This statement has great relevance in the context of the Antarctic environment. A small change in the environment can give rise to drastic developments. Antarctica has a small biodiversity. The example of small grass called phytoplankton can be studied in this context. These microscopic grasses undergo the process of photosynthesis and serve as food for number of marine birds and animals. The author says if there is further depletion of the ozone layer, it will affect the phytoplankton’s and the carbon cycle on the globe. This whole process can jeopardize the existence of all the marine birds and animals. So if we take care that processes carried over by these small grasses are carried out properly, the bigger animals and birds will fall into the place on their own.
What could be the reason for the disintegration of Gondwana? (Journey to the End of the Earth)
Six hundred and fifty million years ago, a giant amalgamated southern supercontinent — Gondwana — did indeed exist, centered roughly around the present-day Antarctica. Things were quite different then: humans hadn't arrived on the global scene, and the climate was much warmer, hosting a huge variety of flora and fauna. For 500 million years Gondwana thrived, but around the time when the dinosaurs were wiped out and the age of mammals got under way, the landmass was forced to separate into countries, shaping the globe much as we know it today.
(Journey to the end of the Earth)