Parental age effects on offspring fitness in a wild population of a short-lived reptile

As organisms age, the fitness of the offspring they produce can decline, which is often attributed to parental senescence. However, few studies have tested for effects of parental age on offspring fitness in wild populations or in short-lived vertebrates, and only recently have studies begun to examine such effects in male and female offspring independently. Here, we use five generations of mark-recapture and genetic parentage data from an island population of a short-lived lizard, the brown anole (Anolis sagrei), to test for effects of maternal and paternal age on the survival to adulthood, first-year reproductive success, longevity, and lifetime fitness of their offspring. We tested for effects of maternal and paternal age on components of offspring fitness using two methods: 1) “within-year” analyses of parents of different ages within the same annual reproductive season, and 2) “within-parent” repeated-measures analyses of the same parents at different ages across successive reproductive seasons. Our study adds to the growing literature suggesting that negative effects of parental age on offspring fitness may not be as prevalent as once thought, particularly in wild populations.

随着生物体衰老，其所产生的后代适合度会逐渐下降，这一现象通常被归因于亲本衰老（parental senescence）。然而，目前鲜有研究在野生种群或短命脊椎动物中检验亲本年龄对后代适合度的影响，且直至近年才有研究开始针对雄性与雌性后代分别考察此类效应。本研究利用来自某岛屿种群的短命蜥蜴——棕色安乐蜥（Anolis sagrei）——的五代标记重捕与遗传亲本身份数据，检验母本与父本年龄对其子代成体存活率、首年繁殖成功率、寿命以及终生适合度的影响。我们采用两种方法检验亲本年龄对后代适合度组分的影响：1) "年内分析"，即对同一年度繁殖季内不同年龄的亲本开展分析；2) "亲本内重复测量分析"，即对连续繁殖季内不同年龄的同一亲本进行重复测量分析。本研究为日益增长的相关研究文献补充了证据，表明亲本年龄对后代适合度的负面影响或许并不如以往所认为的那般普遍，在野生种群中这一效应尤为突出。