Many organisms have powerful control genes that determine how the body is laid out. For example, <span>Hox genes</span><span> are found in many animals (including flies and humans) and designate where the head goes and which regions of the body grow appendages. Such master control genes help direct the building of body "units," such as segments, limbs, and eyes. So evolving a major change in basic body layout may not be so unlikely; it may simply require a change in a Hox gene and the favor of </span>natural selection. Uhh i hope this help (:?<span> </span>
The cortical reaction. It is initiated during fertilization by the release of cortical granules from the egg, which prevents multiple sperm with one egg.
