Our Research
We are interested in all aspects of marine mammal ecology, behavior and evolution and work with a variety of molecular markers and tools to investigate research questions, which currently range from characterizing epigenetic markers involved in aquatic adaptations to large scale population genomics. Our lab has been traditionally focused on seals as study systems, but we also conduct projects on dolphins and whales. We often use archived tissue samples either from established collections or through collaborations with our local stranding network. But as any other wildlife biologists, we also conduct fieldwork to regularly connect with our study animals. We are moving our lab into the 'omics' era, so we are primarily focused in genome-level data acquisition, but still use traditional genetic markers for some projects and provide training in basic genetic laboratory and data analysis techniques to our students.​
Funded Research Projects
Epigenomic adaptations of Dolphin Skin
(NSF EEF # 2000211)
Marine mammal skin has remarkable adaptations to the aquatic environment. For example, the skin of an adult dolphin is smooth (lacks hair) and regenerates faster than human skin. Genomics studies have already shown that these adaptations can be traced to dolphin genomes, but we hypothesize that they are also reflected in their epigenomes. The epigenome comprises of a suite of molecular modes (e.g., histone modifications, DNA methylation and non-coding RNAs) of regulating gene expression; the ultimate link between genotypes to phenotypes. MicroRNAs (miRNAs) are short non-coding (~22nt) RNAs, which can determine if and how much protein is translated from genes. Our project’s ultimate goal is to characterize these markers in marine mammal skin of several species to investigate putative links with known marine mammal skin adaptations. We are also assessing the feasibility of miRNAs as biomarkers to monitor marine mammal health.
Move, Adapt, or Change: Examining the Adaptive Capacity of a
Southern Ocean Apex Predator, the Leopard Seal
(NSF OPP # 2146068)
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This is a collaborative project with researchers from over seven countries by Baylor and Hampton Universities (PIs Sarah Kienle and Carolina Bonin Lewallen). We are investigating leopard seal adaptive capacity to the warming Southern Ocean by quantifying their ability to move (dispersal ability), adapt (genetic diversity), and change (plasticity). Our lab leads a focused global effort to understand genetic connectivity among summer aggregations of leopard seals. To understand patterns of global genetic diversity and historical distribution we also work with leopard seals in areas outside of Antarctica, such as New Zealand and Chile.
Genomic Inferences of Adaptation in an Antarctic Top predator: the leopard seal
(NSF MCB-BIO # 2401877)
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Leopard and Weddell seals are sister Antarctic ice seal species who have key behavioral and physiological differences (e.g., deep diving and diet). This project explores the recent shared ancestry of these species to understand how unique adaptations are reflected in these species’ genomes. The Weddell seal genome has been particularly well studied, while the leopard seal genome has just been assembled by our research group. Our goal is to conduct a deep exploration of the leopard seal genome to detect differences in the expansion and/or contraction of gene families, positively selected and rapidly evolving genes between the two species. We will also characterize microRNAs in Antarctic pinniped species to identify adaptive differences that match habitat specializations. Our work on polar mammal species adaptations will also help assess their potential to cope with climate change.
Other Projects
Genetic assessment of Weddell seals in the rapidly changing North Antarctic Peninsula
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PI: Ian Santos Rodriguez (master’s student in Biology)
Co-PIs & mentors: Dr. Douglas Krause (NOAA SWFSC); Dr. Eric Lewallen and Dr. Julia Canitz (Hampton University)
Funding: NOAA LMRCSC
The Team
I am a marine biologist trained in population genetics and the use of molecular tools to study the ecology and behavior of marine mammals. I earned my PhD at the Scripps Institution of Oceanography University of California San Diego studying Antarctic fur seals and prior to that, I worked for many years for NOAA Southwest Fisheries Science Center, where I still active collaborations. My research interests are centered around three research avenues: 1) genetic diversity (how it is partitioned among populations and how it can inform us about past demographic histories); 2) marine mammal adaptations and their genomic/ epigenomic signatures; 3) marine mammal behavior; particularly social structure and mating systems. At Hampton University I am involved in several formal inclusion and diversity programs, most notably the NOAA LMRCSC program and the Office of Naval Research Internships for Diversity and Inclusion in Marine Mammal Science. Read more
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PI and Group Leader
Dr. Carolina Bonin Lewallen
PostDoc
Dr. Julia Canitz
I am interested in studying the mechanisms that drive speciation and the impact of gene flow on species' evolution. Molecular data is my tool to feed my curiosity. I worked on different organisms but always with an evolutionary perspective including biogeographical patterns, chromosome evolution and sympatric speciation. Now, I started to delve into the biology of the leopard seal (Hydrurga leptonyx) by investigating its global population structure. With the focus on whole genomes, I investigate the close relationships among individuals and reconstruct the demographic history of the species.
Grad Student
Ian Santos Rodriguez
I am a second-year master's student and NOAA LMRCSC Fellow In the MaMMELab. I am working in collaboration with the NOAA Southwest Fisheries Science Center, in La Jolla, CA to study Weddell seal (Leptonychotes weddellii) ecology and population dynamics in the Northern Antarctic Peninsula (NAP). I also plan to analyze Weddell seals' tissue samples to obtain genetic data that would help to place this population in a broader context relative to other breeding colonies around the Antarctic. At the limit of their distribution, NAP Weddell seals can provide unique insights into how the species is responding to environmental change, as this is one of the areas of the globe experiencing the most dramatic warming. Besides marine mammals, I am also generally interested in coral reefs and shark management and conservation. I aspire to earn a doctorate in marine biology, specializing in marine wildlife conservation.
Undergraduate Student
Halia Morris
I am an undergraduate senior majoring in Marine and Environmental Science from Huntsville, AL. My primary interests lie in marine mammal behavioral ecology, predator-prey interactions, and the impacts of anthropogenic stressors on these dynamics. I am currently investigating microRNA preservation in marine mammal skin samples, focusing on optimizing methods for archived samples to maximize research applications. My research broadly aims to assess the feasibility of utilizing microRNAs as biomarkers for marine mammal health. I am set to graduate in May 2025 and plan to pursue a Master's degree starting in the Fall of 2025.
Alumni
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​Graduate
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Arona Bender (2020 — 2022; grad. 2022; PhD student at Duke University)
Jaelyn Leslie (2020 — 2022; grad. 2022; biologist at NOAA Southwest Fisheries Science Center)
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Undergraduate
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Isaiah Milton (2017—2020; grad. 2020)
Nefertiti Smith (2017—2020; grad. 2020; PhD candidate @ University of California Irvine)
Kathryn Cruz (2017- 2021; grad. 2021)
Olivera Stojilovic (2019—2020; grad. 2020; EU project manager @ Sustainability science, Horizon Europe)
Andre Roots (2020—2022; grad. 2022; PhD student @ University of Pennsylvania; NSF GRFP recipient)
Olivia Mitchell (2020—2022; grad. 2022; research assistant @ Boston Children’s Hospital)
Auriel Sanders (2022—2023; grad. 2023; laboratory assistant @ National Institutes of Health)
Jahia Collier (2022—2024; grad. 2024)
Kiera Ward (2022- 2024; grad. 2024; Masters in Teaching program @ Hampton University)
Jorda Prater (2023—2024; still enrolled)
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Lab affiliates (co-mentored by Dr. Carolina Bonin Lewallen)
Langston Forbes-Jackson (masters student; grad. 2024)
Maya Williams (masters student; still enrolled)
Linda Miranda (masters student; still enrolled)
Josette McLean (masters student; grad. 2021; PhD student at Duke University; NSF GRFP recipient)
Janelle Layton (undergraduate, grad. 2020; PhD student at Oregon State University; NSF GRFP recipient)
The Lab
Behavior
Marine mammal species are typically elusive due to the fact that they spend a significant amount of time submerged in water and occur in places where humans cannot track them for long periods of time. Therefore, indirect methods of studying marine mammal behavior can be very useful. Our lab has been particularly interested in the use molecular markers to unravel marine mammal reproductive behavior and social structure. For example, parentage assignments and pedigree reconstruction can also help us understand mating systems, which play a key role in population dynamics and evolutionary trajectories.
We can also use genotypes to match individuals over space and time or use relatedness estimations to assess if there are kin associations among individuals within and across areas where they occur. This gives us clues about what drives marine mammal movements and can help us predict their responses to environmental change. Ultimately, behavioral ecology studies also help contextualize species-level genetic diversity and improve management strategies of marine mammals.
Epigenetics
Epigenetic (or epigenomics, when we refer to genome-scale data) mechanisms such as histone marks, DNA methylation and non-coding RNAs, work beyond the DNA sequence to orchestrate how genes operate. In human genetics, epigenomics has received a lot of attention for the past 40 years, perhaps because most human diseases involve epigenetic alterations (including ageing!) and epigenetic markers are also very useful in diagnostics of numerous diseases. In our lab, we have been exploring a class of epigenetic regulators: microRNAs (miRNAs). They are short non-coding RNAs typically involved in gene expression suppression. There are few key reasons why we are interested in miRNAS.
First, these molecules are highly conserved, allowing for easier functional inferences in non-model organisms. Second, due to their coupling with proteins, they resist degradation very well, so high quality data can be obtained from archived tissues. Our miRNA projects explore how marine mammal adaptations (e.g., the remarkable skin of dolphins!) are reflected in the epigenome; but we also believe in these molecules’ future potential to serve as biomarkers for disease and organ injury in marine mammals.
Genetics & Genomics
Our lab has been making the transition from genetics to genomic scale data and questions, by taking two approaches: 1) bringing bioinformatics experts to our lab and 2) fostering interdisciplinary, highly collaborative teams that can help us integrate various aspects of ecology, behavior and physiology into our research. Our lab just completed the first assembly of the leopard seal genome, and we look forward to exploring questions about the biology and evolution of the this species in a comparative framework. We are also continuing the sequencing of single genes to gain basic insights into population structures of marine mammals like the Weddell seal.
