In which generation does sexual reproduction occur

Fertilization of gametes in the female reproductive system and then, an offspring. 

Biodiversity depends on a species' ability to reproduce itself. If a species cannot reproduce then it will die out. This depends on the climatic conditions of the region. If there is a natural disaster for example, it will affect a species' ability to reproduce. This reduces the number of diverse species on earth. Biodiversity is the recognised variety of different types of life found on the earth. It also measures the variety of number and variety of plants, animals and other organisms found in different ecosystems.