Statement I: Keystone species are not essential for biodiversity conservation.

Statement II: Keystone species play a crucial role in shaping community structure and characteristics.

Only statement II is correct.

The correct answer is Option (2) - Only statement II is correct.

Statement I: Keystone species are not essential for biodiversity conservation.

This statement is not true. Keystone species are indeed relevant and crucial for biodiversity conservation. Keystone species are species that have a disproportionately large impact on their ecosystem relative to their abundance. Their presence or absence can significantly influence the structure and function of the entire ecosystem. Conservation efforts often focus on protecting keystone species because their preservation can have cascading effects on other species and the overall ecological balance.

Statement II: Keystone species have a significant impact on community structure and characteristics.

This statement is true. Keystone species play a vital role in maintaining the balance and stability of ecological communities. They can regulate the population sizes of other species, control the abundance of certain resources, and even create or modify habitats. Removing a keystone species from an ecosystem can lead to disruptions in the food web and ecosystem dynamics, potentially leading to the decline of various other species and negative consequences for biodiversity. Therefore, understanding and conserving keystone species are crucial aspects of biodiversity conservation.