Darwin’s explanation for evolution was dependent on which scientific concept

Hummingbirds drink nectar from flowers, while robins eat plant seeds. what does this reduce?

When analyzing tree rings, what do scientists assume a thin ring indicates?

How did the discovery of the rhesus factor affect society? o more patients died from having a transfusion with the wrong rhesus factor 0 new treatments during pregnancy could prevent harm to the developing child. o less donated blood could be used in the treatment of patients. the number of blood types was reduced by half