Isvaran Kavita, Sankaran Sumithra
Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India
Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India.
Biol Lett. 2017 Oct;13(10). doi: 10.1098/rsbl.2017.0313.
Fertilizations by males outside the social breeding group (extra-group paternity, EGP) are widespread in birds and mammals. EGP is generally proposed to increase male reproductive skew and thereby increase the potential for sexual selection, but the generality of this relationship is unclear. We extracted data from 27 mammals in seven orders and used phylogenetic comparative methods to investigate the influence of EGP and social mating system on measures of inequality in male fertilization success, which are indices of the potential for sexual selection. We find that EGP and social mating system can predict the potential for sexual selection in mammalian populations, but only when considered jointly and not individually. EGP appears to increase the potential for sexual selection but only when the degree of social polygyny is relatively low. When social polygyny is high, EGP appears to result in a more uniform distribution of reproduction and a decrease in the potential for sexual selection. A possible explanation to be investigated is that the phenotype of extra-group fathers differs systematically across social mating systems. Our findings have implications for the use of EGP and social mating system as indices of sexual selection in comparative analyses of trait evolution under sexual selection.
社会繁殖群体之外的雄性受精行为（婚外亲子关系，EGP）在鸟类和哺乳动物中广泛存在。一般认为，EGP会加剧雄性繁殖偏态，进而增加性选择的可能性，但这种关系是否普遍尚不清楚。我们从七个目27种哺乳动物中提取数据，并运用系统发育比较方法，研究EGP和社会交配系统对雄性受精成功率不平等指标的影响，这些指标是性选择潜力的指数。我们发现，EGP和社会交配系统能够预测哺乳动物种群的性选择潜力，但只有在综合考虑而非单独考虑时才成立。EGP似乎会增加性选择潜力，但前提是社会一夫多妻制程度相对较低。当社会一夫多妻制程度较高时，EGP似乎会导致繁殖分布更加均匀，性选择潜力降低。一个有待研究的可能解释是，婚外父本的表型在不同社会交配系统中存在系统性差异。我们的研究结果对于在性选择下性状进化的比较分析中，将EGP和社会交配系统用作性选择指标具有启示意义。
