Biology knows many cases when a group accidentally breaking away from the main population can, after several centuries, form a completely new species. Sometimes it even happens that at the same time individuals of the maternal species continue to live on the same territory.
There are also a few examples when species are forced to dwell in a constantly changing external environment. Often, “change” refers to the continuous deterioration of some vital indicator. When going beyond this range, the species most often simply dies out.
Prerequisites for survival
Scientists have come to the conclusion that a species has a chance of survival only if it begins to actively change, adapting to dramatically changing conditions. This phenomenon is called phyletic speciation. In this case, not only the adaptability of organisms to the environment is formed, but also signs completely new for living beings develop.
Today, millions of species live on our planet. Is this not evidence of the strength of life, its constant variability ?! Unfortunately, several million years ago there were significantly more living creatures. Several ice ages and constant climate perturbations led to a sharp decrease in species diversity. Only the most adaptable survived.
Important examples of adaptations
From time immemorial, the brilliant correspondence of the organs of living creatures and the functions performed by them has attracted the attention of people: attempts to create gliders with a bird-shaped wing, the construction of ships with contours resembling the bodies of sea fish. But much more striking is the ideal, harmonious correspondence of the appearance of animals and plants with their natural habitat.
Of course, the examples can be continued indefinitely. And therefore, within the framework of this article there is an opportunity to tell only about some living creatures, whose traits of adaptability to the environment most clearly and clearly prove the correctness of Darwin.
Birds
So, a person has long been aware of the importance of protective coloring for birds, as well as their chicks and eggs in particular. In capercaillie, black grouse and partridge (openly nesting), the eggshell blends almost perfectly with the background of the surrounding area. In general, the female’s back is also indistinguishable from the surrounding landscape when viewed from the side. All the more interesting is the fact that the females and eggs of birds that nest in hollows and other hidden places often have a very bright color (the same parrots, for example).
Insects
And what features of adaptability to the environment do insects have? Well, they are even more numerous than all representatives of this class. We think that everyone knows the striking similarity of stick insects with dry twigs. Some research in this area is still used by the military in the field of creating "forest" camouflage suits.
However, the bodies of many caterpillars are very reminiscent of twigs, and the wings of butterflies can pass for the leaves of the trees of the area where they live. It should be noted here that in this case a harmonious combination of the protective form of the body and the protective color is observed. Some butterflies, when they merge with the surrounding area, it is difficult to distinguish from the leaves even point blank. If you more or less know biology, then you perfectly imagine the entire diversity of the class of insects. Getting into a forest or field, you see no more than 2-3% of their total number. The rest are simply disguised.
But! It should not be considered that examples of the fitness of organisms are limited to banal disguise. Remember the adaptive color, when brightly colored, “colorful” insects are just not popular among predators, since they are well aware of their sharply negative food qualities. So, a tit or a sparrow, a couple of times trying to bite a bug with a soldier a couple of times in youth, they remember their pungent, poisonous taste for the rest of their lives.
In addition, traits of the adaptability of organisms to the environment include mimicry. This phenomenon resembles a patronizing coloration, but "vice versa." So, some defenseless and edible species can perfectly imitate those insects that are poisonous or have a disgusting taste. For example, wasp-like flies are very similar to wasps, which even many birds fear. All this suggests that the adaptability of organisms to environmental conditions is just adaptive, adaptive in nature.
Higher mammals
All this can be seen in the example of higher mammals. The coloring of zebras seems bright and even somewhat ridiculous to us, only it perfectly repeats the alternation of light and shadow in the thickets of grass, which allows these animals to perfectly mask themselves in the savannah. Eyewitnesses confirm that unprepared people sometimes do not notice zebras even in open areas, from a distance of only 50-70 m.
Other features
Some living things have an even more amazing and effective adaptability to the organismic habitat. We are talking about chameleons and flounder, which can change the color of their body, producing a redistribution of organic pigments in the chromatophores of the skin. Do not forget that the protective color and other protective factors dramatically improve their effectiveness, subject to appropriate behavior. This includes the reflex of fading, taking a rest pose, which is characteristic of a huge number of animal species.
Where does living beings have this ability?
In general, where did the adaptability of organisms to the environment come from? In general, in the previous part, we already expressed the opinion of the great Darwin: if an animal or plant can survive a sharp change in climate or other conditions, then its descendants will become the most common. Thus, the main reason for the emergence of living creatures of some new adaptations is precisely natural selection. Let us show this with a practical example, discussing the life of the family of black grouse that live in the lower canopy of the forest.
Structural features
Let us recall the main features of the external structure of these birds: the beak is short, does not interfere with pecking food directly from the forest litter (including from the snow cover); on their feet - a thick fringed substrate, with which they can safely walk even in deep snow. The structural features of the pen allow them to spend nights with their heads buried in the snow, and short, wide wings make the black grouse few of the birds that have access to a direct, almost vertical take-off.
It would be logical to assume that their distant ancestors did not have such adaptations at all. Most likely, after changing a number of some environmental factors (it became banal colder), they were forced to adapt to a sharply changed habitat, including the cold.
Change process
New mutations constantly appeared, when they were crossed, their various combinations took place, and the wave number made the population more heterogeneous and stable. It is not surprising that birds were distinguished from each other by a number of signs: someone had fringes on their fingers, and beaks or wings were shortened on some individuals.
What expressed the adaptability of organisms to the environment? The fact is that in the course of constant intraspecific struggle, only those birds survived whose structural parameters were most consistent with the surrounding world. In the selection process, only they left more offspring, and it was she who survived most often and in an amount sufficient to form a new population. The new generation brought with it new mutations and the whole process was repeated from the very beginning.
Fixing useful signs and qualities
Surely among the mutations were those that reinforced and consolidated the manifestation of signs that had appeared earlier. Naturally, the birds in which these changes were manifested had significantly more chances not only to survive, but also to give offspring later. For generations, all these signs have accumulated and consolidated until the black grouse that we know now have appeared.
The contradictions of the theory of Lamarck
As you know, Darwin's theory is fundamentally different from the assumption that was put forward by Jean Baptiste Lamarck. The latter said that all living organisms can change under the influence of the environment, but only in the direction that is extremely useful to them. But this is absurd: what kind of influence could contribute to the appearance of thorns in hedgehogs?
Only the influence of natural selection can explain the emergence of such a useful device. It is assumed that the very distant ancestors of the hedgehogs were able to survive, being covered with an increasingly coarser hair. Staying alive and giving offspring turned out to be an advantage for those “promenades” who were lucky to have the longest and most rigid spines.
Other "scratchy" examples
The "bristly hedgehogs" from Madagascar went exactly the same way. We are talking about tenreks and a few species of prickly mice and hamsters.
Does the adaptability of organisms to the environment have at least some common signs? Scientists suggest that the mechanism for the emergence of such devices remains common in all cases: the fact is that they do not appear immediately, not in one or two generations. On the contrary, their occurrence is a long and complex process. It should never be forgotten that the evolutionary path is full of dead ends and unsuccessful "technical solutions" of nature. We’ll talk about this now.
Fitness relativity
In the period before Darwin, the adaptability of animals to their environment served as unanimous evidence of the existence of the Lord and the immense wisdom of the Creator: could nature without such “guidance” independently arrange the world around it in such a reasonable, balanced way !?
It was believed that every feature of any living organism was absolutely perfect and exactly corresponded to the task that was assigned to it. Thus, the butterfly's mouth apparatus extended into the proboscis helps it to extract nectar from even the most “complex” flowers, and the plants' adaptability to the habitat in the form of thick trunks of cacti and other succulents is ideally suited for storing water for a long time.
Unfortunately, even many modern scientists continue to regard nature as a brilliant sculptor, each creation of which is perfect and infallible. But! It is important to clearly realize that this is far from the case!
A modern study of adaptability to the environment has shown that all sorts of changes are always relative, since they form much slower than a real change in environmental conditions. Accordingly, many features may be unnecessary, or even directly harmful to the body, if the world around changes.
Evidence of relativity
The proof of the fact that the fitness of living organisms is a very, very relative concept, are the following examples:
- Protective devices are very effective from some enemies, but they are not particularly well rescued from other animals. Snail cones are happy to eat poisonous fish , and the cuckoo includes poisonous shaggy caterpillars in its diet.
- Not all animal reflexes are really expedient and adequately correlate with environmental conditions. Think of the nocturnal butterflies that collect pollen from light flowers that are clearly visible at night: they fly just as hastily into the flames of bonfires and candles, although they die.
- The organs of adaptation, which in one environment are really useful, in other conditions turn out to be harmful and even dangerous. So, mountain geese, which never in their lives descend into the water, have membranes on their paws.
- Beavers, one of the best "engineers" in nature, actively build dams even in standing ponds and pools, which is a waste of energy.
Relativity is especially pronounced in the case of those animals whose homeland is located on the other side of the globe, but which were introduced by humans into a completely new habitat for them. Simply put, it is the
relative nature of adaptability that most convincingly and convincingly proves that nature is far from always infallible.