Department of Zoology, University of Graz, Universitätsplatz 2, Graz 8010, Austria Behavioural Ecology, University of Bern, Wohlenstrasse 50A, 3032 Hinterkappelen, Switzerland.
Mol Ecol. 2012 Jun;21(11):2805-15. doi: 10.1111/j.1365-294X.2012.05573.x. Epub 2012 Apr 12.
Uniparental maternal brood care often coincides with multiple paternity and single maternity of broods, possibly reflecting benefits of polyandry and costs of uniparental care. Genetic data from the maternally mouthbrooding cichlid fish Simochromis pleurospilus revealed the opposite pattern--low polyandry and allomaternal care. More than 70% of the investigated females had mated with a single male, and 14% of the females had unrelated fry in their broods. Broods with foreign fry were in the late stage of brood care, in which females guard free-swimming fry and recall the broods into their mouths for protection. With one exception, fostering females were related to their adopted fry at the level of first cousins (R(QG) > 0.12), but relatedness between fosters and adopted fry was not significantly higher than between fosters and fry tended by other females. Relatedness among breeders extended to the level of first-order relatives. Mean relatedness among contemporaneously breeding dams (R(QG) = 0.08) was significantly higher than among dams breeding in different seasons (R(QG) = -0.04), which suggests a temporal or spatial concentration of mouthbrooding relatives. Indeed, females sometimes brood in small groups. This behaviour may reduce brood predation but will increase the risk of brood mixing, which is possibly mitigated by low costs of brood care and indirect benefits accrued by relatedness among the breeders in the group. Remarkably, the apparent inbreeding potential did not give rise to bet-hedging polyandry or active avoidance of relatives, as half of the mated individuals were related at R(QG) > 0.13 and polyandry did not coincide with high within-pair relatedness.
单亲母性亲代育幼通常与多父体和单母体的育幼同时发生，这可能反映了多父体的益处和单亲育幼的成本。来自亲代口育慈鲷鱼 Simochromis pleurospilus 的遗传数据显示出相反的模式——低多父体和异亲育幼。超过 70%的调查雌性与单一雄性交配，14%的雌性在其育幼中有非亲缘关系的幼鱼。带有外来幼鱼的育幼处于育幼后期，此时雌性会保护自由游动的幼鱼，并将育幼召回口中进行保护。除了一个例外，寄养雌性与其收养的幼鱼在一级表亲（R(QG) > 0.12）的水平上有关联，但寄养者与其收养的幼鱼之间的亲缘关系并不显著高于其他雌性抚养的幼鱼之间的亲缘关系。亲代之间的亲缘关系延伸到一级亲属的水平。同期育母之间的平均亲缘关系（R(QG) = 0.08）显著高于不同季节育母之间的亲缘关系（R(QG) = -0.04），这表明存在亲代的时间或空间集中现象。事实上，雌性有时会在小群体中育幼。这种行为可能会降低育幼被捕食的风险，但会增加育幼混合的风险，这可能通过低育幼成本和群体中亲代之间的间接利益得到缓解。值得注意的是，明显的近亲繁殖潜力并没有导致风险分散的多父体或主动回避亲缘关系，因为一半的交配个体在 R(QG) > 0.13 时具有亲缘关系，并且多父体并不与高的个体内亲缘关系同时发生。
