Basics of Evolution - O.P. Korzh - 2006

Part II. MACROEVOLUTION

Chapter 16. Modern Problems of Evolution

16.6. Evolution of Evolutionary Mechanisms

Today, it is a well-established fact that not only individual species, communities, and the environment in which evolutionary transformations took place have changed historically, but also the mechanisms of evolution themselves, along with Other components of the evolutionary process. First of all, this concerns the asynchronous formation of all Levels of biological Organization. Thus, it is believed that natural Selection operated even at the pre-biological level, consisting in the selection of macromolecules that best implemented the mechanisms of hereditary Variability and mutual coordination. The first prokaryotic organisms lacked many genetic properties that are present only in eukaryotes and play a crucial role in their subsequent evolution. Multicellular Organisms also significantly altered the modes of action of microevolutionary mechanisms, providing extraordinary opportunities for Anatomical and morphological transformations. The improvement of The Nervous system in higher animals enhances Structure/19.html">The Importance of behavioral changes.

The population-species level of biological organization emerged far from immediately, which must have affected evolutionary mechanisms in a certain way. An even more complex question is the mechanisms of ecosystem evolution, for which natural selection is recognized as the leading factor: they must have formed almost simultaneously with THE ORIGIN OF life on Earth (even before the appearance of the population-species level).

It should also be recalled that such secondary Forms of natural selection as sexual and group selection did not appear immediately in the course of evolution. In particular, sexual selection emerged no earlier than bisexual animals (as noted earlier, L.Sh. Davitashvili predicted the presence of sexual selection only in trilobites). Group selection can be spoken of only with respect to animals with certain social structures (no earlier than social insects).

The Evolutionary Significance of Anthropogenic impact on nature deserves separate consideration. This issue merits attention not only because of significant Changes in the principles of biosphere functioning, its overall pollution, the Introduction of an extraordinary amount of xenobiotics, and other similar troubles. The fact is that humans and their activities at the present stage are capable of influencing practically all microevolutionary factors, and this influence often occurs independently of human will. The introduction of an extraordinary amount of new substances into the biosphere, whether intentionally (e.g., pesticides) or unintentionally (As a result of pollution), significantly increases The rate of Organism mutagenesis and can alter the direction of natural selection.

Examples include the extraordinary rates of adaptation of agricultural pests to new chemicals, which constantly keeps the chemical industry in business.

The transformation of natural biotopes also significantly affects changes in the species composition of individual ecosystems. On the one hand, this concerns the disappearance of many stenobiont species or their transition to the status of rare and endangered, as well as the spread of eurybionts to a cosmopolitan level (primarily synanthropic species). The consequence of such impacts is the interpenetration of flora and fauna from different regions and the smoothing of differences between various ecosystems through The formation of relatively impoverished, significantly altered, and unnatural entities (agrolandscapes, urbanized territories, which today are not even recognized as ecosystems due to fundamental differences in their organization from natural ones).

One cannot fail to mention the NEGATIVE IMPACT OF human activity on the state of populations of so-called commercial animal species. This concerns both the extinction of certain species due to the overexploitation of their populations (the most striking example is Steller's sea cow, Hydrodamalis gigas, which was exterminated in just 27 years) and changes in The structure of the latter. Well-known examples include changes in range size, sex and age structure of populations, body miniaturization, shifts in the timing of fertility, and other consequences that can be traced in animal populations subjected to excessive human exploitation. Such changes can be regarded exclusively as microevolutionary transformations of the populations of the respective species.

Through their activities, humans exert yet another important influence on natural populations. This concerns the artificial creation of an extraordinary number of barriers that significantly affect the population structure of many species. This problem is particularly acute in cities, where, due to the small areas of individual habitats and the lack of any natural connections between them (the island biogeography principle comes into play), a significant number of species cannot exist normally at all.

The consequences of such changes in evolutionary mechanisms are an increase in the overall rates of organism evolution as a whole.

Thus, while the formation of prokaryotic life took about a billion years, and eukaryotes, plant, and multicellular organisms appeared over the next two billion years, their subsequent evolution took just a little over half a billion years. The Rates of evolution have increased particularly in recent centuries, when human activity has driven unprecedented transformations of nature, creating new biotopes that are only just beginning to be colonized by new biotic complexes (apart from urban and agricultural formations, these include various spoil heaps, slag dumps, etc.).