title: A cost for high levels of sperm competition in rodents: increased sperm DNA fragmentation.
abstract: Sperm competition, a prevalent evolutionary process in which the spermatozoa of two or more males compete for the fertilization of the same ovum, leads to morphological and physiological adaptations, including increases in energetic metabolism that may serve to propel sperm faster but that may have negative effects on DNA integrity. Sperm DNA damage is associated with reduced rates of fertilization, embryo and fetal loss, offspring mortality, and mutations leading to genetic disease. We tested whether high levels of sperm competition affect sperm DNA integrity. We evaluated sperm DNA integrity in 18 species of rodents that differ in their levels of sperm competition using the sperm chromatin structure assay. DNA integrity was assessed upon sperm collection, in response to incubation under capacitating or non-capacitating conditions, and after exposure to physical and chemical stressors. Sperm DNA was very resistant to physical and chemical stressors, whereas incubation in non-capacitating and capacitating conditions resulted in only a small increase in sperm DNA damage. Importantly, levels of sperm competition were positively associated with sperm DNA fragmentation across rodent species. This is the first evidence showing that high levels of sperm competition lead to an important cost in the form of increased sperm DNA damage.
authors.affiliation: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales (CSIC), Madrid 28006, Spain School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool L3 3AF, UK delbarcotrillo@gmail.com.
authors.forename: Javier
authors.identifier: http://orcid.org/0000-0002-9948-6674
authors.initials: J
authors.lastname: delBarco-Trillo
authors.affiliation: SaBio IREC (CSIC-UCLM-JCCM), Albacete 02071, Spain.
authors.forename: Olga
authors.identifier: http://orcid.org/0000-0003-4310-0557
authors.initials: O
authors.lastname: García-Álvarez
authors.affiliation: SaBio IREC (CSIC-UCLM-JCCM), Albacete 02071, Spain.
authors.forename: Ana Josefa
authors.identifier: http://orcid.org/0000-0002-6429-5157
authors.initials: AJ
authors.lastname: Soler
authors.affiliation: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales (CSIC), Madrid 28006, Spain.
authors.forename: Maximiliano
authors.identifier: http://orcid.org/0000-0002-5833-9117
authors.initials: M
authors.lastname: Tourmente
authors.affiliation: SaBio IREC (CSIC-UCLM-JCCM), Albacete 02071, Spain.
authors.forename: José Julián
authors.identifier: http://orcid.org/0000-0002-3667-6518
authors.initials: JJ
authors.lastname: Garde
authors.affiliation: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales (CSIC), Madrid 28006, Spain.
authors.forename: Eduardo R S
authors.initials: ER
authors.lastname: Roldan
mesh_terms: D000818:Animals; D053938:DNA Fragmentation; D008297:Male; D051379:Mice / Q000502:physiology*; D013045:Species Specificity; D013094:Spermatozoa / Q000502:physiology*
keywords: capacitation; oxidative stress; rodents; sperm DNA fragmentation; sperm chromatin structure assay; sperm competition