Deleterious mutations

Definition

Deleterious mutations are genetic changes that negatively affect an organism's fitness, making them less likely to survive and reproduce. These mutations can disrupt normal biological functions or processes, leading to harmful traits or diseases. The impact of deleterious mutations is crucial in understanding the dynamics of evolution, particularly in relation to how natural selection acts on different alleles within a population.

5 Must Know Facts For Your Next Test

1. Deleterious mutations can be point mutations, insertions, deletions, or larger chromosomal changes that impair gene function.
2. These mutations are typically subject to negative selection, where individuals carrying them have reduced fitness compared to those without.
3. In large populations, deleterious mutations can persist due to mutation-selection balance, where new mutations arise at a rate that compensates for those removed by selection.
4. Some deleterious mutations may only have harmful effects under specific environmental conditions, allowing them to be maintained in a population until those conditions change.
5. Understanding deleterious mutations is essential for fields like medicine and conservation biology, as it helps identify genetic factors contributing to diseases and species vulnerability.

Review Questions

• How do deleterious mutations influence the overall genetic diversity within a population?
  • Deleterious mutations contribute to genetic diversity by introducing new alleles into a population. However, because these mutations reduce fitness, they are typically eliminated through negative selection. This means that while they can increase variation temporarily, their persistence is usually limited. Over time, natural selection works to favor beneficial alleles and remove deleterious ones, which shapes the genetic landscape of the population.
• What role does negative selection play in the fate of deleterious mutations within a population?
  • Negative selection actively removes deleterious mutations from a population by reducing the reproductive success of individuals carrying these harmful alleles. When a mutation adversely affects an organism's fitness, individuals with that mutation are less likely to survive and pass it on to the next generation. This selective pressure ensures that over time, the frequency of deleterious mutations decreases within the gene pool, promoting overall population health and adaptability.
• Evaluate how environmental changes can affect the impact of deleterious mutations on a population's evolutionary trajectory.
  • Environmental changes can significantly alter how deleterious mutations impact a population's evolutionary trajectory. A mutation that is harmful under one set of environmental conditions may become neutral or even beneficial if the environment changes. This flexibility can lead to shifts in allele frequencies as different traits become advantageous or disadvantageous. Such dynamics illustrate the complexity of evolutionary processes, where deleterious mutations may persist or be selected against depending on fluctuating environmental pressures and interactions with other genetic factors.

Related terms

fitness:

The reproductive success of an organism, often measured by the number of offspring that survive to reproduce themselves.

natural selection:

The process by which organisms better adapted to their environment tend to survive and produce more offspring, influencing the evolution of species.

genetic drift:

A mechanism of evolution that involves random changes in allele frequencies within a population, often having a more pronounced effect in small populations.