Fitness is the result of natural selection
The emergence of adaptability of organisms.
The main reason for the emergence of various adaptations of living organisms to the environment is selection. For example, it is known that the partridge is a forest bird. Depending on the habitat, it has various adaptations: a) shortening of the beak in connection with getting food from under the snow and leaf litter; b) the appearance of horn folds at the ends of the fingers to facilitate movement through the thick snow cover; c) expansion, rounding of the wings for quick rise into the air (the ancestors of the partridge did not have such a structure).
For further distribution, the fruits and seeds of plants also underwent various changes. These are hooks, thorns with which they are attached to animals, or light fluff that is dispersed by the wind.
The appearance of fitness in plants and animals is a characteristic phenomenon, but in any case, fitness does not appear immediately. As a result of a long evolutionary process, individuals with special features adapted to the conditions of the external environment appear.
Features of fitness in structure, color, body shape and behavior are clearly visible in the example of an aquatic mammal – a dolphin. The pointed shape of the body gives it the ability to easily and freely move in the water in different directions. The speed of the dolphin reaches 40 km / h. And in birds, indicators of fitness for flight are the presence of feathers covering the body; lack of auricles and teeth; the ability to turn the head 180 ‘; lightness of bones; rapid digestion of food in the stomach, etc.
In many animals, fitness is so developed that it is difficult to distinguish them from the environment. The shape of the body, the color of fish, animals living in dense thickets of algae, help them successfully hide from enemies.
- Protective (masking) coloring and its types.
- Instinctive adaptation.
- Caring for offspring.
- Physiological adaptation.
Rice. 21. Adaptability of night butterflies by changing the color to the corresponding colors of the tree trunk: 1 – the same number of marked dark and light butterflies; 2 – light tree trunk; 3 – increase in the number of light butterflies; 4 – increase in the number of dark butterflies; 5 – dark tree trunk
1. Protective (masking) color and its types. Protective coloration is the adaptability of organisms that live openly and can be accessible to enemies. Birds that incubate their eggs on the ground (grouse, partridge, quail, etc.) merge with the surrounding background. A bird sitting motionless on the nest is almost invisible to its enemies. The eggs with pigmented shells and the chicks hatching from them are also hardly noticeable. In large predators whose eggs are inaccessible to enemies, or in birds that lay eggs high on rocks or bury them. into the ground, the protective color of the shell does not develop. Butterfly caterpillars are usually green, the color of the leaves, or dark, the color of the bark. Bottom fish (stingray, flounder) are often painted in the color of sand.
Desert animals are usually sandy-yellow in color. Monochromatic protective coloration is characteristic of insects (locust), lizards, saigas, lions. Many animals change color depending on the season. For example, arctic fox, white hare, partridge are white in winter. Diurnal butterflies have a protective coloration on the lower part of the wings, while night butterflies have a protective color on the upper part of the wings, so during the day they become visible to enemies and may die (the lower part of the wings is light). Protective coloration can also be observed in the form of insects: the chrysalis of butterflies on a branch is very similar to a kidney; a larva attached to a branch in a motionless state, similar to a tree branch, etc.
Protective coloration is especially useful at the initial stages of the individual development of the organism (eggs, larva, nestling). Protective coloring is needed for slow moving animals or those that have passed into a state of rest.
Many animals are able to quickly change color depending on the color of the environment, and this ability is inherited. For example: chameleon, flounder, agama.
Types of protective coloring:
- protective coloring;
- attractive coloring;
- menacing coloration;
- imitative coloration.
1. Protective warning coloration is characteristic of poisonous, stinging or burning insects. For example, a ladybug (red, yellow, brown, dark red, striped) is never pecked by birds because of the release of a poisonous, bitter yellowish liquid (Fig. 22). If the chicks accidentally peck at this beetle, then the next time they do not approach it. The scavenger beetle emits an unpleasant burning liquid, has a bright red striped color. The coloring of bees, bumblebees, wasps, poisonous snakes protects them from predators. Protective coloration also depends on the behavior of some insects and animals. Sometimes crawling beetles freeze in moments of danger. Bittern, nesting in the reeds, accidentally seeing the enemy, stretches its neck, raises its head and freezes. Warning coloration in animals is combined with behavior that repels predators.
Rice. 22. Warning coloring: 1 – ladybug; 2 – blister
2. Attractive coloring. This coloration is especially important during breeding. The bright color of red butterflies, blue-winged grasshoppers, jerboas, plumage of male birds attracts females during the breeding season. On ordinary days, the coloring merges with the environment and becomes invisible to enemies (Fig. 23).
Rice. 23. Attractive coloring: 1 – red sash; 2 – blue-winged filly; 3 – jerboa
3. Menacing coloration. In times of danger, animals take a threatening posture. For example, in moments of danger, a cobra raises its head straight, puffs out its neck and assumes a threatening posture; the darkling beetle raises its abdomen and emits an unpleasant odor. The eared roundhead instantly opens the skin folds on the head and freezes with its mouth open. On the open wings of the praying mantis there are spots that look like eyes. In case of danger, opening its wings, the praying mantis scares away its enemy. The same spots are also found in night butterflies (Fig. 24).
Rice. 24. Threatening coloration: eye spots on the wings of a butterfly (1) in a threat pose look like the eyes of an elf owl (2)
4. Imitative coloring – mimicry (Greek mimikos – “imitation”). This is the imitation of animals and plants of living organisms or certain inanimate objects of the environment. The warning coloration of unprotected organisms bears a resemblance to one or more species. For example, in terms of body shape, size, bright color, a cockroach is similar to a ladybug. The body shape of a seahorse and a fish-walker resembles an algae. The white butterfly imitates inedible butterflies from the heliconid family (Fig. 25) with an unpleasant odor and bright color, and flies imitate wasps. The similarity of non-venomous snakes with poisonous ones helps them to protect themselves from enemies and survive.
Rice. 25. Imitative coloration: white butterfly (1) looks like a poisonous heliconid butterfly (2)
Examples of imitative plant coloration.
Imitative coloration in plants is necessary to attract or intimidate animals. Usually there is no nectar on the Belozor flower. To attract insects, it is similar to a honey plant. Insects, sitting on a flower, contribute to its pollination. The flowers of the insectivorous plant (nepenthes) are brightly colored. Insects, sitting on a flower, instantly fall into the “trap” and die. The orchid resembles the female of some insects in the shape of the flower and smell, so male insects involuntarily sit on the flower and pollinate it.
Mimicry occurs “under the control” of natural selection. Its occurrence is associated with the accumulation of small beneficial mutations in edible species in the conditions of their coexistence with inedible ones. One of the main weapons of defense against enemies and adaptive features is: bugs and crabs have a chitinous cover, mollusks have shells, crocodiles have scales, armadillos and tortoises have a shell, and a hedgehog and porcupine have quills.
Fitness. Protective coloration. Protective coloring. Attractive coloring. Threatening coloration. Imitative coloration (mimicry).