The 2 main pre-fertilization events are gamete transfer and gametogenesis. These events are crucial for successful fertilization and subsequent development of the embryo. Let's understand these events in detail:

Gametogenesis:
Gametogenesis is the process of formation of gametes from germ cells. It involves two main processes: spermatogenesis (formation of sperm) and oogenesis (formation of egg). In spermatogenesis, diploid germ cells undergo meiosis to form haploid spermatids which later mature into functional sperm cells. In oogenesis, a single diploid germ cell undergoes meiosis to form a single haploid egg and three polar bodies.

Gamete transfer:
Gamete transfer is the process by which gametes are transferred from one organism to the other. In animals, it involves various methods such as copulation, external fertilization, and internal fertilization. In external fertilization, the release of gametes occurs outside the body of the organism, while in internal fertilization, the transfer of gametes occurs inside the body of the organism.

Importance of pre-fertilization events:
Pre-fertilization events are important for successful fertilization and embryonic development. Gametogenesis ensures the formation of haploid gametes with a complete set of genetic information. Gamete transfer ensures the transfer of gametes to the appropriate site for fertilization. These events also ensure that the gametes are healthy and viable, which is crucial for successful fertilization.

Conclusion:
In conclusion, pre-fertilization events play a crucial role in the process of fertilization and subsequent development of the embryo. Gametogenesis and gamete transfer are the two main pre-fertilization events that ensure the formation and transfer of healthy and viable gametes.