Question

Which of the following statements is FALSE based on Darwin’s theory of evolution? A. Natural selection is the driving force of evolution. B. Favorable genetic variations become more and more common in individuals throughout their lives. C. Natural selection drives organisms to live in groups and ultimately become distinct species. D. Fitness is measured in terms of reproductive success.

Short answer

Statement B is FALSE.

Step-by-step solution

- Understanding Natural Selection

Natural selection is a mechanism by which individuals with favorable traits are more likely to survive and reproduce. Therefore, the statement ‘Natural selection is the driving force of evolution’ (A) aligns with Darwin's theory.

- Genetic Variations in Individuals

Darwin’s theory suggests that favorable genetic variations are passed on to offspring, not that they become more common in an individual’s lifetime. This makes statement (B) incorrect.

- Social Behavior and Species Formation

Natural selection can lead to the formation of groups and distinct species over time due to advantageous traits. Therefore, statement (C) is consistent with Darwin's theory.

- Fitness and Reproductive Success

Fitness, in Darwin’s terms, is measured by an individual's reproductive success, meaning how well they can pass their genes to the next generation. This means statement (D) is true.

Key concepts

Natural Selection

Natural selection is a key mechanism in Darwin's theory of evolution. It is the process by which certain traits become more common in a population because they offer some advantage for survival and reproduction. When individuals with these advantageous traits reproduce, they pass these traits to their offspring. Over time, these traits become more common in the population. This process drives the evolution of species.
For example, if a bird species lives in a region where having a longer beak makes it easier to find food, birds with longer beaks will have a better chance of surviving and reproducing. Consequently, their offspring will likely inherit the longer beaks, gradually leading to a population where this trait is predominant.

Genetic Variations

Genetic variations are differences in DNA sequences among individuals in a population. These variations are crucial for evolution because they are the raw material on which natural selection acts. Genetic variations can be caused by mutations, gene flow, and sexual reproduction.
A key point to remember is that favorable genetic variations are passed from parents to their offspring, not that they become more common within an individual's lifetime. This means individuals are born with these variations, and natural selection determines which variations are advantageous.
For example, imagine a population of beetles where some have green shells, and others have brown shells. If the brown shells offer better camouflage and protection from predators, those beetles are more likely to survive and reproduce. Their offspring will inherit the brown shell trait, making it more common in future generations.

Reproductive Success

Fitness, in the context of Darwin's theory, refers to an individual’s ability to pass on its genes to the next generation. This concept is known as reproductive success. An individual that produces more offspring that survive to reproduce themselves has higher fitness.
Reproductive success is often influenced by factors like the ability to find food, evade predators, and attract mates. These factors are often tied to the advantageous traits that natural selection favors.
For example, in a population of peacocks, males with more vibrant and larger tail feathers may attract more females. These peacocks will likely have more offspring, and their offspring will inherit these attractive tail feathers, leading to higher reproductive success.

Species Formation

Species formation, also known as speciation, is the process by which new species arise from existing ones. Natural selection plays a crucial role in this process by accumulating advantageous traits in different populations, which can lead to divergence and the formation of new species.
Over time, isolated populations may experience different selective pressures based on their environments. These differences can lead to significant genetic changes that result in new species.
For instance, if a bird population gets divided by a geographic barrier, such as a mountain range, each group may adapt to its specific environment. After many generations, these adaptations can lead to the development of distinct species that can no longer interbreed.