Q. Which of the following can be threats to the biodiversity of a geographical area?

1. Global warming
2. Fragmentation of habitat
3. Impact of alien species
4. Promotion of vegetarianism

Select the correct answer using the codes given below: (UPSC Prelims 2012)
Answer: 1, 2 and 3 only
Notes: The correct answer is [A] 1, 2 and 3 only. Biodiversity threats are factors that lead to the decline in the number and variety of species in a particular habitat. While the first three points are globally recognized "drivers of extinction," the fourth is a dietary preference that generally has a positive or neutral impact on biodiversity.

• Global Warming (1 is Correct): Rapid changes in temperature and weather patterns force species to migrate, alter their breeding cycles, or face extinction if they cannot adapt quickly enough. It leads to phenomena like coral bleaching and the melting of polar ice, destroying specialized habitats.
• Fragmentation of Habitat (2 is Correct): This occurs when large, continuous habitats are divided into smaller, isolated patches (often due to roads, agriculture, or urbanization). This prevents animals from dispersing, finding mates, and accessing resources, making populations more vulnerable to local extinction.
• Invasion of Alien Species (3 is Correct): When non-native species are introduced to a new area, they often lack natural predators. They can outcompete, prey upon, or bring diseases to native species, leading to a massive imbalance in the local ecosystem (e.g., the Lantana camara plant or the Water Hyacinth in India).
• Promotion of Vegetarianism (4 is Incorrect): This is not a threat. In fact, moving toward a plant-based diet is often cited by ecologists as a way to reduce the pressure on biodiversity, as it requires significantly less land and water compared to livestock farming, which is a leading cause of deforestation.