Reproductive science and wildlife conservation: the knowns and unknowns!

Abstract: Conservation biologists specializing in reproductive science for the support of threatened species are hampered by many knowledge gaps. One of the objectives of this review is to point out a few of those gaps. We discuss the surprising observation that modern genomic technologies are revealing inaccuracies in the identification of cryptic species, which is critically important for wildlife biobank management or where reproductive interventions are required. If confronted with a familiar species, but of unfamiliar origin, it would be unwise to assume that every aspect of their reproductive biology is exactly as expected. Serious gaps in detailed knowledge can mislead the biologist, and new projects and species are therefore usually hampered by unforeseen problems. Developmental plasticity is one of the key processes behind species diversity, whereby instead of embryos always developing along inflexible pathways, it is now clear that embryonic development can be modified by modulating gene expression through epigenetic mechanisms. In some cases, animals can improve their survival by migrating to optimal feeding or breeding grounds. Others can exploit reproductive delays that relax the synchrony that normally forces mating, or insemination, to occur at the same time as ovulation. While genetic properties such as inbreeding are known to modulate reproductive success, more recent research shows that even the microbiome can influence mammalian fertility. It is therefore becoming clearer that not only has evolution resulted in a bewildering diversity of reproductive adaptations, but attempts to support wildlife have to be backed up by a great deal of fundamental knowledge. Lay summary: All animal species, past and present alike, are the products of evolution, and although they have diversified in multiple directions, they currently occupy niches that optimize their future chances of survival. While animal evolution as an abstract concept usually brings to mind a series of changes taking place over long timescales, recent advances in developmental biology have shown that many animal species can also adapt surprisingly rapidly if their environment changes. For example, some tadpoles and fish embryos can sense that their watery habitat is drying out, whereupon they can either accelerate their development or bury themselves in mud until the waters return. How do they do it? While biologists are gradually discovering the mechanisms behind these, and other, unexpected responses confront biologists every day with knowledge gaps that have to be filled. Here, we explore some of these gaps and their influence on efforts to protect threatened species.