The work of?

stated that reproduction in a species will decrease once

it has hit a limiting factor or "catastrophe."

The work of Liebig.

Explanation:

Liebig's works, generally associated with agriculture, affirm that the development of a living being and its population is limited by the factors provided in the environment in which it lives, that is, for living organisms to survive, it is necessary that the biotic and abiotic factors in an environment are presented in a limiting way, so that the growth of this population is controlled. As a result, these works claim that reproduction in a species will decline once it has reached a limiting factor or "catastrophe"