Abstract
Age determination of wild cetaceans influences interpretation of both veterinary health assessments and biological data. Historically, aging methodologies included morphometric data and growth layer group (GLG) analysis post tooth extraction.1,2 Recently, dental and pectoral flipper radiography for non-invasive age estimation has proven useful in bottlenose dolphins (Tursiops truncatus).3,4 These methods require physical examinations during live animal health assessments, or post-mortem evaluations.5 We propose to compare epigenetic analysis of skin, which can be remotely sampled, to tooth and pectoral flipper radiography age estimations on known aged dolphins.6 Epigenetics is the study of chemical modifications to DNA and is used to create species specific aging clocks with expected changes occurring to DNA over time.7 Methods were compared on bottlenose dolphins of known age from the U.S. Navy Marine Mammal Program. Epigenetic analysis is currently underway; DNA methylation arrays were profiled using a custom Infinium methylation array (HorvathMammalMethylChip40) based on 37492 CpG sites. Tooth analysis is pending due to COVID lab closures.a We hypothesize that epidermal epigenetics is the most accurate methodology across the entire dolphin lifespan, with pectoral radiography the most accurate methodology in dolphin <5 years of age due to the low standard error of ±0.35 years in females and ±0.87 years in males.3 Future application of epigenetic aging to larger or endangered cetaceans, could allow for the filling of critical data gaps in population demographics, aiding conservation efforts. Use of this technique for the comparison of biological and chronical aging in managed and wild cetaceans, is also possible.
Acknowledgements
The authors wish to thank the involvement of Dr. Eric Jensen and the U.S. Navy Marine Mammal Program dolphins, biotechnicians, and managers, and the National Marine Mammal Foundation trainers, veterinary and medical records staff who facilitated this study. This research was made possible by a generous grant from NOAA Prescott funding. In addition the authors would like to thank Veronica Cendejas and Brittany Novick for their help with sample management.
Endnotes
a. All results, data analysis and interpretation are expected by May 2021.
*Presenting author
Literature Cited
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