Clark M M, Galef B G
Physiol Behav. 1986;36(6):997-1003. doi: 10.1016/0031-9384(86)90470-1.
In previous papers, we have identified a number of differences in both the reproductive profiles and patterns of maternal care shown by female gerbils exhibiting vaginal opening either before or after weaning. Early-maturing females delivered their first litters when younger, produced a greater percentage of female offspring/litter, and a greater percentage of early-maturing daughters than late-maturing females. Further, early-maturing females exhibited reduced levels of maternal care, as assessed by time spent nursing, time pups were gathered in the nest, and probability of retrieval of displaced young. In the present experiments, we found that equating age at first parity of early- and late-maturing females (Experiment 1) eliminated differences between them in pup gathering, but not in pup retrieval or nursing. Further, equating age at first parity affected neither sex-ratios of litters at birth nor rate of maturation of daughters. Equating litter size at birth, sex-ratio of litters at birth, and maternal age at first parturition (Experiment 2) eliminated differences in the nursing behavior of early- and late-maturing females and reduced differences in retrieval behavior, but left rate of maturation of daughters unaffected. Last (Experiment 3), both daughters born to early-maturing females, reared by late-maturing females, and daughters born to late-maturing females, reared by early-maturing females, exhibited rates of maturation typical of daughters reared by their natural mothers.
在之前的论文中，我们已经确定了断奶前或断奶后出现阴道开口的雌性沙鼠在生殖特征和母性照料模式上存在一些差异。早熟雌性在更年轻时产下第一窝幼崽，每窝产雌性后代的比例更高，且早熟女儿的比例比晚熟雌性更高。此外，通过护理时间、幼崽在巢中聚集的时间以及找回被移动幼崽的概率来评估，早熟雌性表现出的母性照料水平较低。在本实验中，我们发现使早熟和晚熟雌性的初产年龄相等（实验1）消除了它们在幼崽聚集方面的差异，但在幼崽找回或护理方面没有消除差异。此外，使初产年龄相等既不影响出生时窝仔的性别比例，也不影响女儿的成熟率。使出生时的窝仔大小、出生时窝仔的性别比例和首次分娩时的母龄相等（实验2）消除了早熟和晚熟雌性在护理行为上的差异，并减少了找回行为上的差异，但女儿的成熟率不受影响。最后（实验3），由晚熟雌性抚养的早熟雌性所生的女儿，以及由早熟雌性抚养的晚熟雌性所生的女儿，都表现出由其自然母亲抚养的女儿典型的成熟率。
