BIOLOGICAL SUITABILITY: COMPONENTS AND METHODS - BIOLOGY - 2025

The biological adaptation, biological fitness, biological efficacy or fitness in evolutionary biology, is a measure of the ability of certain biological entity to leave fertile offspring to future generations. However, the operational definition is complex and there is no exact method or measure to quantify it.

Although its definition is confusing and many times misinterpreted, fitness is a fundamental concept to understand the evolutionary process, since selection operates through differences in fitness between individuals (or alleles) in the population.

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In fact, according to SC Stearns, fitness is a concept that everyone understands, but no one is able to define it precisely.

What is the

Definitions

The term fitness refers to the ability of a group of organisms to reproduce and survive. In other words, it is the characteristic that determines the ability to spread its genes in the population, with the passage of generations. In the literature, we find dozens of definitions, including:

- The tendency of an individual, or individuals, to carry an allele that allows them to survive and produce viable offspring.

- The rate at which an allele or characteristic spreads numerically.

- The ability of an individual with certain alleles to exploit resources and face environmental conditions to survive and reproduce.

- Quantifiable characteristic of alleles, genotypes or characteristics of individuals that predict their numerical representation in future generations.

Some authors attempting to define fitness confuse it with evolutionary dynamics - which is a logical consequence of variation in fitness.

In conceptual terms, fitness is a similar parameter for geneticists and for ethologists and ecologists. However, the difference is in the way in which both branches of evolutionary biology estimate or quantify the parameter.

Origin of the term

Contrary to popular belief, the British naturalist Charles Darwin did not use the term fitness in the early editions of El or the rule of species.

In contrast, Darwin used the verb "to fit" to refer to the ability of a phenotype to function and "fit" in the environment where it lives.

Using a key and lock model as an analogy, the key is represented by the organism and the lock by the environment, these must fit together in terms of survival, development, growth and reproduction.

Mark-recapture experiments

In the second method, the proportions of the number of individuals recaptured over the number of individuals released are simply calculated. The highest value is assigned fitness 1 and the remainder is divided by that value.

Deviations in the Hardy-Weinberg principle

Finally, the deviations from the Hardy-Weinberg principle are calculated as the relationship between the observed and expected frequencies. And, as in the previous case, fitness 1 is assigned to the highest value, and the rest is divided by it.

References

1. Darwin, C. (1859). On the origins of species by means of natural selection. Murray.
2. Freeman, S., & Herron, JC (2002). Evolutionary analysis. Prentice Hall.
3. Futuyma, DJ (2005). Evolution. Sinauer.
4. Ridley, M. (2004). Evolution. Damn.
5. Soler, M. (2002). Evolution: the basis of Biology. South Project.
6. Westneat, D., & Fox, CW (Eds.). (2010). Evolutionary behavioral ecology. Oxford University Press.