Biotic potential: what it is and how it is reflected in biological evolution

The goal of every living being on this planet is the expansion of their genes, in one way or another. Animals develop their behaviors, behaviors and anatomical adaptations based on a very simple premise: leave a mark on subsequent generations in the form of their own offspring or of other blood relatives (cousins, brothers, etc.). Even if it costs him his life, the only thing that the living being ultimately seeks is, without a doubt, to have children.

According to the theory of natural selection, the biological evolution of living things depends on environmental pressures and interactions with other species. When an animal suffers a spontaneous mutation in its development, it may have an advantage biological compared to the rest, for example, that an insect is born with slightly larger jaws large. If this insect lives longer than the rest because it obtains food more easily and the character is heritable, it is to be expected that it will have more children than the others.

Thus, the character "large jaws" can be expanded in a population because it increases the biological fitness of the species: the insects that present this mutation will reproduce more easily, so the children with this trait will be more and more common. What happens when a species reaches an adaptive pinnacle based on accumulated adaptations? Is there a limit to the spread of a species? We cover these topics and many more in the following lines, as we will tell you everything about

biotic potential.

• Related article: "The theory of biological evolution: what it is and what it explains"

The reproductive potential of the living being

Before moving on the scales of populations and species, it is necessary to look at the potential of each of their members. For this reason, it's time to take a general tour of fitness, fitness or biological suitability.

Fitness is defined as a quantitative representation of the mechanisms of natural selection that act on the adaptation of living beings to the environment. Put more simply, this parameter shows the proportion of genes that an individual of a species leaves in the next generation, with respect to the total gene pool present in the population in which it lives.

Colloquially, the number of children that a father has throughout his life is conceived as fitness, but siblings, cousins ​​and other blood relatives are also part of the gene pool of the individual. Therefore, the fitness rate of an organism is sometimes defined not only by how attractive it is to females, but by the ability he presents to keep a society or family unit afloat.

This term can be calculated with the following mathematical formula:

W: L x M

With W being the absolute fitness or adequacy, L the survival of the individual and M its fertility, the viability of a population over time can be roughly calculated. Finally, it should be noted that fitness can be absolute (number of descendants expected for an individual) or relative (number of descendants in relation to other conspecifics). In general, the higher the fitness of each of the members of a population, the better the performance of the species in its ecosystem.

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What is the biotic potential?

In a colloquial way, it could be said that the biotic potential is the consequence of sustained high fitness over time in a population of a given species. If we take a more technical approach at the biological level, this term can be defined as growth not restricted species of a species in an ecosystem, to the point where the population rate is reached maximum.

As you can imagine, this does not happen in nature, except for very rare occasions that are seen influenced by factors exogenous to the ecosystem (such as the release of exotic species in an environment that is not yours). In order for the biotic potential to be developed, the species in question must be free of predators, not carry diseases and have a practically unlimited availability of resources. The natural selection mechanisms themselves prevent this from happening since, otherwise, ecosystems would end up collapsing.

At a mathematical level, the biotic potential can be obtained and applied using the following two formulas:

• Number of individuals = biotic potential / resistance to the environment (living + non-living)
• Vital index = (number of births / number of deaths) x 100

The probability of reaching biotic potential increases the more adaptations or tools a species has to cope with natural selection and genetic drift, the two main processes that shape the evolution of living things throughout the ages. centuries. In any case, as we have said, being perfectly adapted to an environment is impossible, since the natural impositions themselves prevent this from happening.

The components of biotic potential

As noted ecologists who have developed this parameter (such as R.N Chapman), the biotic potential It is made up of two different sections: the reproductive potential and the survival potential.

The first of the terms is closely related to fitness: the more offspring each individual has, the better, since the birth rate will tend to exceed the death rate.

Still, a particularly fit specimen may lay 2,700 eggs in one sitting, but all of them end up in a single bite inside a predator's stomach. Therefore, not only can the number of offspring be taken into account: it is also essential to record that it survives over time.

Biotic potential = reproductive potential + survival potential

Why don't species reach biotic potential?

To answer this question, we have to go back years, to Isaac Newton's third law of motion:

If object A exerts a force on object B, then object B must exert a force of equal magnitude in the opposite direction on object A.

Let's apply this premise in a biological setting. If a rabbit population begins to grow because climate change has encouraged the development of certain herbaceous species that these lagomorphs feed on, predators are expected to grow exponentially in the ecosystem given in response to the presence of more herbivores.

If more and more rabbits are available, the females will be able to eat more before giving birth, so hopefully the litters will be larger. In addition, as there are more prey, the survival rate of the cubs will be higher, since the weaker specimens will not die of starvation. If there are more predators due to the increase in prey, the logical thing is that the number of prey decreases over time, thus tending to stabilize the balance again.

In the ecosystem, every action has a diametrically opposite reaction, unless the dynamics are not conceived within the environment naturally. Let's take a completely different example: the human being.

As you can imagine, humans are the only example of a species that has consistently and clearly reached biotic potential. The population numbers of our species grow exorbitantly, but since we have gotten rid of predators, we have systems of extremely efficient production and it is difficult for diseases to kill us, there is no regulatory mechanism that returns the biological balance to the normal.

Thus, our species is at a point of biotic potential, at least for now. As much as we develop technology and move away from the mechanisms of natural selection, one thing is clear: resources are still not unlimited.

Resume

Thus, we can conclude with the following idea: the biotic potential is the stage that is reached when the beings alive they are freed from all environmental impositions and grow as much as they can at the population level to the maximum possible. For the biotic potential to take place, animals not only have to reproduce a lot, but the offspring must also survive in time.

In a natural ecosystem, it is not conceivable that a species will achieve long-term biotic potential: at some point the resources and, if this is not the case, predators in the area or other species will be responsible for preventing the expansion of the population Dadaist. Fortunately or unfortunately, we are the only ones who have been in this state of continuous expansion for thousands of years, with all the good and bad that it entails.