نتایج جستجو برای: population fluctuations
تعداد نتایج: 762077 فیلتر نتایج به سال:
The dynamics of adaptation is difficult to predict because it is highly stochastic even in large populations. The uncertainty emerges from number fluctuations, called genetic drift, arising in the small number of particularly fit individuals of the population. Random genetic drift in this evolutionary vanguard also limits the speed of adaptation, which diverges in deterministic models that igno...
Seasonal fluctuations in mean dry weight of the copepod Calanus helgolandicus were large and contrasted markedly with the small seasonal fluctuations of cephalothorax length. Dry weight was related linearly to cephalothorax length on logarithmic axes by a series of regression equations which were significantly different for each of 8 cruises. Carbon and nitrogen were likewise linearly related t...
This study aimed to investigate the vulnerability of Sistan plain to fluctuations and Water Scarcity in Hirmand River using the vulnerability framework, by applying the resilience approach. The socioeconomic and biophysical components presented in this framework were embedded in a set of subsystems of the System Dynamics (SD) model. According to this, four levels of reference resilience were de...
Long-term surveys of entire communities of species are needed to measure fluctuations in natural populations and elucidate the mechanisms driving population dynamics and community assembly. We analysed changes in abundance of over 4000 tree species in 12 forests across the world over periods of 6-28 years. Abundance fluctuations in all forests are large and consistent with population dynamics m...
We determine the critical patch size below which extinction occurs for populations living in one-dimensional habitats surrounded by completely hostile environments in the presence of environmental fluctuations. The population dynamics is reformulated in terms of a stochastic reaction-diffusion equation and is reduced to a deterministic equation that incorporates the systematic contributions of ...
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