Problem 1 - Campbell Biology

Question

Which of the following is not an observation or inference on which natural selection is based? \begin{equation}\begin{array}{l}{\text { (A) There is heritable variation among }} \\ {\text { individuals. }} \\ {\text { (B) Poorly adapted individuals never produce }} \\ {\text { offspring. }} \\ {\text { (C) Species produce more offspring than the environment can }} \\ {\text { support. }} \\ {\text { (D) Only a fraction of an individual's offspring may survive. }} \end{array}\end{equation}

Step-by-Step Solution

Answer

Statement (B) is not an observation or inference on which natural selection is based.

Step 1: Understanding Natural Selection

Review the principles of natural selection. Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring. The theory is based on observations and inferences such as variation in traits, differential survival, and reproduction.

Step 2: Reviewing Given Statements

Examine each statement provided:(A) There is heritable variation among individuals.(B) Poorly adapted individuals never produce offspring.(C) Species produce more offspring than the environment can support.(D) Only a fraction of an individual's offspring may survive.

Step 3: Identify the Non-Matching Statement

Identify which statement does not align with the principles of natural selection. Natural selection does not imply that poorly adapted individuals 'never' produce offspring; rather, they produce fewer offspring than better-adapted individuals. Therefore, statement (B) is not an accurate observation or inference.

Step 4: Conclusion

Conclude that out of the given statements, statement (B) about poorly adapted individuals never producing offspring, is not a valid observation or inference used to support the concept of natural selection.

Key Concepts

heritable variation

Heritable variation is a key concept in natural selection. It refers to the differences in traits that can be passed from parents to their offspring. These traits are encoded in the DNA and can influence an individual's ability to survive and reproduce. For example, some plants may have genes that make them more resistant to drought. When drought conditions occur, these plants have a better chance of surviving compared to those without this trait. Consequently, the genes for drought resistance are more likely to be passed on to the next generation. This process results in a population that gradually becomes better adapted to its environment.

differential survival

Differential survival means that not all individuals in a population have an equal chance of surviving to reproduce. Survival depends on how well an organism's traits match its environment. Those with traits that provide an advantage are more likely to survive and reproduce. For example, consider a population of beetles where some are green, and some are brown. If birds can see the green beetles more easily against the brown soil, the green beetles are more likely to be eaten. As a result, brown beetles are more likely to survive and pass on their genes to the next generation. Over time, you would expect to see more brown beetles in the population. This is an example of how differential survival acts as a driving force of natural selection.

reproduction

Reproduction is a fundamental aspect of natural selection. It is through reproduction that heritable traits are passed from one generation to the next. An individual's reproductive success is often influenced by how well-suited they are to their environment. Better adaptation often leads to more offspring. For example, consider a species of fish where some individuals are faster swimmers. In an environment with many predators, faster fish are less likely to be caught and more likely to grow up and reproduce. These fish then pass their fast-swimming traits to their offspring. Over several generations, the population becomes dominated by faster-swimming fish. Reproduction, therefore, ensures that beneficial traits are passed on, making the population more adapted to its environment over time.