Reproduction refers to the propagation of a new individual, and may arise sexually or asexually. While sexual reproduction involving the fusing of gametes from different individuals is the norm in the animal kingdom, sexual reproduction by hermaphrodite individuals (in which a single individual produces both the eggs and sperm of a mating) and asexual reproduction also occur in both invertebrates and vertebrates. For example, the mangrove killifish ( Kryptolebias marmoratus ) has a mixed mating strategy, with hermaphrodites engaging in both self-and cross-fertilization, while the female hammerhead shark ( Sphyrna ) may reproduce asexually through parthenogenesis. Some species can alternate between sexual and asexual reproduction (heterogamy) according to the prevailing conditions, in order to capitalize on the advantages associated with each strategy. Sexual reproduction has the advantage of allowing genetic mixing through the fusion of gametes produced by meiosis (even in the case of…