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81.
The effect of cyclic-AMP and GA3 on ATPase production in embryolessbarley half-seeds was examined. Similarities in the responseinduced by 5 mM cyclic-AMP and GA3 were observed in (1) thetotal amount of ATPase produced, (2) the time course for therelease of ATPase, and (3) the effect of abscisic acid on ATPaseinduction by these compounds. Of a variety of adenine nucleotidesexamined only cyclic-AMP was found to promote high levels ofATPase activity. Some of the implications of these results arediscussed. (Received May 11, 1971; ) 相似文献
82.
ALAN N. ANDERSEN 《Austral ecology》1991,16(3):273-279
The relative abundances of ant species captured in pitfall traps was compared with those obtained by direct counts in quadrats at a savanna site in Kakadu National Park, Northern Territory. Two measures of abundance in traps were used, one based on total numbers of ants, the other on species frequency of occurrence. All species commonly recorded in quadrats were collected in traps, and their relative abundances were highly correlated on all occasions. Of the 20 most common species in quadrats, five occurred with a significantly different (in all cases lower) frequency in pitfall traps, but these species represented only 1.8–3.1% of total quadrat counts. Results from quadrats and pitfall traps were particularly similar (r > 0.8) when species-were classified into functional groups. Frequency data from traps may sometimes overestimate the abundance of widespread, solitary foraging species (e.g. ‘Chelaner’ and Tetramorium spp.) and underestimate species with large colony sizes (e.g. Iridomyrmex spp.). Data based on total numbers of ants in traps may be more prone to distortion arising from species differences in locomotor behaviour. Species counts in traps could be scaled to reduce these distortions. The finding that pitfall traps gave results comparable with those from quadrat counts provides support for the use of pitfall traps in studies of Australian ant communities in open habitats. 相似文献
83.
Compsognathus longipes sits at an important point in theropod evolution at the base of Coelurosauria . Despite its relative completeness and oft-cited morphology, however, the manual morphology has been unclear. This work provides the first detailed study of the morphology of the manus of Compsognathus longipes . It shows that Compsognathus longipes had two fully formed functional digits as well as a reduced, perhaps even non-functional, third digit. That conclusion runs counter to the usual interpretation that Compsognathus longipes had only two phalanges, rather than the expected complement of three, in digit II. This work also identifies a unique suite of metacarpal I morphologies that are used to diagnose a subclade among species often referred to as 'Compsognathidae'. These features are used to construct an apomorphy-based definition of a new clade name: Compsognathidae. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 149 , 569–581. 相似文献
84.
DIEGO F. SEGURA M. TERESA VERA JUAN RULL VIWAT WORNOAYPORN AMIRUL ISLAM ALAN S. ROBINSON 《Biological journal of the Linnean Society. Linnean Society of London》2011,102(2):346-354
Reproductive isolation among populations of Anastrepha fraterculus has been found acting at the pre‐ and post‐zygotic levels. Differences in timing of sexual activity and male sexual pheromone composition among populations could partially account for prezygotic isolation. Hybrid males were found to produce a novel pheromone, which is a mix of parental pheromones. In the present study, we found that the hybrid females showed a significant preference to mate with hybrid males than with parental males. Male location during pheromone emission is associated with its reproductive success and, thus, differences in the location of males during courtship could also play a role in isolation. We found evidence that reproductive isolation is also related to the location of males during courtship. Hybrid male behaviour regarding location during pheromone release was found to be influenced by the maternal lineage. If these populations hybridized in the field, the hybrid females would tend to mate with hybrid males probably leading to the formation of a new entity within the A. fraterculus complex. This simple and fast process could be one reason explaining the high number of taxonomic entities within this complex. Further studies on other members of the fraterculus species group may reveal whether this can be considered as an example of homoploid hybrid speciation. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 346–354. 相似文献
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86.
The conservation values of ‘old‐growth’ forests in landscapes subject to repeated disturbance by fire or logging have received considerable conservation attention. However, little is known of the conservation values of old‐growth sites in ecosystems with an evolutionary history of highly frequent disturbance. Here we address the value of low fire frequency (<1 fire/10 years) in tropical savannas, the world's most fire‐prone biome, in terms of ant biodiversity. We do this by comparing savanna ant communities within the Territory Wildlife Park (TWP) near Darwin in the Australian monsoonal tropics, which has experienced a low incidence of fire over 25 years due to active fire exclusion, with those of adjacent (outside) sites experiencing the ambient fire regime of burning every 2–5 years. Ants were sampled using terrestrial and arboreal pitfall traps at 16 sites, eight each inside and outside TWP. More than 16 000 ants were recorded during the study, representing a total of 98 ant species from 30 genera. More species in total were recorded outside (90) than inside (74) TWP, but there was no difference in mean site species richness or abundance, and overall species composition was similar. All species recorded inside TWP are common and widespread throughout the savanna landscapes of the broader region, in the absence of active fire exclusion. Low fire frequency at the Territory Wildlife Park therefore does not appear to have enhanced regional ant conservation values. Our findings reinforce the importance of targeting fire regimes that are clearly linked to positive conservation outcomes, rather than assuming a need for maximum ‘pyrodiversity’. 相似文献
87.
88.
89.
ALAN R. HEMSLEY F.L.S. MARGARET E. COLLINSON F.L.S. ANTHONY P. R. BRAIN 《Botanical journal of the Linnean Society. Linnean Society of London》1992,108(4):307-320
HEMSLEY, A. R., COLLINSON, M. E. & BRAIN, A. P. R., 1992. Colloidal crystal-like structure of sporopollenin in the megaspore walls of Recent Selaginella and similar fossil spores. TEM and SEM studies of iridescent fossil Erlansonisporites and Recent Selaginella spores reveal a wall composed of three regions. The central region consists of close-packed particles in a semi-crystalline arrangement. This organization is compared with that of aggregated Iridoviridae, prolamellar bodies, lipid micelles and precious opal. Our observations suggest that the structure of this wall region (and that of the remaining regions) can be explained by derivation from colloidal mixtures. It is concluded that colloids and their precursors may play a far more significant part in spore and pollen wall structure than was previously believed. 相似文献
90.
ALAN HOWARD 《American anthropologist》1972,74(4):811-823