Aromorphosis are adaptive changes in living organisms that occur during evolution, are of general importance and are aimed at increasing the level of organization, which increases viability.
General value of aromorphoses
The appearance of aromorphoses is crucial in the struggle for existence. Living organisms in which such changes occur become more adapted to the conditions of the external environment and can develop a new habitat. An example of aromorphosis is any evolutionary change that leads to the emergence of new, progressive groups of organisms.
The formation of aromorphoses is a rather long process and is associated with hereditary variability. In addition, natural selection plays a role in the emergence of new properties of living beings, when more adapted organisms survive. They have more physiological ability to fight for their existence and give more offspring with useful properties that are passed on to the next generations.
It can be said that aromorphosis is an important morphophysiological process. It leads to the emergence of more complex organisms, which to a lesser extentdepend on environmental conditions.
Aromorphoses in plants
Progressive changes are also characteristic of plants. They concern not only the improvement of morphological features, therefore, instead of the term "aromorphosis", the word "arogenesis" is often used, which means "origin" in translation.
The appearance of various types of algae is associated with a different combination of morphological properties and the ability to photosynthesize, but they do not have real tissues, therefore they are considered primary aquatic organisms (there are no evolutionary changes in their structure).
If you give examples of aromorphosis, then the most important is the differentiation of tissues, which led to the emergence of terrestrial higher plants. The most primitive of them are mosses, since cell differentiation in these plants was weak, the root is absent, and the shoots are characterized by a primitive structure.
The next important aromorphosis was the division of the plant body into a shoot and a root. Later, spore plants arose, which include ferns, horsetails and club mosses, but they still lack seeds, and the sporophyte develops from an embryo that is little differentiated. Since water is needed for fertilization, this limits the wide distribution of spore plants to a certain extent.
Examples of aromorphosis in plants
If we talk about radical changes in the structure and structure of plants, then we should recall the Gymnosperms department, whose representatives have a number of aromorphoses:
- yan ovule appears in them, in which the endosperm (female gametophyte) develops;
- there are pollen grains that germinate into the pollen tube; a male gametophyte is formed; fertilization does not require water;
- These plants have seeds that consist of a well-differentiated embryo, as well as endosperm, which is a source of nutrients for the development of the embryo.
Angiosperms also belong to seed plants. They originated in the Jurassic period. Examples of aromorphosis of this plant department are as follows:
- they always have a closed carpel with an ovule (pistil);
- there are special "baits" - nectar and perianths, which provide entomophily - pollination with the help of insects, which is characterized by the accuracy of the process within a particular species and allows different plants to exist;
- Angiosperms have an embryo sac with a structure that allows for double fertilization.
It should be noted that this group of plants has about 250 species and is on the path of biological progress. Thus, angiosperms are represented by various life forms (these are trees, bushes, lianas, herbs, water representatives), which are constantly being improved regarding the structure and functions of individual parts.
Evolutionary changes in the structure of animals
Eukaryotic organisms, which were characterized by a heterotrophic type of nutrition, gave rise to fungi andanimals. The first of them are represented by unicellular organisms that did not have tissues. In the Proterozoic era, multicellular invertebrate creatures appear. The most primitive were two-layered animals, for example, coelenterates. Examples of aromorphosis in animals of this group are a two-layer embryo and a body that consists of two sheets - ectoderm and endoderm.
The next important improvement in the structure was the appearance of the middle germ layer - the mesoderm, which provoked tissue differentiation and the appearance of organ systems (Flat and Roundworms). The next aromorphosis was the appearance of a coelom - a secondary cavity, thanks to which the body of animals began to be divided into sections.
Primitive Protostomes (eg Annelids) emerged that already had parapodia (primitive limbs) and a homonomous segmented body. Examples of aromorphosis that occurred later are the appearance of heteronomous segmentation of the body and articulated limbs (arthropods arose). At the beginning of the Devonian, arachnids and insects came to land, in which a serious aromorphosis was observed - the appearance of embryonic membranes.
Evolution of Deuterostomes
The appearance of the notochord, neural tube, abdominal aorta, and then the heart in these organisms led to the formation of a new type - chordate animals. In the future, the fish develops a visceral and axial skeleton. So, they already have a brain case and a jaw region of the skull.
Bone fish also underwent a number of important aromorphoses(pulmonary respiration and real limbs appeared), which gave rise to amphibians.
Further, amniotes develop, which had three embryonic membranes. Reptiles were their first representatives. They were independent of water, but due to the lack of a vicious circle of blood circulation, they could not control a constant body temperature, which led to their mass extinction at the end of the Mesozoic.
Further examples of aromorphosis are the appearance of a complete septum in the heart between the ventricles. This made it possible to separate the circles of blood circulation, which led to the appearance of warm-blooded animals, which later acquired the ability to fly. This is how the Bird class was born.
Aromorphoses that led to the appearance of mammals
In the animal-toothed reptiles, over time, the hemispheres of the forebrain increased, the cortex developed, a four-chambered heart appeared, and the reduction of the aortic arch took place. In addition, mammals arose as a result of the appearance of auditory ossicles, woolen cover and mammary glands, and differentiation of teeth in the alveoli. The next example of aromorphosis in mammals is the appearance of the placenta and live birth.
Thus, the feeding of young with milk, the progressive development of the lungs, brain, circulatory system, as well as a number of other aromorphoses are the reasons for a sharp increase in the general level of animal organization and the emergence of higher organisms.
The last significant aromorphosis can be called an increase in the brain in human ancestors (epimorphosis). To date, Homo sapiens has mastered the adaptive zones of the earth,that provoked the emergence of the noosphere. At the same time, the organic world has entered a new era - psychozoic.
To summarize, it should be said that large aromorphoses lead to the capture of new habitats and the emergence of new organisms with specialized features that play a leading role in the evolutionary process.
