Extinction?

Question

Besides man and environment, has a species ever caused another species to become extinct? If so...can you tell me which? Thanks

Answer 1

Joe Willy Neckbone says, "I don't rightly know the answer to your question, but I will be right here in case you ask a question that I do know the answer to!"

Answer 2

"Environment" is impossible to remove from the extinction scenario, since the sum total of factors fro survival IS the environment. When humans cause an extinction, it usually happens because of human effects on the environment which make it impossible for the species of interest to survive (although there are also examples where the actual direct killing of too many members of a species brought the numbers so low that species viability was lost, as with the passenger pigeon).

Consider all the extinctions that happened before humans appeared. Out the greater than 2 billion years that life has been on Earth, humans have been part of the scene for less than one-tenth of a percent of that time. Thus, most of the extinctions that have occurred have been without the influence of humans.
These pre-human extinctions, however, all occurred in the greater context of an environment: ecosystem, habitat, geology, climate, etc.

In some cases it is very likely that extinction occurred because another species out-competed the one it replaced. But note: such competion occurs in an environment and is all about competition for critical factors within that environment, including food and space. One probably example is the sceled tree-fern: Lepidodendron of the Carboniferous period.

Even if a predator hunts another species to extinction, that is in the context of environment, since the ability of the prey to reproduce and find adequate shelter and food for itself is critical to their numbers, and the environmental pressures that cause the relative balance of predator to prey to be such must be weighed. Nothing happens in complete isolation in nature.

Answer 3

The causes of prehistoric extinctions are only theoretical, and somewhat speculative. One instance that is often cited as a likely case where competition caused extinction is the disappearance of marsupial carnivores in S. America. Species compositions in North & South America changed dramatically after a land bridge opend between N. America and South America (at what is now Panama) after being isolated for a long period of time. Mammalian carnivores (mostly large cats) apparetly outcompeted their marsupial counterparts. Many other shifts in species also occured.

A silimar thing is happening today with the intorduction of exotic species. Numerous species throughout the world are threatened by exotic species that displace the native species. Invasive exotic species are a huge problem in Hawaii, Florida, and the Great Lakes, and many other places around the world.