ECOPHYSIOLOGY: WHAT IT STUDIES AND APPLICATIONS IN ANIMALS AND PLANTS - BIOLOGY - 2025

The ecofisiología is the branch of ecology which studies the functional response of organisms to adapt to environmental changes. Every living being must adapt to its environment in order to survive and this adaptation is both structural and functional.

This discipline is also known as physiological ecology or environmental physiology, and generates both basic and applied knowledge. Thus, it is possible to know the relationship between the physiology of an organism and environmental alterations.

Ecophysiological experiments. Source: Rasbak

Likewise, ecophysiology provides information in the field of plant and animal production to generate food. For example, studies of the ecophysiology of plants tolerant to extreme environmental conditions have been useful in genetic improvement.

Likewise, ecophysiological studies make it possible to establish which are the most suitable environmental conditions to achieve greater animal productivity. Thus, ranges of variation of environmental factors can be established to provide comfort to the animals in the production units.

What does ecophysiology study?

Ecophysiology is a discipline where physiology and ecology converge. Physiology the science that studies the functioning of living beings and ecology addresses the relationships between living beings and their environment.

In this sense, ecophysiology studies the dynamic relationship between the changing environment and the adaptations of plant or animal metabolism to these changes.

- Ecological experimentation

To achieve its objective, ecophysiology applies both descriptive research and the experimental method. For this, it identifies the physical-chemical factors that act in the environment and determines their effect on the body.

These factors can be resources that the organism uses for its survival or conditions that affect its functioning. Subsequently, the physiological response of the living organism to the variations of said factor is established.

Metabolic systems involved

It is necessary to identify the organic and functional systems involved in the adaptive response of the organism to the change of a certain factor. For example, when there are changes in temperature there is a response from the individual's thermoregulatory system.

Experimental design

Ecophysiology uses the design of experiments to establish the physiological response of the organism to changes in a factor. An example of this may be subjecting individuals of a plant species to different salt concentrations in the substrate.

- Types of environmental changes

Once the factors to be studied have been defined, it is necessary to identify the changes that occur in the environment and their temporal nature, defining three types:

Cyclical changes

These changes are recurring periodically, such as the alternation of the climatic seasons or day and night. Faced with these, the living being has developed a cyclical functioning, following the rhythm of environmental change.

Day and night cycle. Source: Caliver

For example, the fall of the leaves in the dry season to reduce perspiration due to the lack of water. In the case of animals, there are also adaptations to these cyclical changes; for example the change of plumage of certain birds.

The ptarmigan (Lagopus muta) of the tundra has seasonal homochromia and presents white winter plumage while in spring it changes to dark and variegated tones. Thus, their camouflage is adapted to the uniform white of the snow and then to the dark tones of the environment during the rest of the year.

Another animal adaptation to cyclical changes is the hibernation of bears and other species in the winter time. This involves changes in metabolic rate that include decreasing bodily functions, such as temperature and heart rate.

Random changes

These types of changes occur randomly, without an established regularity. For example, the landslide of a mountain slope, an oil spill or the arrival of a new predator or pathogen.

These types of changes represent a greater risk for the species, because they occur drastically. In these cases, the response of the organisms depends on the plasticity in the already existing functions.

Directional changes

They are changes in the environment intentionally caused by humans for certain purposes. A case of this is the deforestation of a forest to establish a pasture or the intervention of a wetland to cultivate rice.

- General postulates

Starting from the accumulation of experimental and observational evidence in the natural environment, ecophysiology tries to define general postulates. These are general principles that emerge from the regularity of certain physiological responses to environmental changes.

Liebig's Law of the Minimum

Sprengel (1828) postulated that the determining factor in the growth of an organism is the one most scarce in the environment. Later this principle was popularized by Liebig (1840), and is known as the Law of the Minimum or Liebig's Law.

Bartholomew (1958) applied this principle to the distribution of species, pointing out that it is determined by the most limiting environmental factor.

Shelford's Law of Tolerance

In 1913, Victor Shelford stated that a certain species exists in a defined range of variation for each environmental factor and their interactions. This is known as tolerance limits, outside of which the species does not survive.

Shelford's Law of Tolerance. Source:

This principle defines that in the amplitude of variation of a certain environmental factor there are three possible states for the organism. These states are optimal, physiological stress and intolerance.

In this sense, in the optimal range of the factor, the populations of the species will be abundant. When moving away from the optimum, one enters a stress zone where populations decrease and, outside the tolerance limit, the species disappears.

- Digital technology and ecophysiology

As in all science, ecophysiological studies have been enhanced by the development of new technologies. Due to its experimental nature, this discipline in particular has been favored by the development of digital technology.

Today there is a diversity of portable electronic devices that allow measuring environmental factors in the field. Among these are solar radiation meters, temperature, relative humidity, leaf area, among others.

Examples of applications in animals

- Effect of temperature on the productivity of farm animals

A very relevant field is ecophysiology applied to animal production, which seeks to understand the response of breeding animals to the variation of environmental factors. One of these factors is temperature, taking into account the current trend of increasing global average temperature.

Homeothermy

The vast majority of breeding animals are homeothermic, that is, they maintain a stable internal temperature despite environmental variations. This is achieved through the investment of chemical energy to compensate for increases or decreases in outside temperature.

This external temperature compensation process is achieved through thermoregulation, which involves the hypothalamus, respiratory system, and skin.

Laying hens

The time of day a laying hen is fed has been found to be important to its productivity. In this case it has to do with the assimilation capacity of the food as a function of heat stress.

Laying hens. Source: Peloy (Allan HM)

If feed is supplied in the hottest hours of the day, the hen assimilates it less and its production decreases. Consequently, the increase in environmental temperature implies a decrease in the productivity of free-range hens.

Cattle

The increase in temperature forces the animals to activate physiological mechanisms of thermoregulation. This involves an investment of energy that is subtracted from weight gain or milk production.

On the other hand, as the temperature increases, the animals vary their feeding priorities. In these cases, the intake of water increases and the consumption of dry matter decreases, with the consequent loss of weight.

- Pollution and frogs

Ecophysiological studies make it possible to relate the physiology of animal species with their environment and establish the possible negative effects of pollution. An example of this is the current state of threat to which frogs and toads are subjected.

Frog (Atelopus zeteki) sensitive to pollution. Source: Brian Gratwicke

About half of the 6,500 known species of amphibians are threatened with extinction. These animals are very sensitive to changes in temperature, humidity or environmental contaminants.

The respiration and circulation of amphibians

The physiology of respiration of amphibians is very peculiar, since they breathe both through the lungs and through the skin. When they are out of the water they use their lungs and in the water they breathe through their skin, which is permeable to O2, CO2 and water.

Impact

The form of respiration makes these animals susceptible to the absorption of pollutants from both air and water. On the other hand, due to the low concentration of oxygen in the water, they weaken because they do not absorb it properly.

Under these conditions they can die or become weak and be susceptible to attack by pathogenic fungi and bacteria. One of the biggest threats is the pathogenic fungus Batrachochytrium dendrobatidis, which inhibits the flow of electrolytes in the skin.

Examples of applications in plants

- Ecophysiology of plants

Global warming will result in the production of certain crops in some areas due to the law of tolerance. That is, factors such as the availability of water will go outside the tolerance range of the species.

Xerophytes. Source: Tomas Castelazo

However, arid zone species have developed strategies to adapt to the water deficit. In this sense, research in the ecophysiology of arid zone plants provides possible avenues for plant genetic improvement.

Osmolytes

One of these strategies is the modification of gene expression to produce proteins that help tolerate water deficit. Among these proteins are osmolytes that help cells maintain their turgor even with little water.

Knowledge of these proteins and their metabolism can be used by genetic engineering to improve crops.

- Ecophysiology of halophilic plants

One of the problems facing agriculture is the salinity of soils due to the concentration of salts added by irrigation waters. As more soils become salinized, the less cropland is available for food production.

Halophilic plants

However, there are species of plants adapted to survive in conditions of high concentration of salts in the soil. These are the so-called halophytic plants (Halos = salt; phyto = plant).

These species have developed a series of morphological and physiological adaptations as mechanisms to avoid salt absorption, immobilize it or excrete it.

Halophytic plants as food

Knowledge of the ecophysiology of these plants serves as the basis for developing agricultural systems and using them as food sources. In this way, halophytic species cultivated on salinized agricultural soils can be used as feed for livestock.

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