We admire the perfection of living organisms - plants, fungi, animals, manifested in the harmony and expediency of their structure and functions. However, do not forget that with a sharp change in the environment, whole species of living creatures were on the verge of extinction and even completely disappeared from the face of the Earth. Recall the giant reptiles that flourished in the Mesozoic and died at the end of this era, or the flora and fauna of the first periods of the Cenozoic era, which died out during the great glaciation.
The phylogenesis of many systematic groups of living organisms proves the fact of the fitness of organisms and its relativity. In our article, we will consider the mechanisms of adaptations and give examples of their positive role in certain conditions of the existence of a species.
Fitness: why it occurs in living organisms
Adaptation is based on the process of variability. It is a phenomenon of the acquisition of new signs and properties by individuals living in certain conditions of illumination, humidity, temperature. An important role is played by the influence of organisms of other species living in this area. The outstanding English scientist C. Darwin identified two forms of variability: hereditary and non-hereditary.
He also established the manifestation of the relative nature of fitness arising as a response of the organism to new living conditions. Volatility itself does not carry adaptation functions. Nevertheless, in nature there are special mechanisms that implement the appearance of devices. Let's consider them further.
Drivers of evolution and their role in the emergence of adaptations
What forces cause the phenotypic manifestation of new characters that serve to preserve and flourish individuals of the species in the changing conditions of nature? It is a struggle for existence and natural selection. Interestingly, the views of the English sociologist T. Malthus regarding population issues, Charles Darwin transferred to the processes occurring in nature. Indeed, the ability of plants and animals to unlimited reproduction causes an imbalance in their numbers. What is the relative nature of fitness in these organisms? The fact that most of them necessarily die, despite the presence of a well-functioning adaptation mechanism in these individuals. The populations that survived as a result of the struggle for existence acquire new traits in the changed living conditions.
Adaptations in the animal world
All shells of the Earth's biosphere are inhabited by organisms belonging to the animal kingdom. Each of them has an amazing number of adaptations to living conditions, expressed in the peculiarities of the external and internal structure, methods of reproduction and settlement on the territory of the habitat. A classic and vividly illustrating how the relative nature of the fitness of organisms is manifested, an example is the story voiced by C. Darwin.
An enormous population of butterflies of the birch moth lived in the vicinity of the city . Adult insects had a protective coloring of the wings, resembling the color of a birch bark. Their main enemies - birds - did not notice the butterflies sitting on the trunks, so the population was high. After the construction of an industrial enterprise that threw a large amount of soot and soot into the air, the trunks of birch trees began to darken, and against this background, white butterflies were clearly visible. What did this lead to?
The results of changes in abiotic factors
It becomes clear what the relative nature of fitness is manifested in, because camouflage coloring has lost its meaning. Birds destroyed almost the entire insect population. Only a few individuals survived that had a darker pigment of wings that appeared as a result of a gene mutation. As you can see, adaptations are an ideal tool for survival in specific conditions. Nevertheless, they become useless and even harmful if environmental factors change.
What is the relative nature of the fitness of plants
For representatives of the world of flora, as well as for other groups of living organisms, adaptations are not absolute. For example, a wax coating on ficus leaves protects the plant from excessive water loss due to transpiration. However, it becomes unnecessary for room culture, and with improper care and excessive watering of the ficus, signs of necrosis of leaf blades and rotting of the roots appear.
Another example. Leaf fall is the adaptation of plants to changing the length of daylight. If you grow birch, maple or poplar in a greenhouse with round-the-clock artificial lighting, the trees do not drop leaves and become evergreen. The given examples well explain the relative nature of fitness, because when the abiotic factors change, the old adaptation mechanisms cease to work, and individuals are forced to adapt to new living conditions.
Seed adaptation
It is known that the temperature of air and soil is one of the decisive factors when choosing the time of planting seeds in open ground. The classification existing in agronomy divides crops into winter crops (wheat), cold-resistant crops (carrots, radishes) and heat-loving crops (tomatoes, zucchini, cucumbers) based on the ability of seeds to germinate at different temperature ranges. However, environmental conditions can be changed, for example, sowing seeds in closed ground conditions. What is the relative nature of seed fitness in this case?
Their germination will now depend on the artificial conditions of the greenhouse. The early harvests of sweet pepper, tomatoes and other vegetables obtained in the winter serve as a clear illustration of the changes in the adaptation processes in seeds that arise in connection with the emergence of new environmental conditions.