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181.
Darrell A. Posey Graham Dutfield Kristina Plenderleith 《Biodiversity and Conservation》1995,4(8):892-902
Scientists find themselves working more and more with indigenous, traditional and local communities in all aspects of their collections and investigations. Indigenous knowledge has become increasingly important in research while at the same time local communities have become increasingly politicized in the use, misappropriation, and commercialisation of their knowledge and biogenetic resources. It is becoming more and more difficult for even the most well-intentioned scientists to stride into indigenous areas and collect plants, animals, folk tales, and photos without having first to convince local leaders that the scholarly efforts will somehow benefit the communities — that the benefits of research results will directly and indirectly lead to strengthening the traditional society. In many parts of the world, indigenous peoples only allow Collaborative Research in which the scientific priorities and agendas are controlled by the communities, or Community Controlled Research in which the communities actually contract scientists to carry out the group's research plan. Control over data has become one of the key battle cries for the indigenous movement, that is now demanding Intellectual Property Rights over information obtained through research and just compensation for economic benefits that eventually may accrue. This paper deals with some of the ethical and practical issues that frame this rapidly evolving debate. 相似文献
182.
M. Noirot D. Couvet S. Hamon 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(3):479-483
Most apomicts are hermaphroditic and pseudogamous (pollination is necessary to trigger parthenogenesis). In these plants,
fitness depends on the number of progeny obtained by maternal reproduction. We determined the evolutionary stable strategy
for male and female sex allocation. We show that the efficiency of pollination determines male and female resource allocations.
Predictions are made of these allocations, of pollen/ovule ratio and of seed-set. We show that self-compatibility in apomicts
is necessary for the maintenance of an apomictic population, and thus can account for the association between the loss of
self-incompatibility and pseudogamous apomixis. In contrast to sexuals, male investment in pseudogamous apomicts increases
with the rate of self-pollination.
Received: 15 June 1996 / Accepted: 20 September 1996 相似文献
183.
Abstract. Most African Acacia trees occur in semi-arid savannas, but some species grow in deserts at the periphery of their range in northern Africa and the Middle East. We studied Acacia raddiana and A. tortilis in the southern Negev desert of Israel. According to the resource availability hypothesis, plants in poor habitats invest heavily into anti-herbivore defense because losses to browsers are costly when growth rates are low. Few plants invest simultaneously in different categories of defense. This suggests that trade-offs exist, although little is known about how individuals allocate resources to defence in natural populations. In a field experiment, we studied chemical and mechanical defences as a response to differential browsing for more than 10 yr. Both Acacia species increased spinescence but there was no clear response in the production of total polyphenols, condensed tannins, and protein-precipitating tannins (only A. raddiana may increase secondary compounds under very high browsing levels). There was an age effect in spinescence but not in secondary compounds for both species, with younger trees investing more into anti-herbivore defense than older individuals. We were unable to find negative correlations between traits of chemical and mechanical defense. We conclude that inducibility and age effects suggest a cost for mechanical but not necessarily for chemical defense. Contrary to the predictions of the resource availability hypothesis, concentrations of secondary compounds were not higher in this desert environment than in savannas. 相似文献
184.
为了开发利用富含β-胡萝卜素的江苏沿海盐田盐藻(Dunaliellasalina)资源,我们采用常规调查方法,对江苏省灌西盐场的天然盐藻进行调查,并推算出约有259公斤左右的β-胡萝卜素年产量。而且,藻数量和β-胡萝卜素含量都受到光照、温度、雨水等气候因素影响。本调查为灌西盐场盐藻资源开发提供了一个可靠的依据,为其它盐场估计本场资源量提供了一个参考。 相似文献
185.
In early stages of primary succession, colonizing plants can create resource patches that influence the abundance and distribution of other species. To test whether different colonizing shrubs generate contrasting patches on coastal sand dunes, we compared soil characteristics and light availability under the nitrogen-fixing shrub Lupinus arboreus, under the non-nitrogen-fixing shrub Artemisia pycnocephala, and between shrubs on dunes at a site in northern California. Concentrations of inorganic nitrogen and net nitrogen mineralization rates were generally 1–10 times greater in soil under Lupinus than under Artemisia or between shrubs. Soil water content was mostly lower under shrubs. Mean photon flux density near ground level was reduced by at least 80% at 35 cm inside shrub canopies. Topography appeared to have more effect on soil moisture but less direct effect on nitrogen availability than did Lupinus. However, Lupinus probably increases nitrogen levels more on higher, drier dunes. Microhabitats under and between nitrogen-fixing shrubs constitute a mosaic of individually poor but complementary patches in which high levels of light and moderate levels of soil nitrogen are present but tend not to occur together. 相似文献
186.
Field experiments were established to assess possible allelopathic suppression by Lantana camara L. of two indigenous tree species. The design allowed comparison of allelopathic effects with density-dependent resource competition effects. Fire and its role in competitive interactions was included as an experimental treatment. Allelopathic responses were measured in L. camara thickets by germinating and growing Alectryon subcinereus (A. Gray) Radlk. in dry rainforest ecotones (Macleay River) or Cryptocarya rigida (Meissner) in warm temperate rainforest and wet sclerophyll forest (Lake Macquarie) at 10, 20 and 30 seedlings m-2, where L. camara was either physically removed (LR), burnt (LB), or cut and left in place (LT). Germination for both species increased significantly by completely removing L. camara (LR) whereas burning (LB) was significant only for C. rigida. Seedling growth for both species was negatively related to increasing density when all L. camara was removed (LR) but was positively related in the other two treatments (LB and LT). C. rigida seedling biomass increased 47.4% (1.75%2.58 g) and 68.6% (1.98%2.95 g) with increasing seedling density for LT and LB respectively and decreased 23.2% (2.93–2.25 g) for LR. A. subcinereus seedling biomass increased 29.7% (1.95–2.53 g) and 34.7% (2.25–3.03 g) with increasing seedling density for LT and LB respectively and decreased 27.9% (3.30–2.38 g) for LR. Phytotoxin dilution effects were inferred in LT and LB rather than density-dependent intraspecific competition, whereas the reverse was true for LR. Seedling biomass for C. rigida resulting from potential phytotoxin dilution at high seedling density was not significantly different from the response of LR at low seedling density but, for A. subcinereus, the phytotoxin dilution response was significantly less than LR at low seedling density. Moderately intense fire (LB) was not significantly different from the LT treatment at both locations, emphasising that moderate to low intensity fires should not be used to control existing invasions of L. camara. Competitive strategies for invasive populations are identified that may modify succession following disturbance, thereby allowing thicket formation and long-term persistence to affect community dynamics. Such strategies need to be recognised in managing natural communities, particularly for biodiversity conservation.Nomenclature: Harden (1990). 相似文献
187.
Alysa G. McCall Nicholas W. Pilfold Andrew E. Derocher Nicholas J. Lunn 《Population Ecology》2016,58(3):407-419
Individual variation in habitat selection has emerged as an important component necessary for understanding population ecology. For threatened species, where habitat loss and alteration affect population trends, understanding habitat use provides insight into mechanisms of population change. Polar bears, Ursus maritimus, in the Western Hudson Bay subpopulation have experienced declines in body condition, survival, and abundance associated with delayed freeze-up and earlier break-up of sea ice due to climate change. Although this subpopulation has been intensively studied, sea ice habitat selection remains poorly understood. We developed a habitat selection model using a mixed conditional logistic regression to determine habitat selection across seasons (freeze-up, early winter, late winter, break-up) and assess individual variation in habitat selection. We used 8487 locations collected between 2004 and 2010 from 64 GPS satellite linked radio-collars on adult females to compare habitat selected to habitat available. Selection changed across seasons and varied the most among individuals during the freeze-up and break-up seasons. During later winter, there was less variation in habitat selection among individuals and bears showed the least amount of selection in habitat use. Distance to the denning area, a core terrestrial refuge habitat, was the top-ranked covariate in all seasons suggesting site fidelity plays a role in habitat selection. Some individual variation may have been due to reproductive status, though we could not account for this directly. Recognizing individual differences, especially in a rapidly changing environment, allows managers to identify critical habitats instead of simply average resources, and may lead to more successful efforts to protect habitats. 相似文献
188.
- In this study, we have developed a new method to estimate population parameters and applied it to a concrete example on the situation that there are two fisheries resources which are depleted only by catch, and that these two resources are not caught equally because of the difference of prices.
- Switching function, which is originally used to describe the effort allocation that one predator eats two preys, has been introduced. We have constructed a model of fishery in which each fisherman pursues economical optimum.
- The population size of two species at the beginning of the fishing season, catchability coefficient and parameters of switching function are estimated by the criterion of minimum error sum of squares between CPUE (catch per unit effort) of data and that by model.
- We have applied it to the diver fishery of abalone in Ojika Island, Nagasaki Prefecture. The model describes well the situation during the season that CPUE of the less expensive species increases gradually as the population of the other species is depleted.
189.
Nobuhiko Suzuki 《Ecological Research》1989,4(3):373-385
The effects of herbivory by the guild of chrysomelid beetles on the growth and survival ofRumex plants were examined in relation to the distribution and size of the plants.
Gastrophysa atrocyanea never appeared on solitary plants whereasMantula clavareaui showed even utilization of solitary and clumped plants.Galerucella vittaticollis utilized large solitary plants most frequently. In patches of the host plants, the frequency of withering of the aerial parts
was higher on small plants. The regrowth rate was higher when the aerial parts withered in spring than in summer. In patches
of the host plants, the regrowth rate was higher on small plants. On the other hand, it was lower on small solitary plants
than on large solitary plants and small plants in patches. In large plants, no difference in survival rate was recognized
between solitary and clumped plants, because both the frequency of withering of the aerial parts and the regrowth rate were
lower in clumped than solitary plants. The high vigor against intense herbivory by the chrysomelid beetles brought on the
delay in the phenology ofRumex plants. This shift permits in parts the existence ofG. vittaticollis in mid summer. The temporal and spatial interactions between herbivore guild and the host plants were discussed. 相似文献
190.
Diet spectra and resource partitioning in the larvae and juveniles of three species and six cohorts of cyprinids from a subalpine lake 总被引:1,自引:0,他引:1
Summary Diet composition based on gut analyses was studied in larvae and juveniles belonging to six (out of eight) age groups (cohorts) of three species of cyprinids (Rutilus rutilus L., Leuciscus cephalus L., Scardinius erythrophthalmus L.) from a small meso-oligotrophic lake in Tyrol, Austria.A basic pattern of ontogenetic shifts of resource use is postulated for the first weeks after hatching, consisting of the sequence: phytoplankton-rotifers-crustaceans-chironomid larvae. However, there are several variations to this general theme.Diet overlap is of about the same magnitude between representatives of different species or different cohorts, and between members of schools belonging to one cohort. This points to the importance of random food selection in all larvae and juveniles during this phase of life.Prey size is a very poor predictor of food choice by young cyprinids, but there is greater similarity in diet between the larger juveniles than between the smaller larvae, irrespective of whether the fish compared represent different species, different cohorts or are members of homogeneous groups.The lack of correlation between prey size and predator size may be explained by assuming that out of a limited range of available prey size the fish always try to include in their diet also the largest items they are able to swallow. This would be a good strategy considering that growth rates are positively correlated with food size.One clearcut interspecific difference in resource use may be noted: The larvae of L. cephalus are distinguished from those of the other two species by the absence of rotifers and nauplii in their diet, and by their greater ability to handle both adult copepods and chironomid larvae. 相似文献