Question

1. Interspecific interactions have evolved over many generations and been favoured by natural selection which is why these interactions persist today. Discuss this statement with reference to at least five (5) types of interspecific interactions using relevant species examples.

2. Community structure is a dynamic that is influenced by many factors. Describe and discuss the interplay of five (5) factors with reference to Pacific Island biological communities

Answer 1

Interspecific interactions occur between the members of different species. It usually arises for food, space and protection. These interactions have evolved in such a way that today we have a diverse range of species. Also, evolutionary history unfolds the records of coevolution between the interacting species. Following are the five different types of interspecific interactions which have evolved with time. These are-

1. Mutulism- It is a type of interaction which results in providing mutual benefits to the individuals of two different species. Classic example of this interaction is gut bacteria in humans. This bacteria helps in digesting proteins, carbohydrates and fats by breaking down them into simpler forms. It protects small intestine from other harmful pathogens. In turn, this bacteria consumes un-used nutrients obtained during the process of digestion. It is believed these bacteria have evolved and adapted million years ago to form symbiotic association with humans.

2. Commensalism- This type of interaction occurs between two species where one species gets profit while other gets neither positive nor negative effect. Several microbiota occupied our body for food and shelter but we do not get any benefit from them.

3. Parasitism- This is a type of negative interaction by which one member of a species gets benefit while the member of other species has a negative impact of it. In this, one organism acts as a parasite as it feeds on other organism which serves as host. An example of parasitism is tapeworm, that lives in the human intestine.

4. Predation- It is also called as predator-prey interaction. Here, member of one species (predator) ends up consuming the member of other species (prey). Lion preying on an antelope is an example of predation. It has been revealed by many ecologists that this interaction has resulted in evolving new adaptation in the species. For example, many animals have developed defence techniques such as camouflage (mimicking to the surrounding environment), develpement of large horns for protection against predators.

5. Herbivory- This is a special type of predation which includes plants or trees as prey. Example of this is grazing animals feeding on grass. Some plants have evolved defense mechanism by which they release toxins or chemical agents. Due to these toxins, animals or insects cannot consume their prey.