Aromorphosis is the adaptive changes in living organisms that occur during evolution, are of general importance and are aimed at increasing the level of organization, which increases vitality.
The general value of aromorphoses
The emergence of aromorphoses is crucial in the struggle for existence. Living organisms in which such changes occur, become more adapted to environmental conditions and can develop a new environment. 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 lengthy process and is associated with hereditary variability. In addition, natural selection is of importance in the emergence of new properties of living things when more fit organisms survive. They have more physiological capabilities to fight for their existence and give a greater number of offspring with useful properties that are passed on to next generations.
We can say that aromorphosis is an important morphophysiological process. It leads to the appearance of more complex organisms, which are less dependent on environmental conditions.
Aromorphoses in plants
Progressive changes are also characteristic of plants. They concern not only the improvement of morphological features, therefore, often instead of the term “aromorphosis” they use the word “arogenesis”, which means “origin”.
The appearance of various types of algae is associated with a different combination of morphological properties and the ability to photosynthesis, however, they do not have real tissues, therefore they are considered primary water organisms (there are no evolutionary changes in their structure).
If examples of aromorphosis are indicated, then the most important is the differentiation of tissues, which led to the appearance of terrestrial higher plants. The most primitive of them is mosses, since in these plants the differentiation of cells was weak, the root is absent, and the shoots are characterized by a primitive structure.
The next important aromorphosis was the separation of the plant body into shoot and root. In the future, spore plants arose, which include ferns, horsetails and clowns, but they still lack seeds, and sporophyte develops from an embryo, which is slightly differentiated. Since fertilization requires water, this to some extent limits the widespread distribution of spore plants.
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:
- they develop ovule, in which the endosperm (female gametophyte) develops;
- there are pollen grains that germinate in the pollen tube; male gametophyte is formed; fertilization does not need water;
- these plants have seeds that consist of a well differentiated embryo, as well as an 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 ovule (pestle);
- there are special "baits" - nectar and perianths, which provide entomophilia - pollination with the help of insects, which is characterized by the accuracy of the process within a particular species and allows various plants to exist;
- angiosperms are characterized by an embryonic sac with a structure that allows double fertilization.
It should be noted that this group of plants has about 250 species and is on the path of biological progress. So, angiosperms are represented by various life forms (these are trees, bushes, vines, 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 and animals. The first ones are represented by unicellular organisms that did not have tissues. In the Proterozoic era , multicellular invertebrate creatures appear. The most primitive were two-layer animals, for example, enteroecious. Examples of aromorphosis in animals of this group are a two-layer embryo and a body that consists of two leaves - an ectoderm and an endoderm.
The next important improvement in the structure was the appearance of the middle germinal leaf - the mesoderm, which provoked the differentiation of tissues and the appearance of organ systems (Flat and Round worms). The next aromorphosis was the appearance of coelom - a secondary cavity, due to which the body of animals began to separate into departments.
Primitive Primorotors (for example, Ringworms) appeared, which already had parapodia (primitive limbs) and a homogeneous segmented body. Examples of aromorphosis that occurred later on are the appearance of heteronomic segmentation of the body and articulated limbs (Arthropods arose). At the beginning of the Devonian, arachnids and insects appeared on land, in which serious aromorphosis was observed - the emergence of germ shells.
Secondary Evolution
The appearance of chords, neural tube, abdominal aorta, and then the heart in these organisms led to the formation of a new type - chordates. Subsequently, the fish develops visceral and axial skeleton. So, they already have the presence of the brain box and the jaw of the skull.
Bone fish also underwent a number of important aromorphoses (pulmonary respiration and true extremities appeared), which gave rise to amphibians.
Further developed are amniotes, which had three germ layers. Their first representatives were reptiles. 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 allowed us to separate the circles of blood circulation, which led to the appearance of warm-blooded animals, which later acquired the ability to fly. So the Bird class came into being.
Aromorphoses that led to the emergence of mammals
In reptiles, the hemispheres of the forebrain increased over time, the cortex developed, a four-chambered heart appeared, and the aortic arch was reduced. In addition, mammals arose as a result of the appearance of auditory ossicles, coat and mammary glands, differentiation of teeth in the alveoli. The next example of aromorphosis in mammals is the appearance of the placenta and live birth.
So, feeding the young with milk, the progressive development of the lungs, brain, circulatory system, as well as a number of other aromorphoses are the reasons for the sharp increase in the general level of organization of animals and the appearance of higher organisms.
The last significant aromorphosis can be called an increase in the brain in human ancestors (epimorphosis). Today, Homo sapiens have mastered the adaptive zones of the earth, which provoked the appearance 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 traits that play a leading role in the evolutionary process.