Is dealing with multiple concurrent influences a fundamental trait of life?
This must be important at all levels of the biological hierarchy from individuals (cells) to communities
Imagine a tree in the courtyard in a city. Not much appears to be happening, but this organism is experiencing quite a lot of simultaneous environmental inputs: it interacts with symbiotic and pathogenic fungi and bacteria in its roots, its roots sense the nutrient environment, the leaves respond to herbivores, the canopy intercepts temporally highly dynamic light pulses, there are neighboring plants with which the tree competes, there are various organic and inorganic chemical pollutants in the soil, there are microplastic particles, there are heat pulses, the tree may experience drought, and there may be ozone in the atmosphere, and for sure elevated concentrations of carbon dioxide compared to when the tree was younger.
Somehow all these inputs must be integrated. And this must also happen at all scales, also in the cells in the tissues of a leaf, or for a bacterium or fungus in the soil. For a fungus in the soil, this must be even more of an issue, since as a linear organism, it will experience a range of different environmental conditions as they change along its length. Again, all this must be integrated somehow.
Also imagine yourself, various pressures are acting on you at any moment in time, expectations, deadlines, work assignments, relationships, interacting with your mental and physical state, past experiences, altogether giving rise to your behavior.
But this will also be the case at higher levels of the biological hierarchy, for example in communities. A plant community will at any point in time collectively ‘experience’ a whole range of environmental influences and stressors. And any ecosystem process rate at any point in time will also be influenced by a whole range of drivers and stressors, positive, negative, and neutral.
There must be complex interactions among the various influences. Here are some examples:
The environmental factors could directly influence each other, even before they reach the organism(s), for example drought in the soil increasing the solute concentrations, and thus the concentration of any pollutant. We have written about this point before, from the perspective of a plant-soil system.
There will be cross-talk and information processing inside of an organism, involving signal pathways. See for example the very nice paper by Zandalinas et al.
One environmental stressor may make the target system more susceptible to another.
Some stressors move down the ecological hierarchy while others percolate upwards. Simmons et al. have brilliantly made this point in their paper. For example, invasive species ‘enter’ at the level of the community, while chemical pollutants have effects on individuals.
Can we derive some common, fundamental principles from this processing of environmental information and stimuli (I mean principles that go beyond non-additivity and null-model testing)? Are the differences among the different levels of the biological hierarchy - there must be - but what do they look like?
Calling on the cell biologists out there? how does such a diversity of information get integrated at the cellular level?
I’d be very interested in hearing your ideas, please let me know in the comments.