Occurrence Of Individual Species Research Articles

A pre‐Ipswichian cold stage mammalian fauna from the Balderton Sand and Gravel, Lincolnshire, England

AbstractThe Balderton Sand and Gravel has yielded one of very few mammalian faunas dated to the penultimate Cold Stage in Britain. The assemblage is dominated by mammoth and woolly rhinoceros, with subordinate horse, red deer, bison, straight‐tusked elephant, musk ox, reindeer, wolf, lion, brown bear and cf. narrow‐nosed rhinoceros. This fauna indicates cold stage conditions, probably including one or more interstadial episodes. The presence of straight‐tusked elephant and cf. narrow‐nosed rhinoceros supports its pre‐Devensian age, and provides corroboration for the occurrence of these taxa in the British Wolstonian. An attempt is made to analyse the fossil collection by preservation type and adhering sediment: the occurrence of individual species appears to be largely uncorrelated with lithology. The Balderton assemblage corresponds well to other British mammal faunas assigned to a cold interval between the Hoxnian and Ipswichian Interglacials.

Factors influencing the occurrence of vesicular-arbuscular mycorrhizas

Vesicular-arbuscular (VA) mycorrhizas are widely distributed but there is limited knowledge of the occurrence of individual species in relation to soil, climate and vegetation. Recent developments in methods for identifying and quantifying VAM fungi, both in soil and within roots, should enable the clearer definition of the factors that influence their distribution. Careful attention must be paid to sampling procedures to avoid bias and subjectivity. Soils commonly contain more than one VAM fungus. The development of VA mycorrhizas varies with soil type and depth, season and vegetation. The dynamics of root colonization by individual species within a population have not been adequately explored. Minor or gradual disturbances in agricultural and natural ecosystems may, or may not, lead to marked changes in mycorrhiza formation. Populations of VAM fungi appear to be capable of adjusting to gradual changes in the environment without abrupt changes in the extent of colonization. In contrast, more extreme, or rapid environmental changes such as those associated with mining or erosion, may markedly decrease mycorrhiza formation. The restoration of populations of mycorrhizal fungi will depend on the availability of accessible sources of propagules and on the suitability of the disturbed soils for plant and fungal growth.

Keratinophilic fungi from Nigerian soil

During a survey of keratinophilic fungi in Nigerian soil samples, twelve species of fungi were isolated. These included Chrysosporium keratinophilum, C. tropicum, Curvularia lunata, Microsporum audouinii, M. canis, M. fulvum, M. gypseum, M. vanbreuseghemii, Trichophyton ajelloi, T. mentagrophytes, T. soudanense and T. yaoundei. These keratinophilic fungi had a higher incidence by occurrence of individual species during the rainy season (May-October) than the dry season (November-April).

Patterns of Occurrence of Ascomycetes Associated with Decomposing Twigs in a Midwestern Stream

Packs of twigs from cherry, oak, silver maple, and sycamore trees were placed in an Illinois stream and samples were recovered periodically over 30 months. Ash-free dry weights remaining over time were determined and twigs were examined for Ascomycetes directly and after incubation. Twigs disappeared at rates much lower than those reported for leaves and provided an enduring substrata for fungi. Thirty-three Ascomycetes were collected: Pseudohalonectria lignicola and Savoryella lignicola are reported from the United States for the first time. Nectria lucidum, Pseudohalonectria lignicola, Leptosphaeria sp. 1, and Aniptodera sp. 1 occurred most frequently. With the exception of the decline of blastocladiaceous and saprolegniaceous species after one week, and the disappearance of N. lucidum after the first year, distinct changes in community structure did not occur during the submersion period. Generally, the numbers of species and the frequencies of occurrence of predominant species increased with increased time of submergence. Long-term incubation of substrata yielded the greatest number of Ascomycetes; incubation in light/dark conditions increased the number of species and the frequencies of occurrence of individual species over dark incubation.

A note on the distribution and approximate areas of mangroves in South Africa

The occurrence of individual species, of which there are five in South Africa, and the approximate total area of mangroves in all known South African estuarine systems are presented for the first time for South Africa as a whole. Natural increase is occurring throughout the region although this is masked in many places by the direct destruction of the mangroves themselves or through adverse effects on their habitats. S. Afr. J. Bot . 1982, 1: 51-53

Factors contributing to non-randomness in species Co-occurrences on Islands.

There has been dispute whether patterns of species co-occurrence on islands are largely random. We present a new method for testing this question; this method lets one not only examine whether a whole fauna is non-randomly structured, but also identify in which direction and by how much each particular species combination deviates from expectations based on randomness. Application of this method to the whole Bismarck and New Hebridean avifaunas, and to two particular guilds, shows that some pairs of species have more exclusive distributions than expected for random placement of species, because of competition, differing distributional strategies, or different geographical orgins. Other pairs of species have more coincident distributions than expected, because of shared habitat, single-island endemism, shared distributional strategies, or shared geographical origins. Much of the information about non-random co-occurrence is contained in the incidence graphs for occurrence of individual species. Finally, our present understanding of assembly rules is summarized.

Species Diversity and Ecological Release in Caribbean Land Bird Faunas

Communities of breeding, non-raptorial land birds were studied in nine major habitat types (secondary grassland and scrub, young and old secondary forest, mature lowland forest, cloud forest, mangroves, savanna, residential land) in each of five Caribbean areas (Panama, Trinidad, Jamaica, St. Lucia, St. Kitts). In each habitat, the frequency of occurrence of individual species was determined in ten 20-min observation periods. Foliage height profiles were determined for all areas except St. Kitts. Data on frequency of occurrence were converted to indices of absolute abundance. Ecological release, involving both increase in the average number of habitats occupied per species and increase in within-habitat abundance, was extensive, and complete density compensation or overcompensation occurred in Jamaica, St. Lucia, and St. Kitts. Dropout of species along the species diversity gradient from Panama to St. Kitts appeared to be random with respect to generic or familial status. Habitat distribution appeared to shift from-being strongly influenced by interspecific relations in Panama to being largely independent of such influence in St. Kitts.

Preliminary survey of the epigaeic invertebrate fauna with particular reference to ants, in areas of different land use at Dwellingup, Western Australia

A pilot pitfall trap sampling programme was performed at Dwellingup, Western Australia in order to compare the epigaeic fauna in unburnt jarrah ( Eucalyptus marginata), burnt jarrah, dieback-infested jarrah, pine plantations, and urban, farmed and mined areas. Analysis of similarity of the ant fauna produced a broad division into two groups. The first group consisted of a rich ant fauna of moderate equitability and was associated with only slightly modified native forest sites. The second group consisted of a less rich and, to some extent, less equitable ant fauna and was associated with sites with highly modified vegetation. The occurrence of individual species in each area is discussed in relation to forest succession and incidence of pioneer species.

The structure of tick-borne encephalitis (TBE) foci in Central Europe.

The investigations on the structure of TBE foci were carried out in the localities Jívová (northern Moravia), Topolčianky and Žírany (Tribeč Mountains), and environs of Debreczén (Pannonian lowland, Hungary). The biphasic activity curve of Ixodes ricinus, characteristic for the central European conditions was confirmed in all three types.In some localities two or three tick species as vectors come into consideration and the unequal seasonal occurrence of individual species results in a permanent presence of virus-harbouring ticks in nature throughout the year.The average population density of ticks per hectare in a focus near topolčianky in mid-April, 1969, reached 46,000 nymphae and 50,000 adults. About 1% of the tick population were found to be viruliferous.Great differences were found in the composition of plant communities, mammalian synusies and in the population density of small mammals and ticks within the regions studied.Each elementary focus consists of many "microfoci" where the territories of individual host species overlap in space and time. Nests in tree holes and underground probably also belong to these microfoci. The maintenance hosts and indicators in each type of focus are mentioned. Free-living Carnivora can be considered as incidental hosts in each type of focus.

A comparison of the numbers and distribution of aphid species flying over Eastern Australia in two successive years.

The results of the two year's operations, using Moericke aphid traps at 12 sites in eastern Australia, are compared. The basic stability of the aphid fauna flying in successive years is established in terms of primary effects of geographical distribution and seasonal phenology in association with climate. The causes of variability of the magnitude and timing of flights of aphids are discussed in terms of properties of species and of local variations in the weather pattern. There appears to be a latitudinal pattern of areas where aphid catches were highly consistent and of areas where consistency was low. A study of the consistency of occurrence of individual species in the two years, shows that the numbers of some species appear inherently more stable than of others. A large overall effect in the collecting performance of the traps seems to be traceable to a climatic difference between the two years.

THE MICROFUNGAL FLORA OF BAT CAVE SOILS FROM ELEUTHERA ISLAND, THE BAHAMAS

A total of 55 species of microfungi, representing 30 genera, were isolated from 19 samples of soil and 1 sample of dung obtained from a bat cave located on Eleuthera Island, the Bahamas.Frequencies of occurrence of individual species and major groups of fungi plus a brief comparison with other ecological studies of soil fungi are presented. Guano deposits of insectivorous bats represent the dominant factor in determining the fungal composition of the cave.

Researches in Western Samoa I. General sanitation and intestinal parasites

1. (1) A short description is given of the living and sanitary conditions prevailing in the village of Laulii, Western Samoa, and of the physical health of the villagers. 2. (2) Of 210 specimens of faeces examined for the presence of helminthic infections, 59.0 per cent. were positive for helminths generally, Ancylostoma 15.7 per cent., Ascaris 31.4 per cent., Trichuris 31.9 per cent., Strongyloides 2.9 per cent. 3. (3) Examinations for protozoa numbered 168, protozoal cysts were found in 18.5 per cent. The incidence of occurrence of individual species was E. histolytica 4.2 per cent., E. coli 11.9 per cent., E. nana 1.2 per cent., I. bütschlii 1.2 per cent.