Alexander Martynov developed the concept of distinguishing organisms, similar to the theories of scientists of the 19th-20th centuries
Introduce the broader term MOD (Multilevel Organismal Diversity) or the concept of multilevel diversity of organisms instead of the concept of “species” , emphasizing a greater number of distinguishing features in different species of living beings, was proposed by employees of the Zoological Museum of Moscow State University and the Institute of Developmental Biology of the Russian Academy of Sciences. Their work on this topic was recently published in the famous book series of the University of Cambridge.
Photo: Wikipedia biologists have not found. And this despite the fact that at different times more than 30 different interpretations were proposed.
For a long time, the so-called biological concept of the species ruled the ball. She attributed both individuals to the same species if, when mating, they could produce fertile offspring. For example, a horse can be crossed with a donkey, – they will have a mule, but he will not give offspring. So the horse and donkey are not the same species. This concept was strong even in the middle of the last century, before the advent of molecular genetics. However, it is now obsolete, because in nature, examples of fertile offspring have been identified between two seemingly different species, for example, a wolf and a dog.
Today, biologists rely mainly on the morphological way of defining one species – by similar features of the structure of animals (for example, by the number of legs, outgrowths on their backs, the shape of the skeleton), as well as by the method of molecular difference between species that appeared 10 years ago. That is, now they are looking not only at external similarities, but also at the structure of the DNA of compared living beings. Deepening into the genetic level showed that in the animal world everything is much more complicated: where morphologists distinguish 3-4 types of worms, geneticists can find 9-10! This phenomenon has been termed «hidden biodiversity». For example, before everyone thought that the clouded leopard – this is one kind. But after looking at the sequence of the genomes of its various representatives, we found out that there is & nbsp; three different types of clouded leopard. Therefore, for the last 3-4 years, some scientific journals no longer accept papers that rely only on morphological features when determining the species.
So why is it necessary to introduce another theory? The thing is, scientists say, that while there is complexity & nbsp; in determining the similarity of two individual creatures, even in terms of the genome. It is clear that one to one in two different creatures, it cannot coincide. Then what is considered a sign of one type — & nbsp; 98% or 97.5% genome similarity? There is no consensus yet. In addition, each group of animals has its own practice and its own idea of a single species at the molecular level.
Alexander Martynov from the Moscow State University Zoom Museum and Tatyana Korshunova from the IBR RAS suggested instead of & nbsp; the concept of «view» introduce a more universal – MOD (Multilevel Organismal Diversity), that is – rely on the concept of multilevel diversity of organisms, which would rather consider each animal as an individual. Similar theories of classification of organisms and, in particular, the problem of species, & nbsp; discussed and are currently being discussed in many monographs and collections by other scientists around the world.
Just like previous taxonomists, Martynov and Korshunova proposed to take into account in the biological classification of organisms, in addition to morphology and genetics, also ontogeny – life cycle of an animal from embryo, larva to adult stage. Since the organism is a developing system, ontogeny is its main characteristic. This factor would make it possible to very accurately understand all the hidden features of a particular species from the beginning of fertilization – the fusion of female, male genes, the appearance of a unicellular, then a two-celled organism, and so on, up to development into an adult. Each species has similar development patterns & nbsp; are similar.
— This is normal when the theory of systematics is developed.
In particular, the idea of using ontogenesis was first proposed back in the 18th century by the Russian naturalist, the founder of embryology, Karl von Baer. In the 50s of the last century, it was promoted by the American Grace Orton, then by the Englishman Colin Peterson, & nbsp; who advocated a similar theory in the 1980s. Each generation puts forward a leader in this direction.
However, the difficulty lies in the fact that to trace the paths of ontogeny from zygote to adulthood scientists can now only have a small number of organisms. This requires a large amount of research material, large funding and expensive equipment. It is one thing to dissect at each stage of development of the embryo in a mollusk or worm, and quite another, for example, in an elephant. Imagine how many pregnant elephants would have to be killed in order to study the development of her fetus at different stages of its development! It's simply impossible. Who will allow elephants to be killed, and pregnant females at that?!
So for the time being, molecular and morphological methods still remain working tools for determining species characteristics. Someday, scientists will begin to take into account ontogenesis, because science is moving forward, but so far we are not ready for this.