title: Sperm morphology in two house mouse subspecies: do wild-derived strains and wild mice tell the same story?
abstract: Being subject to intense post-copulatory selection, sperm size is a principal determining component of male fitness. Although previous studies have presented comparative sperm size data at higher taxonomic levels, information on the evolution of sperm size within species is generally lacking. Here, we studied two house mouse subspecies, Mus musculus musculus and Mus musculus domesticus, which undergo incipient speciation. We measured four sperm dimensions from cauda epididymis smears of 28 wild-caught mice of both subspecies. As inbred mouse strains are frequently used as proxies for exploring evolutionary processes, we further studied four wild-derived inbred strains from each subspecies. The subspecies differed significantly in terms of sperm head length and midpiece length, and these differences were consistent for wild mice and wild-derived strains pooled over genomes. When the inbred strains were analyzed individually, however, their strain-specific values were in some cases significantly shifted from subspecies-specific values derived from wild mice. We conclude that: (1) the size of sperm components differ in the two house mouse subspecies studied, and that (2) wild-derived strains reflect this natural polymorphism, serving as a potential tool to identify the genetic variation driving these evolutionary processes. Nevertheless, we suggest that more strains should be used in future experiments to account for natural variation and to avoid confounding results due to reduced variability and/or founder effect in the individual strains.
authors.affiliation: Research Facility Studenec, Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic; Department of Zoology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Albrechtová
authors.affiliation: Research Facility Studenec, Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic; Department of Zoology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Albrecht
authors.affiliation: Research Facility Studenec, Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
authors.forename: Ludovít
authors.initials: L
authors.lastname: Ďureje
authors.affiliation: Department of Ecology and Evolutionary Biology and Museum of Zoology, University of Michigan, Ann Arbor, MI, United States of America.
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Pallazola
authors.affiliation: Research Facility Studenec, Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Piálek
mesh_terms: D000818:Animals; D049810:Genetic Speciation; D014644:Genetic Variation; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D013094:Spermatozoa / Q000166:cytology*