HUMANS’ IMPACT Involving the introduction of new diseases

Dutch Elm Disease  Introduced in 1910 from Asia  Caused by elm bark beetles which carried the fungi, Ascomycota  Native elms did not have time to evolve resistance to the disease  They were wiped out by the thousands

Smallpox & Native Americans  Caused by the first direct European contact  Native Americans did not have resistance to the disease because they had never seen it before  Wiped out 30% of the population

Potato Blight  Potato disease called Phytophthora infestans  Causes them to rot from the inside  Spreads quickly through the population  Ruins potato crops, thus causing events such as the Irish Potato Famine

Conclusion  The introduction of new diseases due to human meddling can be devastating to populations because they have not been previously exposed to it  The lack of resistance can cause large-scale global and local changes due to massive deaths of organisms devastating native species, and therefore, the whole ecosystem