5.3.1. Bi-directional selection
To understand the physiological or genetic mechanism underlying a specific trait, it can be useful to obtain individuals that manifest extreme values for this trait. A breeding design in which the best and worst individuals are chosen and reproduced is referred to as “bi-directional selection”. An example of a bi-directional design is described in detail in Page and Fondrk, 1994. The basic steps are the following:
- The 10 best and 10 worst colonies are selected.
- Five sublines within the best and worst groups are created by inseminating virgin queens with semen from a single drone (from a different colony of the same group). See the BEEBOOK paper on instrumental insemination (Cobey et al., 2013)
- At each generation, the best colony of the “best” group and the worst colony of the “worst” group are used for the production of virgin queens and drones.
- The colonies from the 3rd generation queens are used for the experimental observations.