When a species becomes extinct, the plant and animal species associated with it, in an obligatory way, also become extinct, e.g., when a host fish species becomes extinct, its parasites also vanish. This is called co-extinction.

Some other examples of co-extinction are; plant-pollinator mutualism where extinction of one leads to the extinction of other. Monophagous insect that feeds on particular plant species becomes extinct due to extinction of that plant species.

When alien species are introduced unintentionally or deliberately in a habitat, some of them can cause decline or extinction of indigenous species, e.g., extensive environmental damage caused and threat posed to our native species by invasive weed species like carrot grass (Parthenium), Lantana and water hyacinth (Eichhornia). Another example of exotic species invasion is Nile perch, a large predator fish.

When this alien species was introduced into lake of Victoria in East Africa, it started feeding on native, cichlid fish. As a result indigenous cichlid fish became extinct and due to scarcity of food, predator Nile perch died too.

Biodiversity is the occurrence of different type of species, habitat, ecosystem, gene, genepool in a particular place and various parts of earth.

As an individual, biodiversity can be conserved with conservation strategies and management of both biotic and abiotic resources.

Some of the conservation strategies are as follows

(i) Protection of useful animals and plants in their natural habitat or in situ conservation.

(ii) Preservation of critical habitats like feeding and breeding areas and resting area of endangered species to promote their growth and multiplication.

(iii) Hunting should be banned or regulated.

(iv) Habitat of migratory animals should be protected by bilateral or multilateral agreements.

(v) People should be made aware of the importance of biodiversity and its conservation.

(vi) Over exploitation of natural resources must be avoided.

(vii) Biodiversity plays an important role in maintaining and sustaining supply of goods and services.

(viii) Conservation of biodiversity ensures well being of all the living creatures and their future generations.

Scientific explanation for the direct relationship between diversity and stability of an ecosystem could be as follows

Imagine a forest area, where diverse species of plants are growing. Plants harbour a variety of insects on which a lot of bird species would depend for their food.

If a specific plant species dies, the related insect population will be affected that would lead to food unavailability for the birds.

In addition, if the plant species was a nitrogen fixer, the death of these plants would mean no replenishment of soil with nitrogen. This will obviously affect the other plants as well. So, if the cycle continues, the whole habitat/ecosystem will be negatively affected.

The humans first evolved around 2.5 million years ago and agriculture began about 11 thousand years ago. It is since then that humans have started to exploit the forest land for agriculture. Development in medical technology has increased the lifespan of humans, decreased the mortality rate of mother and child, further aggravating the problem of human population.

Along with this, the industrial revolution caused enormous consumption of earth's resources but giving back nothing. The monumental amount of waste is destroying the natural habitat of other species, be it aquatic or terrestrial, endangering and later causing extinction thereof.

This is how human activities have led to the increase in conflict between humans and wildlife.