All ETDs from UAB

Advisory Committee Chair

Stacy Krueger-Hadfield

Document Type


Date of Award


Degree Name by School

Master of Science (MS) College of Arts and Sciences


Sex has generated incredible life cycle diversity across eukaryotes. Differences in the timing of meiosis and fertilization have generated tremendous variation in the duration of haploid and diploid phases. To understand what drives eukaryotic sexual diversity, there remains a need to determine the rates of sexual and asexual reproduction in natural populations. Moreover, life cycle diversity is predicted to be correlated with the reproductive system. Yet, most studies on reproductive variation have focused on diploid or diploid dominant organisms, hindering the ability to understand sex. Macroalgae can serve as useful models to overcome this limitation via life cycle and reproductive system variability. Variation among reproductive systems are often demonstrated during range expansion events, such as biological invasions. Shifts to uniparental reproduction may facilitate colonization and establishment. Across marine ecosystems, macroalgae are significant invaders, yet there is still a lack of information regarding their eco-evolutionary response during invasion, and this includes their reproductive mode. In the Hawaiian Archipelago, the spread of nuisance macroalga Avrainvillea lacerata is thought to be facilitated by asexual reproduction, but no population genetic data exist. To characterize the reproductive system of A. lacerata on Oʻahu, we developed seven microsatellite loci to genotype 321 blades collected between 2018 and 2023 at two locations along the southern coastline of Oʻahu. We found one to four alleles at a locus, suggesting A. lacerata is tetraploid. We also found high genotypic richness at all sites (R > 0.848). However, clonal rates (c) were also high at both Maunalua Bay (c = 0.5) and ʻEwa Beach (c = 0.8), suggesting asexual reproduction plays a significant role in the spread of A. lacerata. Genetic signatures of asexual reproduction are consistent with ecological data collected for A. lacerata and observations of other major macroalgal invaders in Hawaiʻi and other regions of the world. These data will provide insight into the effectiveness of management strategies in controlling the spread of A. lacerata based on its reproductive system as well as expand upon the limited available data on macroalgal population genetic patterns that are necessary for understanding the evolutionary maintenance of sex.



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