Yang Louie H, Cenzer Meredith L, Morgan Laura J, Hall Griffin W
Department of Entomology and Nematology, University of California, Davis, California, 95616, USA.
Ecology. 2020 Jul;101(7):e03029. doi: 10.1002/ecy.3029. Epub 2020 Apr 1.
Seasonal windows of opportunity represent intervals of time within a year during which organisms have improved prospects of achieving life history aims such as growth or reproduction, and may be commonly structured by temporal variation in abiotic factors, bottom-up factors, and top-down factors. Although seasonal windows of opportunity are likely to be common, few studies have examined the factors that structure seasonal windows of opportunity in time. Here, we experimentally manipulated host-plant age in two milkweed species (Asclepias fascicularis and Asclepias speciosa) in order to investigate the role of plant-species-specific and plant-age-varying traits on the survival and growth of monarch caterpillars (Danaus plexippus). We show that the two plant species showed diverging trajectories of defense traits with increasing age. These species-specific and age-varying host-plant traits significantly affected the growth and survival of monarch caterpillars through both resource quality- and quantity-based constraints. The effects of plant age on monarch developmental success were comparable to and sometimes larger than those of plant-species identity. We conclude that species-specific and age-varying plant traits are likely to be important factors with the potential to structure seasonal windows of opportunity for monarch development, and examine the implications of these findings for both broader patterns in the ontogeny of plant defense traits and the specific ecology of milkweed-monarch interactions in a changing world.
季节性机遇窗口代表一年中的时间段，在此期间生物实现生长或繁殖等生活史目标的前景有所改善，并且通常可能由非生物因素、自下而上因素和自上而下因素的时间变化构成。尽管季节性机遇窗口可能很常见，但很少有研究探讨在时间上构成季节性机遇窗口的因素。在这里，我们通过实验操纵了两种马利筋属植物（束花马利筋和美丽马利筋）的寄主植物年龄，以研究植物物种特异性和随植物年龄变化的性状对帝王蝶幼虫（黑脉金斑蝶）存活和生长的作用。我们发现，随着年龄增长，这两种植物表现出不同的防御性状轨迹。这些物种特异性且随年龄变化的寄主植物性状通过基于资源质量和数量的限制，显著影响了帝王蝶幼虫的生长和存活。植物年龄对帝王蝶发育成功的影响与植物物种身份的影响相当，有时甚至更大。我们得出结论，物种特异性和随年龄变化的植物性状很可能是构建帝王蝶发育季节性机遇窗口的重要因素，并探讨了这些发现对植物防御性状个体发育更广泛模式以及不断变化的世界中马利筋 - 帝王蝶相互作用特定生态学的影响。
