Answer:
because of different antigen
I think this happens when there is no gene flow or when the population is small. Small population, germ line mutation, beneficial mutation that gets into many progeny and is of high chance of luck. Genetic drift involves a process in which allele frequencies within a population change by chance only, as a result of sampling error from generation to generation. Genetic drift occurs mostly in small population since the infrequently occurring alleles face a greater chance of being lost.
Dizziness, damaging of heart , Serious health problems.
Answer: Humans impact the physical environment in many ways: overpopulation, pollution, burning fossil fuels, and deforestation. Changes like these have triggered climate change, soil erosion, poor air quality, and undrinkable water.
Explanation: Hope that helped, I typed my own answer but it earased it so i copied and pasted from a article, hope this helps!