11/03/2026
By Irma Silva

The Kennedy College of Sciences, Department of Biological Sciences, invites you to attend Michael Olufemi’s Ph.D. dissertation defense in applied biology, titled “Epigenetic Regulation and the Evolutionary Trajectories of Gene Duplicates in Natural Stickleback Populations.”

Details

  • Date: Monday, November 16, 2026
  • Time: 10:30 a.m. – 1 p.m.
  • Location: Lydon Library, Room 110

Committee members

  • Frederic Chain (Advisor), Associate Professor, Biological Sciences, University of Massachusetts Lowell
  • Jessica Garb (Chair), Professor, Biological Sciences, University of Massachusetts Lowell
  • Rachel Melamed, Assistant Professor, Biological Sciences, University of Massachusetts Lowell
  • Philine Feulner, Group Leader, Aquatic Ecology Department, Eawag: Swiss Federal Institute of Aquatic Science and Technology

Abstract

Gene duplication can cause genetic disorders while also providing genetic material for the evolution of new functions, with both outcomes depending on its effects on gene expression. This dissertation investigates the genomic and regulatory variation associated with recent gene duplications that vary in copy number among individuals in natural marine and freshwater populations of threespine stickleback. Long-read genome assemblies and pangenome analyses were used to characterize structural diversity and establish the genomic context of duplicated genes. Native-DNA sequencing was used to measure CpG methylation across tissues and distinguishable gene copies, while RNA sequencing was used to evaluate gene-level expression differences among copy-number states. Copy-number-variable genes showed elevated levels of promoter CpG methylation, but associations varied among genes and tissues, and individual duplicated copies frequently differed in methylation. Expression responses were also heterogeneous, with some genes showing increases below the expectation of proportional scaling with copy number. Together, these findings reveal unequal methylation among duplicated copies and an association between stronger promoter-methylation responses and weaker expression increases with copy number, supporting a potential role for DNA methylation in moderating the transcriptional consequences of gene duplication.