Mar\u00eda Varea-S\u00e1nchez; Maximiliano Tourmente; Markus Bastir; Eduardo R.S.\u00a0Roldan<\/p>\n
Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales\u00a0(CSIC), Madrid, Spain;\u00a0Department of Paleobiology, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.<\/em><\/p>\n Rodents have spermatozoa with features not seen in other species. Sperm heads in many\u00a0rodent species bear one or more apical extensions, known as \u00abhook(s)\u00bb. The process by which\u00a0hooks have evolved, together with their adaptive significance, are still controversial issues. In\u00a0order to improve our understanding of the biological meaning of these sperm head adaptations,\u00a0we analyzed hook curvature angles, hook length and overall hook shape in muroid rodents by\u00a0using geometric morphometrics. We also searched for relationships between hook design and\u00a0measures of inter-male competition to assess if postcopulatory sexual selection is an important\u00a0selective force driving changes in this sperm structure. Finally, we sought possible links between\u00a0aspects of sperm hook design and sperm velocity as a measure of sperm performance. Results\u00a0showed that one hook curvature angle is under strong selective pressure. Similarly, hook length\u00a0appears to be strongly selected by sexual selection with this selective force also exhibiting a\u00a0stabilizing role reducing inter-male variation in this trait. The adaptive significance of changes in\u00a0hook structure was underlied by the finding that there is a strong and significant covariation doi: 10.1095\/biolreprod.115.138008<\/p>\n","protected":false},"excerpt":{"rendered":"
\nbetween hook dimensions and shape and between hook design and sperm swimming velocity.
\nOverall, this study strongly suggests that postcopulatory sexual selection has an important effect\u00a0on the design of the sperm head that, in turn, is important for enhancing sperm velocity, a\u00a0function crucial to reaching the vicinity of the female gamete, and winning fertilizations under\u00a0competitive situations.<\/p>\n