Experimental evidence for antagonistic effects of sperm competition in two sea urchin species
- 1University of Gothenburg
Abstract
Sperm competition can occur when sperm from two or more males compete for fertilization of a batch of eggs. While it has been extensively studied in internal fertilizers, it remains poorly under-stood in external fertilizers. To investigate how sperm competition affects fertilization under sperm limitation, we conducted controlled experiments on two sea urchin species: Paracentrotus lividus and Dendraster excentricus. Eggs from a single female were exposed to sperm from three individ-ual males separately (non-competitive treatment) or to a pooled sample from three males (competi-tive treatment). We measured fertilization success as proportion of eggs fertilized after two hours and assessed sperm motility as percentage of motile sperm and curvilinear velocity. For P. lividus , we estimated the sperm concentrations where fertilization success was 50% of maximum observed fertilization success (F50), and the fertilization efficiency of the sperm (Fe), i.e. the likelihood that a sperm - egg encounter results in a fertilizing contact, using the fertilization kinetics model of Styan (1998). For D. excentricus, fertilization success was measured at a sperm concentration expected to produce 50% fertilization success. Sperm competition reduced fertilization success and increased F50 compared to non-competitive treatments, suggesting antagonistic effects that may compromise fertilization under sperm-limited conditions in external fertilizers.
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BibTeX
@misc{kumpitsch2026experimental,
title = {{Experimental evidence for antagonistic effects of sperm competition in two sea urchin species}},
author = {L. Kumpitsch and L. M. Beckmann and S. E. Hanson and E. Paredes and J. Gonzalez Fernandez and L. Langer and J. T. Lifjeld and E. H. Leder and J. N. Havenhand},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.08.757654},
url = {https://www.biorxiv.org/content/10.64898/2026.10.08.757654v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Experimental evidence for antagonistic effects of sperm competition in two sea urchin species
AU - L. Kumpitsch
AU - L. M. Beckmann
AU - S. E. Hanson
AU - E. Paredes
AU - J. Gonzalez Fernandez
AU - L. Langer
AU - J. T. Lifjeld
AU - E. H. Leder
AU - J. N. Havenhand
PY - 2026
DA - 2026/10/08
PB - bioRxiv
DO - 10.64898/2026.10.08.757654
UR - https://www.biorxiv.org/content/10.64898/2026.10.08.757654v1
AB - Sperm competition can occur when sperm from two or more males compete for fertilization of a batch of eggs. While it has been extensively studied in internal fertilizers, it remains poorly under-stood in external fertilizers. To investigate how sperm competition affects fertilization under sperm limitation, we conducted controlled experiments on two sea urchin species: Paracentrotus lividus and Dendraster excentricus. Eggs from a single female were exposed to sperm from three individ-ual males separately (non-competitive treatment) or to a pooled sample from three males (competi-tive treatment). We measured fertilization success as proportion of eggs fertilized after two hours and assessed sperm motility as percentage of motile sperm and curvilinear velocity. For P. lividus , we estimated the sperm concentrations where fertilization success was 50% of maximum observed fertilization success (F50), and the fertilization efficiency of the sperm (Fe), i.e. the likelihood that a sperm - egg encounter results in a fertilizing contact, using the fertilization kinetics model of Styan (1998). For D. excentricus, fertilization success was measured at a sperm concentration expected to produce 50% fertilization success. Sperm competition reduced fertilization success and increased F50 compared to non-competitive treatments, suggesting antagonistic effects that may compromise fertilization under sperm-limited conditions in external fertilizers.
ER -