Question

If a predator affects all phenotypes within the prey population equally will the interaction function as an agent of natural selection?

Short answer

Explain your answer. Answer: No, a predator that affects all phenotypes within a prey population equally does not function as an agent of natural selection. This is because there is no differential survival or reproduction based on phenotype, meaning that the phenotypic composition of the prey population would not change over time due to this predator-prey interaction.

Step-by-step solution

Understand Natural Selection

Natural selection is the process by which traits become more or less common in a population due to their impact on reproductive success. It involves the differential survival and reproduction of organisms with particular traits. In other words, individuals with traits that improve their chances of surviving and reproducing will pass on those traits to their offspring, making those traits more prevalent in the population over time.

Identify agents of natural selection

Agents of natural selection, also known as selective pressures, are factors that influence an organism's survival and reproduction. These can include factors such as predation, competition, disease, and environmental conditions (e.g. availability of food, water, or mating partners). When an agent of natural selection disproportionately impacts certain phenotypes, it leads to a shift in the proportion of those traits in the population.

Analyze the impact of the predator on the prey's phenotype

In this exercise, it is stated that a predator affects all phenotypes within the prey population equally. This means that no single phenotype is more vulnerable to predation than any other phenotype. Consequently, there would be no differential survival or reproduction of individuals based on their phenotype.

Determine whether the interaction functions as an agent of natural selection

Since the predator affects all phenotypes within the prey population equally, i.e., there is no differential survival or reproduction based on phenotype, this interaction would not function as an agent of natural selection. As a result, the phenotypic composition of the prey population would not change over time due to this predator-prey interaction.

Key concepts

Selective Pressures

Selective pressures are environmental factors that influence which traits are beneficial for survival and reproduction within a population. These pressures act as natural selection agents by favoring certain phenotypes over others. Over time, the presence of selective pressures can lead to the adaptation of organisms within a population, enhancing their ability to survive in their specific environment. Some common examples of selective pressures include:

• Predation, where predators target specific traits in prey.
• Availability of resources such as food and water.
• Environmental changes like climate shifts or habitat alterations.

These pressures lead to changes in species, as organisms with favorable traits reproduce more successfully. When a selective pressure does not discriminate between different phenotypes and impacts all equally, it may not cause any particular trait to become more common, as seen in a uniform predator-prey interaction.

Phenotypic Variation

Phenotypic variation refers to the differences in traits expressed by individuals within a population. These traits can manifest in several ways, such as size, color, and behavior. They arise due to genetic differences and are influenced by environmental factors.
Phenotypic variation is crucial for natural selection to take place because it provides the raw material for selective pressures to act upon. When a population exhibits a wide range of phenotypic variation, it is more likely that some individuals will possess traits that help them adapt to changing conditions.
Without phenotypic variation, all individuals would respond similarly to environmental pressures, reducing the adaptability of the population. In predator-prey interactions, variation might make certain prey more elusive, or enable some to better survive predation attempts.

Predator-Prey Interaction

Predator-prey interaction is a critical aspect of natural ecosystems that shapes the dynamics of communities. This interaction involves a predator feeding on prey, and it can significantly impact the population size and composition of both predators and prey.
In many cases, predators exert selective pressures on prey, leading to adaptations like increased speed or camouflage, which promote survival. When predators selectively target certain traits, prey populations can exhibit changes in phenotype frequencies over time.

• For instance, if faster prey are less likely to be caught, speed may become a more common trait in the population.
• Alternatively, if a predator preys on all individuals equally, it may not serve as an effective agent of natural selection.

This balance between predation risk and prey adaptation drives evolutionary change and affects the overall stability and health of ecosystems.