How are human economics and ecology linked?
A few ways that I can think of.
Ecology basically studies ecosystems and organisms' relations to one another. The global economy, the US economy, the New York economy, etc. are all like ecosystems in that all the entities (businesses, corporations, etc.) are all interconnected in a way.
Competition between businesses is not unlike competition between species, just like cooperation in business mirrors mutualistic symbiosis between organisms.
Another way they're related is in the theory of evolution and natural selection. Evolutionary theory states that no two competing species can coexist. Eventually, they will either find separate niches and cease to compete or one will outcompete the other, and the losing species will go extinct. In business, it is oftentimes (though certainly not always) the same.
If two grocery stores open next to each other they will go through an arms race of prices and quality to outcompete the other until one goes out of business or they diverge in their specialties after they realize both their businesses are suffering. It's by no means a perfect comparison, but economics does mirror evolution in some ways.