Question

Why are parasites often more lethal outside of their native range?

1) DNA mutates more quickly outside of a parasite's native range, so the parasite evolves faster.
2) Parasites cannot be transmitted from host to host outside of their native range.
3) Therapeutic treatments, like fungicides, are ineffective outside of a parasite's native range.
4) The host population in the new region lacks defensive adaptations against foreign parasites.

Answer 1

Parasites tend to be more lethal in new ranges primarily because the local hosts have not developed defenses against them, resulting in higher vulnerability to the parasites. Option number 4 is correct.

Step-by-step explanation:

Parasites are often more lethal outside of their native range because the host population in the new region lacks defensive adaptations against foreign parasites.

This lack of evolutionary history with the parasite means the hosts have not developed the necessary immune responses or behaviors to effectively deal with the new threat. Moreover, the rapid spread of invasive parasites can also be attributed to factors like high propagule pressure and the parasites' ability to exploit the Free-living stage(s) for survival and expansion in new habitats. Specialists and generalists may perform differently based on available hosts, and environmental conditions can strongly influence the survival and spread of ectoparasites in new areas.