Question

mention how have organisms optimised their survival and reproduction in a habitat?

Answer 1

It is beleived that all the organisms which are present on the earth and surviving in the present conditions have optimised their survival and reproductive capabilities through the natural selection of the favourable traits and adaptations. Mutation occurs randomly. It could create positive variation or negative variation in an individual with respect to the environmental conditions.
If the environmental condition changes then the population which has adaptation ( positive variation) in the form of mutation to adapt to changed environmental condition will be selected by nature and survive. This is called natural selection.