Burger Dominik, Meuwly Charles, Thomas Selina, Sieme Harald, Oberthür Michael, Wedekind Claus, Meinecke-Tillmann Sabine
Swiss Institute of Equine Medicine ISME, University of Berne, and Agroscope, Avenches, Switzerland.
Unit for Reproductive Medicine-Clinic for Horses, University of Veterinary Medicine Hannover, Hanover, Germany.
PLoS One. 2018 Feb 21;13(2):e0191845. doi: 10.1371/journal.pone.0191845. eCollection 2018.
Although female preferences are well studied in many mammals, the possible effects of the oestrous cycle are not yet sufficiently understood. Here we investigate female preferences for visual and non-visual male traits relative to the periodically cycling of sexual proceptivity (oestrus) and inactivity (dioestrus), respectively, in the polygynous horse (Equus caballus). We individually exposed mares to stallions in four experimental situations: (i) mares in oestrus and visual contact to stallions allowed, (ii) mares in oestrus, with blinds (wooden partitions preventing visual contact but allowing for acoustic and olfactory communication), (iii) mares in dioestrus, no blinds, and (iv) mares in dioestrus, with blinds. Contact times of the mares with each stallion, defined as the cumulative amount of time a mare was in the vicinity of an individual stallion and actively searching contact, were used to rank stallions according to each mare's preferences. We found that preferences based on visual traits differed significantly from preferences based on non-visual traits in dioestrous mares. The mares then showed a preference for older and larger males, but only if visual cues were available. In contrast, oestrous mares showed consistent preferences with or without blinds, i.e. their preferences were mainly based on non-visual traits and could not be predicted by male age or size. Stallions who were generally preferred displayed a high libido that may have positively influenced female interest or may have been a consequence of it. We conclude that the oestrous cycle has a significant influence on female preferences for visual and non-visual male traits in the horse.
虽然在许多哺乳动物中对雌性偏好已有充分研究，但发情周期可能产生的影响尚未得到充分理解。在此，我们研究了在多配偶制的马（Equus caballus）中，相对于性接受能力（发情期）和不活跃期（间情期）的周期性变化，雌性对视觉和非视觉雄性特征的偏好。我们在四种实验情境下分别让母马与种马接触：（i）处于发情期的母马，允许与种马有视觉接触；（ii）处于发情期的母马，设置了隔板（木制隔板可防止视觉接触，但允许听觉和嗅觉交流）；（iii）处于间情期的母马，不设隔板；（iv）处于间情期的母马，设置隔板。母马与每匹种马的接触时间定义为母马在某匹种马附近并积极寻求接触的累计时间，以此根据每匹母马的偏好对种马进行排名。我们发现，处于间情期的母马基于视觉特征的偏好与基于非视觉特征的偏好存在显著差异。此时母马表现出对年龄较大和体型较大的雄性的偏好，但前提是有视觉线索。相比之下，处于发情期的母马无论有无隔板都表现出一致的偏好，即它们的偏好主要基于非视觉特征，且无法通过雄性的年龄或体型来预测。通常受青睐的种马表现出较高的性欲，这可能对雌性的兴趣产生了积极影响，也可能是其结果。我们得出结论，发情周期对马的雌性对视觉和非视觉雄性特征的偏好有显著影响。
