Artificial Selection (selective breeding) vs Natural Selection

Review Sexual reproduction requires gametes or sex cells egg and sperm. Compare natural selection with artificial selection (selective breeding) Once she sits on the eggs that starts incubation, which for a chicken takes 21 days, keeping the eggs warm enough so they can develop. Temperatures of over 104.9 F could kill the embryos. 99.5 F is perfect for embryo development. All chickens that hatch will have 78 chromosomes in their diploid or body cells. 39 chromosomes came from the haploid or sperm cell from the rooster after internal fertilization and 39 chromosomes came from the haploid or egg cells of the hen.