As a result of a major environmental change, such as a volcanic eruption, earthquake, or an asteroid hitting Earth, which changes the environment so much that natural selection leads to large changes in the traits of a species.
(an asteroid hitting Earth; changes; the environment; so much that natural selection leads to large changes in the traits of a species) (natural selection; leads; to large changes in the traits of a species)
an asteroid hitting Earth natural selection
changes leads
the environment so much that natural selection leads to large changes in the traits of a species
to large changes in the traits of a species