Why Understanding Genetics Matters in Evolution
It is commonly seen that members of a species are largely alike. A horse looks like another horse and a rose Plant Looks Like another rose plant. This is to be natural because only horses can produce more horses, and only rose plants can give rise to rose plants. The resemblance among the individuals of a species has given rise to the aphorism “like begets like''. The aphorism, in a way, implies the continuity of life. It is, however, not absolutely true as the members of a species are seldom exactly alike. The children, also the two-egg twins, often have some individual characters in which they differ from one another and also from their parents. In fact, their differences are as marked as their resemblances. Every living organism has a set of characters by which it can be assigned to a particular Species, and can also be identified from other members of its species.
The scientific study : (i)the mechanism of inheritance by which characters pass from parents to offspring and (ii) the causes of hereditary variation in living organisms related by descent is known as genetics.
What is Heredity?
Genetics is also the study of heredity and heredity is the transmission of characters, resemblances as well as variation, from one generation to the next. It is a biological process where a parent transfers certain genes onto their offspring. These genes are inherited by every child from both biological parents which in turn, expresses specific traits.
Mendelism
Mendel’s Life
Gregor Johann Mendel (Austrian, 1822-1884) was born in a peasant family of Moravia. He received school education mainly by his own hard work and passion for studying. Due to poverty, he became a priest. He was later, in 1847, made an abbot (head) of the Augustinian monastery (religious place) of St. Thomas at Brunn, Austria (now Bruno in the Czech Republic). From here, he went in 1851 to the University of Vienna where his interest in the study was natural history and mathematics. Whilst in Vienna, he became interested in the process of hybridization. His choice of the subjects and his aptitude for hybridization had a significant influence on his later work on inheritance on pea plants.
Meaning of Evolution
Evolutionary biology Is that branch of biology which talks about the word
'evolution'. Now, what exactly is evolution? Evolution means the act of unfolding or unrolling and in simple terms, evolution Is an orderly ‘change' from one form to another. But before we learn about how an organism evolved, we must have an understanding of how that organism originated. Therefore, before teaming ‘evolution of life’, we must learn ‘Origin of Life'.
Origin of Universe
Big Bang Theory
The origin of the universe was the most important phenomenon in the origin of life. And the Big Bang Theory attempts to explain the same. This theory proposes that the universe is very old and its origin took almost 20 billion (20 x 109) years ago. It states that a single huge explosion (i.e., Big Bang) took place in space which was so powerful that it is unimaginable in physical terms. Due to this explosion, the universe expands in volume, and the temperature of the space decreases. Slowly Hydrogen and Hahn gases formed, which condensed due to the gravitational forces present in the surroundings. This all resulted in the formation of billions of galaxies.
Did You Know?
In an Experiment: Pasteur took two flasks that were sterilized by him to make them from the microbes. He made a thick soup of yeast and water in both the flasks. ’. He kept one flask open to the air and curved the neck of another one so that the yeast present in the second flask was not in direct contact with the air. He showed that in the "ask which was open to the air. New living organisms took birth while the absence of life appeared in the flask which did not open to the air. He showed that in pre-sterilized flasks, life did not come from killed yeast in the flask with the curved neck, while in another flask open to the air. new organisms arose from “killed yeast’. The purpose of the experiment was not to show that new organisms arose from the “killed yeast“ but to explain that it was actually the ‘air’ in which living organisms were present inside the flask when it was kept open to air to come inside. On the other hand, the curved neck trapped the microbes from entering inside the other flask thereby preventing their growth inside the flask. Hence, it was proved that life cannot arise from the non-living objects (here killed yeast) and could only arise from pre-existing living organisms.
FAQs on How Genetics Drives Evolution and Species Diversity
1. What is the fundamental relationship between genetics and evolution?
Genetics provides the raw material and mechanisms for evolution. Evolution is essentially the change in heritable traits and allele frequencies in a population over successive generations. Genetics explains how these traits are inherited (via genes), how variation arises (through mutation and recombination), and how these variations are passed on, forming the basis for evolutionary processes like natural selection.
2. What are the primary sources of genetic variation that fuel evolution?
The primary sources of genetic variation, which are essential for evolution, are:
- Mutation: A permanent alteration in the DNA sequence. This is the ultimate source of new alleles in a gene pool.
- Gene Recombination: The shuffling of existing alleles into new combinations during meiosis (crossing over). This creates new combinations of traits for natural selection to act upon.
- Gene Flow: The introduction of new genes into a population from other populations through migration and interbreeding, which increases genetic diversity.
3. How does natural selection act upon genetic variation to cause adaptation?
Natural selection acts as a filter on the genetic variation present in a population. Individuals with certain alleles may have traits that give them a survival or reproductive advantage in a specific environment. These individuals are more likely to survive, reproduce, and pass on their advantageous alleles to the next generation. Over time, the frequency of these favourable alleles increases in the population, leading to adaptation and evolutionary change.
4. What is the importance of genetic diversity for the survival of a species?
High genetic diversity is crucial for a species' long-term survival and resilience. It ensures that a population has a wide range of alleles and traits. When the environment changes (e.g., a new disease emerges or climate shifts), there is a higher probability that some individuals will possess genetic variations that allow them to survive and reproduce. A population with low genetic diversity is more vulnerable to extinction because a single environmental challenge could wipe out the entire population if no individuals have the necessary traits to cope.
5. How is speciation, the formation of new species, driven by genetics?
Speciation is the evolutionary process by which new biological species arise. It occurs when a population becomes reproductively isolated from other populations. This isolation prevents gene flow, allowing the separated populations to diverge genetically. Over many generations, mechanisms like mutation, natural selection, and genetic drift cause the accumulation of distinct genetic differences. Eventually, these differences become so significant that individuals from the new populations can no longer interbreed successfully, resulting in the formation of one or more new species.
6. Can evolution occur without natural selection? Explain with a genetic mechanism.
Yes, evolution can occur without natural selection through a mechanism called genetic drift. Genetic drift refers to random fluctuations in allele frequencies from one generation to the next, purely due to chance. It is most significant in small populations. For example, by random chance, some individuals might leave more offspring than others, irrespective of their fitness. This can lead to the loss of some alleles and the fixation of others, causing the population's genetic makeup to change over time—which is, by definition, evolution.
7. What is the difference between genetic diversity and species diversity?
These terms describe diversity at different biological levels:
- Genetic Diversity: Refers to the total number of different genetic characteristics within a single species. It is the variation in alleles and genes among the individuals of one species. For example, the different breeds of dogs represent high genetic diversity within the species Canis lupus familiaris.
- Species Diversity: Refers to the variety of different species within a particular ecosystem or habitat. It is a measure of the number of different species and their relative abundance. For instance, a rainforest with thousands of different types of insects, birds, and mammals has high species diversity.
8. How does the Hardy-Weinberg principle help us understand if a population is evolving?
The Hardy-Weinberg principle provides a baseline model for a non-evolving population. It states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. By comparing a real population's observed genotype frequencies to the frequencies predicted by the Hardy-Weinberg equilibrium, scientists can determine if evolution is occurring. If the frequencies are changing, it indicates that one or more evolutionary forces (like natural selection, mutation, or genetic drift) are at play.
