title: MHC-correlated preferences in diestrous female horses (Equus caballus).
abstract: Genes of the major histocompatibility complex (MHC) have been shown to influence communication in many vertebrates, possibly with context-specific MHC-correlated reactions. Here we test for MHC-linked female preferences in the polygynous horse (Equus caballus) by repeatedly exposing 19 mares to a group of seven sexually experienced stallions. Each mare was tested four times during two consecutive reproductive cycles, twice during estrus and twice during diestrus. Male plasma testosterone concentrations were determined from weekly blood samples, and equine leukocyte antigen (ELA) class I and II alleles were determined serologically at the end of the experiments. Perception of male attractiveness was strongly dependent on estrous cycle: mean preference scores did not correlate for mares in diestrus and estrus and varied more during estrus than during diestrus. We found elevated female interests for MHC-dissimilar stallions, but only during diestrus, not during estrus. Female preferences were not significantly predicted by mean male testosterone plasma concentrations. However, testosterone concentrations changed during the 11 weeks of the experiment. By the end of the experiment, average testosterone concentration was significantly correlated to the average number of MHC alleles the stallions shared with the mares. We conclude that the MHC affects female preferences for stallions, but non-MHC linked male characteristics can overshadow effects of the MHC during estrus.
authors.affiliation: Swiss Institute of Equine Medicine, Agroscope and University of Bern, Avenches, Switzerland. Electronic address: dominik.burger@vetsuisse.unibe.ch.
authors.forename: D
authors.initials: D
authors.lastname: Burger
authors.affiliation: Swiss Institute of Equine Medicine, Agroscope and University of Bern, Avenches, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Meuwly
authors.affiliation: Department of Clinical Research, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Marti
authors.affiliation: Institute for Reproductive Biology, University of Veterinary Medicine Hanover, Hanover, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Sieme
authors.affiliation: Unit for Reproductive Medicine-Clinic for Horses, University of Veterinary Medicine Hanover, Hanover, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Oberthür
authors.affiliation: Department of Clinical Research, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Janda
authors.affiliation: Unit for Reproductive Medicine-Clinic for Horses, University of Veterinary Medicine Hanover, Hanover, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Meinecke-Tillmann
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Wedekind
mesh_terms: D000818:Animals; D030762:Estrous Cycle; D005260:Female; D006736:Horses / Q000235:genetics*; D008285:Major Histocompatibility Complex / Q000235:genetics*; D008297:Male; D052586:Mating Preference, Animal; D013739:Testosterone / Q000097:blood
chemical_list: D013739:Testosterone
keywords: Estrus cycle; Horse; MHC; Mate choice; Social communication; Testosterone