Whittington, C. M. | bioRxiv Science

bioRxiv2021

Gene expression phylogenies and ancestral transcriptome reconstruction resolves major transitions in the origins of pregnancy

Structural and physiological changes in the female reproductive system underlie the origins of pregnancy in multiple vertebrate lineages. In mammals, for example, the glandular portion of the lower reproductive tract has transformed into a structure specialized for supporting fetal development. These specializations range from relatively simple maternal provisioning in egg-laying monotremes to an elaborate suite of traits that support intimate maternal-fetal interactions in Eutherians. Among these traits are the maternal decidua and fetal component of the placenta, but there is considerable uncertainty about how these structures evolved. We identified the origins of pregnancy utilizing ancestral transcriptome reconstruction to infer functional evolution of the maternal-fetal interface. Remarkably, we found that maternal gene expression profiles are correlated with degree of placental invasion. These results indicate that an epitheliochorial-like placenta evolved early in the mammalian stem-lineage and that the ancestor of Eutherians had a hemochorial placenta, and suggest maternal control of placental invasiveness. Collectively, these data resolve major transitions in the evolution of pregnancy and indicate that ancestral transcriptome reconstruction can be used to study the function of ancestral cell, tissue, and organ systems.

evolutionary biology↗

bioRxiv2020

Exercise training in a color-polymorphic lizard reveals differential effects of mating tactics and color morphs on telomere, body condition and growth dynamics

Alternative reproductive tactics (ARTs) are correlated suites of sexually selected traits that are likely to impose differential physiological costs on different individuals. While some level of activity might be beneficial, animals living in the wild are often working at the margins of their resources and performance limits. Individuals using ARTs may have divergent capacities for activity, and when pushed beyond their capacity, they may experience condition loss, oxidative stress, and molecular damage that must be repaired with limited resources. We used the Australian painted dragon lizard that exhibits color-polymorphims with corresponding alternative reproductive tactics (ARTs) as a model to experimentally test the effect of exercise on body condition, growth, reactive oxygen species (ROS), and telomere dynamics--a potential marker of stress and aging and a correlate of longevity. For most males, ROS tended to be lower with greater exercise; however, males with yellow throat patches--or bibs-- had higher ROS than non-bibbed males. At the highest level of exercise, bibbed males exhibited telomere loss, while non-bibbed males gained telomere length; the opposite pattern was observed in the no-exercise controls. Growth was positively related to food intake but negatively correlated with telomere length at the end of the experiment. Body condition was not related to food intake but was positively correlated with increases in telomere length. These results, along with our previous work, suggest that aggressive bibbed males suffer physiological costs that may reduce longevity.

evolutionary biology↗