The specific identity and the life history of JapaneseSyringoderma (Syringodermatales,phaeophyceae)

Observations on JapaneseSyringoderma from Rishiri Island, which had been previously identified asS. australe, were made based on newly collected fertile material. These results and comparisons with the type specimen ofSyringoderma abyssicola (=Chlanidophora abyssicola) revealed that the Rishiri Island plants should be identified asSyringoderma abyssicola. Syringoderma abyssicola from Rishiri Island formed unilocular sporangia among the paraphyses on the fan-shaped blades in winter. The first products (uni-spores) in the unilocular sporangia form flagella, and soon after form cell walls before release. Then these reduced gametophytes divide into tetrads and form swarmers, each of which contains a chloroplast with a stigma. These swarmers germinate into branched filaments, from which thicker erect filaments of apical growth tissue. At 5–10 C these erect filaments formed fan-shaped blades under long-day conditions, and unilocular sporangia under short-day conditions corresponding respectively to spring and winter at Rishiri Island. Accordingly, the seasonal growth pattern of the species is considered to be controlled by responses to photoregime and temperature. Dedicated to the memory of the late Professor Muneao Kurogi.     

Culture studies on the life history of Arthrocladia villosa (Desmarestiales,Phaeophyceae)

The life history of Arthrocladia villosa f. australis (Kütz.) Hauck isolated from the Mediterranean has been studied in culture. Monoecious microscopic gametophytes form antheridia and oogonia morphologically similar to those of Desmarestia viridis. Fertilization has not been observed and chromosome counts reveal that sporophyte and gametophyte have the same chromosome number (23 to 27). Thus, sexuality seems to be suppressed and replaced by apomeiosis and parthenogenesis. These findings re-interpret the incomplete observations of Sauvageau and confirm placement of Arthrocladia within the order Desmarestiales.     

Apomeiosis inAcinetospora (phaeophyceae,ectocarpales)

Acinetospora crinita from the Mediterranean Sea has been studied in laboratory cultures. The plants formed monospores and unilocular sporangia. Both monospores and zoids from unilocular sporangia developed to new plants with the same habitus and chromosome number (average ca 47). This indicates that meiosis in unilocular sporangia fails, and that sexuality has been lost in the cultures studied. It is concluded that loss of sexuality is the cause of the great variability and establishment of distinct geographically isolated populations in the genusAcinetospora.     

Phylogeographic patterns and demographic history of Schiedea globosa (Caryophyllaceae) on the Hawaiian Islands

Geomorphological changes have been demonstrated to have had profound impacts on biodiversity, often leading to demographic expansions and contractions and allopatric divergence of taxa. We examined DNA sequence variation at two nuclear and one maternally inherited plastid locus among 10 populations of Schiedea globosa on the Hawaiian Islands to assess the primary factors shaping genetic structure, phylogeographic patterns, and the importance of geographic isolation to population divergence. Schiedea globosa has characteristics that may promote gene flow, including wind pollination and rafting of plants in ocean currents. However, we detected significant differentiation among populations on all islands except Hawaii, with the maternally inherited plastid locus having the greatest genetic structure (F(ST) = 0.81). Migration rates across all loci are less than one migrant per generation. We found evidence of growth in several populations and on the islands of Molokai and Maui, which supports population expansion associated with the formation of Maui Nui during the last glacial maximum. Similar to data for many other Hawaiian taxa, these data suggest S. globosa originated on Oahu and subsequently colonized Molokai, Maui, and Hawaii in progression. Given the high level of genetic structure, allopatric divergence will likely contribute to further divergence of populations.     

The history of myxosporean (Myxozoa Grasse, 1970, Myxosporea Butschli, 1881) life and nuclear cycles studies

The paper presents a historic review of various hypothesis concerning the myxozoan life and nuclear cycles. The comparison of DAPI- and Feulgen-image-cytometry results of DNA amount in myxozoan actinospora and myxospora nuclei, in connection with the new data on the animal life and nuclear cycle, has been performed. Possible reasons for the data discrepancy are considered. The further perspectives of myxozoan biology, cytology, karyology and taxonomy investigation in Russia are discussed.     

Observations on the life history and ecology of some Lumbriculidae (Annelida,Oligochaeta)

Summary Data on the abundance and sexual state of some aquatic Oligochaeta, derived from two series of monthly samples taken over a period of a year from two sites in North Wales (United Kingdom), with notes on similar data from other localities, are presented. In summary these data indicate the following facts concerning: 1) Lumbriculus variegatus, a. fragmentation may occur with equal frequency at all seasons, b. the sexual period is restricted to the summer months, c. this species has the physiological potential to form dehydration-resistant cysts; 2) Stylodrilus heringianus, a. the optimum period for cocoon deposition is late spring to early summer, b. young worms hatch in mid-summer, c. a two year life cycle is suggested; 3) Eclipidrilus lacustris, a. cocoons deposited in mid-summer, b. young hatch one to two months later, c. 11/2 year growth period ensues and worms reach full maturity in summer when two years old.

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Zusammenfassung An Hand von Untersuchungen an zwei Reihen von Proben, die im Zeitraum eines Jahres monatlich an zwei Orten in Nord-Wales (Grobritannien) gesammelt worden waren, und unter Hinweis auf ähnliche Angaben anderer Autoren werden das Vorkommen und der geschlechtliche Zustand einiger Süwasseroligochaeten beschrieben. Zusammenfassend lät sich folgendes sagen: 1) Lumbriculus variegatus, a. die Teilung als ungeschlechtliche Fortpflanzung kann zu jeder Jahreszeit mit gleicher Häufigkeit auftreten, b. die geschlechtlich aktive Periode ist auf die Sommermonate beschränkt, c. die Art besitzt das physiologische Potential zur Bildung trockenheitsunempfindlicher Zysten; 2) Stylodrilus heringianus, a. optimale Bedingungen für die Eikokonablage herrschen in den letzten Frühlingswochen und den ersten Sommerwochen, b. die jungen Würmer schlüpfen im Hochsommer, c. ein zweijähriger Lebenszyklus wird angenommen; 3) Eclipidrilus lacustris, a. die Eikokons werden im Hochsommer abgelegt, b. die jungen Würmer schlüpfen 1–2 Monate später, c. eine Wachstumsperiode von 11/2 Jahren folgt, und im Alter von zwei Jahren, im Sommer, erlangen die Würmer Geschlechtsreife.

     

On the life history ofTurnerella mertensiana (Rhodophyta,Gigartinales)

Turnerella (Gigartinales) withT. mertensiana known from northern Japan was studied to determine its life history. Carpospores cultured from foliose female plants gave rise on germination to crustose plants containing tetrasporangia, as noted previously inT. pennyi from the Atlantic. The crusts were slow to develop and required 3–5 years to achieve reproductive maturity. Tetraspores liberated in culturedT. mertensiana gave rise on germination eventually to thalli similar to gametophyticT. mertensiana. Thus this species may be said to adhere to the pattern of life history in which a large, foliose gametophyte alternates with a small crustose tetrasporophyte. The erect filaments of the small sporophytes branch laterally and tetrasporangial mother cells are found there, exemplifying an unusual method for crustose species to produce tetrasporangia.     

Effect of life history on the squirrel monkey (Platyrrhini,Saimiri) cranium

Among primates, squirrel monkeys uniquely possess an interorbital fenestra, in which the midline bony orbitosphenoid septum is largely absent and the soft tissues of the orbits are separated only by a thin membrane. Neural development may contribute to the approximation of the orbits to the midline in Saimiri, insofar as other platyrrhines with relatively large brains also have relatively narrow interorbital spaces compared to their near relatives. In Saimiri the narrow spacing of the orbits is further exacerbated by intense predation pressure on infants that may select for precocial neonates. The result is a large-headed neonate that is subject to unusual parturition constraints. These parturition constraints apply to the size and dolichocephalic shape of the squirrel monkey head in general, and to the relatively large eyes and approximated orbits in particular. The unique interorbital condition in Saimiri is an example of the effects of life history on skeletal morphology. © 1995 Wiley-Liss, Inc.     

Comparative studies on the life history of Angiostrongylus mackerrasae Bhaibulaya, 1968 and Angiostrongylus cantonensis (Chen, 1935)

The life history of A. mackerrasae was found to differ from that of A. cantonensis as follows: (1) the moulting times of A. cantonensis in the definitive host occurred a few days earlier than those of A. mackerrasae; (2) the growth rate of A. cantonensis was more rapid than that of A. mackerrasae. However, there were no differences in the migratory pattern of the third-stage larvae of both species in experimentally-infected definitive hosts. It is concluded that Mackerras & Sandars (1955) described the life history of A. mackerrasae and not A. cantonensis.     

Notes on the life history of the planktonic alga, Dysmorphococcus globosus (Volvocales)

Several strains of Dysmorphococcus globosus, a planktonic greenflagellate, were examined during this study. Dysmorphococcusglobosus has a generation rime of 48 h, at which time four bi-flagellateddaughter cells were released. In some instances, four to eight,rarely 16, noo-flagellated aplanospores will be formed per cell,germinating when placed in fresh medium with the subsequentrelease of from one to four motile individuals. Sexual reproductionwas recorded in detail for the first time although it had beenpreviously reported that pairs of individual cells had beenobserved attached at their anterior poles. Sexual reproductionwas isogamous to anisogamous with the clones being homothallic.During zygote germination, the zygote undergoes two rapid divisionsto form four products of meiosis which were released followingrupture of the lorica.     

Observations on the life history of the belted sandfish,Serranus subligarius (Serranidae)

Synopsis The biology of Serranus subligarius, a typical inhabitant of low limestone reef outcroppings and artificial reefs from North Carolina to Florida and in the northern Gulf of Mexico, was studied on inshore jetties in the northeastern Gulf of Mexico from February 1974 to April 1975. The length-weight relationship was expressed by the equation W = 0.000006L^3.431. Growth was greatest in the first year (43.5 mm SL) and declined in the remaining three years of life (17.3, 10.5, and 7.1, respectively). In individuals larger than 40 mm SL, gammaridean and caprellid amphipods were the most numerous food items but crabs, shrimp, and fishes were the most important food items by weight. In individuals less than 40 mm SL, copepods were the most numerous food item, but gammaridean amphipods and shrimp were the most important items by weight. Two incidents of cannibalism were recorded. The ovotestis of the belted sandfish is composed of two lobes which are broadly united posteriorly, with the testicular tissue restricted to a broad band encircling the posterior region of the gonad. Age-group 1 fish are functional synchronous hermaphrodites. Testicular tissue matures in the fall or winter of a fish's first year (all specimens examined histologically, including those from the nonspawning season, contained flagellated spermatozoa) while ovarian tissue matures in the following spring. Spawning season in 1974 extended from late April or early May to September. Crossfertilization is the usual reproductive mode, although individuals are capable of selffertilization.     

球状棕囊藻的形态结构、生活史及生态意义研究进展

球状棕囊藻生活史独特,在两种完全不同的生活状态--游离单细胞和粘液质的囊体之间相互转换.生活史中共出现4 种不同类型的单细胞,存在有性和无性两种生殖方式.不同的细胞能够适应不同的环境,占据不同的生态位,有利于棕囊藻细胞的生长.球状棕囊藻的囊体直径最大可达几个厘米,外被坚韧、紧密并且具有弹性,为内部的单细胞提供了一个良好的栖息和保护场所,并且储存着能量可供细胞在营养盐限制条件下继续生长.由于囊体粒径较大,浮游动物难以摄食,并且有效的抵御了细菌和病毒的侵蚀,从而降低了棕囊藻的死亡率.与其它浮游植物相比,球状棕囊藻的竞争策略更加优越,提高了球状棕囊藻在海洋生态系统中的竞争能力.     

The life history ofAcrochaete wittrockii (Ulvellaceae,Chlorophyta)

Acrochaete wittrockii (Wille) Nielsen is a heteromorphic diplohaplont. The haplophase consists of isomorphic, dioecious filamentous epiphytes on brown algae. Several generations follow each other by triflagellate zoospores from spring to early summer. By late summer and throughout autumn, quadriflagellate zoopores are produced by the epiphytic thalli; they give rise to male and female gametophytes of a globular, pseudoparenchymatic appearance in culture. The gametophytes produce anisogamic biflagellate gametes which, after gametic union, develop into diploid unicellular sporophytes. After 6–7 days, the sporophyte produces triflagellate zoospores, repeating the life history when germinating on brown algal hosts. Alternatively, triflagellate zoospores which settle on the bottom of petri dishes, develop into unicellular, autonomous sporangial plants. Their triflagellate spores repeat the epiphytic stage on brown algal hosts, or the sporangial plant cycle on non-living substrate, respectively.     

Marine antifoulants from bifurcaria bifurcata (phaeophyceae,cystoseiraceae) and other brown macroalgae

In this study, the antifouling activity of a series of extracts and linear diterpenes isolated from Bifurcaria bifurcata (Velley) Ross, a common brown alga of the Atlantic shores of Europe, and derivatives of these compounds was investigated. Antifouling assays with crude extracts from other brown algae, found abundantly along the coast of South Africa (Bifurcaria brassicaeformis, Bifurcariopsis capensis), the Atlantic shores of Europe (Halidrys siliquosa) and the coast of Mediterranean sea (Cladostephus verticillatus, Halopteris scoparia), are also reported. The fractions were tested in laboratory assays against representative species of the major groups of fouling organisms, viz. bacteria, fungi, diatoms, spores and zygotes of macroalgae and the blue mussel Mytilus edulis. Several components showed promising levels of activity. The high, albeit variable, level of antifouling activity suggests a potential for novel active ingredients in antifouling preparations.     

Aspects of the life history of Rhodophysema elegans (Rhodophyta,Peyssonneliaceae)

The life history of Rhodophysema elegans is described from laboratory culture and the field in Newfoundland, Canada. Sexual plants are lacking and tetraspores germinate to produce new tetrasporangial plants. Approximately 30–35 chromosomes were counted in vegetative cells of successive generations. There was no evidence of chromosome pairing in the early stages of division of tetrasporangial initials, indicating that the tetrasporangia are apomeiotic.     

Population regulation and the life history studies of LaMont Cole

Transformative changes marked the growth of mid-twentieth century American ecology. This included redirection of the scholarly focus of the discipline, especially on the role evolutionary theory and "levels of selection", and increased visibility of ecologist as public figures in the environmental movement with special knowledge of how natural systems work. Cornell ecologist LaMont Cole is an important figure to examine both of these trends. Like many of his contemporaries, Cole was devoted to a perspective on natural selection operating at levels above the individual. However, because of his influential mathematical treatment of animal demography he has been historically subsumed into a group of scholars that views the events in the life course as adaptations to the maximization of individual fitness--life history theory. Cole's popular writings and lectures, which consumed his later career, extend his scholarly portrayal of natural populations as tending toward stable and homoeostatic equilibrium, with the goal of drawing contrasts with the deviance of rapid human population growth. In both regards, Cole serves as a topical and temporal extension of the well-documented and analyzed ecology of his mentors--Alfred Emerson, Thomas Park, and Warder Allee--in the University of Chicago Zoology Department.