A new species of Clivia (Amaryllidaceae) endemic to the Pondoland Centre of Endemism, South Africa

Clivia robusta B.G. Murray, Ran, de Lange, Hammett, Truter et Swanevelder sp. nov. (Amaryllidaceae) is a tubular, pendulous-flowered Clivia species, restricted to the Pondoland Centre of Endemism, South Africa. The unique morphology, distribution, karyotype and molecular fingerprint distinguish it from all other pendulous-flowered species in the genus.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 369–374.     

The Development of Activities of Some Enzymes Concerned with Glycollate Metabolism in Greening Bean Leaves

The activities of phosphoglycollate phosphatase (EC 3.1.3.18 [EC] ),glycollate oxidase (EC 1.1.3.1 [EC] .). catalase (EC 1.11.1.6 [EC] ), theperoxisomal NADH-glyoxylate reductase (EC 1.1.1.26 [EC] ) which isconsidered to function as a hydroxypyruvate reductase in theperoxisomes, and the chloro-plastic NADPH-dependent glyoxylatereductaae, have been measured in extracts prepared from 14-d-olddark-grown bean leaves during the course of their greening inresponse to exposure to continuous illumination. All of theenzymes were found in the dark-grown leaves and on a per-leafbasis the activities increased from 6- to 12-fold with the exceptionof a 2–3-fold increase of NADPH-dependent glyoxylate reductaseduring 96-h greening, while the activities either remained constantor declined during similar periods in darkness. Initial lagperiods were evident before the illumination-induced increasesin enzyme activities. As D-threo-chloramphenicol did not affectthe increase in activity of any of these enzymes it would appearthat the increases were in no way dependent on protein synthesisby 70S ribosomes, or on the development of photosynthetic activity.     

A COMPARISON OF 30° AND 37° AS INCUBATION TEMPERATURES IN THE PRESUMPTIVE COLIAEROGENES TEST FOR RAW AND PASTEURIZED MILK

SUMMARY: Incubation at 30° and 37° for the presumptive coli-aerogenes test for raw and pasterurized milk has been investigated. There were more positives at the lower temperature and it is suggested that in this test, incubation at 30° might provide a much better guide to the hygienic quality of both raw and pasterurized milk. The ability of the coli-aerogenes bacteria studied to ferment lactose in MacConkey's broth at 30° but not at 37° was found to be a stable factor which was unchanged by prolonged storage on agar slopes at room temperature or on continued incubation in MacConkey's broth at temperatures above the optimum for lactose fermentation.     

Avifauna response to hurricanes: regional changes in community similarity

Global climate models predict increases in the frequency and intensity of extreme climatic events such as hurricanes, which may abruptly alter ecological processes in forests and thus affect avian diversity. Developing appropriate conservation measures necessitates identifying patterns of avifauna response to hurricanes. We sought to answer two questions: (1) does avian diversity, measured as community similarity, abundance, and species richness, change in areas affected by hurricane compared with unaffected areas, and (2) what factors are associated with the change(s) in avian diversity? We used North American Breeding Bird Survey data, hurricane track information, and a time series of Landsat images in a repeated measures framework to answer these questions. Our results show a decrease in community similarity in the first posthurricane breeding season for all species as a group, and for species that nest in the midstory and canopy. We also found significant effects of hurricanes on abundance for species that breed in urban and woodland habitats, but not on the richness of any guild. In total, hurricanes produced regional changes in community similarity largely without significant loss of richness or overall avian abundance. We identified several potential mechanisms for these changes in avian diversity, including hurricane‐induced changes in forest habitat and the use of refugia by birds displaced from hurricane‐damaged forests. The prospect of increasing frequency and intensity of hurricanes is not likely to invoke a conservation crisis for birds provided we maintain sufficient forest habitat so that avifauna can respond to hurricanes by shifting to areas of suitable habitat.     

Life‐history and ecological correlates of decline and extinction in the endemic Australian frog fauna

Abstract Frog populations are rapidly disappearing throughout the world. An important issue for ecologists to resolve is why some frog species are more susceptible to decline than others. Here, we performed a comparative study of the endemic Australian frog fauna to determine whether the life history and ecology of declining species have predisposed them to extinction. Decline was consistently found to be correlated with geographical range size across contemporary species and in analyses based on phylogenetically independent contrasts (PICs). Species with narrow geographical ranges have been disproportionately more susceptible to decline. Across species, decline was also correlated with large body size and a high proportion of the geographical range overlapping with the distribution of cane toads and landscape stress (e.g. land clearing). We show that with the exception of range size, however, correlates of decline across species are underpinned by a small number of evolutionary events. Hence, the suite of traits that correlate with decline in the cross‐species analysis is only relevant to a small number of clades. We also found that clutch size, testes mass, ova size and distributional overlap with feral pigs were not significantly related to decline. In the ongoing search for life‐history and ecological correlates of decline and extinction, our results highlight the importance of performing analyses across contemporary species and using PICs.     

Confirmation of Ancient Polyploidy in Dahlia (Asteraceae) Species using Genomic In Situ Hybridization

The successful production of interspecific hybrids between membersof the dysploid chromosome series inDahlia offers a unique opportunityto investigate chromosome evolution. Analysis of meiotic metaphaseI in these hybrids using genomic in situ hybridization (GISH)has shown that pairing occurs both between and within parentalgenomes. These results have provided clear evidence for theallotetraploid origin of Dahlia species with 2n=32 and suggeststhat species with 2n=34 and 2n=36 have also arisen via allopolyploidy.A bivalent promoting mechanism proposed for species with 2n=32also appears to be present in Dahlia species with 2n=34 and2n=36 .Copyright 1999 Annals of Botany Company Dahlia , GISH, dysploidy, chromosome pairing, karyotype analysis, polyploidy.     

Improvement of the 15N dilution method for estimation of absorption of NOx by plants supplied with 15N-labelled fertilizer

To develop further the methods for estimation of NOx absorption by plants supplied with ¹⁵N-labelled fertilizer, we proposed a new calculation method, total N fixed method (TNF), and compared with the ¹⁵N dilution method and the classical mass balance method (MB).
Hydroponically grown soybean plants were supplied with ¹⁵N-labelled nitrate and exposed to 200–250 nl l⁻¹ NO₂ for 7 d. The proportions of the N derived from NO₂ to total N in exposed plants were estimated by the three methods.
The reported rates of NO₂ absorption by several plant species, estimated by the ¹⁵N dilution method, were recalculated using the TNF method. The results of the two methods were compared and showed that: (1) The ¹⁵N dilution method overestimated the content of NO₂-N in exposed plants compared with the MB method whilst the TNF method produced estimations of NO₂-N closer to those by the MB method when the plants were supplied with 5 m M nitrate. (2) The differences in estimations between the MB method and either the ¹⁵N dilution method or the TNF method increased with decreasing supply of ¹⁵N-labelled nitrate to roots.     

Assessment of Canada Lynx Research and Conservation Needs in the Southern Range: Another Kick at the Cat

Abstract The ecology of Canada lynx (Lynx canadensis) and their main prey, snowshoe hares (Lepus americanus), is poorly understood in southern Canada and the contiguous United States compared to the boreal forest of Canada and Alaska, USA, where both species are well studied. However, given recent listing of lynx under the Endangered Species Act, accurate understanding of lynx and snowshoe hare ecology and conservation requirements in the United States is a high priority. We critically examined unchallenged perceptions and important research needs related to lynx and hare ecology and conservation at the southern extent of their range. Contrary to popular dogma, lynx do not require old-growth forest for denning, but further research on lynx and hare use of fragmented landscapes at lower latitudes is required. The contention that southern lynx are subject to higher interference or exploitative competition compared to their northern counterparts remains without strong empirical support. Lynx rely more on red squirrels (Tamiasciurus hudsonicus) and possibly other alternate prey at lower latitudes, but hares are the predominant food type for lynx across their range. Southern lynx and hare populations do not exhibit periodic cyclicity, but harvest statistics suggest that lynx abundance in the southern range is highly variable, implying that numerical fluctuations likely are fueled by immigration from Canada. Southern lynx population viability in the absence of ingress is suspect and thus maintaining connectivity with northern areas of occupancy should be a priority. Successful conservation of lynx populations in the contiguous United States will require 1) improved understanding of lynx population and habitat ecology at lower latitudes, 2) protection and management of large tracts of lynx and snowshoe hare habitat, and 3) ensured connectivity between lynx populations at the core and periphery of the species' range. However, in light of the numerous challenges facing conservation of populations of many species at their southern distributional limit, the long-term prognosis for lynx in the southern range currently is uncertain.     

Aminopeptidases Isolated from Cotyledons of Cowpea, Vigna unguiculata

Three aminopeptidases have been separated from cotyledon extractsfrom cowpea, Vigna unguiculata (L.) Walp., and numbered in orderof decreasing affinity for the anion exchange medium DEAE-Sephacel.API showed a wide acceptance of model substrates, with highestactivity under standard conditions against arginyl ß-naphthylamide(NA). AP2 did not act on basic substrates and preferred phenylalanylß-NA. AP3 displayed the narrowest substrate specificity,with strong activity against only alanyl ß-NA andglycyl ß-NA. The chelator 1,10-phenanthroline completelyor almost completely inhibited forms AP1 and AP3, whereas AP2was insensitive to phenanthroline at the same concentration(5 mM). All three aminopeptidases were totally inhibited byAg⁺ or Zn²⁺ ( 0.5 mM). Vigna unguiculata (L.) Walp., aminopeptidase, cotyledon, cowpea, isoenzyme, 1, 10-phenanthroline