In the Publication “One Hundred Years Beekeeping In British Columbia 1858 – 1958” by W. H. Turnbull, on Page 28, second Paragraph, it describes a time where their “Native Bee” was  described as “a bit smaller” than the their recent imports of bees, in 1878,  that came in from California. A little proof perhaps that bees are smaller naturally. Below is a PDF down load of Chapter IV, Take note of page 28, paragraph 2, where you can read this.

100 years beekeeping in British Columbia 1858-1958 by W. H. Turnbull