共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
3.
4.
5.
Selman, R.G., Hunter, M.L. & Perrin, M.R. 2000. Rüppell's Parrot: status, ecology and conservation biology. Ostrich 71 (1& 2): 347–348. We have started the first in-depth study into the behaviour of Rüppell's Parrot in the wild. Here we provide the initial results with information on its breeding biology, diet and use of natural and artificial water pools in northern Namibia. A variety of predators are listed, the terrestrial and arboreal ones causing complete losses at some nests. Illegal trade is the major threat to this species. 相似文献
6.
《Cell biology international reports》1988,12(12):1001-1004
Since the late seventies, molecular biology has infiltrated into the field of plant sciences that aims at crop improvement through gene transfer. T. Hall and his contemporaries J. Schell and Van Montagu in Cologne and Ghent respectively, succeeded in gene transfer to higher plant cells through an improved vector-Ti-plasmid and obtained expression (1,2). A series of reports then appeared which were summarised in the 6th International Congress of Plant Tissue and Cell Culture held in Minneapolis in 1986 and also in the International Symposium of Plant Protoplasts held in Holland in 1987. This report will be restricted to the recent work of importance with emphasis on that being carried out in the Peoples Republic of China. 相似文献
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
Abstract Banksia brownii is an endangered species, now limited to ~ 15 disjunct populations in southwestern Western Australia. Data on flowering phenology, plant size, fruit set, pollination and the mating system were gathered for two of these populations between March and October 1993. Flowering for both populations followed a similar pattern, with open flowers first evident in April, and the number of inflorescences with open flowers peaking in June. At both locations, trees differed considerably with respect to their size, the total number of inflorescences produced and the length of their flowering season. Fruiting success was typically low, with approximately half of all inflorescences failing to develop into infructescences. Only 1. 8% of the flowers originally present on inflorescences developed into follicles. The distribution of follicles along each infructescence was non-random, with most forming in the middle third of the infructescence for reasons relating to nutrient supply and pollinator behaviour. More flowers opened during the day than at night, although pollen was lost from individual flowers during both periods. Honeyeaters such as Phylidonyris novaehollandiae were common at the two study sites, and often carried large loads of B. brownii pollen. Though less frequently caught, the nocturnal mammals Rattus fuscipes and Tarsipes rostratus also bore substantial amounts of pollen. Most inflorescences from which these mammals and birds were excluded remained barren. Fruiting success was further reduced when invertebrates such as Apis mellifera were also prevented from visiting inflorescences. The ability of B. brownii to set at least some fruit in the absence of biotic poli-nators indicates that the species is partially self-compatible. Honeyeaters foraged preferentially at inflorescences with one to two thirds of their flowers open, probing mainly along the ‘advancing front’ of open flowers. These animals moved more frequently between inflorescences on the same plant than between those on different plants, and were often recaptured in the same locations. Mammals also appeared to be sedentary. Both B. brownii populations had mixed mating systems, with genetically determined outcrossing rates of ~0.7. The unusually high level of selfing in each population is presumably a reflection of the species’ self-compatibility and the foraging behaviour of its pollinators. 相似文献