Apollonio Marco, Brivio Francesca, Rossi Iva, Bassano Bruno, Grignolio Stefano
University of Sassari, Department of Science for Nature and Environmental Resources, via Muroni 25, I-07100 Sassari, Italy.
Behav Processes. 2013 Sep;98:44-50. doi: 10.1016/j.beproc.2013.05.001. Epub 2013 May 11.
Alternative mating tactics (AMTs) are intrasexual variants in mating behaviour of several species ranging from arthropods to mammals. Male AMTs coexist between and within populations. In particular, male ungulates rarely adopt just one tactic throughout their lifetime. Tactics commonly change according to internal factors (age, body size, condition) and external conditions (weather, resources, predation, animal density). However, the influence of weather has not yet been investigated in upper vertebrates. Such influence may be relevant in species whose rutting period occurs late in fall or in winter, when environmental conditions and the snow cover in particular may vary considerably. We detected two AMTs in Alpine ibex (Capra ibex) males: older and full-grown males mainly adopted the tending tactic, while younger males usually pursued an alternative one (coursing tactic). Weather was found to influence the use of AMTs by males: in snowy mating seasons, the coursing tactic was no longer used due to difficulties in moving through deep snow. In snowy rutting periods, males appeared to delay or even avoid mating activities and a decrease of births was reported in the second part of the following birth season. Snow cover may have a negative effect on population dynamics by reducing the recruitment and on population genetic variability, as a consequence of poorer mating opportunities. Studies on factors affecting mating behaviour and leading to a reduced availability of mates and a decrease in female productivity are especially relevant in species, like Alpine ibex, whose genetic variability is low.
替代交配策略(AMTs)是从节肢动物到哺乳动物等多种物种交配行为中的种内变异。雄性替代交配策略在种群之间和种群内部共存。特别是,雄性有蹄类动物在其一生中很少只采用一种策略。策略通常会根据内部因素(年龄、体型、身体状况)和外部条件(天气、资源、捕食、动物密度)而改变。然而,天气对高等脊椎动物交配行为的影响尚未得到研究。这种影响在发情期发生在深秋或冬季的物种中可能很重要,因为在这个时期环境条件,尤其是积雪情况可能会有很大变化。我们在阿尔卑斯野生山羊(Capra ibex)雄性中检测到两种替代交配策略:年龄较大且发育成熟的雄性主要采用照料策略,而年轻雄性通常采用另一种策略(追逐策略)。研究发现天气会影响雄性对替代交配策略的使用:在多雪的交配季节,由于在深雪中行动困难,追逐策略不再被采用。在多雪的发情期,雄性似乎会推迟甚至避免交配活动,并且在随后产仔季节的后半段报告出生数量有所下降。积雪可能会通过减少新生个体数量对种群动态产生负面影响,并由于交配机会减少而影响种群遗传变异性。对于像阿尔卑斯野生山羊这样遗传变异性较低的物种,研究影响交配行为并导致配偶可得性降低和雌性繁殖力下降的因素尤为重要。