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The evolutionary history proves that even the strongest and intelligent could survive the challenges posed by nature. Instead of this, the most adaptable species can easily survive and complete the biological journey. Adaptation can be defined as a biological process that makes a species genetically and phenotypically fit for all the changes in its environment. Charles Darwin used the term “biological fitness” for the ability to adapt to changes.
What is Adaptation?
Adaptations can be of different types, among which physiological adaptations show a wealth of diversity, significances, and functions in forms of life present on earth. The physiological adaptations can be defined as: “it shows the ongoing intracellular, biochemical and metabolic adjustments in any organism to survive in any kind of environmental conditions”.
According to the organism’s requirements, it keeps evolving. It can take different forms hence it is dynamic. All plant and animal species require adaptation to their environment to get reproductive advantages and sustenance. The adaptations take place in organisms due to various reasons. It could be:
• Search for a suitable place to live
• Availability of resources
• Fight for a mate
The above challenges result in the production of various stimuli in any organism or species. A set of adaptive responses were developed over millions of years to counter the stress that was brought due to the challenges.
Types of Adaptation
Adaptations can be classified into three types: structural adaptations, behavioral adaptations, and physiological adaptations.
i. Structural Adaptations
Role: It is responsible for the changes in the physical structure of any organism. Examples: change in the shape of organs, and appendages, change in the size and coloration of body.
Nature of adaptations: They are generally inheritable.
• In the plant kingdom, the development of thick stems and reduced leaf size in desert plants is an example of structural adaptations. These changes are adapted by these plants to survive in extremely hot conditions.
• In the animal kingdom, the example of structural adaptation includes camouflage in Chameleons and some other organisms. They use this mechanism to protect themselves from their predators.
ii. Behavioral Adaptations
Role: It brings changes in behaviors and in the way of acting of members of a species.
Examples: Hibernation, insect trapping, mating behavior, and migratory skills in animals and birds.
Nature of adaptation: The adaptations are inherited from one generation to another generation.
• In the plant kingdom, the examples of behavioral adaptations include phototropism, thigmotropism, gravitropism, etc.
• In the animal kingdom, the migratory behavior of birds is a common example of behavioral adaptation, in which they move from one habitat to another in search of food, and reproduction.
iii. Physiological Adaptations
The physiological responses of an organism to the changes in its environment are called physiological adaptations. These adaptations can occur in cellular, physiological, metabolic, and biochemical levels. Physiological adaptations can be defined as “changes in the basic metabolome of an organism to maintain homeostasis”.
• Metabolome: all the metabolites produced by an organism’s body are collectively called the metabolome. These metabolites are produced due to various metabolic activities carried out in the body.
• Homeostasis: It is the mechanism of the body to maintain a fairly stable equilibrium. There are two primary factors used to determine if the organism is in its natural physiological equilibrium or not.
Nature of Physiological Adaptations
There are many conflicts of opinion on the nature of physiological adaptations. The phenotypic changes at the cellular level are guided by the genes of the organism thus it is considered that these adaptations are genetically defined and also inheritable among the generations. However, any organism can acquire various internal changes in response to altered external conditions, thus these adaptations don’t seem to be inheritable.
Functions of Physiological Adaptations
Some common functions of physiological adaptations include:
• It increases the survival rate of an organism in its ecological niche.
• Helps in growth and development.
• Maintain the body temperature, pressure, metabolic rates in an organism.
Physiological Adaptation Examples
i. Fungi and Bacteria
• Development of antibiotic and antifungal resistance: the population of bacteria and fungi has a huge range of variability and very fast growth. They can evolve rapid mutations while exposing to anti-growth agents and stressful conditions that help them to spread rapidly even under antibiotic use.
• Heavy metal resistance: they consist of R-plasmids that provide various types of resistance to bacteria. The example includes the resistance of mercury.
• Antifreeze proteins: the presence of antifreeze proteins save the cells from damage to the cell membrane by preventing the ice crystal formation.
• CAM mechanism: this mechanism helps in carbon fixation in plants of arid areas. This physiological adaptation can be seen in pineapple, jade, cacti, etc.
• Production of poison: several plants develop venom-producing mechanisms to prevent them from herbivores. Example- stinging nettle plant, members of the nightshade family.
• Seed dormancy in plants of coastal areas: the plants of coastal areas become dormant to protect them from saline conditions are germinate in favorable conditions. Example- mangroves
iii. Animals and Humans
• Production of venom: some animals adapted venom-producing mechanisms to ward off predators and capture their prey easily. Examples are snakes, spiders, and bees
• Offensive odor production: skunk produces a disgusting chemical to keep away the predators and protect itself by spraying it.
• Tanning: human populations living in different temperature ranges have varying intensities of UVB depending upon the season. It is one of the most important adaptations in humans.
• HIIT (in humans): high-intensity interval training (HIIT) in humans helps in invading various chronic health issues caused by modern lifestyles. The adaptation empowers and increases mitochondrial biogenesis in humans.