Extensions

• Creeper hen and creeper rooster gave birth to 2:1 ratio of creeper:normal
• "dominant" lethal: when a mutation in one allele is lethal
• well known "dominant" lethals:

  • tailless mice
  • white horses
  • powder puff dogs
  • yellow leaves in snapdragons
  • achondroplastic dwarfism in humans (short limbs but normal trunk and large head)