A argue against a conventional explanation for the extinction of certain salmon populations and suggest an alternative
B correct a common misunderstanding about the behavior of salmon in response to environmental degradation caused by human activity
C compare the effects of human activity on salmon populations with the effects of natural disturbances on salmon populations
D differentiate the particular effects of various human activities on salmon habitats
E describe how environmental degradation can cause changes in salmon populations that extend beyond a numerical reduction
The numerical effect is
obvious:there are fewer salmon
in degraded regions than in pristine ones; however, habitat loss
also has the potential to reduce genetic diversity.Indeed, mostanalysts believe that some kindof environmental degradation underlies the demise of many extinct salmon populations.
