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 its genes, in one way or another. Animals develop their behaviors, behaviors and anatomical adaptations based on a very simple premise: leaving their mark on subsequent generations in the form of their own offspring or those of other blood relatives (cousins, siblings, etc.). Even if it costs its life, the only thing the living entity ultimately seeks is, without a doubt, to have children.
According to the theory of natural selection, The biological evolution of living beings depends on environmental pressures and interactions with other species When an animal suffers a spontaneous mutation in its development, it may have a biological advantage compared to the rest, for example, an insect may be born with slightly larger jaws. 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 “large jaws” trait can spread in a population because it increases the biological fitness of the species: insects that present this mutation will reproduce more easily, so offspring with that trait will become increasingly common. What happens when a species reaches an adaptive pinnacle based on accumulated adaptations? Is there a limit to the expansion of a species? We cover these topics and many more in the following lines, as we tell you everything about the biotic potential
Before moving to 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 aptitude or biological adequacy.
Fitness is defined as a quantitative representation of the natural selection mechanisms that act on the adaptation of living beings to the environment. In simpler terms, this parameter shows the proportion of genes that an individual of a species leaves in the next generation, with respect to the total genetic pool present in the population in which it lives
Colloquially, fitness is conceived as the number of children that a father has throughout his life, but siblings, cousins and other blood relatives are also part of the individual’s genetic pool. Therefore, the fitness rate of an organism is sometimes defined not only by how attractive it is to females, but by the ability 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 fecundity, the viability of a population over time can be approximately calculated. Finally, it should be noted that fitness can be absolute (number of offspring expected for an individual) or relative (number of offspring in relation to other conspecifics). In general, the higher the fitness of each member of a population, the better the performance of the species in its ecosystem.
What is biotic potential?
Colloquially, it could be said that biotic potential is the consequence of high fitness sustained over time in a population of a given species If we take a more technical approach at a biological level, this term can be defined as the unrestricted growth of a species in an ecosystem, up to the point at which the maximum population rate is reached.
As you can imagine, this does not happen in nature, except on very rare occasions that are influenced by factors exogenous to the ecosystem (such as the release of exotic species into an environment that is not their own). 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 mechanisms of natural selection 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:
The probability of reaching biotic potential increases the more adaptations or tools a species has to deal with natural selection and genetic drift, the two main processes that shape the evolution of living beings over the 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 indicated by renowned ecologists who have developed this parameter (such as RN Chapman), the biotic potential It is made up of two different sections: reproductive potential and survival potential
The first term is closely related to fitness: the more offspring each individual has, the better, since the birth rate will tend to exceed the mortality rate.
In any case, a particularly suitable specimen may lay 2,700 eggs in a single sitting, but all of them end up in a single bite inside the stomach of a predator. Therefore, not only can the number of offspring be taken into account: it is also essential to record that they survive over time.
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 field. If a population of rabbits begins to grow because climate change has encouraged the development of certain species of herbaceous plants that these lagomorphs feed on, predators can be expected to grow exponentially in the ecosystem given in response to the presence of more herbivores.
If more rabbits become available, females will be able to eat more before giving birth, so larger litters can be expected. Furthermore, as there is 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 another completely different example: the human being.
As you can imagine, the human being is the only example of a species that has achieved biotic potential in a sustained and evident way. The population numbers of our species are growing exorbitantly, but since we have gotten rid of predators, we have extremely efficient production systems and it is difficult for diseases to kill us, there is no regulatory mechanism that returns the biological balance to normal.
Thus, our species is at a point of biotic potential, at least for now No matter how much we develop technology and move away from the mechanisms of natural selection, one thing is clear: resources are still not unlimited.
Summary
Thus, we can conclude with the following idea: biotic potential is the scenario that is reached when living beings 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 over time.
In a natural ecosystem, it is not conceivable that a species will reach its biotic potential in the long term: at some point the resources will run out and, if this is not the case, local predators or other species will be responsible for preventing the expansion of the species. given population. 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.
