Weed macaques: The evolutionary implications of macaque feeding ecology

Patterns of feeding ecology among the living macaques conform poorly with recognized phyletic distinctions within the genus because there is an important ecological division which cross-cuts phyletic groupings. This division, between weed species and non-weed species, is based on the differing abilities of macaques to tolerate and even prosper in close association with human settlements. Based on available information about their ecology in the wild, we tentatively assign macaque species to these two categories. Finally, we consider the implications of our argument for scenarios of the initial spread of the macaques.     

The selection of microbial communities by constant or fluctuating temperatures

Abstract The diversity of bacterial communities isolated from Antarctic lake sediment in chemostats under constant low temperature (8°C) or diurnally fluctuating temperature (1°C to 16°C) was examined. The median optimum temperature for growth of the freshwater bacteria isolated from the fluctuation chemostat was significantly lower ( P < 1%) than that for those from the constant temperature chemostat. The diversity of the enriched bacterial community isolated in the chemostat culture subjected to short-term temperature fluctuations was greater than that enriched under constant temperature. At least 4 different groups of bacteria, that occupied separate 'temperature niches', were isolated from the fluctuating chemostat compared to only one group isolated from the stable chemostat. Furthermore, a pseudomonad from the fluctuating chemostat was shown to out-compete another pseudomonad from the stable chemostat when both were subjected to the fluctuating temperature regime. However, the pseudomonad of constant (8°C) temperature origin out-competed that isolated under fluctuating conditions when subjected to a stable temperature regime.     

Host Status of Five Weed Species and Their Effects on Pratylenchus zeae Infestation of Maize

The host suitability of five of the most common weed species occurring in maize (Zea mays L.) fields in South Africa to Pratylenchus zeae was tested. Based on the number of nematodes per root unit, mealie crotalaria (Crotalaria sphaerocarpa) was a good host; goose grass (Eleusine indica), common pigweed (Amaranthus hybridus), and thorn apple (Datura stramonium) were moderate hosts; and khaki weed (Tagetes minuta) was a poor host. Only the root residues of khaki weed suppressed the P. zeae infestation of subsequently grown maize. When goose grass, khaki weed, and mealie crotalaria were grown in association with maize in soil infested with P. zeae, goose grass and khaki weed severely suppressed maize root development; this resulted in a low number of nematodes per maize root system and a high number of nematodes per maize root unit. Mealie crotalaria did not restrict maize root growth and did not affect nematode densities per maize root system or maize root unit. Special attention should be given to the control of mealie crotalaria, which is a good host for P. zeae, and goose grass, which, in addition to its ability to compete with maize, is also a suitable host for P. zeae.     

Predators and avian community organization: an experiment in a semi-desert grassland

Summary We provide experimental evidence that predators are a major factor organizing a community of granivorous grassland birds (mostly emberizid finches). Our focus is not on the lethal effects of predators, but on the simple idea that (i) birds will not settle where they perceive a high risk of predation, and (ii) species differ in their perception of the safety of woody vegetative cover due to differences in antipredator escape behavior. Consistent with this idea is the fact that the composition of this grassland community responds markedly to minor manipulations in the distribution of woody cover. In particular, with the addition of cover to open grasslands, species with cover-dependent escape tactics increase in abundance, while the abundance of cover-independent species decreases greatly; this decrease may reflect aggression from cover-dependent species, but evidence suggests that some cover-independent species may actively avoid cover-rich areas per se. Non-predatory effects of cover, most notably those concerning food resources and microclimate, appear unable to explain these results. Predators may influence many communities of terrestrial vertebrates via species-specific responses to cover.     

Wetland vegetation ecology on a reclaimed coal surface mine in southern Illinois,USA

An early successional wetland complex on a reclaimed surface coal mine in southern Illinois was studied 1985–1987. Seasonally, biomass was low, with above-ground values of 10–210g m^–2 and below-ground biomass of 1.5–2435 g m^–2. Biomass peaked in spring and did not vary much throughout the remainder of the growing season. Stem densities were high (179–1467 m^–2) because large numbers of seedlings became established as falling water levels exposed large areas of mudflats. Fluctuating water levels led to a lack of community zonation. Species diversity (H) was low to moderate over all sites with diversity values ranging between 1.86 and 3.27.     

Biology of Subanguina picridis,a Potential Biological Control Agent of Russian Knapweed

The knapweed nematode, Subanguina picridis, forms galls on the leaves, stems, and root collar of Russian knapweed, Acroptilon repens. After being revived from a dormant, cryptobiotic state, second-stage juveniles required at least 1 month in a free-living state before becoming infective. Galls were induced on relatively slow-growing host plants that retained their apical meristems at or near the soil surface for 2-5 weeks. Galls developed extensive areas of nutritive tissue. The nematode was introduced from the Soviet Union and released in Canada for the biological control of Russian knapweed.     

Seed dispersal and seedling emergence in an old field community in central New York (USA)

Summary Seed dispersal and seedling emergence of common taxa growing in a Solidago-dominated old field in central New York (USA) were monitored from May 1982 to June 1984. Over 3.5x10⁴ seeds per m² were captured on seed traps in each of the two years, with peaks occuring in July (due to Hieracium) and in November (due to Solidago). About 4.0x10³ seedling/m² emerged beneath the intact community in each of the two years. Although seedlings emerged predominantly in the early spring, a secondary peak occurred in September and October when many seedlings of introduced grasses appeared. Two additional aspects of the reproductive biology of the major taxa were related to the seasonal timing of seed dispersal: As the date of peak seed dispersal (among taxa) became progressively later in the season, (1) the duration of dispersal increased from about one week to about one-half year, and (2) the delay between the peak of seed dispersal and the peak of seedling emergence increased from a few days to about one-half year.     

元江干热河谷山地五百年来植被变迁探讨

元江河谷是云南省最干热地区之一,在海拔800—900米以下的山地上广泛分布着稀树灌草丛。根据《元江府志》(1714年编纂)、《元江州志》(1826年编纂)、《元江志稿》(1922年编篡)及对现存植被的考察,本文探讨了元江干热河谷山地五百年来植被的变迁。 元江县森林复盖率的减少与人口的增加有密切关系,十七世纪中期以前,森林复盖率在75％以上,十八、十九世纪时为70％左右,1958年为61.5％,1975年为27.3％,至1982年则为19.3％。研究表明,在十九世纪以前,这个地区分布的主要植被是热带季雨林,甚而热带季节雨林,以后热带稀树灌草丛则迅速发展。植被的历史变化与土壤流失密切相关。植物群落的演变是由以乔木树种为优势演变为以灌木种类为优势,再演变为以多年生草木植物为优势,而最后则成为裸地。本文也讨论了这个地区植被恢复的方法。     

The chorologic pattern of European Nardus-rich communities

Two types of Nardus-rich communities may be distinguished in Europe according to their geographic pattern:I. Communities of high mountains showing discontinuous variation. Different florogenesis in island-like high mountains results in a number of alliances characteristic for particular mountain systems: Trifolion humilis Quézel 57 (Atlas, N Africa), Plantaginion thalackeri Quézel 53 (Sierra Nevada), Campanulo-Nardion Rivaz-Martinez 63 (mountains of the central Iberian peninsula), Nardion Br.-Bl. 26 (from Pyrenees, Auvergne to W and E Carpathians), Potentillo ternatae-Nardion Simon 58 (S Carpathians, Pirin, Rila), Jasionion orbiculatae Lakui 66 (Dinarids), Trifolion parnassi Quézel 64 (S Greece), Nardo-Caricion rigidae Nordhagen 37 (Iceland, Scotland, Scandinavia, W Sudeten).II. Communities at lower altitudes with continuous variation, where particular syntaxa are difficult to distinguish. Along the climatic gradient from a subatlantic to a subcontinental climate, a cline in floristic composition of the communities under discussion is found. Towards the eastern borderline, the communities are poorer in characteristic species. Here only one alliance is considered-Violion caninae Schwickerath 44. A Similar situation occurs along the altitudinal gradient in mountains. Only in mountains with a belt of alpine communities the montane Nardeta are saturated with alpine species. This thpe of communities was described as Nardo-Agrostion tenuis by Sillinger (1933).