Question

Alien species are highly invasive and are a threat to indigenous species. Substantiate this statement with the help of any two examples.

Hint:

Include a relevant concept, shortcut, or useful trick related to solving this type of problem. Give useful quick tips for the question. Also properly format the text in quick tip as per latex. \textbf{Quick Tip (a):} When citing examples of invasive alien species, try to include details about their origin, how they were introduced, and the specific ways they harm native ecosystems and biodiversity. \textbf{Quick Tip (b):} Remember the two key characteristics of a biodiversity hotspot: it must be rich in unique species (endemism) and under significant threat of habitat loss. The specific thresholds (1,500 endemic plant species and 70% habitat loss) are important to recall.

Answer 1

Alien species, also known as exotic or non-native species, are those that are introduced to a habitat outside their native range. Many alien species become invasive when they establish themselves and spread rapidly, causing harm to the native biodiversity and ecosystems. Their invasiveness often stems from a lack of natural predators, competitors, or diseases in the new environment. Here are two examples to substantiate this statement: Water Hyacinth (Eichhornia crassipes): Native to South America, water hyacinth was introduced to many parts of the world as an ornamental plant. In India, it has become a notorious invasive species in freshwater bodies. Its rapid vegetative propagation leads to the formation of dense mats on the water surface. These mats: Block sunlight, reducing photosynthesis by submerged plants and algae, leading to oxygen depletion (eutrophication) when they decompose. Impede water flow, affecting navigation and irrigation. Alter water chemistry and temperature, negatively impacting aquatic life, including native fish and invertebrates. Provide breeding grounds for disease vectors like mosquitoes. The unchecked growth of water hyacinth outcompetes native aquatic vegetation, leading to a loss of biodiversity and disruption of the natural ecosystem. Lantana (Lantana camara): Originating from tropical America, Lantana was introduced to India and many other regions as an ornamental shrub. It has become a highly invasive weed in a variety of habitats, including forests, grasslands, and agricultural lands. Its dense thickets: Outcompete native plant species for sunlight, water, and nutrients, suppressing their growth and reproduction. Reduce biodiversity by forming monocultures and altering habitat structure, affecting native herbivores and other wildlife that depend on the indigenous flora. Can be toxic to livestock. Alter fire regimes in some ecosystems. Lantana’s ability to spread aggressively through vegetative reproduction and seed dispersal has made it a significant threat to native plant communities and ecosystem functioning in many parts of the world. These examples illustrate how alien species, when they become invasive, can outcompete, displace, and otherwise harm indigenous species, leading to a loss of biodiversity and ecosystem degradation. Correct Answer : Alien species like Water Hyacinth in Indian water bodies and Lantana in various habitats are highly invasive. Water Hyacinth blocks sunlight, depletes oxygen, and outcompetes native aquatic life. Lantana forms dense thickets, outcompetes native plants, reduces biodiversity, and can be toxic to livestock, demonstrating their threat to indigenous species and ecosystems.