” Every action carried out by nature can’t be done in a shorter way with the same means”. (Leonardo Da Vinci[1]).
Let’s imagine a huge and perfect machine the gears of which are all connected one another, the movement of the smallest of them influences all the others. Similarly, in nature, all living things but also elements (air, water, soil, rains, gases….) happen to be linked one another through interaction relations the study of which was called with the word ecology.
Every organism, both plants and animals, is considered as a set. The various sets react one another, linking or better combining in more complex sets that are continuously modified by the changes in the envirnment. Each element of a system can be part of another one in a continuous change the final result of which is homeostasis. The whole of all this as to the entire earth is indicated as ecosystem. All the elements of ecosystem tend to balance[2].
Let’s imagine, instead of the gears of our machine, more animal species in each of them every individual aims at surviving and reproducing. This implies every species tends to increase endlessly taking away space and resources to the other species.
To keep balances among the latter, nature selected a regulation system at genetic feedback[3-4] (genetic retroaction or negative retroaction). This mechanism involves herbivores and plants,predators and preys, parasites and hosts.
As a determinate population, an animal one in our study, increases numerically,inferior genetic types will be born. The latter word doesn’t have to deceive us and we could replace it with susceptible or sensitive.
Inferior genetic types are however weaker and therefore they are more easily subjected to the classic factors of reduction of animal number: predation, want of food, competition, disease. So as E B Ford[5],[6] has asserted: numerical increase inevitably opens the way to reduction and vice versa; so there are some fluctuations with periods in which population may be, numerically, higher or lower.
Once the number of animal population is reduced, selective pressure stops and a return to the original genetic types occurs because nature tends to genetic homeostasis.
If a gazelle population increases numerically too much, at a certain point cubs, ill, weak, unfit to run and escape predators are generated. After some time under the pressure of predators, which , in this case, represent natural selection, these weak creatures disappear and there is a return to the original population from a genetic point of view.
The same happens among predators: as the number of gazelles increases, lions, since they have more food at their disposal, reproduce more easily, breed more cubs and risk autoextinction (for the extinction itself of prey population). At this point even among lions inferior genetic types start appearing: weaker, less fit to running and predation; the latter are less fit to survival and can reproduce with difficulty, so lion population tends to return to the original condition from a genetic point of view.
[1] Leonardo DaVinci. Codice Arundel, foglio 175 (1478-1518). British Library London. Re-edited in Leonardo Da Vinci Scritti Letterari, pag. 66. BUR Milano 1991.
[2] Heish,quoted in: The Ecology of plague by Pollitzer R and Meyer Kand F. Chapter 13 pag.474 of Studies in Disease Ecology Edited by May J M. Hafner Publishing Company, INC New York,1961.
[3] Pimentel D. Animal population regulation by the genetic feedback mechanism. Am Nat XCV:881, pag.67-79
[4] See also:
-mechanism at genetic feedback in human population Rebellious Angels 1°
–mechanism at genetic feedback in human population Rebellious Angels 2°
[5] Ford E B. Mendelism and Evolution, pag.122.Methuen and CO.LTD London 1931
[6] Ford H D, and Ford E B, Fluttuation in number, and its influence on variation, Melitea Aurina, Rott. (Lepidoptera). Trans ntom Soc 78:345-51 London 1930.
To be continued in:
2) Mechanism at Negative Retroaction-Genetic Feedback 2°
3) Mechanism at Negative Retroaction-Genetic Feedback 3°
Ferdinando Gargiulo offers you a new perspective on why new viral epidemics, assaults, infanticides, suicide epidemics and even environmental catastrophes. Always engaged in his research decides to create a blog to offer his readers content of high value.