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JOHNSTONE O. YOUNG 《Freshwater Biology》1972,2(4):355-359
Five new British records of freshwater Microturbellaria are illustrated: Gieysztoria infundibuliformis, Castrada lanceola, Castrada neocomensis, Castrada viridis and Strongylostoma elongatum. These species together with a new species, Macrostomum johni described by Young (1972), are woven into the fabric of the existing key for the group (Young, 1970). All six species were recorded from the littoral zone of lakes in Caernarvonshire, N. Wales. The times of the recordings are indicated. 相似文献
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ANDREW BOURKE 《Journal of Zoology》1989,217(3):522-523
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Measuring the effect of observations on Bayes factors 总被引:2,自引:0,他引:2
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Sexual swarms in Daphnia magna, a cyclic parthenogen 总被引:3,自引:0,他引:3
J. P. W. YOUNG 《Freshwater Biology》1978,8(3):279-281
SUMMARY. Dense swarms were observed in a population of Daphnia magna (Crustacea: Cladocera). The swarms appeared during a sexual period in which females were abundant but males were rare. Each swarm contained several males and large numbers of 'imminently sexual' females, a class of females that was rare except in the swarms. This implies that both sexes respond to attractant stimuli, and that the female response occurs only during a brief critical phase in the ovarian cycle. 相似文献
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Regular unscheduled movements of rancherías within a confined area or settlement district result in the phenomenon described as "village drift," a process whereby a settlement may change its location gradually by several kilometers over a period of years. This article presents a model of village drift based on data acquired from recent archaeological and geomorphological field studies and archival research on the Akimel O'odham, the Gila River Pima of south-central Arizona. The model provides an excellent example of human ecodynamics---an emerging landscape perspective that emphasizes the coevolution of humans and their ecosystem---with implications for understanding prehistoric and historic settlement in desert riverine environments. 相似文献
8.
C. A. WATKINS R. J. McNICOL K. YOUNG A. T. JONES † 《The Annals of applied biology》1990,116(3):489-492
Because there is some evidence that June Yellows (JY) of strawberry may be caused by a pathogenic agent, combinations of heat treatment and meristem-tip culture that are known to eliminate some viruses from tissues were used in attempts to cure affected Cambridge Favourite strawberry plants from JY. None of 397 propagants derived from JY-affected plants subjected to various combinations of these treatments were freed from JY. Indeed, all propagants showed more obvious JY symptoms than the parent plants from which they were derived, suggesting that such treatments may be useful for detecting incipient JY in symptomless strawberry stocks. 相似文献
9.
Fructan biosynthesis in excised leaves of Lolium temulentum L. 总被引:2,自引:2,他引:0
ANDREW J. CAIRNS 《The New phytologist》1989,112(4):465-473
10.
A technique is described to accurately assess the dermal contactdose-mortality response of molluscicides. The technique involvescarbon dioxide anaesthesia of laboratory reared Deroceras reticulatum(Müller) followed by application of test substances insolution to the dorsal surface. The LD50 of the substances testedwere as follows: Sodium pentachlorophenate, 55.9 ng.mg1,Copper sulphate, 124.1 ng.mg1, Methiocarb, 314.6 ng.mg1and Potassium permanganate, 418.9 ng.mg1 body weight. (Received 18 August 1988; accepted 17 December 1988) 相似文献