Diversity creates variants on which selection can act. As the environment changes, selection takes place and the average traits of the species gradually change. Evolution means that the distribution of genes and traits in a species changes over generations.
For many years, such a well-founded opposition to evolution prevailed in Turkey that evolutionary changes were only related to the transformation of one species into another (more precisely, “the transformation of ape into man”) and that it would take millions of years to observe what is called “evolution” (hence that). The lie that evolution is not based on observational facts) was very popular among the public. It even took more than 10 years to explain the fact that “evolution” is a law of nature, and that all of the scientific information explaining this law is called “The Theory of Evolution”! The education system is so weak that it is unable to even teach that “gravity” is the law, “Newton’s theory of gravity” or “Einstein’s theory of general relativity” are theories which explain this law, different in scope and power. Consequently, young people (and by extension the public) were unable to generalize and use the information they had memorized in school just to pass the exam, and they could not grasp the essence of science. (and therefore of the Universe in which we live, that educational system should present to us).
But thanks to the tireless efforts of science communicators, we can say that this vicious and distorted perception of evolution is slowly beginning to break down. From what I’ve been able to observe, people, at least young people interested in science, say that evolution no longer means “ape becoming man”; they know that evolution is the change over generations of any distribution of genes/traits within a population. They began to realize that the formation of one species into another was not the definition of evolution but an inevitable consequence of it (just as the curvature of the fabric of spacetime is the definition of evolution). gravity, the fall of an apple or the formation of planets are a consequence of this law of nature). Humans are much more familiar with the fact that all that is needed for evolution to occur is the pressure of intraspecific diversity and environmental selection, and that when these two conditions are met, evolution will occur almost inevitably, that new species can evolve.
Take diversity. Every one of the trillions of cells in our body is mutating every moment; that is, their body’s genetic information changes randomly. Most of these changes can be corrected by intracellular mechanisms; but every hundred millionths is ignored and remains uncorrected, passed on to the offspring of that lineage (remember, each of your trillions of cells contains about 3 billion nucleotides susceptible to mutation). If this mutation; If this occurs in the tissues that produce reproductive cells, in reproductive cells such as sperm and egg cells, in the zygote formed by their union, or in the early divisions of the embryo formed from that zygote, it permanently modifies all the genetic information of the living being (because all our other cells contain the genetic information carried by these few cells. It is copied trillions of times, and if an error occurs in these ancestral cells , all of our cells, and even the cells of our offspring and grandchildren, inherit this error).
But even if there were no mutations, our diversity would increase simply because we reproduce sexually (that is, we combine a female and male germ cell to produce offspring). Because in order for these cells to be produced, a special division called meiosis must be experienced, and the genes inside the cell are randomly mixed together. This constantly increases diversity.
A set of “diversity mechanisms” like this ensure that different individuals of living species have different characteristics from each other. These are not necessarily the physical differences seen from the outside. Its infrastructure can be anything partially or completely determined by genetics, from how an organelle in the cell behaves in the presence of a certain chemical, to the rate of transmission of electrical signals in nerve cells, to the amount of salt allowed to accumulate in the space between cells, or the amount of spread of the root hairs of the living thing.
A great diversity is a great advantage; because the environment is constantly changing and the combinations of genes and traits that are advantageous today may not be advantageous tomorrow under natural conditions. For example, your species’ body size is adapted to a certain ambient temperature; but the climate is changing and you now have to live in much lower temperatures. If the suitable temperature variation within its population is small, that is, if all individuals of the species (I throw) can live on average between 16 and 18 degrees, but if temperatures have dropped to 10 degrees on average as a result of environmental changes, the extinction of your species will be inevitable. However, if your species diversity is between 8 and 24 degrees (most individuals are compatible with 12 and 20 degrees, although some individuals in your population may live in temperatures as low as 8 degrees or as high as 24 degrees), then the species as a whole will adapt much more easily to changes in temperature. This increases your chances of preserving your lineage under drastically changing environmental conditions. As the environment changes and these extreme members of your species survive and multiply, the average characteristics of the species change to reflect theirs. If you think about it in millions of characteristics, and not just one, you can see that it’s not at all difficult for an ancestral species to change into a new species that looks (and has) completely different characteristics.
This is why diversity is known as the “fuel of evolution”. Diversity creates variants on which selection can act. As the environment changes, selection takes place as I described above, and the average characteristics of the species gradually change. Since evolution means that the distribution of a species’ genes and traits change over generations, “that species evolves.” we say. “A new species has evolved”, when that species has differentiated itself sufficiently from its ancestors to be statistically distinguishable. we say. This is the point I mentioned at the beginning that confuses people.
Measuring diversity is essential; because, as Ronald Fisher showed in the 1930s, the amount of genetic variance (i.e. diversity) in a population at any given time is a direct measure of how fast the population of this organism has evolved according to its environment. For example, the Drosophila serrata vinegar flies, bred only in New Guinea and only in Australia, when forced to live in conditions with little food and limited habitat, can evolve much slower and slower than flies. from a mixture of these two geographical populations. , and therefore more diversified. A highly diverse mixed population can have a much larger number of individuals than the other two populations once the selection pressure is removed. These experimental results show that there is a close relationship between diversity and the rate of evolution.
So how do we measure the amount of diversity within a species? One method is to look at the genes. If you sequence the genes of a large number of individuals and detect their nucleotide differences, it is possible to make statistical inference about diversity within the species.
Another method is to look at historical data: For example, in a new study published a few days ago, experts analyzed changes in diversity over 30 years (a total of 2.6 million hours of data collected on field) of 19 different animal populations monitored by 40 different researchers from 27 different research institutes around the world. ) were examined. These species included desert wrens from Australia, spotted hyenas from Tanzania, song sparrows from Canada and red deer from Scotland.
The results are amazing: the amount of diversity between species over the past 30 years is 2 to 4 times greater than we thought! This means there is more “fuel” for evolution. However, it is not yet known if this amount has increased recently or if it has remained stable. The increase in diversity could potentially mean an increase in the speed of evolution, and if this can be shown, it can be concluded that species adaptation effort has increased due to the human-induced climate crisis. .
Let’s not go without saying: “Living beings evolve. We often use words like “the effort of the species to adapt”, but evolution; It is not something that happens by will, desire or effort. Living things struggle to survive and reproduce in their daily lives; only a few succeed, and when we trace the genealogy of those who succeed, we see that the species change in their favor. As laggards (“detectives”), we make statements such as “evolved alive” or “trying to adapt” to describe this pattern. Otherwise, neither species is aware of having evolved over generations; anyway, a single individual of any species never evolves at any time. What we call evolution is something that happens through populations of species, over generations.
But in any case, as such studies show, it is not necessary to study millions of years to observe the evolutionary change of species and detect their traces. 30 years of data are enough to observe the evolution and its effects.
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