Answer: pathogen–host coevolution
Explanation:
A major driver of evolution is Reciprocal coevolution between host and pathogen. Rather than pathogen, one-sided adaptation to a nonchanging host, high virulence specifically favoured during pathogen–host coevolution. In all of the independent replicate populations under coevolution, the pathogen ( B. thuringiensis ) genotype BT-679 with known nematocidal toxin genes of C. elegans and high virulence specifically swept to fixation but only some of them go under one-sided adaptation,
so relative change in B. thuringiensis virulence was greater than the relative change in C. elegans resistance is due to the elevated copy numbers of the plasmid containing the nematocidal toxin genes
.
