Vertebrate female reproduction

Vertebrate female reproduction is a prime example of the evolution of an increasingly complex organismal system. Starting from an ancestral system functioning to transport gametes from the gonads to the environment in a single step, it subsequently added internal fertilization, and ever prolonged phase of intrauterine embryonal development with active maternal involvement, the fetal-maternal interaction reaching an extreme in mammalian pregnancy. This evolutionary process can be seen as a gradual decoupling, and with it physiological and evolutionary individualization of the single reproductive phases, such as ovulation, diapause, intrauterine development and finally expulsion, occurring as the egg or embryo travels through the reproductive tract. In the context of phylogeny, such decoupling and the potential for independent modification of single developmental phases resulted in an enormous complexity and diversification of female reproductive types.

To address such complexity, our goal is to first identify the basic processes as building blocks that are shared in vertebrate reproduction, in order to then understand their modifications as well as novel features, and how they have influenced the subsequent evolutionary diversification.