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 (2021, 2023), at Kuaihelani (2022, 2023), and at Hōlanikū (2023) to characterize the reproductive mode and patterns of gene flow. Tetrasporophytes overwhelmingly dominated, although eight cystocarpic female gametophytes (<1%) were documented. We observed evidence of very high clonal rates, accompanied by an increase in homozygosity. Surprisingly, our temporal analyses suggested site-specific trends in the predominance of selfing, outcrossing, or clonality. A very small haploid proportion combined with high genetic drift rendered temporal analyses of genotypic frequencies challenging to implement and interpret, such that point estimates were a better reflection of reproductive mode variation. Genetic differentiation increased with geographic distance, with strong temporal and spatial structure. The reduced genetic diversity, decreasing heterozygosity over time, and high spatial and temporal genetic discontinuities combined with the dominance of tetrasporophytes suggest a recent introduction of C. tumulosa in this region, possibly via marine debris rather than a regional opportunistic species undergoing population eruptions. Future studies should focus on identifying the native range to document the ecological and evolutionary shifts that have facilitated the rapid increase and spread of C. tumulosa and its potential similarities to other invasive haploid-diploid algae.
Related
- De novo transcriptome of the red alga Gracilariopsis tenuifrons (Gracilariales, Rhodophyta) in response to prolonged temperature stress
- Characteristics and consequences of H2O undersaturation and low melt fertility in mountain belt interiors
- Consequences on energy and water exchanges of airflow modifications in agrivoltaic systems
- From extreme weather to agricultural consequences with agentic AI
- Spatially compounding climate extremes and environmental risk: cross-regional synchrony, spatial buffering loss, and systemic consequences
BibTeX
@article{williams2026consequences,
title = {{The consequences of partial clonality on the spatiotemporal genetic structure of the red alga Chondria tumulosa (Ceramiales, Rhodophyta)}},
author = {Taylor Williams and Heather Spalding and Solenn Stoeckel and Brian Hauk and Jonathan Plissner and Randall Kosaki and Stacy Krueger-Hadfield},
journal = {Journal of Phycology},
year = {2026},
month = jul,
doi = {10.1111/jpy.70214},
url = {https://hal.inrae.fr/hal-05797388v1},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - The consequences of partial clonality on the spatiotemporal genetic structure of the red alga Chondria tumulosa (Ceramiales, Rhodophyta)
AU - Taylor Williams
AU - Heather Spalding
AU - Solenn Stoeckel
AU - Brian Hauk
AU - Jonathan Plissner
AU - Randall Kosaki
AU - Stacy Krueger-Hadfield
PY - 2026
DA - 2026/07/29
JO - Journal of Phycology
DO - 10.1111/jpy.70214
UR - https://hal.inrae.fr/hal-05797388v1
AB - 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 (2021, 2023), at Kuaihelani (2022, 2023), and at Hōlanikū (2023) to characterize the reproductive mode and patterns of gene flow. Tetrasporophytes overwhelmingly dominated, although eight cystocarpic female gametophytes (<1%) were documented. We observed evidence of very high clonal rates, accompanied by an increase in homozygosity. Surprisingly, our temporal analyses suggested site-specific trends in the predominance of selfing, outcrossing, or clonality. A very small haploid proportion combined with high genetic drift rendered temporal analyses of genotypic frequencies challenging to implement and interpret, such that point estimates were a better reflection of reproductive mode variation. Genetic differentiation increased with geographic distance, with strong temporal and spatial structure. The reduced genetic diversity, decreasing heterozygosity over time, and high spatial and temporal genetic discontinuities combined with the dominance of tetrasporophytes suggest a recent introduction of C. tumulosa in this region, possibly via marine debris rather than a regional opportunistic species undergoing population eruptions. Future studies should focus on identifying the native range to document the ecological and evolutionary shifts that have facilitated the rapid increase and spread of C. tumulosa and its potential similarities to other invasive haploid-diploid algae.
SN - 0022-3646
SN - 1529-8817
ER -