Fitness is one of the most important factors in evolution. What features does it have? How is the relative nature of the fitness of a cactus, a chameleon, a turtle manifested?
Organisms and the environment
Each individual species of living creatures has its own habitat. Within it, various factors act that have special characteristics, for example, a certain air temperature, salinity of soils or water, certain inhabitants.
To survive in a particular environment, the body must adapt to it. Anyone who does this as efficiently as possible can survive and have offspring. During evolution, plants, animals, and even humans have developed various tools to help them adapt.
These tools were formed gradually. Species that had any advantage in structure or color survived under certain conditions better than others. Useful traits were inherited and became more pronounced. Over time, the desired traits became characteristic of all representatives of the species or population.
Relative nature of fitness
Adaptation refers to the presence in animals or plants of signs that correspond to their lifestyle and the environment in which they are found. For example, the fish’s body is streamlined and covered with mucus to make it easier to move around in the water. Arctic bears have a white color in order to merge with the environment as much as possible.
However, the developed auxiliary mechanisms in wildlife are not absolute, but relative. Why is fitness relative? Everything is simple. If the body adapts to specific environmental conditions, then it may be unprepared for other conditions. Environmental factors usually change faster than organisms that need to go through at least several generations.
The relative nature of fitness is also manifested in the fact that, having a reliable means of protection from some enemies (bright colors, spikes or poison), you can get into the network to others. So, the poison of many snakes affects small prey, scares away large mammals, but does not stop the hedgehogs and mongooses that feed on snakes. Detailed examples are discussed below.
Cacti
An excellent example of survival in harsh conditions is demonstrated by plants of the cactus family. They feel great in an environment unbearable for many living things. Plants are common in deserts and semi-deserts, mountains, savannahs, arid forests.
A powerful fleshy stalk allows you to accumulate a lot of moisture from the air, and leaves, modified into thorns, do not allow it to evaporate. In addition, sharp thorns scare away those who want to feast on a cactus. Strongly developed roots reaching deep underground waters saturate the plant with water.
Thus, the plant is fully prepared for life in regions where rainfall is extremely rare. The relative nature of the fitness of the cactus lies in the fact that when conditions change, for example, when long rains occur, the plant may die from excessive water intake.
In indoor conditions, all the benefits of a cactus are lost and become neutral. The powerful stem and thorns will no longer carry within themselves those functions important for survival, only the aesthetic aspect will remain.
Chameleons
Chameleons spend most of their time on trees; flexible limbs help chameleons climb them. The fingers of the animals grew together, forming two almost opposed groups (in appearance they resemble a claw), the tail is twisted and long - all this makes it easy to grab the branches and move along them.
The relative nature of the fitness of the chameleon lies precisely in its color. The natural color of the animal disguises it as much as possible under the environment, making it invisible to predators. But chameleons often change color, using it as a means of communication.
Some species are capable of repainting in almost all colors. So they express their reaction to a change in lighting, humidity or the appearance of other animals. At the moment of danger, the “lizard” is stressed and can turn bright red or yellow, betraying itself, instead of merging with the environment and hide.
Turtles
Reptiles unique in their structure are turtles. The body of animals is in a dense shell, covered with skin or horny shields. It is a bit like a shell, as it consists of the upper and lower parts.
The tortoise is not just located inside the shell, it represents a single whole with it. The upper part of the "frame" fused with the spine of the animal, the lower part is formed by the clavicle and abdominal ribs. The tortoise cannot be pulled out of the “house” without crippling it.
In case of danger, the animal hides its head and limbs inward. How does the relative nature of fitness manifest in this case? Predators cannot gnaw out a shell or pick a turtle out of it. But the eagles raise it high above the ground, release it so that the carapace breaks, and then eat their prey.
Conclusion
The fitness of organisms is the correspondence of their external and internal structure, behavior to the environment in which they live. It is formed during a long historical process and is an important factor in evolution.
The relative nature of fitness is that the characteristic features of the body can help it only in certain conditions and situations. When external factors change, adaptations can be ineffective, and sometimes even harm their master.