Relative fitness

Definition

Relative fitness refers to the contribution an individual organism makes to the gene pool of the next generation, compared to other individuals in the population. It takes into account both reproductive success and survival, highlighting how some individuals may be more successful than others based on their traits. This concept is crucial for understanding natural selection, as it drives which traits become more common or rare in a population over time.

5 Must Know Facts For Your Next Test

1. Relative fitness is often expressed as a ratio, comparing an individual's reproductive success to that of others in the same population.
2. An individual's relative fitness can change based on environmental factors, mating opportunities, and competition for resources.
3. Traits that enhance relative fitness are likely to be passed on to future generations, shaping the evolutionary trajectory of a species.
4. In some cases, an individual with lower absolute fitness can have higher relative fitness if they outperform others in specific environmental conditions.
5. The concept of relative fitness helps explain phenomena like altruism, where individuals may sacrifice their own reproductive success for the benefit of related individuals.

Review Questions

• How does relative fitness influence natural selection within a population?
  • Relative fitness plays a key role in natural selection by determining which individuals contribute more effectively to the next generation's gene pool. Individuals with higher relative fitness are more likely to survive and reproduce, passing on advantageous traits. As these traits become more common, the overall characteristics of the population shift over time, aligning with the principles of evolution.
• Discuss how environmental factors can affect an individual's relative fitness.
  • Environmental factors such as resource availability, predation pressure, and climate conditions can significantly impact an individual's relative fitness. For example, a particular trait might enhance survival in one environment but be disadvantageous in another. As these conditions change, what constitutes high relative fitness can also shift, leading to changes in population dynamics and potentially triggering evolutionary adaptations.
• Evaluate the implications of relative fitness on group behaviors such as altruism in evolutionary biology.
  • Relative fitness challenges traditional views by suggesting that behaviors promoting group welfare can be beneficial at a genetic level. Through inclusive fitness, individuals may enhance their genetic success by supporting relatives, thus contributing to the survival of shared genes. This understanding complicates the notion of survival of the fittest by showing that cooperation and altruistic behaviors can also be strategies for achieving evolutionary success.

Related terms

Natural Selection: The process where organisms better adapted to their environment tend to survive and produce more offspring, influencing relative fitness within a population.

Fitness: A measure of an organism's ability to survive and reproduce, often expressed in terms of the number of offspring produced compared to others.

Inclusive Fitness: An extension of traditional fitness that includes the effects an individual has on the reproductive success of its relatives, contributing to overall genetic success.