Live birth has evolved many times independently in vertebrates, such as mammals and diverse groups of lizards and snakes. Here we report the discovery of a pregnant long-necked marine reptile (Dinocephalosaurus) from the Middle Triassic (∼245 million years ago) of southwest China showing live birth in archosauromorphs.
The origins of sex chromosomes are not well understood experimentally, or theoretically, and are a fundamental focus in modern biology. We are using broad comparative data to figure out how sex chromosomes evolve. Colors on the tree correspond to the evolutionary rate of sex determination in amniotes.
Exaggerated cranial structures such as crests and horns are pervasive across animal species and perform vital roles in visual communication and physical interactions within and between species. We find that body size evolved directionally toward phyletic giantism an order of magnitude faster in theropod species possessing ornaments compared with unadorned lineages...
The evolution of the number of exons in DMRT1 (a conserved component of the vertebrate sex-determining pathway). A) The molecular phylogeny with “fish” on top and amniotes on the bottom with rate of exon evolution mapped on. Notice the marked rate variation in the number of exons in amniotes. B) The posterior distribution of log-likelihoods for a model with equal rates of evolution (red), compared to a variable rates model (blue).
Urodeles (salamanders and newts) have have large genomes compared with other extant tetrapods, and their last common ancestor, which lived at least 168 Ma ago, likely already evolved a large genome. We are using histological data from a Middle Jurassic (Bathonian, 166–168 Ma) urodele (one of the oldest known stem-urodeles) to find out when salamander genomes expanded.
Macroevolutionary Biomechanics: The rate of gear ratio (log10 lever-out/lever-in) evolution of the primary forelimb retractors mapped onto a time-calibrated phylogeny (scale bar = 100 million years) of dinosaurs. Warm colors indicate higher rates of gear ratio evolution, while cool colors indicate lower rates of gear ratio evolution.
Our research goal is to help develop a macroevolutionary theory of genome biology by integrating data across disciplines. There is much work to be done and the answers we discover will address emerging theories about how and why the animal genome evolved.
Comparison is fundamental to biological research, dating to Aristotle, advanced by Whewell and Darwin, and matured with modern computational modelling. We take a small part in this legacy by using and developing phylogenetic comparative methods.
The biology we see today has unfolded over billions of years. Large-scale evolutionary questions have traditionally been the purview of paleontology, but we apply computational approaches to address macroevolutionary hypotheses across fields of biology.
“It is my task to convince you not to turn away because you don't understand it.” - Richard Feynman. Engaging students with demonstrations and narratives, while maintaining rigor, made Feynman a great teacher, and is an approach we try to emulate.