Question

(a) Alien species are highly invasive and are a threat to indigenous species. Substantiate this statement with the help of any two examples.
(b) State any two criteria for determining biodiversity hotspots.

Hint:

Alien species can cause ecological disruption by displacing native species. Biodiversity hotspots are rich in endemic species and under severe threat due to habitat loss.

Answer 1

Step 1 (a): Alien species, also called exotic species, are non-native species introduced—intentionally or unintentionally—into an ecosystem. They often become invasive and outcompete native species. Examples:

• Parthenium hysterophorus (Congress grass): Invasive weed that causes ecological imbalance and allergic reactions in humans.
• Eichhornia crassipes (Water hyacinth): Blocks waterways, reduces oxygen levels, and hampers aquatic biodiversity.

Step 2 (b): Two criteria for identifying biodiversity hotspots:

• The region must have at least 1,500 species of vascular plants as endemics.
• It must have lost at least 70% of its original natural vegetation.