Date of Graduation

5-2023

Document Type

UAF Access Only - Thesis

Degree Name

Bachelor of Science in Biology

Degree Level

Undergraduate

Department

Biological Sciences

Advisor/Mentor

Zhuang, Xuan

Committee Member/Reader

Pummill, Jeff

Committee Member/Second Reader

Coridan, Robert

Committee Member/Third Reader

Levine, Bill

Abstract

Over millions of years, new genes continuously form, leading to the fundamental question of how genetic novelty arises. To understand the process of gene birth and newly evolved traits, it is essential to investigate the evolutionary origins and mechanisms of new genes. The diverse fish antifreeze protein (AFP) provides a unique system for studying new gene and novel function formation, as they have reasonably recent origins, and their lifesaving function of preventing freezing is clearly defined and can be directly linked to natural selection. In this study, we investigate the genomic origin and evolutionary process of type I AFP (AFPI) genes in four distinct fish lineages. We have sequenced the complete genome of two AFPI-bearing species from two lineages and combining the available closely related AFPI-lacking outgroup species and other AFPI-endowed species from public database, we isolated the loci containing AFPI or homologous regions. In each lineage, the AFPI genes from AFPI-bearing species are annotated to show the gene structure, then used to compare against the genome of outgroup species and find the evolutionary precursor and homologous genomic regions. The AFPI genes in the four lineages show dissimilar sequence structure to each other and the loci do not share microsynteny, suggesting AFPI independently evolved in each lineage. The AFPI genes in AFPI-bearing species have been linked to homologous regions in outgroup species that potentially contain the ancestor sequence. We identified different precursor genes in different lineages and will further deduce the evolutionary process and molecular mechanism of the new gene birth. This study could provide an example of how novel functions arise and advance our understanding of new gene formation.

Keywords

AFP; New gene formation; novel genes; polar fish

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Available for download on Sunday, May 03, 2026

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