Question

Under what circumstances can a predator experience strong selection pressure from the prey? Explain with examples.

Answer 1

The prey may escape from the predator by strategies such as mimicry, or can simply outrun or hide from the predator. Some species act co-ordinately to repel the predator. Animals that have sharp eye-sight, or are poisonous to their predators or can camouflage themselves is likelier to reproduce and survive than animals without these traits. A predator which continually pursues prey without a successful kill will soon become exhausted and will be in danger of starvation. Hence, under these circumstances the predator will experience a strong selection pressure from the prey.

Explanation with examples:-

• Adaptations such as camouflage can make a prey species better able to avoid detection. By blending into the background foliage or landscape, and remaining motionless, an insect or animal offers no visual cue to the predator since it mimics it's surroundings. For e.g.- some moths have markings on their outer wings that resembles the eyes of an owl or that make the creature look larger in size and hence is avoided by the predator.
• Some species act co-ordinately to repel a predator. For e.g.- a flock of birds may collectively turn on a predator such as a larger bird or an animal to drive off the predator. This moving type of repulsion can be highly orchestrated. For e.g when attacked by an animal such as a dog, moking birds have been observed to coordinate their attack, with some birds flying close to the animal's face with others pestering it from the rear when it lunges in response. As well, some bird species use different calls which are thought to be a specific signal to other birds in vicinity, to join the attack.
• A prey can be vividly coloured or have a pattern that is similar to another species that is otherwise poisonous or undesirable to the predator. This sort of strategy, is meant to repel a potential predator, based on the predator's previous experience with the genuine noxious species.
• If the prey population is over-exploited or drops due to disease or some other calamity, the predator population will soon decline. For e.g- if the rabbit population is over-exploited or drops down then over time, the fox population may also drop down in number.