Natural selection is one of the primary and fundamental concepts of evolution; that only those organisms that adequately adapt to their environment can survive and produce viable and fertile offspring. These organisms survive by selective reproduction, which brings changes in the organism’s genotype. Selective reproduction also has an influence on the organism’s phenotype, which is evident in heritability that results in genetic differences and genetic variance (Clark, 2018). Evolution, on the other hand, is the successive change in inheritable traits and characteristics that are passed from parent to offspring over different generations.
Components of Natural Selection
The four key elements of natural selection are variation, inheritance, selection, and competition. These components of Natural Selection are what determine the survival and extinction of a particular species in their natural habitat.
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Variable traits that Natural Selection acts upon within a specific population
As a result of Natural Selection, certain characteristics are selected and retained in a particular species making it possible for that species to survive. Only advantageous traits are chosen to ensure that the species adapt adequately to the environment. If the species adapt successfully, then it can reproduce and ensure the survival of the species in that particular environment (Frank, 2020). As years go by, these traits become more common in the animal population, and eventually, the genetic composition of that population is said to be changed entirely. Examples of such traits include beak shapes and sizes in birds, coloration, for instance, the color of wings in moths, structural adaptations such as the shape of the skeleton, and even physiological traits such as the presence of enzymes in the digestive tract to help in the breakdown of food.
Sexual selection as a special case of Natural Selection
Sexual selection, as referred to in Natural Selection, is the process by which members of one biological sex choose suitable mates of the opposite sex to mate with. Sexual selection deals with the advantage individuals of particular sex have over other members of the same sex with respect to reproduction (Servedio, 2017). Sexual selection is perfectly evident in the peacock species. During the mating season, peahens choose specific males to mate with by the size and patterns of their tails. The male peacocks perform a unique mating display in which they turn, strut and preen, exposing the bright colors and patterns of their tails. The quantity, size, and distribution of the colorful eyespots on the tails of male peacocks are what appeals to peahens.
Evident studies have suggested that male peacocks with big and beautiful tails are healthy and can survive to old age, and these desirable genes that will be passed onto the offspring are what is attractive to the female peacocks. This method of mate-choosing is clear evidence of sexual selection, and individuals those peacocks that are better suited to survive will have more offspring compared to those that are less likely to survive. Experiments have gone further to prove that the offspring of the males with more eyespots on their tails have a better survival rate in the wild than those of males with fewer eyespots.
How the unique traits of the peacock increase its fitness
In reproductive terms, male peacocks with bigger, brighter, and beautiful tails have better fitness than male peacocks with smaller and less bright tails. This is because females choose male peacocks with more luminous tails as their potential mates, and the desirable genes of the selected male peacocks are then passed onto the next generations. The resulting offspring inherit these strong traits, and the cycle continues onto successive generations. Peahens choose only about five percent of the total male peacocks for mating, and those selected are the most glorious among the lot possessing the best physical traits. Certain factors, such as a population's genetic structure, influence the population variation, and this is what causes the physical characteristics to be distributed in the population (Clark, 2018). Thus, the unique traits of the selected males are what sets them apart, and the offspring that are produced are even better than their predecessors, thereby becoming fitter and suitable to their natural habitat.
In conclusion, the theory of natural selection is what seeks to support the concept of evolution. Evolution is the basis of the existence of all living organisms, and individuals of a particular species with more heritable traits can survive in their natural environment while those with less heritable traits wither off and die.
References
Clark, M. A., Choi, J., & Douglas, M. (2018). Population genetics. Biology 2e .
Frank, S. A., & FOX, G. A. (2020). The inductive theory of natural selection. The Theory of Evolution: Principles, Concepts, and Assumptions , 171.
Servedio, M. R., & Boughman, J. W. (2017). The role of sexual selection in local adaptation and speciation. Annual Review of Ecology, Evolution, and Systematics , 48 , 85-109.
