Question

why are these species considered dynamic groups

Answer 1

species is considered the dynamic group because it contains the maximum no. of similarities among the different organisms that help to distinguish it from other species. Moreover, when we go from kingdom to species in descending order the specificity increases in hierarchy of classification.

Answer 2

Because it contains the max. no. of similarities amount the different organisms that help to distinguish it from other species .
Moreover, when we go from Kingdom to species in descending order the specificity increases in hierarchy of classification.