Tetrasporophytic bias coupled with heterozygote deficiency in Antarctic Plocamium sp. (Florideophyceae, Rhodophyta)

• Published in: Journal of Phycology
• Main Authors: Heiser, Sabrina, Amsler, Charles D., Stoeckel, Solenn, Mcclintock, James B., Baker, Bill J., Krueger-Hadfield, Stacy, A
• Other Authors: University of Alabama at Birmingham Birmingham (UAB), University of Texas at Austin Austin, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Université de Rennes (UR)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro Rennes Angers, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), University of South Florida Tampa (USF), Antarctic Science Bursary; Clonix2D; National Science Foundation ANR-18- CE32-0001, Phycological Society of America PLR-1341333, PLR-1341339, Sigma Xi; University of Alabama at Birmingham, ANR-18-CE32-0001,Clonix2D,Les conséquences génétiques de reproduction partiellement clonale dans les populations colonisant de nouveaux territoires(2018)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: clonal rates; gametophytes; homozygote excess; mating system; seaweed; [SDE]Environmental Sciences; Antarctic; Antarctic Peninsula; Antarc*
• Online Access: https://hal.science/hal-04167428; https://doi.org/10.1111/jpy.13339

International audience Meiosis and syngamy generate an alternation between two ploidy stages, but the timing of these two processes varies widely across taxa, thereby generating life cycle diversity. One hypothesis suggests that life cycles with long-lived haploid stages are correlated with selfing, asexual reproduction, or both. Though mostly studied in angiosperms, selfing and asexual reproduction are often associated with marginal habitats. Yet, in haploid-diploid macroalgae, these two reproductive modes have subtle but unique consequences whereby predictions from angiosperms may not apply. Along the western Antarctic Peninsula, there is a thriving macroalgal community, providing an opportunity to explore reproductive system variation in haploid-diploid macroalgae at high latitudes where endemism is common. Plocamium sp. is a widespread and abundant red macroalga observed within this ecosystem. We sampled 12 sites during the 2017 and 2018 field seasons and used 10 microsatellite loci to describe the reproductive system. Overall genotypic richness and evenness were high, suggesting sexual reproduction. Eight sites were dominated by tetrasporophytes, but there was strong heterozygote deficiency, suggesting intergametophytic selfing. We observed slight differences in the prevailing reproductive mode among sites, possibly due to local conditions (e.g., disturbance) that may contribute to site-specific variation. It remains to be determined whether high levels of selfing are characteristic of macroalgae more generally at high latitudes, due to the haploid-diploid life cycle, or both. Further investigations of algal life cycles will likely reveal the processes underlying the maintenance of sexual reproduction more broadly across eukaryotes, but more studies of natural populations are required.