The environmental tolerance of the body is a natural property that allows you to survive in adverse, inappropriate and difficult conditions. Thanks to him, animals and plants can adapt to some environmental changes. Which ones?
Categories of environmental factors
Depending on the law of changes in time, one can distinguish:
- Unchanging in time circumstances. For example, gravity.
- Regularly periodic, which change with a certain interval. It can make up a day (the so-called circadian rhythms), a year, etc. For example, a change in illumination during the day, temperature over a year, etc.
- Irregular, changing randomly. These factors may be unpredictable natural disasters: earthquakes, floods, etc.
- Continuously and irreversibly changing (or periodically, but with an interval significantly longer than the life span of one individual). These, for example, include global climate change associated with geological and space processes.
The environmental tolerance of an organism is a harsh natural law.
How do you know if a particular animal or plant can survive in specific conditions? The ecological tolerance of an organism is determined by genetic variation in biological populations; therefore, the ratio of optimal, pessimal, and lethal values ββfor different individuals may not be the same.
In ecology, there is a rule of limiting factors called the reception of the minimum of J. Liebig. It is also known as the law of tolerance. The meaning of this rule is as follows.
The possibility of a prosperous existence is determined by those factors whose significance approaches or goes beyond the limits of environmental tolerance. In other words, if one of them makes survival impossible, then the other factors no longer have any meaning. Every circumstance is important.
The zone of ecological tolerance of an organism is the specific values ββof environmental factors in which the survival of the species becomes possible.
The optimal, pessimal and lethal regions of different individuals do not coincide. However, factors act in conjunction. For example, tolerance to temperature and humidity are closely dependent on each other.
Species must differ by at least one valency. If they completely coincided, then they would end up in one niche. And such coexistence conflicts with the law of competitive exclusion.
However, private deviations from the law are still possible. They are due to the absence of absolutely strict boundaries in ecological niches and the variability of individuals within each species.
Temperature Tolerance
There are several abiotic environmental factors. The most important of these is the outside temperature. The speed of all chemical reactions taking place both inside and outside the body depends on it. In the Universe, temperatures range from almost absolute zero (interstellar vacuum, where, however, temperature is relative, since there is no medium whose temperature can be measured directly) to several million degrees in the bowels of stars.
The temperature range of the existence of living organisms is approximately 200 Β° C (from -100 Β° C to + 100 Β° C). The upper limit for bacteria living in hot springs reaches 90ΛC. At this temperature, they can live permanently.
The state of suspended animation
For more highly organized animals, the upper limit is lower. However, for a short time, even a person without harm to health can withstand more than 100 Β° C. The lower temperatures at which animals can exist are even lower. So, cats can remain viable at temperatures up to -120Λ C.
One of the tricks of the environmental tolerance of the body is the state of suspended animation, that is, a decrease in vital functions. With it, individual living cells can persist at even lower temperatures. The sperm of animals and humans can be stored indefinitely in liquid nitrogen and even tolerate cooling to values ββclose to absolute zero. Bacterial spores and protozoal cysts withstand heat up to 200 Β° C.
The environmental tolerance of an organism is the specific survival limit. They can be maximum and minimum. But real life processes can be carried out within narrower limits.