Adaptability of organisms to habitat. Fitness of living organisms: examples
Biology knows quite a few cases, when accidentallybreakaway from the main population of the group can in a few centuries to form a completely new species. Sometimes it even happens that at the same time, individuals of the maternal species continue to live in the same territory.
Nemalo also examples, when species are forcedto inhabit in conditions of constantly changing external environment. Often, "change" is understood as the permanent deterioration of some vital indicator. If you go beyond this range, the species most often simply dies out.
Prerequisites for Survival
Scientists came to the conclusion that the species has asurvival only if it starts to actively change, adapting to sharply changed conditions. This phenomenon is called phyletic speciation. In this case, not only the adaptability of organisms to the habitat is formed, but signs that are completely new for living beings are developing.
On our planet by now livemillions of species. Is this not evidence of the strength of life, its constant variability? Unfortunately, several million years ago there were much more living things. Several glacial periods and constant perturbations of the climate have resulted in a sharp decrease in species diversity. Survived only the most adaptable.
Important examples of adaptations
Brilliant correspondence of the organs of living beings andperformed by them from time immemorial attracted the attention of people: attempts to create gliders with a wing in the form of a bird, the construction of ships with contours reminiscent of the bodies of marine fish. But much more strikingly affects the ideal, harmonious correspondence of the appearance of animals and plants with the environment of their natural habitat.
Of course, the examples can be continuedinfinitely. Therefore, within the framework of this article, it is possible to tell only about some living beings whose features of adaptation to the environment are most evident and clearly prove Darwin's rightness.
Thus, a person has long been aware of the importance of protectivecoloring for birds, as well as their chicks and eggs in particular. In wood grouses, black grouses and partridges (openly nesting) eggshell almost perfectly merges with the background of their surroundings. In general, the female's back is also indistinguishable from the surrounding landscape when viewed from the side. The more interesting is the fact that females and eggs of birds that nest in hollows and other hidden places, often have a very bright color (the same parrots, for example).
And what are the features of adaptability to the environmentare there insects? Well, they are even more numerous than all representatives of this class. We think that everyone knows the striking similarity of sticks with dry twigs. Some studies in this area are still used by the military in the field of creating "forest" camouflage suits.
However, the bodies of many caterpillars are very similartwigs, and the wings of butterflies can go for the leaves of trees in the area where they live. Here it should be noted that in this case there is a harmonious combination of the protective form of the body and the patronizing same color. Some butterflies, when they merge with the surrounding terrain, it is difficult to distinguish from the leaves, even at close range. If you are more or less familiar with biology, then you are perfectly aware of the diversity of the class of insects. When you get to the forest or field, you see no more than 2-3% of their total number. The rest simply masks.
But! It should not be considered that examples of the fitness of organisms are limited to banal masking. Remember the adaptive coloration, when brightly colored, "colorful" insects are not very popular with predators, as they are well aware of their sharply negative food qualities. So, a titmouse or a sparrow, having tried a couple of times in youth to eat a bug-soldier, remember their caustic, poisonous taste until the end of their life.
In addition, the traits of the adaptability of organisms toenvironment include mimicry. The phenomenon is reminiscent of patronizing, but "on the contrary." So, some defenseless and edible species can perfectly imitate those insects that are poisonous or have a disgusting taste. For example, the flies are very similar to the wasps, which even many birds are afraid of. All this suggests that the adaptability of organisms to environmental conditions is just an adaptive, adaptive character.
All this can be seen and the example of highermammals. The coloring of zebras seems bright and even somewhat ridiculous, but only it perfectly repeats the alternation of light and shade in the thickets of grass, which allows these animals to perfectly camouflage themselves in the savannah. Eyewitnesses confirm that unprepared people sometimes do not notice zebras even in open terrain, from a distance of only 50-70 m.
Some living things have even moresurprising and effective adaptability to the organism's 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 patronizing coloring and other protective factors dramatically improve their effectiveness, provided appropriate behavior. To this is the reflex of fading, the acceptance of a resting posture, which is characteristic of a huge number of animal species.
Where does this ability come from living things?
In general, whence appeared the fitnessorganisms to their habitat? 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 of climate or other conditions, then it is his descendants that will become the most common. Thus, the main reason for the emergence of some new adaptations in living beings is natural selection. Let's show this in a practical example, discussing the life of a family of grouse birds that live in the lower forest canopy.
Features of the structure
Let's recall the main features of the externalThe structure of these birds: the beak is short, does not interfere with the stitching of food directly from the forest litter (including the snow cover); on the paws - a thick fringe substrate, with which they can walk calmly even in deep snow. Features of the structure of the pen allow them to spend the night, with a head buried in the snow, and short, wide wings make the black grouse a few of the birds, which are available direct, almost vertical takeoff.
It would be logical to assume that theirfar ancestors of such adaptations were not in sight. Most likely, after a change in a number of environmental factors (they got banally cold), they were forced to adapt to the sharply changed habitat, including the cold.
The process of change
There were new mutations, withcrossed their various combinations, and the wave number made the population more heterogeneous and stable. It is not surprising that the birds distinguished from each other a number of signs: on the fingers of someone had fimbria, some individuals shortened their beak or wings.
What was the expression of the adaptability of organismsto the habitat? The fact is that in the course of a constant intraspecific struggle, only those birds survived, the parameters of the structure most in line with the surrounding world. In the selection process only they left more offspring, and it was it that 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 attributes and qualities
Probably among the mutations were those whostrengthened and fixed the manifestation of the signs that had been manifested earlier. Naturally, the birds, in whom these changes manifested themselves, had a much greater chance of not only surviving, but also giving offspring afterwards. Over the course of generations, all these signs have been accumulated and fixed until the black grouse that we know now has appeared.
Contradictions of the theory of Lamarck
As you know, Darwin's theory is radically differentfrom 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 for them. But this is absurd: what kind of influence could have contributed to the appearance of thorns in hedgehogs?
Only the influence of natural selection canexplain the emergence of such a useful device. It is assumed that the very distant ancestors of the hedgehogs could survive, becoming covered with increasingly coarser hair. Staying alive and giving offspring was an advantage for those "proto-characters" who were lucky to have the longest and hardest thorns.
Other "prickly" examples
On exactly the same path went "bristly hedgehogs" from Madagascar. We are talking about tenrets and a few species of frenched mice and hamsters.
Does the fitness of organisms to the environmentHabitat at least some common signs? Scientists suggest that the mechanism for the appearance of such adaptations remains common in all cases: the fact is that they appear not at once, not in one or two generations. On the contrary, their occurrence is a long and complex process. One should never forget that on the evolutionary path there are complete dead-end branches and unsuccessful "technical solutions" of nature. We will now talk about this.
Relativity of fitness
In the period before Darwin, the fitness of animals tohabitat served as a unanimous proof of the existence of the Lord and the immeasurable wisdom of the Creator: how could nature without such "guidance" independently arrange the surrounding world in such a sensible, balanced way !?
Tsarilo felt that every feature of whatever it waswas a living organism is absolutely perfect and exactly corresponds to the task that was assigned to it. Thus, the butterfly's mouthpiece extended into the proboscis helps it to extract nectar even from the most "complex" colors, and the adaptability of plants 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 scientistscontinue to treat nature as a genius sculptor, every creation of which is perfect and infallible. But! It is important to clearly realize that this is far from being so!
Modern study of fitness to the environmenthabitat has shown that any changes are always relative, since they form much slower than real changes in environmental conditions. Accordingly, many features may be unnecessary, and even directly harmful to the body, if the world around will change.
Evidence of Relativity
The following examples serve as a proof of the fact that the fitness of living organisms is a very, very relative concept:
- From some enemies protective deviceseffective, but from other animals are not particularly well rescued. Poisonous fishes are happy to eat snail-cones, and poisonous hairy caterpillars include a cuckoo in their diet.
- Not all animal reflexes are reallyare appropriate and adequately correlated with environmental conditions. Remember the nocturnal butterflies that collect pollen from light colors that are clearly visible at night: they fly to the flames of fires and candles just as hastily, although they perish at the same time.
- The organs of adaptation, which are in the same environmentare really useful, in other conditions are harmful and even dangerous. So, in mountain geese, which never in life fall on the water, there are membranes on the paws.
- Beavers, some of the best "engineers" in nature, are actively building dams even in standing ponds and basins, which is a waste of effort.
Relativity manifests itself particularly clearly inthe case of those animals whose homeland is located on the other side of the globe, but which were brought by man into a completely new habitat for them. Simply put, it is the relative nature of adaptability that proves most convincingly and convincingly that nature is far from always infallible.