The Female Snark Is Still a Boojum: Looking toward the Future of Studying Female Reproductive Biology

Philosophical truths are hidden in Lewis Carroll's nonsense poems, such as "The hunting of the snark." When the poem is used as a scientific allegory, a snark stands for the pursuit of scientific truth, while a boojum is a spurious discovery. In the study of female biology, boojums have been the result of the use of cultural stereotypes to frame hypotheses and methodologies. Although female reproduction is key for the continuation of sexually reproducing species, not only have females been understudied in many regards, but also data have commonly been interpreted in the context of now-outdated social mores. Spurious discoveries, boojums, are the result. In this article, we highlight specific gaps in our knowledge of female reproductive biology and provide a jumping-off point for future research. We discuss the promise of emerging methodologies (e.g., micro-CT scanning, high-throughput sequencing, proteomics, big-data analysis, CRISPR-Cas9, and viral vector technology) that can yield insights into previously cryptic processes and features. For example, in mice, deoxyribonucleic acid sequencing via chromatin immunoprecipitation followed by sequencing is already unveiling how epigenetics lead to sex differences in brain development. Similarly, new explorations, including microbiome research, are rapidly debunking dogmas such as the notion of the "sterile womb." Finally, we highlight how understanding female reproductive biology is well suited to the National Science Foundation's big idea, "Predicting Rules of Life." Studies of female reproductive biology will enable scholars to (1) traverse levels of biological organization from reproductive proteins at the molecular level, through anatomical details of the ovum and female reproductive tract, into physiological aspects of whole-organism performance, leading to behaviors associated with mating and maternal care, and eventually reaching population structure and ecology; (2) discover generalizable rules such as the co-evolution of maternal-offspring phenotypes in gestation and lactation; and (3) predict the impacts of changes to reproductive timing when the reliability of environmental cues becomes unpredictable. Studies in these key areas relative to female reproduction are sure to further our understanding across a range of diverse taxa.

Dietary vitamin D in female rock lizards induces condition-transfer effects in their offspring

One way that maternal effects may benefit the offspring is by informing them about the characteristics of the environment. Through gestation, environmentally induced maternal effects might promote in the offspring-specific behavioral responses like dispersal or residence according to their new habitat characteristics. Females of the Carpetan rock lizard (Iberolacerta cyreni) seem to choose their home ranges using the smell of provitamin D3 in scent marks produced by males. Here, we supplemented gravid females of I. cyreni with dietary provitamin D3 or vitamin D3 to examine whether these food resources, also associated with the scent of males, affect the motivation to disperse and the locomotor performance of their offspring. Our results suggest that the supplementary availability of the resource (vitamin D3) to mothers may provoke condition-transfer maternal effects that motivate the residence or the dispersal of the offspring in their postnatal habitat. Thus, hatchlings of supplemented females had a lower dispersal trend in spite of having a greater climbing ability than hatchlings from nonsupplemented females. This suggests that the levels of provitamin D3 and vitamin D3 inside the body of the mother could act as an informative compound of the habitat quality for the offspring.