Question

Differences in survival and reproduction caused by chance events can cause the genetic makeup of a population to change at random over time. This process is called a. mutation. b. natural selection. c. macroevolution. d. genetic drift.

Short answer

The answer is d. genetic drift.

Step-by-step solution

Understanding the Concepts

Begin by understanding the concepts defined in the options. Mutation refers to changes in the DNA sequence. Natural selection is a process where traits become more or less common depending on their impact on survival and reproduction. Macroevolution involves large-scale changes that occur over long periods. Genetic drift is a random process affecting the genetic makeup of a population.

Identifying Key Clues

The key clues in the question are 'differences in survival and reproduction caused by chance events' and 'genetic makeup of a population changes at random'. These indicate that the changes are random rather than driven by environmental pressures.

Match Concept with Definition

Compare each option against the key clues. Mutation (a) is specific to DNA changes. Natural selection (b) involves non-random survival based on traits. Macroevolution (c) refers to large-scale evolutionary changes. Genetic drift (d) describes random changes due to chance events.

Choosing the Correct Term

Based on the understanding and matching definitions, 'genetic drift' is the correct term as it explains random changes in a population's genetic makeup due to chance events affecting survival and reproduction.

Key concepts

Mutation

Mutations are changes in the DNA sequence of an organism. These changes can occur naturally during DNA replication or be caused by external factors such as radiation or chemicals. Mutations can have various effects, such as favorable, harmful, or neutral. For example, a mutation might introduce a new trait that improves an organism’s ability to survive. But most of the time, mutations have no effect or might even be harmful.

Keep in mind:

• Mutations are random and can occur in any cell.
• They are a primary source of genetic variation.
• Without mutations, evolution would not be possible.

When we talk about mutations in the context of evolution, we usually focus on those that are passed on to the next generation. These inherited mutations contribute to the diversity within a population, which other evolutionary processes like natural selection and genetic drift act upon.

Natural Selection

Natural selection is the process by which traits that improve an organism's ability to survive and reproduce become more common over time. Unlike genetic drift, which is random, natural selection is driven by environmental pressures. Organisms with advantageous traits are more likely to survive and reproduce, passing those traits to the next generation.

Key points to grasp:

• Natural selection is non-random and depends on the environment.
• It increases the frequency of beneficial traits over many generations.
• It’s one of the main mechanisms of evolution.

For instance, if a population of beetles has a variety of colors, and birds are more likely to eat the brighter beetles, the darker beetles will have a better chance of surviving and reproducing. Over time, the beetle population will become darker. This example shows how natural selection pressures influence genetic makeup.

Macroevolution

Macroevolution refers to large-scale evolutionary changes that occur over very long periods. It encompasses significant events like the emergence of new species and the extinction of existing ones. While microevolution looks at changes within a single population, macroevolution zooms out to consider broader transformations.

Important aspects include:

• Macroevolutionary changes accumulate from many microevolutionary events.
• It can result in the formation of new species (speciation).
• Extinction events also play a big role.

Think of macroevolution as looking at the bigger picture of life's history. For example, the transition from single-celled organisms to complex multicellular life forms is a result of macroevolution. This process involves many intermediate steps over millions of years.