Genome relationship betweenPsathyrostachys huashanica andP. fragilis (Poaceae)

Hybrids between the Chinese endemic speciesPsathyrostachys huashanica Keng and the SW. Asian speciesP. fragilis (Boiss.)Nevski (all 2n = 14) developed normally but were completely sterile. Meiotic analyses revealed a high chiasma frequency indicating that the two species as well asP. juncea (Fisch.)Nevski share the same basic genome (called N). The hybrid nature of the plants was established through karyotype analysis and Giemsa C-banding.     

On the origin ofVeronica persica (Scrophulariaceae)—a contribution to the history of a neophytic weed

A character analysis reveals a clearly intermediate position of the tetraploidV. persica (2n = 28) between the two diploid speciesV. polita andV. ceratocarpa (both 2n = 14) which are morphologically rather different and have been placed by several authors in different sections of the genus.V. ceratocarpa is native to subhumid deciduous forests of the Caucasus and of the Elburz mountains (N. Iran);V. polita has its centre of variation in the Elburz range where it grows in therophyte habitats. Three other closely related species,V. bungei, V. siaretensis, andV. francispetae, are endemic to the Elburz range which is the main centre of diversity and variability of theV. agrestis group. This comprises all the above mentioned species and also two more European weeds:V. agrestis andV. opaca. Veronica polita, was probably originally native to open places in deciduous mountain forests, before becoming a weed in neolithic times and migrating to Europe; nowadays it has an almost world-wide distribution. The allotetraploidV. persica combines the ecological characters of its parents, the slightly xerophyticV. polita and the more mesophyticV. ceratocarpa, thus being preadapted to become a highly successful weed with a large ecological range. It has spread rapidly almost all over the world since the early 19th century.Dedicated to Hofrat Univ.-Prof. DrKarl Heinz Rechinger on the occasion of the 80th anniversary of his birthday.     

bcd: A mutation affecting the width of organelle domains in the cortex of Tetrahymena thermophila

Summary A single-gene recessive mutation, bcd (broadened cortical domains), of Tetrahymena thermophila is characterized by a variable broadening of the spatial domains within which cortical organelles, including both the contractile vacuole pores (CVP) and oral apparatus (OA), are formed. The phenotype is not temperature-sensitive. During the development of the organelles of the mutant prior to cell division, extra CVPs and extra oral primordia (OP) appear near ciliary rows adjacent to the rows at which these structures normally form. In the later stages of development, some, but not all, of these extra structures are resorbed, or in the case of the oral domain, multiple adjacent OPs may be completely or partially integrated into a single enlarged OA. When multiple OAs persist, one or more of these may display a reversed orientation reminiscent of those encountered in janus mutants. However, unlike janus, bcd cells do not express any sign of a mirror-image global organization.Our results can best be accounted for by postulating that the bcd mutation affects some common determinant of the widths of both CVP and OA domains. Studies are in progress which explore the relationship between this width-determining mechanism(s) and the mechanism(s) determining the location of cortical organelles around the cell circumference.     

Kofyar cash-cropping: Choice and change in indigenous agricultural development

Amid discussions of an agricultural crisis and the failure of largescale, mechanized, capitalintensive development schemes in Nigeria, the Kofyar of Plateau State provide a case study of farmers spontaneously expanding food crop production for the market, using indigenous lowenergy technology. Temporary, followed by permanent, migration from the Jos Plateau homeland to frontier settlements on the fertile Benue plains has been accompanied by a change from initial shifting cultivation in forest clearings to permanent, intensively tilled and fertilized homestead fields. Labor is organized primarily in households that have grown in size and complexity. Cooperative and exchange work groups are also important for meeting seasonal bottlenecks and providing the careful, disciplined cultivation that intensive agriculture requires. Kofyar now devote up to 50% of their labor to cash crops, and they purchase considerable quantities of manufactured goods and medical services. Their uncoerced adaptation to an environment of new land resources and market incentives suggests both the advantages of indigenous development with a minimum of state control or interference and the limitations of a conventional dependency theory perspective.     

The effect of a pattern in palmar interdigital II on a-b ridge count in black and white Down syndrome cases and controls

An unconfirmed study by Fang (Ph.D. thesis, Univ. of London, 1950) in Britain showed that individuals with Down syndrome had lower total a-b ridge counts in palmar Interdigital area II (ID II) than a group of controls. This study compares 603 white Down syndrome cases and 93 black Down syndrome cases with 668 white and 402 black controls. Our results confirm those of Fang in that the Down syndrome cases in both racial groups had lower total a-b ridge counts than their respective controls. In addition, the black controls and Down syndrome cases had lower a-b ridge counts than their white counterparts. The mean a-b ridge count was significantly lower in individuals with a pattern in ID II compared to individuals without a pattern in ID II in both the Down syndrome and control groups. Some of the lower a-b ridge counts in the Down syndrome samples can be accounted for by the fact that there is an increased frequency of a pattern in ID II in Down syndrome cases. Both Down syndrome and normal individuals who had a pattern unilaterally had a lower than expected a-b ridge count on the contralateral hand that did not have a pattern. There was a tendency also for increased asymmetry in Down syndrome cases with a pattern in ID II.     

Individual variation in the foraging strategies of young yellow perch (Perca flavescens) from the Ottawa River

Differences in the foraging strategies among young individuals of the yellow perch (Perca flavescens) were observed in the laboratory by using two kinds of food (Daphnia and brine shrimp) separately and together. Individuals differed significantly in their ability for feeding attempts, time interval between two consecutive feeding attempts, feeding angles, regurgitation rate, and number of unsuccessful attempts and in their food preference. It is concluded that there are individuals with different foraging strategies. Variability in foraging strategies within single species populations is important because it may explain how the conspecific individuals may differ in their overall feeding behaviour.     

C-banding patterns in the AustralianBulbine (Liliaceae): The annual group,B. semibarbata s. lato

Chromosome C-band patterns have been studied in 34 populations of the Australian annualBulbine group, which comprises 4x (2n = 26, 28), 8x (2n = 52, 54) and 12x (2n = 78) populations. The 2n = 26B. semibarbata populations have a simple, low heterochromatin pattern with very minor polytypic variation. The 2n = 28 populations, corresponding morphologically to a group given separate status asB. alata, are similar in pattern but exhibit pronounced enhancement of telomeric and, more particularly, centromeric dot bands. NOR heterochromatin and satellites are difficult to identify inB. alata but appear to occur in different positions from the 26-chromosome karyotype. Eastern Australian 8 x patterns are consistent with a proposed hybrid ancestry,B. semibarbata ×B. alata. Annual and perennial C-band profiles in the AustralianBulbine are discussed briefly in relation to the additive and transformation models of heterochromatin evolution and to the possible adaptive significance of variation in heterochromatin content.Cytoevolution in the AustralianBulbine 2; for part 1 see Pl. Syst. Evol.157, 201–217.     

The genetic structure of a primate species: Rhesus macaques and other Cercopithecine monkeys

Among rhesus macaques (Macaca mulatta)and other cercopithecine monkeys, social groups occupying adjacent home ranges (i.e., members of the same local population) exchange individuals and genes and thus exhibit marked genetic similarities. To assess the degree to which this pattern extends beyond the local population, the genetic structure of M. mulattaand six other primate species was determined using Nei’s (1973) gene-diversity analysis. The genetic similarities seen among social groups in the Dunga Gali population of M. mulatta (Melnick et al.,1984a) can be seen over the entire species range. Comparison of these results with the structures of other similarly organized primate species indicates that (1) the average social group contains most of its local population’s genetic diversity, (2) the average local population contains the majority of the genetic diversity found in the region to which it belongs, and (3) the proportion of species gene diversity found in the average regional population varies substantially between species. Genetic homogeneity within local and regional populations is probably the product of gene flow. The application of a number of analytical models of selection and gene flow strongly suggests that gene flow, genetic drift, and zoogeography offer a more parsimonious and plausible explanation for interspecific variation in regional differentiation than does stabilizing selection.     

Effect of adaptation to high light intensity on the kinetics of energy transfer from phycobilisomes to photosystem II in Anabaena cylindrica

Transfer efficiencies between phycobilisomes and photosystem II antenna chlorophylls were determined on membrane fragments isolated from low and high light adapted Anabaena cells. The observed increase in energy transfer in high light adapted cells is a consequence of shorter interchromophore distances and a decrease in the number of jumps of the exciting photons. Calculation of the rates of energy transfer and the coupling energies indicate that the weak interaction inferred for energy transfer between phycobilisome and photosystem II in low light adapted cells is replaced by an intermediate interaction in high light adapted cells.Abbreviations LLA low light adapted - HLA high light adapted - PBS phycobilisome - PS photosystem     

Activity patterns and egg production in Coccophagus bartletti, an aphelinid parasitoid of scale insects

ABSTRACT.

• 1 Daily patterns of oviposition and host-feeding were examined in Coccophagus bartletti Annecke & Insley. Females began to host-feed and oviposit during the second or third day after emergence. Thereafter, both activities occurred regularly.
• 2 During long observation periods (5 h) most oviposition (93%) and host-feeding (90%) occurred within the first 3.5 h of wasps first encountering hosts. Experiments demonstrated that levels of activity were low for the rest of the day, and nocturnal oviposition occurred only if wasps had no alternative.
• 3 Dissection of female wasps that had been exposed to hosts, or withheld from them, for given periods of time, revealed that activity levels are governed by egg availability. Dispersal activity may also be influenced by the physiological state of the ovaries.
• 4 Production of a full complement of eggs (at 24±1°C (12 h L) and 18±1°C (12 h D)) took 48h or longer after host-feeding, and if wasps were withheld from hosts and provided with honey, the effects of egg resorption could be detected after about 10 days. Trends in oögenesis and oösorption in C. bartletti females seem not to conform with interpretations of oögenesis-oösorption cycles in other parasitoids.
• 5 The pattern of activity exhibited by C. bartletti females is not inflexible, but the major aspects mentioned above are species-specific. In general, information is needed about daily and hourly patterns of parasitoid oviposition and host-feeding before experiments are designed to test theories of parasitoid behaviour. Interpretation may otherwise rest on assumptions about their physiological condition.