Answer:
A new mutation
Explanation:
A mutation refers to the random changes in the DNA of organisms. A mutation changes the allele and genotype frequencies by the introduction of a new allele in the gene pool. 
However, mutations are not the major factor responsible for changes in the gene pool of a population as mutations are rare. The rate of mutations is very slow and does not allow it to serve as a major factor to change the allele and genotype frequencies.
 
        
             
        
        
        
He discovered the theory that cells are created from the division of cells. He discovered many things related to cellular theory, pathology, and social medicine. He also discovered leukemia.   
        
             
        
        
        
Answer:The reason for this is because fungi and their host are eukaryotic and in treatment of fungal infections drug used can also affect their host.
Explanation: 
Antifungal drugs are drugs used in the treatment of fungal infections and so are antibiotics and antiviral drugs used to treat bacterial infections and viral infections respectively.
Fungi and their host are both eukaryotic and this make them closely related. They attack by colonizing and destroying the tissues of the animal host. When treating infections caused by fungi, the compounds used to kill fungi also harm the animal host because of the eukaryotic property they both possessed, this therefore set limitations to antifungal drugs. Unlike fungi, bacteria attack prokaryotic cell and also bacterial infections are systematic not superficial or topical like fungal infections.
 
        
             
        
        
        
Antibiotics are medicines used to treat infections caused by bacteria. Antibiotics don't work against infections caused by viruses, such as colds and flu. ... This is called antibiotic resistance and it happens when bacteria are exposed to antibiotics and learn to resist them.