Variation - Organisms And Their Copies: Definition, Overview, Importance, Accumulation, FAQ
Variation in biology refers to the differences among individuals of the same species, shaped by genes and environment. It is the foundation of evolution, adaptation, and biodiversity. Understanding variation helps in conservation, agriculture, medicine, and NEET exam prep.
This Story also Contains
- What Is Variation?
- Types of Variation
- Genetic Basis of Variation
- Reproduction and Variation
- Factors Influencing Variation
- Measurement and Analysis of Variation
- Importance of Variation
- Variation NEET MCQs (With Answers & Explanations)
- Recommended Video On Variation
What Is Variation?
Variation in biology refers to the differences that exist in individuals of the same species. The variation can be at a genetic, environmental, or even developmental level and affects the diversity we see in organisms. Studying variation is important in understanding evolutionary processes, adaptation to environments, and exploring how ecosystems work. Two of the most important factors that create and maintain variation within populations are genetic diversity and reproduction.
Types of Variation
Variation is categorised into three main groups:
Genetic Variation
Genetic variation is caused by differences in the DNA sequence of individuals. To a large extent, this results from mutations, changes in DNA sequence in replication due to replicative errors, environmental factors, or spontaneous change. Examples may include variations of alleles and gene mutation, leading to altered protein products involved in traits.
Environmental Variation
The environmental variation occurs due to the variation of the external conditions that different organisms face. Such things as climate, nutritional factors, and general habitat play an enormous role in the development of an organism, thus changing its phenotype. For example, plants of a particular species have varying heights due to variations in sunlight exposure during their growth.
Continuous vs. Discontinuous Variation
Continuous variation are minute variations which occur in graded series. These are important for evolution and speciation. Discontinuous variations are sudden and large.
Continuous variation | Discontinuous variation |
It is the types of genetic variation, which shows an unbroken range of phenotypes of a particular character in the population | It is the type of genetic variation, which shows two or more separate forms of a character in the population. |
Phenotypes show continuous range and they are difficult to classify into specific categories. | Phenotypes show a discontinuous range and they can be easily categorised. |
Darwin called them fluctuations and described them to be significant for evolution and origin of species. | Darwin termed them as saltations and believed they are useless for evolution. |
Several genes are present for the determination of a particular trait. | One or few genes are present for determination of a trait. |
Intermediate groups are present. | Intermediate groups are absent |
Examples: height, weight, length of organisms, etc. | Example: blood groups, gender of animals, color of petals, etc. |
Genetic Basis of Variation
DNA provides the blueprint of genetic information to an organism. Genes are sections or parts of DNA that carry the instructions that are put into action when building a protein. As a result, particular genes bring out specific traits in organisms. Genetic diversity manifesting in populations is created by differences in genes and alleles.
They are permanent changes in the DNA sequence and can take place in the form of point mutations, meaning single changes of bases, or insertions/deletions. The mechanisms of mutation introduce new genetic variants into populations; thus, underpinning evolution through natural selection.
During meiosis, recombination represents a means of shuffling genetic material from two parents and recombining it into unique genetic combinations in the offspring. In this way, it increases the net genetic diversity within populations for adaptation to changing environments.
Reproduction and Variation
Asexual reproduction is a process where the offspring produced are genetically identical to each other and the parent. Therefore, there is no genetic variation. Aspects of variation may still be related to mutation, but the event will have limited genetic diversity compared to sexual reproduction.
Sexual reproduction is a process in which two parent gametes fuse into one individual; their genes are recombined by meiosis. When this occurs, the resultant offspring have new allele combinations. Therefore, there will be an increase in the genetic variability of the populations. Genetic diversity enhances resilience to environmental challenges.
Factors Influencing Variation
It is a process through which favourable characteristics get more frequent in any population over successive generations to adapt to their surroundings. Variations that provide advantages in survival and reproduction are favoured and passed on by natural selection to the offspring.
Artificial selection is driven by human activity and can be described as the process of selective breeding of organisms for desirable traits for specified purposes like agriculture or companionship. Therefore, it accelerates the changes of the traits or populations concerned within a very short period compared to natural selection.
Measurement and Analysis of Variation
Population genetics is interested in the distribution and change in allele frequencies in populations. The maintenance or change in genetic variation over generations applies meaningfully to concepts like the Hardy-Weinberg equilibrium. Genetic variation can also be affected by a host of other factors, notably genetic drift, which randomly alters allele frequencies, and gene flow involving gene exchange between populations.
Quantitative genetics deals with the study of characteristics whose measurement is quantitative, like height and weight. It is in this view that the statistical methods on standard deviation and variance were developed, for the measurement of the amount of variation existing within a trait under study and the establishment of the mode through which it gets transmitted.
Importance of Variation
Genetic variation is needed for biodiversity, while biodiversity is a large component of ecosystem stability. Diverse populations can better absorb environmental perturbations, which ensures the continued existence and productivity of the ecosystem.
Variation provides the raw material on which natural selection acts, and hence drives evolutionary processes. The adaptations which stem from genetic diversity enable an organism to survive and reproduce in dynamic environments, thus shaping the diversity of life on Earth.
Understanding variation in organisms is essential for developing an appreciation for both the complexity and adaptability of life forms. Genetic variation and mechanisms of variation provide knowledge about evolutionary processes, ecological interactions, and the effects on the sustainability of biological systems. Variation studies provide knowledge useful for conservation, productive agriculture, and improvements in medicine, underlining its importance in biology and beyond.
Variation NEET MCQs (With Answers & Explanations)
Important topics from the chapter for NEET preparation:
Genetic variation (sources, role in meiosis)
Continuous vs Discontinuous Variation
Reproduction and Variation
Factors Influencing Variation
Practice Questions for NEET
Q1. Darwinian fitness is represented by the following:
Small r value
Large r value
Significant K value
Low K value
Correct answer: 2) Large r value
Explanation:
Darwinian fitness is distinct from "physical fitness," which is primarily concerned with health, muscle tissues, oxygen, and physical exertion.
Reproductive success is more important in Darwinian fitness. The success of an organism in passing on its genes is described by Darwinian fitness.
The greater the likelihood that an individual will survive and live long enough to reproduce, the greater that individual's fitness.
Hence, the correct answer is Option 2) A large R-value.
Q2. Characteristics of Life History is _________
Evolved in response to the limits imposed by the habitat's abiotic factors
An active research area
Both 1 and 2 are correct.
None of these
Correct answer: 2) an active research area
Explanation:
Life qualities are shared by all living species, from the smallest bacterium to the largest whale. There is no life without these qualities. All living things exhibit order, sensitivity to their environment, growth and development, reproduction, regulation, equilibrium, and the ability to process energy. When taken collectively, these traits serve to define life.
Ecologists believe that creatures' life-history properties evolved in response to the limits imposed by the abiotic and biotic components of their ecosystem. The following are examples of abiotic factors: Food, Space, and Environmental Conditions. Predators are biological factors. Ecologists are currently conducting crucial research on the evolution of life-history features in many species.
Hence, the correct answer is option 2)an active research area.
Q3. Organisms evolve toward the most efficient under a specific set of selection pressures:
Temperature regulation or Thermoregulation
Conservation of water
Breathing
Reproduction plan
Correct answer: 4) Reproduction plan
Explanation:
Mammals use a process called thermoregulation to control their body temperature independently of the outside environment. Temperature regulation is a sort of homeostasis that maintains a steady internal temperature to survive.
Water conservation is the technique of using water as efficiently as possible to reduce wastage. Water conservation is crucial, according to Fresh Water Watch, because fresh clean water is a rare and expensive resource.
Respiration is defined as a metabolic process in which living cells of an organism obtain energy (in the form of ATP) from the oxidation of complex organic molecules by taking in oxygen and expelling carbon dioxide.
Reproductive strategies are a set of behavioural, morphological, and physiological modifications that allow access to potential mates, increase the chances of mating and fertilization, and improve newborn survival.
Hence, the correct answer is option 4) Reproduction plan
Also Read:
Recommended Video On Variation
Frequently Asked Questions (FAQs)
It is through natural selection that variation is moulded by the favouring of only those traits that increase chances of survival and reproduction, hence increasing the frequency of advantageous alleles in the population over time.
Genetic variation describes the differences that exist in the DNA sequences of every individual within a population. It is important in that it sets the basis of raw material for evolution and adaptation to changing environments.
Sexual reproduction increases genetic diversity by mixing genes from two parents during meiosis so that the offspring have different genetic combinations.
This is affected by climate, nutrition, habitat, and other external conditions that exert their influence during development to affect an organism's phenotype.
Genetic variation can be measured using statistical methods like allele frequency, heterozygosity, and the Hardy-Weinberg equilibrium in population genetics studies.