Question

A) Define mutualism in general and differentiate between obligate and facultative mutualisms. Give examples.

B) Discuss some plant-plant, plant-animal, animal-animal mutualisms

Answer 1

Ans:

Mutualism is a symbiotic association between two different species where both the members of the associations is benefit. The mutualism is of two types-

Obligate mutualism: In this type of mutualism, both the organism are benefit by close association and one organism cannot surrvive without the other.

Facultative mutualism: In this type of mutualism, both the organism are benefit by living in close association but one organism can surrvive without the other.

Examples:

Plant-plant interaction: Nitrogen fixing bacteria Rhizobium living in root nodules of leguminous plant. The bacteria derives nutrition from the plant and they fix nitrogen and maake it avialable for the plant. After the death of leguminous plant, the stored nitrogen in the nodules increases soil fertility.

Lichens are plants that are made up by living in close assiciations between fungus and algae. The fungus is attached to the substratum by mycelial threads and this threads help to absorb inorganic substances for algae and algae produces organic substances for fungal members.

Plant-animal interactions:

The fungus Termitomyces sp. is an associations with white ant. The white ant can degrade the soil, thereby the fungus can grow well. On the other hand, the young white ant grow well by feeding the apical region of mycelium.

Honey bees are in symbiotic relationship with different plant species. The honey bees   travels different plants species for the nectar from the flower and these plants will be benefited by the honey bees for pollination.

Animal-animal interaction:

The sea anemone Adamsia palliate attached to the shells of hermit crab Eupagurus predeauxi. The sea anemone is carried by the crab to fresh feeding sites and crab in turn is protected by sea anemone.  

The red-billed Oxpeckers birds eat parasites like ticks, flies, and other insects from cattle and other grazing mammals and the animals are benefited by pest control.