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91.
The vegetables germplasm conservation programme in Poland was started in 1982, activities under this program resulted up to
this date in building up a tomato germplasm collection of 782 accessions that are available for distribution to breeders and
researchers in Poland and abroad. Between 1990 and 1999 we distributed 651 tomato seed samples to breeders and scientists
in Poland, and 95 samples to users abroad. During 1990 – 1999 the 652 tomato accessions were evaluated for 43 traits of plants
and fruits. Work is in progress to expand the collection and identify useful characteristics of the collected material, and
to make use of them in breeding and other research works. 相似文献
92.
The biology of insularity: an introduction 总被引:5,自引:0,他引:5
Donald R. Drake Christa P. H. Mulder David R. Towns & Charles H. Daugherty 《Journal of Biogeography》2002,29(5-6):563-569
93.
94.
Hannah Reid 《Human ecology: an interdisciplinary journal》2001,29(2):135-155
Contractual national parks in South Africa are established on land owned either by the state or by a group of private individuals, but managed by South African National Parks (SANP) according to the terms of a joint management agreement drawn up by a joint management committee consisting of representatives from SANP and the landowners. Since majority rule in 1994, contractual national parks have been seen as a model through which the country's conservation as well as development objectives can be met, particularly where landowners are previously disadvantaged communities. This study looks at the Makuleke region of Kruger National Park in order to ascertain how successful the contractual national park model is in meeting conservation, social, and economic objectives for the area. 相似文献
95.
96.
Allozyme variation and population structure of the very narrow endemic Seseli farrenyi (Apiaceae) 总被引:1,自引:0,他引:1
JORDILÓPEZ-PUJOL MARIABOSCH JOANSIMON CÉSARBLANCHÉ 《Botanical journal of the Linnean Society. Linnean Society of London》2002,138(3):305-314
Analyses have been made of allozyme variation of the narrow endemic species Seseli farrenyi Molero & J. Pujadas (Apiaceae), which has only three known populations in Catalonia with a total of around 2000 individuals. All three populations were sampled and subjected to starch gel electrophoresis. Nine enzymes were resolved and 14 loci were interpreted. We detected high values of polymorphism ( P = 83.3%, A = 3.0, H e = 0.297), far exceeding those expected for endemic species ( P = 26.3%, A = 1.39, H e = 0.063). Genetic diversity was greater within populations than among populations, and the value of gene flow was very high ( Nm = 5.85). Most loci showed deviations from Hardy– Weinberg equilibrium, possibly due to the presence of subpopulations. The main threats to this species are human activities (tourism, fires), while natural threats are minimal due to its high genetic diversity. Finally, we propose some conservation measures which include both in situ and ex situ strategies. © 2000 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 305–314. 相似文献
97.
98.
Lance G. Woolaver Rina K. Nichols Eugene S. Morton Bridget J. M. Stutchbury 《Journal of Field Ornithology》2013,84(2):138-146
Ridgway's Hawks (Buteo ridgwayi) are critically endangered forest raptors endemic to the Caribbean island of Hispaniola, with ~100 pairs remaining in the world. The species is ecologically little known yet such studies are important for understanding critical habitat needs and population dynamics. We studied the provisioning behavior of adults at 22 nests on the northeast coast of the Dominican Republic from 2005 to 2008. Mean brood size was 1.80 ± 0.45, and the mean number of fledglings per nest was 1.10 ± 0.97. We found that 80% of the prey items delivered to nestlings were reptiles, with lizards accounting for 65% of the prey and those in the genus Celestus accounting for nearly 35% of prey. Other prey items included snakes (14%), rats (9%), and smaller proportions of birds, frogs, and centipedes. The number of prey items and amount of biomass delivered to nestlings did not vary with brood size, but adults delivered more prey to 3‐ to 5‐week‐old nestlings and more biomass to 5‐week‐old nestlings. Food delivery rates did not differ between successful or failed nests, suggesting that food availability did not influence nest outcome. Given that most prey items delivered to nestlings in our study were reptiles, conservation strategies developed for Ridgway's Hawks (e.g., translocations and habitat conservation) should take into consideration their specialist reptile diet. 相似文献
99.
《Current biology : CB》2021,31(20):4620-4626.e3
100.
Rhett D Harrison Sylvester Tan Joshua B. Plotkin Ferry Slik Matteo Detto Tania Brenes Akira Itoh Stuart J. Davies 《Ecology letters》2013,16(5):687-694
Hunting affects a considerably greater area of the tropical forest biome than deforestation and logging combined. Often even large remote protected areas are depleted of a substantial proportion of their vertebrate fauna. However, understanding of the long‐term ecological consequences of defaunation in tropical forests remains poor. Using tree census data from a large‐scale plot monitored over a 15‐year period since the approximate onset of intense hunting, we provide a comprehensive assessment of the immediate consequences of defaunation for a tropical tree community. Our data strongly suggest that over‐hunting has engendered pervasive changes in tree population spatial structure and dynamics, leading to a consistent decline in local tree diversity over time. However, we do not find any support for suggestions that over‐hunting reduces above‐ground biomass or biomass accumulation rate in this forest. To maintain critical ecosystem processes in tropical forests increased efforts are required to protect and restore wildlife populations. 相似文献