The most impactful on me of my UCSD college professors was Michael Soule. He taught a class on conservation biology.
It was his last class there since he was planning to retire in despair at the glum prospects for successfully saving species such as cheetahs. He decided to become a zen monk.
I learned about Minimum Viable Populations from him. Most people think a species becomes extinct when it gets down to the last mating couple, but that’s not true.
When the genetic diversity of a species drops below its MVP it becomes walking dead and is no longer saveable because of inbreeding.
As I recall, the MVP for cheetahs is 60 animals. Each animal has a need for a minimum area of territory. I think for cheetahs it’s 60 square miles per animal.
So to preserve cheetahs you have to create a reserve of 60 animals X 60 square miles for each one or 3,600 square miles total (if anybody can correct me on cheetah MVP and territory needs please do so).
What was so disturbing to Soule and to all 300 of us in his class, is that the largest preserve for cheetahs was 1/10 of that needed size. So cheetahs are doomed to extinction.
After each Wednesday night lecture, I always saw about 30 students crying as we walked out. Conservation biology is not a feel-good science!
Fortunately, after about three years out, Soule came back to conservation biology with a roar, first as a college professor again, but at UC Santa Cruz unleashing a herd of precocious con bio grads and in 1985 he started the Society for Conservation Biology. He decided scientists have an obligation to become activist teachers with the knowledge they acquire. That is how he lived out the rest of his life
Soule and his conservation biology advocacy became the biggest scientific inspiration for Earth First! and all of my own wilderness activism of the last forty years.
He was truly a great man who changed a movement, a hero to the Earth and all of her species and ecosystems!