The consequences of partial clonality on the spatiotemporal genetic structure of the red alga Chondria tumulosa (Ceramiales, Rhodophyta)

ABSTRACT The relative rates of sexual versus clonal reproduction partition genetic diversity but the quantification of these rates remains limited in natural populations. This knowledge gap is particularly acute among tropical macroalgae. Chondria tumulosa is a red macroalga that has been documented at high abundance in the three northernmost atolls in the Papahānaumokuākea Marine National Monument. We sampled thalli at Manawai in 2021 and 2023, at Kuaihelani in 2022 and 2023, and at Hōlanikū in 2023 to characterize the reproductive mode and patterns of gene flow. Tetrasporophytes overwhelmingly dominated at all sites, atolls, and years, although eight cystocarpic female gametophytes (