I am driven to better understand how captivating new traits appear in lineages over relatively short periods of evolutionary time. Piecing together the major genomic changes that likely occurred to facilitate novel trait appearance and modification is now much more tenable with the tool of comparative genomics. I study the evolution of male pregnancy in syngnathid fishes (like the dwarf seahorse pictured here) to hopefully learn about the magnitude and forms of genome evolution involved in novelty. What role do structural vs. regulatory changes play? How commonly is gene family expansion involved? Is substantial re-wiring of an existing regulatory network required?
Complex brood pouches have evolved several times in over 50 million years of syngnathid evolution, so we can begin to dissect the genetic origins of novelty (an old problem Ernst Mayr was fond of), and ask whether the same genes or pathways were modified repeatedly to yield complex pregnancy. We know astonishingly little about the function of the pouch and why some lineages, like seahorses, have evolved highly complex pouches, and why others have not (see examples below). I use the information in genomes and transcriptomes to understand what molecular mechanisms play a role in the process of male pregnancy. For example, my work on the Gulf pipefish genome revealed that an astacin-like protease family (called patristacins) is expressed dynamically in the brood pouch with respect to pregnancy status, and that this family underwent lineage-specific expansion. I continue to work on the genomics of male pregnancy across the syngnathid tree, using a host of rich datasets my colleagues and I have generated over the years. Stay tuned for upcoming discoveries!
Syngnathids are fantastic subjects for the comparative study of many traits other than male pregnancy as well. Elaborate skin appendages, exceptional spinal curvature, elongated craniofacial bones, and sexually dimorphic pigmentation are all examples of highly derived traits, many of which have evolved multiple times in Syngnathidae. Increasing the availability of genomic resources to study these incredibly derived traits is one of my primary research aims moving forward. For example, check out our 2022 paper on the fascinating genomes of leafy and weedy seadragons! This work, led by Dr. Susan Bassham and me, revealed some fun surprises about repetitive DNA, loss of highly conserved fgf genes, and expansion of other interesting gene families in seadragons and syngnathids in general.
I’m lucky to be involved in a number of other syngnathid genetics and genomics projects as well. My colleagues and I are sequencing and analyzing numerous chromosome-scale reference genomes for syngnathids and their close relatives, and work with Emily Rose’s lab (Valdosta State) and Heather Mason’s lab (University of Tampa) is focused on molecular ecology and population genomics in Florida and Caribbean seahorses and Syngnathus pipefishes, to name a few.