A Study of the Changes in an Aquatic Insect. Population, using Minnows as Predators


  • E. J. Popham B.Sc., Ph.D., A.R.C.S., F.Z. S.


  • 1Collections of three species of Corixids were made at regular intervals from a small pond at Wilpshire, near Blackburn, Lancashire.
  • 2After fifty Minnows had been introduced the proportions of Corixids adapted to the habitat increased.
  • 3Various possible explanations are considered, and it seems most probable that the Minnows destroyed those insects which did not harmonize with the background.
  • 4There is a lower intensity of selection under natural conditions than that observed in the laboratory.
  • 5The influence of selection and isolation in the spread and preservation of various types of characters is also discussed.