{
  "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.",
  "abstract_shown": true,
  "affiliations": [
    "University of Gothenburg"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 9,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "L. Kumpitsch"
    },
    {
      "name": "L. M. Beckmann"
    },
    {
      "name": "S. E. Hanson"
    },
    {
      "name": "E. Paredes"
    },
    {
      "name": "J. Gonzalez Fernandez"
    },
    {
      "name": "L. Langer"
    },
    {
      "name": "J. T. Lifjeld"
    },
    {
      "name": "E. H. Leder"
    },
    {
      "name": "J. N. Havenhand"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1jdcqkx3s5tc7.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.10.08.757654",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.10.08.757654v1.full",
  "id": "1jdcqkx3s5tc7",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.10.08.757654v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "evolutionary biology"
    ],
    [
      "openalex",
      "1104|Echinoderm biology and ecology"
    ]
  ],
  "openalex": "W7221455195",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.10.08.757654v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1jdcqkx3s5tc7.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:26:59Z",
      "native_id": "10.64898/2026.10.08.757654",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.10.08.757654v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "biorxiv:evolutionary biology",
      "subfield": "evolutionary-biology"
    }
  ],
  "title": "Experimental evidence for antagonistic effects of sperm competition in two sea urchin species",
  "title_text": "Experimental evidence for antagonistic effects of sperm competition in two sea urchin species",
  "type": "preprint",
  "updated_at": "2026-10-30T12:26:59Z",
  "url": "https://research.draconitic.com/paper/1jdcqkx3s5tc7",
  "venue": "bioRxiv",
  "versions": []
}