Kruuk L E, Clutton-Brock T H, Rose K E, Guinness F E
Department of Zoology, University of Cambridge, UK.
Proc Biol Sci. 1999 Aug 22;266(1429):1655-61. doi: 10.1098/rspb.1999.0828.
In polygynous, sexually dimorphic species, sexual selection should be stronger in males than in females. Although this prediction extends to the effects of early development on fitness, few studies have documented early determinants of lifetime reproductive success in a natural mammal population. In this paper, we describe factors affecting the reproductive success of male and female red deer (Cervus elaphus) on the island of Rum, Scotland. Birthweight was a significant determinant of total lifetime reproductive success in males, with heavier-born males being more successful than lighter ones. In contrast, birthweight did not affect female reproductive success. High population density and cold spring temperatures in the year of birth decreased several components of fitness in females, but did not affect the breeding success of males. The results confirm the prediction that selection on a sexually dimorphic trait should be greater in males than in females, and explain the differential maternal expenditure between sons and daughters observed in red deer. Differences between the sexes in the effects of environmental and phenotypic variation on fitness may generate differences in the amount of heritable genetic variation underlying traits such as birthweight.
在一夫多妻、具有两性异形的物种中，性选择对雄性的作用应强于雌性。尽管这一预测适用于早期发育对适合度的影响，但很少有研究记录自然哺乳动物种群中终身繁殖成功的早期决定因素。在本文中，我们描述了影响苏格兰拉姆岛上雄性和雌性马鹿（Cervus elaphus）繁殖成功的因素。出生体重是雄性终身繁殖成功的一个重要决定因素，出生时体重较重的雄性比体重较轻的雄性更成功。相比之下，出生体重并不影响雌性的繁殖成功。出生年份的高种群密度和寒冷的春季温度降低了雌性适合度的几个组成部分，但不影响雄性的繁殖成功。结果证实了这样的预测，即对两性异形性状的选择对雄性的影响应大于雌性，并解释了在马鹿中观察到的雄性和雌性之间母体投入的差异。环境和表型变异对适合度的影响在两性之间的差异可能会导致出生体重等性状的可遗传基因变异量的差异。
