Showing papers in "Biological Journal of The Linnean Society in 1974"

An account of the Chalcidoidea (Hymenoptera) parasitising leaf-mining insects of deciduous trees in Britain

Abstract: Data on the distribution and frequency of hymenopterous parasites of leaf-mining insects on deciduous trees show that Chalcidoidea of the family Eulophidae are the chief component of the parasite faunas. The regular parasite complement of a leaf-mining species is in the order of 10 to 20 species of parasitic Hymenoptera. Many of these are polyphagous, but in almost all instances a preference for a particular type of host is evident. The parasite faunas of tree leaf-mining Lepidoptera, Coleoptera and Hymenoptera are shown to be qualitatively similar, but those of Diptera are rather different. The parasite faunas of tree leaf-miners are different also from those of leaf gall-forming insects on trees and, to a lesser degree, from those of leaf-miners on herbaceous plants. The parasite fauna associated with a tree genus is quantitatively and qualitatively characteristic and, in general, it most resembles that found on allied tree genera. Congeneric leaf miners attacking the same tree species are attacked by very similar parasite faunas, although mine situation and season of development may exert some influence. These latter factors are considered especially in relation to leaf-miners of the genus Phyllonorycter for which most data are available.

Xerophytes, xeromorphs and sclerophylls: the history of some concepts in ecology.

Abstract: Research on xeromorphic and sclerophyllous (the literal meanings of which are “dry-form” and “hard-leaved”) plants offers a case-history illustrating the nature of “progress” in one branch of science. The story runs from about 1890–1970, beginning with the birth of ecological concepts, including Warming's 1895 classification of plants into hydrophytes, xerophytes and meso-phytes, Schimper's pioneer work on the sclerophylls, and with the conceptions that lay behind this work; and so on through the main lines of research, concluding with an account of work on the “anomalous” distribution of the sclerophylls in Australia. This case-history shows how the problems of classification and categorization may be linked to conceptual and empirical problems of substance, and hence are not “merely” classificatory. Indeed, the hypotheses under test are not formulated explicitly, but are encapsulated in the terminology, as is so often the case in the biological sciences.

Numbers of plant, insect and land bird species on nineteen remote islands in the Southern Hemisphere

Abstract: The familiar species-area equation S=cAz may not account for as much of the variation in the numbers of species on islands as it has been held to. The undue emphasis on area as a factor probably results from early workers not considering as many factors as possible in their regression analyses. In the case of 19 remote islands in the Southern Hemisphere, island area and elevation, latitude, mean temperature of coldest month and distance of island from mainland, nearest land and nearest land to west were used to consider variation in number of plant species with the technique of multiple regression. A nonlinear model explained 83% of the variation, with temperature and area accounting for 71% of the variation in number of plant species. The above factors with number of plant species were then used to consider variation in number of insect species on the islands. The linear model was superior, accounting for 91% of the variation. Number of plant species accounted for 73% of the variation in number of insect species. Variation in numbers of passerine bird species and total land bird avifauna was considered using all of the above nine factors. The linear model was superior in both cases. Number of plant species accounts for 60% and 71% of the variation respectively. Various suggestions are made to account for the unexpected result of number of insect species making little contribution to the last two regressions.

Ultrastructure of the scale-covered zoospores of the green alga Chaetosphaeridium, a possible ancestor of the higher plants and bryophytes

Abstract: The zoospores of the green alga Chaetosphaeridium globosum are covered on all surfaces with tiny diamond-shaped scales similar to those of the prasinophycean flagellates and the Charales. The flagella also bear striated hairs (hair scales) so far considered to be a characteristic of the Prasinophyceae. The flagellar apparatus differs from that observed in the Prasinophyceae, shows many similarities to that of the Charales, and is identical with the “Vierergruppe” of the pteridophytes, cycads and bryophytes. The zoospores are opisthokont, with two flagella inserted subapically. There is a lateral chloroplast containing typical grana and intergranal lamellae, but no eyespot. The very complicated Golgi body/contractile vacuole system comprises 10–20 contractile vacuoles. A microbody occupies a characteristic position in the cell, and in a young germling contains a crystalline inclusion. The ultrastructure of the zoospore supports the old theory that the ancestors of the higher plants may well be found among Coleochaete and its relatives, past and present.

A microscopical study of a marine species of Codosiga James‐Clark (Choanoflagellata) with special reference to the ingestion of bacteria

Abstract: Cells of Codosiga gracilis (Kent) de Saedeleer were grown in culture with two strains of bacteria and observed over a period of almost two years. Throughout the growth cycle, cell form varied with rounded motile individuals predominating during the first three days after subculture and stalked cells predominating in older cultures. Electron microscopy of sections revealed the presence of at least two flagellar bases and an elaborate microtubular system associated with the base of the single emergent flagellum. Capture and ingestion of bacteria has been observed using light microscopy, and electron microscopy of sections has demonstrated the relationship between the engulfing pseudopodium and adjacent collar tentacles.

“Chloroplast symbiosis” and the extent to which it occurs in Sacoglossa (Gastropoda: Mollusca)

Abstract: Criteria for defining “chloroplast symbiosis” are outlined. Investigations are described into the presence or absence of chloroplast symbiosis in Limapontia capitata,“pale” and “dark” forms of L. depressa, Alderia modesta and Elysia viridis. Apart from E. viridis, only “pale” forms of L. depressa showed signs of the phenomenon. All sacoglossans hitherto shown definitely to possess “chloroplast symbiosis” have the twin characteristics of being elysioid and having siphonaceous algae as the source of chloroplasts. It is therefore suggested that the phenomenon may not be very widespread in the order, probably occurring in less than half of all species.

Aspects of the ecology of the coral-eating starfish Acanthaster planci

Abstract: In the central region of the Great Barrier Reef, Acanthaster planci eats its own disk area of coral each day. At the southern end of the reef lagoon populations of A. planci eat substantially less than this amount of coral per day. Branching and plate corals are preferred food species and massive and encrusting forms are rejected while the preferred food species are available. Only when branching and plate forms on a reef have been consumed will A. planci attack massive and encrusting species. On Australian reefs preferred food species form between 70–99% of the coral cover. On the Great Barrier Reef A. planci spawns in January and juveniles settle in the top 3 m of water on the windward edge of reefs or on isolated patch reefs behind the main reef. Intolerance of wave attack forces the growing starfish to migrate into deeper water. Lateral movements, probably induced by shortage of living coral in deep water, bring the starfish around the ends of the reef to the leeward side. Here they destroy most of the living coral. It is suggested that the visual impact of A. planci on reefs of the Indo-Pacific region is related to the composition of the coral fauna. Reefs with a high proportion of preferred food species will be severely damaged while those with faunas composed mainly of massive and encrusting forms will not be altered greatly by starfish predation. Work on larval development of A. planci carried out by Henderson & Lucas, 1971 showed that metamorphosis took place only at water temperatures of 28o -29o C. This suggests that the A. planci plague on the Great Barrier Reef will not spread south of latitude 20o S (29o C isotherm in January).

A biological survey of St. Paul's Rocks in the equatorial Atlantic Ocean

Abstract: In May 1971, an ornithological census was taken, and samples of soil and marine invertebrates collected, on St. Paul's Rocks-an isolated group of small islands in the equatorial Atlantic Ocean. Fish were caught nearby. Crabs (Grapsus grapsus) were abundant on the Rocks and rock pools contained anthozoa, polychaetes, Crustacea and gastropods–a marine invertebrate fauna apparently closely related to that of Brazil. Specimens of four species of fish were obtained including one of Holocentrum sanctipauli, a species endemic to the Rocks. Protozoa, nematodes, bdelloid rotifers and cuticles of cryptostigmatid mites were found in the soil; most of the species identified were microbial feeders with a cosmopolitan distribution. The only terrestrial flora observed were green and blue-green algae and a nematode-predacious fungus, continuous sea-spray upon the Rocks preventing the growth of higher plants. Breeding populations of brown boobies and black and brown noddies were observed and counted. The presence of all life-cycle stages of the booby suggested that its breeding is aseasonal.

Sample design for quantitative estimation of sedentary organisms of coral reefs

Abstract: Various methods of sampling sedentary organisms on Australian coral reefs have been examined and a standardized photographic procedure has been suggested to suit the needs of an ecological study of Acanthaster planci and Linckia laevigata. To obtain reliable estimates of percentage cover of sedentary organisms and their spatial distribution metre square quadrats should be taken every fourth metre along transects orientated at right angles to the reef perimeter.

Morphological changes in isolated populations of some passerine bird species in Australia

Abstract: Variation in bill length, bill depth, bill width, tarsal length, hallux length and wing length was studied in isolated versus nonisolated situations in Australia with 14 species or superspecies of passerine birds. Most of these variates are of obvious ecological importance. None is prone to change more than any other in the seven isolates considered (South-western Australia, Eyre Peninsula, Fteurieu Peninsula, Kangaroo Island, King Island, Flinders Island and Tasmania), so presumably none is more advantageous to change than any other. Few shifts were found in the first four isolates, in contrast to the last three in which all populations showed marked change in dimensions. In the isolated populations, shifts most often involve increases in dimension. Whether selective processes other than competition are important in explaining changes in bill length, tarsal length and wing length was analysed with multiple regression. Changes in number of competitor species explains variation in bill length in eight out of 11 species. Variation in tarsal length and wing length are explained about equally by latitude, competitors, and other factors. Bergmann's and Allen's rules probably apply much less generally than is realized. A study of coefficients of variation of bill length, tarsal length and wing length was inconclusive in that most cases could not be explained by either latitude or competitors. When a correlation between coefficients of variation of these dimensions and latitude exists, it is nearly always positive.

A preliminary study of the biology and ecology of the blue starfish Linckia laevigata (L.) on the Australian Great Barrier Reef and an interpretation of its role in the coral reef ecosystem

Abstract: The blue starfish Linckia laevigata grazes coralline algae. The starfish populations studied were composed entirely of adults. Spawning takes place in October at the southern end of the Great Barrier Reef. On reefs which were unaffected by Acanthaster planci, L. laevigata was confined to algae covered reef tops and rubble banks. On reefs affected by A. planci, L. laevigata had extended its range and was feeding on and among the coralline algae covered dead hard coral skeletons on the reef perimeter. Coral regrowth, followingattack by A. planci, was found to be slower on reefs with populations of L. laevigata living on the reef perimeter than on reefs where they were absent from this region. It is suggested that grazing by L. laevigata destroys small coral colonies and newly settled larvae thus slowing down the rate of coral regeneration. The consequences of this reduced rate of recolonisation is also discussed.

The role of vegetative and reproductive attributes in the classification of the Orchidaceae

Abstract: Ninety‐three orchid taxa have been arranged into three classificatory dendrograms employing respectively 40 reproductive, 34 vegetative and 74 attributes combined, and forming the hierarchy by means of group‐average clustering. According to these results the non‐specificity hypothesis does not hold well for vegetative versus reproductive attributes. Both types of attributes are equally efficient predictors of the classification based upon the total data, though neither data set is a very reliable predictor. Hence both should be employed in the production of general classifications and when considering the phylogenetic relationships amongst orchids.

Wool shedding in musk oxen

Abstract: Qiviut is the underwool of the musk ox. This paper details the weight of qiviut produced and describes the time and pattern of the annual moult in three captive herds of musk oxen. Evidence for the stimuli to moulting and for the effects of captivity and selective breeding is reviewed, and a concluding section discusses some implications of these observations for studies of animal domestication.

“Paradoxum insectum”– Linnaeus on Diopsis (Insecta: Diptera)

Abstract: Evidence obtained by examination of documents from Linnaeus' own Library and now preserved in the Strongroom of the Linnean Society of London is analysed to show how doubts and errors in early descriptions of Diopsis ichneumonea Linnaeus arose and were perpetuated by copyists Reference is also made to Paussus microcephalus Linnaeus and to the spelling of this generic name Illustrated by five photographic reproductions from the original documents mentioned above

Catalogue of the Sladen Collection in the Royal Albert Memorial Museum, Exeter, Devon

Abstract: The W. P. Sladen collection at the Exeter Museum is described for the first time. An appraisal is given of Sladen's life and work, his library and the donation of the collection to Exeter Museum by Mrs Sladen. The immense zoological value of the collection should be recognized. There are more than 3800 specimens of recent echinoderms representing 224 genera and 425 species of world-wide distribution. There are over 2000 fossil echinoderms and these represent at least 155 genera and 226 species. Some type-specimens and figured specimens, previously thought to have been lost, have come to light. These, together with many Challenger Expedition asteroid and crinoid specimens examined by Sladen and P. H. Carpenter, make this one of the most important echinoderm collections outside any National Institution. There are over 7000 microscopical foraminiferan, echinoderm and other preparations in the collection. The majority of these were left to Sladen by Drs W. B. and P. H. Carpenter. The foraminiferan slides, in particular, must be ranked with equal importance to the echinoderms. The Sladen library contains over 2200 specialist books and papers.

Chemical studies on some lichens in the Linnaean Herbarium and lectotypification of Lichen rangiferinus L. (em. Ach.)

Abstract: Twenty-one specimens appear under the name ‘Lichen rangiferinus’ in the Linnaean Herbarium. Small fragments of these specimens have been subjected to chemical analysis for the first time using one or more of the following techniques: Lichen mass spectrometry, Ultraviolet spectrophotometry and Thin layer chromatography. The results, which have been stored in full on computer tape, are summarized and discussed in relation to the morphology and annotation of the lichens concerned. These studies have led to the selection of the specimen on sheet number 1273.240 as the lectotype of Lichen rangiferinus L. The fact that the chemical analysis of this specimen was carried out on less than 0.5 milligrams of thallus indicates the power of contemporary physicochemical methods in Herbarium studies of this nature.