Which of the following examples illustrates an alien species invading a new ecosystem and resulting in biodiversity losses?

All of the above.

The correct answer is Option (4) -All of the above.

When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive, and cause decline or extinction of indigenous species.

(1) The introduction of Nile perch into Lake Victoria in East Africa: This is an example of an alien species invasion. The Nile perch, a predatory fish, was intentionally introduced into Lake Victoria for fisheries purposes. However, it led to a decline and extinction of numerous native species of cichlid fish in the lake, resulting in biodiversity losses.

(2) The introduction of water hyacinth into India: Water hyacinth is an alien species that was introduced unintentionally or deliberately for ornamental purposes or due to its use in wastewater treatment. However, it turned invasive in Indian water bodies, causing ecological disruptions and declines in native biodiversity.

(3) The introduction of African catfish into Indian rivers: This is another example of an alien species invasion. The African catfish (Clarias gariepinus) was introduced for aquaculture purposes, but it poses a threat to indigenous catfish species in Indian rivers, potentially leading to biodiversity losses.

In summary, alien species invasions are one of the major causes of accelerated rates of species extinctions and biodiversity losses worldwide. When non-native species are introduced unintentionally or deliberately into new ecosystems, they can disrupt ecological balance and lead to the decline or extinction of native species, resulting in significant biodiversity losses.