Question

Biologists have documented asexual reproduction in some animal lineages. Even in some vertebrates, such as reptiles, some species reproduce only with parthenogenesis (development from unfertilized eggs). However, parthenogenesis has never been documented in mammals. What is the current genetic explanation for this difference between mammals and other vertebrates?

Answer 1

Parthenogenesis is absent in mammals due to complex genetic imprinting and the necessity for genes from both parents, unlike in some other vertebrates where it occurs occasionally, potentially as an adaptation or in isolated females.

Step-by-step explanation:

The current genetic explanation for the absence of parthenogenesis in mammals, compared to its presence in other vertebrates such as reptiles, amphibians, and fish, lies in the differences in their reproductive systems and genetic set-up. In mammals, complex genetic imprinting and the necessity for genes from both a male and female parent are crucial for development, whereas other vertebrates may not have such stringent requirements. Parthenogenesis in other vertebrates is also linked to instances where females are isolated from males or as a potential adaptation in endangered species to ensure the continuation of the species.