Abstract:
Transgenerational phenotypic modification can alter organismal fitness, population demographics, and community interactions. For ectotherms, both dietary composition and temperature have important effects on organismal fitness, but they are rarely investigated together. Mormon crickets Anabrus simplex are capable of diapausing as eggs in the soil for multiple years with duration largely dependent on cumulative heat units or degree days. Because Mormon crickets can be abundant in the landscape in one year and disappear suddenly the next, I asked: does parental nutrition affect the duration of egg diapause? Beginning in the ultimate nymphal instar, Mormon crickets were fed a diet high in protein, one equal in protein to carbohydrate, or a diet high in carbohydrates and the time for eggs to develop after they were laid was measured. If parental nutrition affects temperature-sensitive egg diapause, then that change in sensitivity to temperature might also alter the relationship between embryonic development rate and temperature. I asked: does parental nutrition affect embryonic development rate as a function of temperature? To this end, I manipulated densities of Mormon cricket nymphs and protein-rich prey (grasshoppers) in field cages, collected eggs from the adult Mormon crickets, and measured the optimal temperature, maximum development rate, and thermal breadth for embryonic development of the offspring. I found that Mormon crickets fed a high protein diet laid eggs with shorter diapause. Consistent with this long-term result, those housed with the most grasshoppers to eat laid eggs that had the fastest maximum development rate, whereas those without grasshoppers laid eggs with slower maximum developmental rates but the broadest thermal breadth. Eggs from Mormon crickets housed with intermediate levels of grasshopper densities had a decline in peak development rate with an increase in density. In addition, Mormon crickets housed with more conspecifics laid eggs with faster development rates, whereas thermal breadth and the temperature optima were not affected by cricket density. As predicted, Mormon cricket diets significantly affected egg diapause and development rates. Contrary to expectations based on observed changes in diet preferences during a Mormon cricket outbreak, Mormon crickets fed high protein diets laid eggs with significantly shorter egg diapause and significantly faster egg development rates. Interestingly, doubling of Mormon cricket density caused eggs to develop in nearly half the time. This latter result indicates that Mormon cricket aggregations promote rapid development of progeny. Moreover, the tight, linear structure of migratory bands in which females intermittently stop to lay eggs assures that the progeny hatch and develop in dense cohorts. In this manner, the banding behavior might carry-over into subsequent generations as long as cohorts are dense and protein is available. With band thinning or protein restriction, females spread their bet-hedging and progeny remain longer as eggs in the soil.
摘要:
代际表型修饰可以改变生物体的适应性,人口统计学,和社区互动。对于等温线,饮食成分和温度对机体健康都有重要影响,但他们很少一起调查。摩门教徒的the。Anabrussimplex能够在土壤中作为卵持续数年,其持续时间在很大程度上取决于累积的热量单位或度数。因为摩门教的the在一年内可以在景观中丰富,而在第二年突然消失,我问:父母的营养是否会影响卵滞育的持续时间?从最终的若虫龄开始,摩门教徒的蟋蟀吃了高蛋白的食物,蛋白质等于碳水化合物,或高碳水化合物的饮食,并测量产蛋后发育的时间。如果父母的营养影响对温度敏感的卵滞育,那么对温度敏感性的变化也可能改变胚胎发育速率和温度之间的关系。我问:父母的营养会影响胚胎发育率作为温度的函数吗?我操纵了野外笼子中摩门教徒若虫和富含蛋白质的猎物(蝗虫)的密度,从成年的摩门教徒身上收集到的卵,并测量了最佳温度,最大发展速度,和后代胚胎发育的热宽度。我发现,以高蛋白饮食喂养的摩门教徒会产卵,滞育时间较短。与这个长期结果一致,那些拥有最多的蝗虫吃的人产卵的最大发育速度最快,而那些没有蝗虫的产卵的最大发育速率较慢,但热宽度最大。具有中等密度的摩门教徒of的鸡蛋随着密度的增加,峰值发育率下降。此外,拥有更多物种的摩门教徒以更快的发育速度产卵,而热宽度和最佳温度不受板球密度的影响。正如预测的那样,摩门教徒板球饮食显着影响卵的滞育和发育速度。与基于摩门教板球爆发期间观察到的饮食偏好变化的预期相反,饲喂高蛋白饮食的摩门教徒the产卵的卵滞育明显更短,卵发育速度明显更快。有趣的是,摩门教板球密度加倍导致卵子在近一半的时间内发育。后一个结果表明,摩门教板球的聚集促进了后代的快速发展。此外,紧,雌性间歇性停止产卵的迁徙带的线性结构确保了后代在密集的队列中孵化和发育。以这种方式,只要队列密集且蛋白质可用,条带行为可能会延续到后代。带变薄或蛋白质限制,雌性散布下注,后代在土壤中保持更长的卵。