Questions
Aquatic environments, and the unique challenges they create for the organisms that inhabit them, have generated an awe-inspiring amount of biological novelty and innovation. Exploring the molecular etiology of novel marine phenotypes will expand our basic knowledge of how new traits develop, highlight the interplay between genotype, phenotype, and the aquatic environment, and uncover the fundamental mechanisms of evolution that underly crucial transformations in life’s history.
Exploring Phylogenetic Variation Within Cellular Differentiation Pathways
There is an incredible diversity of marine appendages, such as fish fins and cephalopod arms, that are critical for facilitating movement and feeding. In all cases, these forms develop as cells differentiate, a process that is reliant upon changes in gene expression. Despite the phenotypic diversity, the literature suggests many shared molecular signatures during development. Further study will allow us to identify (1) which appendage developmental pathways are conserved and (2) the variations to said pathways that give rise to the diversity of marine appendages seen today. This work builds upon the single-cell sequencing methods developed to investigate the fin-to-limb transition using zebrafish (Danio rerio), spotted gar (Lepisosteus oculatus), little skate (Leucoraja erinacea), and chained catshark (Scyliorhinus rotifer).
Molecular Response to Life at High Hydrostatic Pressure
Intrinsic to life underwater is a response to the pressure exerted by water upon the organism. The hydrostatic pressure experienced by a marine organism can build quickly. Every 10m an organism descends adds 1 atmosphere of pressure. Therefore, a fish 10m below the water's surface is subjected to twice the pressure than at the surface. At a depth of 4000m, the pressure is 401x that of the surface! Coupled with a lack of light, cold temperatures, frequent hypoxia, and limited food resources, habitats experiencing high hydrostatic pressure are considered some of the most hostile environments on the planet, yet a plethora of life successfully adapted and thrive in these conditions. By leveraging publicly available sequencing and morphometric data, as well as collecting additional samples, we will utilize comparative techniques to identify adaptations to life at depth. Additionally, using tracking and transcriptomic sampling of species found at various depths, we will investigate a previously unexplored question- what is the plasticity in the molecular response to hydrostatic pressure? How can fish with considerable depth ranges safely move vertically in the water column?
Effects of Microbiome Establishment and Perturbation on Marine Vertebrate Development
Microbiomes can rapidly change in the face of environmental challenges, but the role these changes may play in the long-term adaptation of marine vertebrates is unknown. Along with collaborator Alexander Okamoto (graduate student, Harvard University), we have been working to establish the little skate (Leucoraja erinacea) as a model system for oviparous marine vertebrate microbiome studies. With a well sequenced genome and many molecular techniques already established for the species, we have expanded the available baseline data to include profiles of its microbiome across ontogeny in 4 different tissues. Despite months to years of gestation within eggs and little to no extended contact with conspecifics from the time of oviposition until sexual maturity, we found evidence of vertical transmission. We plan to combine additional microbial studies of this species reared in different environments, a closely related species reared in the same environment, and perturbing the microbiome at critical times during development (such as when the gills are reorganizing from external to the body to internal), with morphometric and genetic analyses. Together, these studies will illuminate what role the microbiome may have in driving rapid adaptation to environmental shifts, such as those driven by global climate change.