elektronický časopis
- MeSH
- Ecosystem MeSH
- Population Dynamics MeSH
- Genetics, Population MeSH
- Conservation of Natural Resources trends MeSH
- Conspectus
- Veřejné zdraví a hygiena
- NML Fields
- environmentální vědy
- NML Publication type
- elektronické časopisy
elektronický časopis
- Conspectus
- Demografie. Populace
- NML Fields
- demografie
- NML Publication type
- elektronické časopisy
- MeSH
- Ovarian Follicle drug effects MeSH
- Prostaglandins MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- MeSH
- Arvicolinae MeSH
- Rodentia microbiology MeSH
- Leptospira physiology MeSH
- Mice MeSH
- Population Dynamics MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Geographicals
- Czechoslovakia MeSH
a New Global Consensus 4 -- Wide-ranging Impact 6 -- Long Way to Go 7 -- The Way Forward 9 -- 2 Population -- Millennium Development Goals u -- Reproductive Health and the MDGs 12 -- Economic Impact of Population Dynamics 13 -- HIV/AIDS and Poverty 15 -- Ageing Populations 15 -- National Action to Reduce Poverty 15 -- 3 Population and the Environment 17 -- Population\'s Impact on Resource Use 18 -- Poverty and , 1950-2050 (projected) -- Figure 2 -- Proportion of population over 65 by region, -- 2000 and 2050 (
State of world population ; Y. 2004
iii, 115 s.
- MeSH
- Global Health MeSH
- Poverty MeSH
- HIV Infections prevention & control MeSH
- Public Health Surveillance MeSH
- Reproductive Health MeSH
- Developing Countries MeSH
- Socioeconomic Factors MeSH
- Health Status MeSH
- Conspectus
- Veřejné zdraví a hygiena
- NML Fields
- veřejné zdravotnictví
- NML Publication type
- studie
Since typically there are many predators feeding on most herbivores in natural communities, understanding multiple predator effects is critical for both community and applied ecology. Experiments of multiple predator effects on prey populations are extremely demanding, as the number of treatments and the amount of labour associated with these experiments increases exponentially with the number of species in question. Therefore, researchers tend to vary only presence/absence of the species and use only one (supposedly realistic) combination of their numbers in experiments. However, nonlinearities in density dependence, functional responses, interactions between natural enemies etc. are typical for such systems, and nonlinear models of population dynamics generally predict qualitatively different results, if initial absolute densities of the species studied differ, even if their relative densities are maintained. Therefore, testing combinations of natural enemies without varying their densities may not be sufficient. Here we test this prediction experimentally. We show that the population dynamics of a system consisting of 2 natural enemies (aphid predator Adalia bipunctata (L.), and aphid parasitoid, Aphidius colemani Viereck) and their shared prey (peach aphid, Myzus persicae Sulzer) are strongly affected by the absolute initial densities of the species in question. Even if their relative densities are kept constant, the natural enemy species or combination thereof that most effectively suppresses the prey may depend on the absolute initial densities used in the experiment. Future empirical studies of multiple predator - one prey interactions should therefore use a two-dimensional array of initial densities of the studied species. Varying only combinations of natural enemies without varying their densities is not sufficient and can lead to misleading results.
In Focus: Hunter, M. D., & Kozlov, M. V. (2019) The relative strengths of rapid and delayed density-dependence acting on a terrestrial herbivore change along a pollution gradient. Journal of Animal Ecology, 88, 665-676. Teasing apart the interactions between biotic and abiotic factors affecting animal population dynamics is a difficult task when based solely on the analysis of natural populations. Experimental manipulations of systems using microcosm studies can be powerful tools for probing such interactions, but microcosms are ultimately limited by their lack of complexity compared with nature. Hunter and Kozlov (2019) take a novel field-based experimental approach to studying abiotic influences on biotic interactions by quantifying how the presence of a pollutant source alters biotic processes driving populations of a forest leaf miner. They find that populations in proximity to a pollutant source show weaker direct density dependence and stronger delayed density dependence than more distant populations unaffected by pollution. These differences in density dependence cause higher equilibrium densities near the pollution source but surprisingly they do not alter leaf miner oscillatory dynamics. This creative study provides useful insight into how abiotic forces alter biotic population processes and how density dependence shapes the spatial dynamics of animal populations.
- MeSH
- Ecology MeSH
- Insecta MeSH
- Population Density MeSH
- Forests MeSH
- Population Dynamics MeSH
- Air Pollution * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
Population and development review, ISSN 0098-7921 vol. 26, suppl., 2000
ix, 319 s. : tab., grafy ; 24 cm
- MeSH
- Life Expectancy MeSH
- Population Characteristics MeSH
- Population Dynamics MeSH
- Socioeconomic Factors MeSH
- Geographicals
- Asia, Southeastern MeSH
- Conspectus
- Demografie. Populace
- NML Fields
- demografie
BACKGROUND: Many studies compare the population dynamics of single species within multiple habitat types, while much less is known about the differences in population dynamics in closely related species in the same habitat. Additionally, comparisons of the effect of habitat types and species are largely missing. METHODOLOGY AND PRINCIPAL FINDINGS: We estimated the importance of the habitat type and species for population dynamics of plants. Specifically, we compared the dynamics of two closely related species, the allotetraploid species Anthericum liliago and the diploid species Anthericum ramosum, occurring in the same habitat type. We also compared the dynamics of A. ramosum in two contrasting habitats. We examined three populations per species and habitat type. The results showed that single life history traits as well as the mean population dynamics of A. liliago and A. ramosum from the same habitat type were more similar than the population dynamics of A. ramosum from the two contrasting habitats. CONCLUSIONS: Our findings suggest that when transferring knowledge regarding population dynamics between populations, we need to take habitat conditions into account, as these conditions appear to be more important than the species involved (ploidy level). However, the two species differ significantly in their overall population growth rates, indicating that the ploidy level has an effect on species performance. In contrast to what has been suggested by previous studies, we observed a higher population growth rate in the diploid species. This is in agreement with the wider range of habitats occupied by the diploid species.
