According to the theory of evolution, all animals and plants that exist in the modern world are descended from those primitive organisms that inhabited the Earth millions of years ago. The improvement of living things can occur through various processes. This is idioadaptation, and degeneration, and aromorphosis. Idiadaptation is one of the main directions of evolution, thanks to it the body adapts to a specific environment, while not fundamentally changing its structure. Degeneration involves the disappearance of any organs in the process of evolution. At the same time, one can observe the formation of rudiments, that is, the remains of organs, which ancestors performed important functions. In humans, this is, for example, a lunate fold in the inner corner of the eye, coccyx, etc. On this direction of evolution, as aromorphosis, in this article we will dwell in more detail.
What it is?
Aromorphosis is a complication of the structure of an organism during evolution to increase its vital activity. This may include, for example, the occurrence of sexual reproduction, multicellularity, warm-bloodedness, double fertilization in plants, etc. Thanks to this process, such a diverse biosphere of planet Earth has formed.
The emergence of life and the first aromorphoses
Billions of years ago, life was born in the ocean, and the first organisms on the planet were unicellular prokaryotes. Their cells had a primitive structure, did not have in their composition the nucleus and many organelles that eukaryotes have. The era during which these first organisms existed is called the Archean. It covers the period from 4 to 2.5 billion years ago. During the Archean era, the Earth was still not at all what we see it now: there was almost no oxygen in the atmosphere, there was only one continent, there was still no life on land, the gas shell of the planet was denser, and therefore to the surface there was little sunlight.
During this era, the first cyanobacteria, similar to unicellular algae, which will inhabit the Earth later, have already appeared, however, they were still prokaryotes. But these organisms were no longer heterotrophs, like the first bacteria that inhabited the planet, but autotrophs, they were able to synthesize nutrients on their own from solar energy, carbon dioxide and water. We can say that the emergence of photosynthesis is an aromorphosis, which served as an impetus for the further development of life on Earth. Due to the fact that organisms began to use this process for the production of organic substances, the atmosphere began to be gradually enriched with oxygen.
The emergence and development of plants
We can say that the first plants were cyanobacteria that formed during the Archean period, since they were already capable of photosynthesis. The further development of this kingdom involves the formation of organisms that consisted of more than one cell.
The emergence of multicellularity is an aromorphosis, which, along with the appearance of photosynthesis, is included in the list of the most important. Thanks to this change, it became possible to develop living creatures, the formation of the main kingdoms that exist to this day. Red and
green algae were widespread throughout the
Proterozoic era, until the end of the Ordovician period of the
Paleozoic era, they were the only plants that lived on Earth.
Landing of the first organisms
In the Silurian period, the most important aromorphosis in plants occurred - this is the occurrence of the first spore, rhinophytes. This phenomenon can be considered extremely significant, since these organisms have already reached land: they could live both on land and in shallow water.
Also, they, in fact, were the first plants whose body was represented by shoots, and not thallus, like algae. 410 million years ago, rhinophytes have already mastered the land and spread widely throughout the planet. In the same period, Silurian, thanks to plants in the atmosphere there was already enough oxygen for the existence of the first land animals. The next most important aromorphosis is the appearance of seeds in plants instead of spores. So gymnosperms appeared. Aromorphosis is the appearance of a flower and a fetus, the formation of angiosperms.
The first aromorphoses of animals
In parallel with the development of the plant kingdom, the evolution of the animal world did not stand still. The earliest aromorphosis is the appearance of two germ layers and radial symmetry in multicellular animals. This is how intestinal cavities were formed, which include coral polyps, sponges, jellyfish, etc.
First animals on land
Then the third germinal sheet appeared in the organisms - the mesoderm, as well as the bilateral symmetry of the body, muscle tissues, nervous and excretory systems were formed. All these are characteristic features of such types as flat and annelids, which became the next stage in the evolution of animals. At first they lived in the water, and then became the first animals to land.
Further aromorphoses include the formation of a two-chamber, three-chamber, and then four-chamber heart, two circles of blood circulation, the appearance of organs such as the kidneys. Another major aromorphosis is the appearance of the chord and the further formation of the spine and the entire musculoskeletal system.
Warmblood is aromorphosis, which is also one of the most important in the history of evolution. It served as an impetus for the further development of birds and mammals on Earth. The first animals that possessed warm-bloodedness were some dinosaurs that existed from the beginning of the Triassic period of the Mesozoic era, as well as the first bird-like animal - Archeopteryx. This creature already had such changes as the appearance of feathers, beak, characteristic of birds. Then there was the formation of wool, placenta in other species of fauna - this is how mammals appeared. As a result of the aromorphoses listed in this article, all types and classes of animals that exist today are arose.