 isolates studied was influenced in a dissimilar way by varying concentrations of D-glucose and DL-glutamic acid, or by varying concentrations of D-glucose and of the amino acid mixture. The optimal sugar carbon/amino nitrogen ratio range for sexual reproduction of isolate 572 was about 5–22, whereas that of isolates 4 and 7 was 15–180. The pH range for sexual reproduction was as wide as that for growth. An acid reaction was more favorable than a neutral or alkaline one. The optimal pH range was 4.9–5.4. Vitamins were not essential.     

SEXUAL REPRODUCTION OF PERIDINIUM GATUNENSE (DINOPHYCEAE)1

Sexual reproduction was induced in the dinoflagellate Peridinium gatunense Nygaard when exponentially growing cells were inoculated into nitrogen deficient medium. Small thecate cells produced by division of vegetative cells then acted as gametes. Thecae of fusing gametes broke in the girdle region and were lost. Zygotes thus formed remained motile 3–5 days during which time they enlarged slightly with the newly formed theca becoming warty. Three to 5 days following plasmogamy the zygote became nonmotile, the protoplast contracted, and the cell wall thickened. Hypnozygotes with 4 nuclei were observed ca. 10–12 h following formation. Meiosis was inferred. Hypnozygotes germinated within 12 h of formation producing 2 vegetative cells which divided within a 24 h period. Attempts to induce sexual reproduction by inoculation of cells into media deficient in a number of basic elements other than N were unsuccessful.     

STIMULATION OF ASEXUAL REPRODUCTION OF PILOBOLUS BY MUCOR PLUMBEUS

Page , Robert M. (Stanford U., Calif.) Stimulation of asexual reproduction of Pilobolus by Mucor plumbeus. Amer. Jour. Bot. 46(8): 579–585. Illus. 1959.—The fact that a culture of Pilobolus kleinii which was contaminated with Mucor plumbeus produced far more sporangia than had ever been observed before on a synthetic medium suggested that M, plumbeus produced a substance which stimulated asexual reproduction in Pilobolus. When grown on a medium containing asparagine, sodium acetate, hemin, thiamine, and salts, P. kleinii consistently produced more trophocysts and sporangia when grown with M. plumbeus than when grown alone. Sterilized filtrate of culture medium in which M. plumbeus had grown also stimulated sporangium formation by P. kleinii. By the use of 2 types of 2-membered culture in which there was no liquid connection between the 2 fungi, it was shown that the stimulatory substance was volatile. In addition to being volatile at room temperature, the material was soluble in acid but not in alkali, and it gave a positive reaction with Nessler's reagent. Since (1) the material had some of the properties of ammonia, (2) the intensity of asexual reproduction in 2-membered cultures with absorbents was correlated with the distribution of ammonia, (3) M. plumbeus produced ammonia when grown on asparagine, aspartic acid, or NaNO₃, and (4) the effect of the substance could be imitated either with gaseous ammonia or with ammonium salts at appropriate concentrations, it seems highly probable that the substance produced by M. plumbeus which stimulates asexual reproduction of P. kleinii and some other species of Pilobolus is ammonia.     

SEXUAL REPRODUCTION IN STEPHANODISCUS NIAGARAE (BACILLARIOPHYTA)1

We observed sexual reproduction in a clonal culture of Stephanodiscus niagarae Ehrenb. and used light and scanning electron microscopy to absent flagellated male cells, auxospore growth, initial valve structure and production, and subsequent daughter cell division. Free auxospores were spherical and nonsiliceous throughout growth, producing hemispherical initial valves devoid of spines and with nonfasciculate striae. Pregametangial cells averaged 43% of the diameter of the daughter cell population and were 1/9 the biovolume of initial, cells. This paper is the first confirmed report of sexual reproduction in S. niagarae, although it appears that specimens of Actinocyclus niagarae H. L. Smith, described from Lake Erie in 1878, are actually initial valves of S. niagarae.     

COLONIZATION AND REPRODUCTION OF THE EPIBIOTIC FLAGELLATE COLACIUM VESICULOSUM (EUGLENOPHYCEAE) ON DAPHNIA PULEX1

The epibiotic flagellate Colacium vesiculosum Pringsheim attaches to planktonic species of Daphnia in freshwater habitats. Previous studies found that prevalence (percentage of substrate organisms carrying attached epibionts) and intensity (number of attached epibionts on a given substrate organism) are low early in the Daphnia intermolt period and are high late in the intermolt period. We tested the hypothesis that increases of Colacium cells attached to Daphnia occur both by rapid initial and continuous colonization and by cell reproduction. Epibiont prevalence and intensities were determined at successive intermolt stages of Daphnia pulex Leydig collected from freshwater ponds in Colorado. Colonization was continuous throughout the intermolt period and was most important to epibiont population increase at the beginning of the intermolt period. Cell division was the major contributor to epibiont increase at the end of the intermolt period.     

北方狭口蛙繁殖生态的研究

采用野外定点观察、室内剖检相结合的方法,对北方狭口蛙（Ｋａｌｏｕｔａ ｂｏｒｃａｌｉｓ）繁殖生态进行了研究北方口蛙繁殖期直接与每年的雨季迟早有关,多在大雨过后的傍晚,夜阐及清晨进行繁殖活动,产卵场所为大雨过后形成的临时水坑或流速较缓的沟渠中,产卵场所不受水域大小及水中有无杂草所限,卵分批产出,每批弱卵约２０～３０粒。     

花鼠种群年龄和繁殖的初步研究

1991年3-10月在山西省中条山区猎获花鼠202只。以眼晶体干重为指标划分出4个年龄组,分析了种群年龄组成的季节变化。该鼠每年繁殖1次, 3月下旬-1月中旬怀孕,产仔期在4月中旬-5月中旬,胎仔数5.08±0.16只, 6月上旬幼鼠出现。幼鼠于翌年春季出蛰后参加繁殖。此外,还将晶体干重、齿高指数和臼齿磨损程度3种年龄指标所划分的结果作了比较,也证实体重、体长和尾长不能用于该鼠的年龄鉴定。     

A COMPARATIVE STUDY OF SEXUAL REPRODUCTION IN FOUR SPECIES OF CHLAMYDOMONAS

Trainor , Francis R. (U. Connecticut, Storrs.) A comparative study of sexual reproduction in four species of Chlamydomonas. Amer. Jour. Bot. 46(2) : 65-70. 1959.—This paper reports results of comparative experiments on some factors affecting sexual reproduction in 4 species of Chlamydomonas. Sexuality can be controlled in 3 of these species (C. chlamydogama, C. eugametos and C. reinhardti) by the level of ammonium nitrate in the harvesting medium. It was demonstrated that periodicity of illumination was of importance for high zygospore yields with C. chlamydogama and C. eugametos. Other variables, e.g., various aspects of nitrogen level, illumination and inter-fertility, were investigated and the results summarized in tabular form.     

COST OF REPRODUCTION IN POLEMONIUM VISCOSUM: PHENOTYPIC AND GENETIC APPROACHES

I measured the effect of early reproduction on subsequent growth and survival in the alpine perennial wildflower, Polemonium viscosum. Measurements were made over 4 yr on 34 maternal sibships under natural conditions. A significant phenotypic cost of early reproduction characterized the study population. Plants that flowered after only one year's growth had twice as many leaves and 25% more shoots than nonflowering individuals of equal age. However, early flowering decreased leaf number by 18% in the subsequent year and survivorship by 20% after two years relative to changes in leaf number and survival of nonflowering plants. For such trade-offs to shape the further evolution of reproductive schedules, flowering probability and those age-specific components of plant size that represent the energetic currency for reproductive costs must be heritable. Although families showed significant heterogeneity in the probability of early flowering, most (62%) entirely failed to flower. Moreover, phenotypic variation in vegetative size components at ages 1 and 2 had little genetic basis. Only at ages 3 and 4, after vegetative and demographic costs of early reproduction had been incurred, did vegetative size components (leaf length and number, and shoot number) vary significantly among families. Results of this study provide little evidence of a genetically based trade-off between early reproduction and subsequent survival in P. viscosum.     

VEGETATIVE REPRODUCTION OF THE FRESHWATER DINOFLAGELLATE GLOEODINIUM MONTANUM1

The vegetative life cycle of Gloeodinium montanum Klebs was examined. In unialgal cultures G. montanum divided predominantly by binary fission once every 2-3 weeks. Nuclear division was followed by a delayed cytokinesis producing non-motile G. montanum cells. When placed in fresh media 2-4 biflagellated swarmers were formed. The swarmers, although similar in appearance to those of Hemidinium ochraceum Levander (1900), differ from that species in their dimensions. During vegetative reproduction swarmers developed directly into non-motile vegetative cells.     

REPRODUCTION OF THE ARTICULATED CORALLINE AMPHIROA EPHEDRAEA1

Developmental events in the formation of reproductive structures in tetrasporangial, male, and female plants of Amphiroa ephedraea from South Africa were studied. An early step in the formation of a conceptacle is the elongation of a stratum of cortical cells, the cavity cells, to form a dome surmounted by an a cellular cap. Atrophy of the cavity cells to form a conceptacular cavity accompanies the subsequent development of reproductive structures. Tetrasporangial conceptacles differ from sexual conceptacles in that the reproductive cells develop in a peripheral ring and in the fact that the tissue lateral to these cells does not overgrow the fertile area. Finally, a comparison of some of the features of reproduction in A. ephedraea is made zuith. comparable features in other corallines.     

EFFECT OF NONRANDOM LEAF ORIENTATION ON REPRODUCTION IN LACTUCA SERRIOLA L.

The cauline leaves of an annual, Lactuca serriola L., are naturally oriented vertically with the lamina perpendicular to the east and west. Previous physiological data indicated that this nonrandom leaf orientation should reduce water loss without substantially reducing photosynthesis and could thus influence plant growth and reproduction (Werk and Ehleringer, 1984, 1985). The effect of leaf orientation on flower and seed production was tested experimentally using potted L. serriola grown outdoors. Leaves of half the plants were forced to remain approximately horizontal while the other plants were allowed to orient naturally. The plants with horizontal leaves lost water more rapidly than the plants with naturally oriented leaves. Above-ground weight, below-ground weight, seed weight, and the number of seeds per flower were not significantly affected by leaf orientation. Flower production was a linear function of plant size for both treatments with plants with natural leaf orientation having a significantly greater slope. These results indicate that the nonrandom leaf orientation observed in L. serriola is a morphological character which can enhance reproduction.     

对虾杆状病毒病暴发式大流行的生态机理初步研究

初步探讨中国和沿海和对虾杆状病毒病暴发式大流行的生理机理。分析了病毒病特性与对虾免疫功能的关系;病毒在虾池间的传染机制。着重说明了虾病的群体感染过程,给出模式化的群体传染模型,简要阐述了与虾病相关的社会生态经济问题。     

克隆植物种子繁殖和营养繁殖的适合度分析和度量

植物种群繁殖的适合度指繁殖行为适应环境变化的能力及其对各群更新发展的贡献,不仅表现在个体水平也表现在基因水平。提出度量种子繁殖和营养繁殖在个体和基因水平的适合度的计算公式,并计算了白三叶草繁殖的适合度,较好地解释了种子繁殖和营养繁殖对克隆植物种群更新发展朱同作用。     

SEVERE COSTS OF REPRODUCTION PERSIST IN ANOLIS LIZARDS DESPITE THE EVOLUTION OF A SINGLE‐EGG CLUTCH

A central tenet of life‐history theory is that investment in reproduction compromises survival. We tested for costs of reproduction in wild brown anoles (Anolis sagrei) by eliminating reproductive investment via surgical ovariectomy and/or removal of oviductal eggs. Anoles are unusual among lizards in that females lay single‐egg clutches at frequent intervals throughout a lengthy reproductive season. This evolutionary reduction in clutch size is thought to decrease the physical burden of reproduction, but our results show that even a single egg significantly impairs stamina and sprint speed. Reproductive females also suffered a reduction in growth, suggesting that the cumulative energetic cost of successive clutches constrains the allocation of energy to other important functions. Finally, in each of two separate years, elimination of reproductive investment increased breeding‐season survival by 56%, overwinter survival by 96%, and interannual survival by 200% relative to reproductive controls. This extreme fitness cost of reproduction may reflect a combination of intrinsic (i.e., reduced allocation of energy to maintenance) and extrinsic (i.e., increased susceptibility to predators) sources of mortality. Our results provide clear experimental support for a central tenet of life‐history theory and show that costs of reproduction persist in anoles despite the evolution of a single‐egg clutch.