The production of these compounds by yeasts is influenced by many environmental variables, and could be controlled by the choice of optimized cultivation conditions.
Plants are able to sense and optimally respond to so many environmental variables — light, water, gravity, temperature, soil structure, nutrients, toxins, microbes, herbivores, chemical signals from other plants — that there may exist some brainlike information-processing system to integrate the data and coördinate a plant's behavioral response.
Furthermore, many environmental variables are extremely difficult to replicate in the lab.
Unfortunately, such studies are expensive, time-consuming, and difficult to design; over 10 years, so many environmental variables change that isolating one as a carcinogen is extremely difficult.
Organisms usually respond to a complexity of interdependent factors including many environmental variables (Rydgren et al. 2003), e.g., Grinnell (1917) listed the factors that potentially affect the species distribution as vegetation, food, climate, soil, breeding and refuge sites, inter-specific effects, and species preferences.
The ratio between these two quantities has been called the conversion efficiency of absorbed radiation into dry matter, and was used in many simple models of crop growth, i.e. bypassing the complex process of photosynthesis and respiration known to depend on many environmental variables [21].
Like many other environmental variables, streamflows are asymmetric and non-Gaussian.
The correlations of many individual environmental variables with the axes were relatively high for CCA but were not statistically significant.
In many studies, environmental variables were observed (measured) variables.
Under density-dependent selection (DDS), conspecific density is an environmental variable which, similar to many other environmental variables, determines genotype-specific fitnesses.
This result is perhaps not surprising given that the steep elevational gradient from lowlands to highlands is correlated with steep gradients in many other environmental variables.
