Evolution is a process where populations change over time to better fit their environment. This process is crucial for the survival of all living things. It involves the development of new traits that can be passed down from generation to generation. One important aspect of evolution is speciation, which is when populations become different species through the course of evolution. Understanding the evolution process and how it shapes the world around us is key to understanding our place in the natural world.
In populations, individuals have unique characteristics that come from a combination of their genes and surroundings. These differences can be due to genetic and environmental factors, with mutations being the source of all genetic variation. Since each individual has their own set of traits, they also have a different level of fitness compared to their environment.
For example, in a group of Arctic foxes, those with the whitest fur can blend in better with the snow and are less likely to be attacked by predators. As a result, more of these foxes will live long enough to reproduce and pass on their advantageous traits, leading to higher fitness levels in the population. Understanding how individuals adapt to their environment through genetic and environmental factors is essential to understanding the evolution process.
Evolution takes advantage of variations in observable traits. Different evolutionary processes, such as natural selection, sexual selection, and genetic drift, affect the variety in the population, making some traits more common and others less frequent.
Over time, populations become better suited for their environment, leading to increased fitness. As a result, specialised populations may transform into unique species that can no longer interbreed in a process called speciation.
The process of evolution begins with DNA, where mutations occur, leading to changes in the genotype, which ultimately affect the phenotype. This variability in populations leads to adaptations, resulting in changes in allele frequency in the gene pool. These changes may lead to the creation of new species that either continue to evolve and succeed in their environment or become extinct due to environmental stresses.
All life on Earth shares a common ancestor known as the Last Universal Common Ancestor (LUCA), who lived about 3.5-3.6 billion years ago. However, billions of years of evolution and speciation have resulted in the incredible diversity of life that we can observe today. Understanding the evolution process is critical to understanding the world around us.
Charles Darwin is widely credited with developing the theory of evolution by natural selection, which he outlined in his famous book "On The Origin of Species", although Alfred Russel Wallace also independently conceived of this theory.
Darwin based his theory on several observations. Firstly, he noticed that there is variation in observable traits such as morphology, physiology, and behaviour among individuals within populations. This variation leads to differential fitness, meaning that certain traits lead to more success in terms of survival and reproduction. Finally, these traits are heritable, meaning they are passed down from generation to generation.
Darwin argued that individuals with advantageous traits are more likely to survive and reproduce, leading to their offspring inheriting these favourable traits. Over time, populations change gradually to become better adapted to their environments. This process is known as natural selection.
Darwin's observations and theories revolutionised the way we understand the natural world and have had a significant impact on fields such as biology, ecology, and medicine.
There is overwhelming evidence that the theory of evolution is true. Let’s go over a few examples:
Firstly, the structure of the genetic code is very similar for all organisms on earth. Our DNA is composed of the same nitrogenous bases - A, C, T and G - and we share a significant proportion of our DNA with our closest taxonomic relatives. The closer one species is to another, the more similar their genetic information tends to be.
The record provides us with an extensive history of the organisms that lived on Earth in the past, including those that have gone extinct. By studying fossils, what life looked like on evolved diversified the is. way fossils that organisms may not be accurately represented in our records. Additionally, there are many intermediate forms between kinds of organisms that we have not yet discovered or that were not fossilised at all.
Despite these limitations, the fossil record has provided us with a wealth of information about the history of life on Earth. By studying fossils, we can see evidence of evolutionary trends, such as the development of new structures or adaptations in response to changing environments.
Furthermore, the fossil record has allowed us to trace the origins and diversification of major groups of organisms, such as mammals and birds. This information has helped us understand the relationships different species and the processes that have led to the diversity of life we see today.
In conclusion, while the fossil record is not complete, it remains a crucial tool for understanding the history of life on Earth and the processes that have shaped it.
There are also many examples of plants and animals whose evolution has been guided by humans through selective breeding, including dogs, domesticated farm animals, and agricultural crops. Darwin used selective breeding as strong evidence for evolution - in this case, through artificial selection, when he first introduced his theory to the public.
Finally, we can observe evolution happening in real-time. For example, fast-evolving organisms such as bacteria continue to evolve and adapt to the antibiotics we use against them. There are now many strains of ‘superbug’ that have adapted to resist antimicrobial compounds and will be able to survive heavy doses of medicine.
There are several terms used to describe patterns in which the process of evolution occurs in different organisms. Examples of these include:
Divergent evolution Convergent evolution Parallel evolution
Divergent evolution refers to the process by which groups descended from the same common ancestor accumulate genetic differences, which ultimately leads to speciation. This might occur as a response to changes in the environments of the two groups, such as changes in the abiotic conditions or the introduction of new biotic interactions.
Convergent evolution is the process by which groups that are not closely related - that is, they are not descended from the same direct ancestors - independently evolve similar features in response to similar selection pressures. In other words, through convergent evolution, different groups separately arrive at the same solution to similar problems. For instance, birds, flying insects, and flying mammals have all arrived at the convergent phenotype of wings as a ‘solution’ to the ‘problem’ of mobility. There is no one close common ancestor for all of these winged animals. Indeed, the anatomy of wings looks very different from group to group; however, most wings operate based on the same principles due to flight physics.
Parallel evolution refers to the process by which two groups sharing a similar trait, evolve another trait in a similar environment.
To understand how this might occur, let’s imagine two groups of similar plants that are in different locations but are exposed to very similar environmental conditions. Because they are dealing with the same conditions, they might evolve similar adaptations completely independently from one another. For instance, if they were in an arid environment, they might develop a waxy cuticle and stems that can store water. Parallel evolution is often confused with convergent evolution. The important thing to keep in mind here is that in convergent evolution, two groups arrive at the same phenotype from different starting points, while in parallel evolution both groups come from similar starting points.
Population in Ecosystems - Key takeaways Evolution is defined as the change in the heritable characteristics of populations over several generations. Different evolutionary processes act upon the variation in the population, resulting in favourable traits becoming more common and unfavourable traits more infrequent. There are several patterns in which evolution can occur between different groups, including divergent evolution, convergent evolution, and parallel evolution. The theory of evolution by natural selection is credited to Charles Darwin, although AR Wallace also developed it independently. There is a lot of evidence for evolution, including the fossil record, the universal genetic code, and evolution occurring in real-time today.
What are the three types of evolution?
There are several patterns by which evolution occurs. Examples of them are divergent evolution, convergent evolution, and parallel evolution.
Is evolution a theory?
The theory of evolution by natural selection is a scientific theory that is substantiated by empirical evidence. In science, a theory is defined as a plausible or scientifically acceptable principle used to explain phenomena. In order to become widely accepted, theories must be substantiated with evidence that is obtained in a rational and methodical manner. Scientific theories are reliable and rigorous and are not to be confused with the colloquial usage of the word theory to refer to speculation and unproven ideas.
Who is the author of the theory of evolution?
Charles Darwin is credited as the scientist who first offered the theory of evolution by natural selection.
What process is the driving force behind evolution?
Mutations
What is evolution?
The change in the heritable characteristics of populations over several generations
What is the difference between convergent and parallel evolution?
In convergent evolution, two groups arrive at the same phenotype from different starting points, while in parallel evolution both groups sharing a similar trait, evolve another trait in a similar environment.
Name the book in which Charles Darwin first introduced his ideas about evolution through natural selection.
On the Origin of Species
Evolution is defined as the _____ in the _______ characteristics of populations over ________ ____________.
change, heritable, several generations
Which of the following is not one of Darwin’s original observations that led him to develop the theory of evolution by natural selection? There is phenotypic variation within populations. These varying traits confer differential fitness. Traits are heritable. There is genetic variation within populations.
Last Universal Common Ancestor
Consider the following statement and identify the type of evolution they are likely to undergo or have undergone: Birds, bats, and insects all have wings.
Convergent evolution
Consider the following statement and identify the type of evolution they are likely to undergo or have undergone: Monkeys, octopuses, and birds have evolved eyes that work in very similar ways.
Convergent evolution
Consider the following statement and identify the type of evolution they are likely to undergo or have undergone: Crabs in the Pacific Ocean and crabs in the Atlantic Ocean are evolving smaller body sizes as the global temperature increases.
Parallel evolution
Consider the following statement and identify the type of evolution they are likely to undergo or have undergone: One population of orchids is exposed to dry and hot conditions, while the other is exposed to wet and cool conditions.
Divergent evolution
Give two examples of evidence of evolution.
Any two of: the universal genetic code, the fossil record, artificial selection through selective breeding, the evolution of microorganisms in real-time.
What are the four nitrogenous bases that comprise the DNA of most organisms on Earth?
A, C, T and G (or Adenine, Cytosine, Thymine, and Guanine).
