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811.
Parental investment, potential reproductive rates, and mating system in the strawberry dart-poison frog, Dendrobates pumilio 总被引:1,自引:0,他引:1
We studied the effect of relative parental investment on potential reproductive rates (PRRs) to explain sex differences in
selectivity and competition in the dart-poison frog Dendrobates pumilio. We recorded the reproductive behavior of this species in a Costa Rican lowland rainforest for almost 6 months. Females spent
more time on parental care than males, and `time out' estimates suggest that PRRs of males are much higher than than those
of females, rendering females the limiting sex in the mating process. Males defended territories that provide suitable calling
sites, space for courtship and oviposition, and prevent interference by competitors. Male mating success was highly variable,
from 0 to 12 matings, and was significantly correlated with calling activity and average perch height, but was independent
of body size and weight. Estimates of opportunity for sexual selection and variation in male mating success are given. The
mating system is polygamous: males and females mated several times with different mates. Females were more selective than
males and may sample males between matings. The discrepancy in PRRs between the sexes due to differences in parental investment
and the prolonged breeding season is sufficient to explain the observed mating pattern i.e., selective females, high variance
in male mating success, and the considerable opportunity for sexual selection.
Received: 9 June 1998 / Received in revised form: 27 March 1999 / Accepted: 3 April 1999 相似文献
812.
A general and intuitive prediction from models of mate preference is that when the cost of searching for mates increases,
individuals should become less choosy. Here, we test this prediction by comparing the mating propensity of females in two
populations of the butterfly Pararge aegeria. The populations originated from southern Sweden and Madeira and due to different adult emergence patterns throughout the
year, the average density of males per female is likely to be lower on Madeira. Therefore, we expected that the cost of searching
should be greater on Madeira and, consequently, that the Madeiran females should be less choosy. In line with predictions,
the Madeiran females mated significantly sooner after the first interaction with males than did females from southern Sweden.
This difference may reflect a weaker preference for territorial males over non-territorial patrollers in the Madeiran population,
because of the greater costs of searching. The Madeiran females also showed a shorter time lag between mating and the start
of oviposition. We discuss this unexpected result and propose that the same mechanism could also explain this population difference,
i.e. different costs of searching for suitable host plants. Both search processes are fundamental for female reproductive
success and we find it plausible that they can be generalised into the same theory of optimal search behaviour.
Received: 14 May 1998 / Accepted after revision: 13 December 1998 相似文献
813.
Summary. The African stink ants (Pachycondyla tarsata) lay recruitment trails with secretions from sternal glands. The glandular secretions consist of 10 compounds, 9 of which
have been chemically identified. One of the substances, 9-heptadecanone, elicits trail following behavior in P. tarsata workers that have before been stimulated by a sucessful scout ant.
Received 7 August 1998; accepted 24 November 1998. 相似文献
814.
Thomas Delschen Annegret Hembrock-Heger Jörg Leisner-Saaber Dorothea Sopczak 《Environmental Sciences Europe》1999,11(2):79-87
The results of lysimeter experiments conducted since 1991 dealing with the behavior of PAH in soil/plant systems demonstrate that the PAH pollution to cultivated plants may be caused by both atmospheric deposition and by the soil-to-plant transfer observed in contaminated sites. In the latter, a “direct contamination” of plant surfaces with PAH-loaded soil particles and the subsequent PAH turnover by desorption/adsorption processes is seen to dominate—at least for the most relevant PAHs toxic to humans, benzo(a)pyrene and dibenz(a,h)anthracene. Leafy vegetables growing close to the soil surface are therefore endangered most by a PAH contamination of the soil. The soil-to-plant transfer via “direct contamination” can be reduced to a high degree by covering the contaminated soil with different mulch materials. Systematic PAH transfer via root uptake could not generally be observed. From the reported results, a trigger value in the soil of 1 mg·kg?1 for benzo(a)pyrene is proposed to make a judgement on PAH contaminated soils with regard to the soil-to-plant transfer pathways. Soils with excessive concentrations of benzo(a)pyrene demand special attention when considering the recommendations for the growth and consumption of cultivated vegetables. The “soil”as well as the “deposition pathways” must be integrated into a complete risk assessment of locations with food plant production, especially in urban areas. 相似文献
815.
Lucas Ferrante Augusto Getirana Fabricio Beggiato Baccaro Jochen Schöngart Ana Cristina Monteiro Leonel Renato Gaiga Michel Varajão Garey Philip Martin Fearnside 《Conservation biology》2023,37(3):e14033
Given the speed at which humans are changing the climate, species with high degrees of endemism may not have time to avoid extinction through adaptation. We investigated through teleconnection analysis the origin of rainfall that determines the phylogenetic diversity of rainforest frogs and the effects of microclimate differences in shaping the morphological traits of isolated populations (which contribute to greater phylogenetic diversity and speciation). We also investigated through teleconnection analysis how deforestation in Amazonia can affect ecosystem services that are fundamental to maintaining the climate of the Atlantic rainforest biodiversity hotspot. Seasonal winds known as flying rivers carry water vapor from Amazonia to the Atlantic Forest, and the breaking of this ecosystem service could lead Atlantic Forest species to population decline and extinction in the short term. Our results suggest that the selection of morphological traits that shape Atlantic Forest frog diversity and their population dynamics are influenced by the Amazonian flying rivers. Our results also suggest that the increases of temperature anomalies in the Atlantic Ocean due to global warming and in the Amazon forest due to deforestation are already breaking this cycle and threaten the biodiversity of the Atlantic Forest hotspot. 相似文献
816.
Scenario simulation of water security in China 总被引:1,自引:0,他引:1
OUYANG Zhi-yun ZHAO Tong-qian WANG Ru-song Leif SDERLUND ZHANG Qiao-xian 《环境科学学报(英文版)》2004,16(5):765-769
Umited water resources, increasing demand, low use efficiency, and serious pollution result in severe water resource difficult in China. The evaluation of addressing water problems and the search for effective countermeasures that ensure sustainable water use are key to China‘ s sustainable development. The “compound water security“ consists of food security, life security, environmental security, and economic security. By establishing a conceptual model, the water security of China has been simulated in terms of four scenarios called BAU(the business-as-usual scenario), TEC(the technology and economics scenario), IVL(the institution, values, and lifestyles scenario) and TSD(toward sustainable development) in this paper. The results indicated that water crises, especially water shortages, are being experienced now and will continue to do so for a relatively long time in China and that it is possible to reach a basic balance between supply and demand of water and grain under the TSD developing pattern by a series of approaches including technological innovation, policy adjustments, and behaviour inducement. 相似文献
817.
Axel Hochkirch Michael J. Samways Justin Gerlach Monika Böhm Paul Williams Pedro Cardoso Neil Cumberlidge P. J. Stephenson Mary B. Seddon Viola Clausnitzer Paulo A. V. Borges Gregory M. Mueller Paul Pearce-Kelly Domitilla C. Raimondo Anja Danielczak Klaas-Douwe B. Dijkstra 《Conservation biology》2021,35(2):502-509
Measuring progress toward international biodiversity targets requires robust information on the conservation status of species, which the International Union for Conservation of Nature (IUCN) Red List of Threatened Species provides. However, data and capacity are lacking for most hyperdiverse groups, such as invertebrates, plants, and fungi, particularly in megadiverse or high-endemism regions. Conservation policies and biodiversity strategies aimed at halting biodiversity loss by 2020 need to be adapted to tackle these information shortfalls after 2020. We devised an 8-point strategy to close existing data gaps by reviving explorative field research on the distribution, abundance, and ecology of species; linking taxonomic research more closely with conservation; improving global biodiversity databases by making the submission of spatially explicit data mandatory for scientific publications; developing a global spatial database on threats to biodiversity to facilitate IUCN Red List assessments; automating preassessments by integrating distribution data and spatial threat data; building capacity in taxonomy, ecology, and biodiversity monitoring in countries with high species richness or endemism; creating species monitoring programs for lesser-known taxa; and developing sufficient funding mechanisms to reduce reliance on voluntary efforts. Implementing these strategies in the post-2020 biodiversity framework will help to overcome the lack of capacity and data regarding the conservation status of biodiversity. This will require a collaborative effort among scientists, policy makers, and conservation practitioners. 相似文献
818.
819.
In mammals, the chemical profiles of individuals are complex and variable mixtures, and animals perceive information based on variation in the overall quality of these mixtures. A variety of compounds potentially involved in chemical communication have been characterized in the urine of different felid species, but little is known about the information content of felid scent marks. In this study, we investigated whether chemical composition of Eurasian lynx Lynx lynx urine was related to sex, reproductive state, and individual identity. We further analysed if elemental sulphur in lynx urine could serve as a dietary cue or as an indicator for the freshness of a scent mark. We collected urine from captive and wild Eurasian lynx, and analysed volatile constituents of urine by means of solid phase microextraction and gas chromatography-mass spectrometry. Our results show that lynx scent profiles contain sex-specific information on reproductive state, as well as individual identity cues. Urine marks are, therefore, well-suited to fulfil a role in reproductive behaviour and social organisation of wild lynx populations. Relative sulphur content was unrelated to time since last feeding, but decreased with age of the urine sample. The influence of diet and body condition on scent profiles should be further investigated by means of experimental studies, and may shed more light on the messages encoded in carnivore scent-marks. 相似文献
820.