Question

Q. Nature employs many strategies to defend itself, discuss some of these strategies with a particular focus on chemical defence. In addition, discuss how the use of these chemical defences can be biologically costly, and how other organisms have evolved different methodologies to circumvent this cost.

Answer 1

Both plants and animals have evolved to develop defence in order to protect themselves

Camouflage by changing colour (chameleon), Animals like opossums which play dead to escape from predators. Porcupine spines (physical defence), Sea cucumbers who can throw their body parts at their preys. Some group of animals also have warning calls to warn of a predator nearby, like birds, dogs. There are also chemical defences, which is certain toxins or unpalatable substances secreted by the prey to defend itself

For example, A posture (unken reflex) by amphibians (certain toads) which is taken up to indicate about harmful and distasteful toxins. Predators have evolved to to learn this warning behaviour of their prey to protect themselves

Plants produce Secondary metabolites like resins, alkaloids. phenols and toxins that affects the herbivore animals. For examples - Milkweed plan uses latex fluids and a steroid (cardenolide) to harm the caterpillar of monarch butterfly as self defence, but the butterfly has evolved to be unaffected by the toxins as the toxins consumed by the caterpillar remains in the adult, thus driving its predators away.

Use of chemical defences can become as biologically costly as a lot of resources are diverted away from growth and other important processes. Certain precursors such as NADH, ATP which are needed for the preparation of primary metabolites, and essential enzymes is diverted in the preparation of these secondary metabolites.

If my answer was helpful, please upvote :)