Decrease in common characters as we move up the taxonomical hierarchy:

Genus to Species:
- The number of common characters decreases as we go from genus to species because species are more specific and closely related than genera.
- Species within a genus share more similarities in terms of physical characteristics, behavior, and genetic makeup.
- For example, within the genus Panthera, the common characteristics shared by the species Panthera leo (lion) and Panthera tigris (tiger) are more than the common characteristics shared by Panthera leo and another genus such as Felis (domestic cat).

Family to Genus:
- Moving from family to genus, the number of common characters decreases further as genera within a family can vary significantly in terms of characteristics and genetic makeup.
- For example, the family Felidae includes genera such as Panthera, Felis, and Acinonyx, each with distinct characteristics that set them apart from each other.

Order to Family:
- At the order level, the number of common characters decreases even more as families within an order can be more diverse and have fewer similarities.
- For example, the order Carnivora includes families such as Felidae, Canidae, and Ursidae, each with unique characteristics that differentiate them from one another.

Class to Order:
- Moving from class to order, the number of common characters decreases significantly as orders within a class can vary greatly in terms of physical traits, behavior, and genetic makeup.
- For example, the class Mammalia includes orders such as Carnivora, Rodentia, and Primates, each with distinct characteristics that separate them from one another.