S8-1.7 Friday, Jan. 6 Inherited adaptation via transgenerational plasticity: a case study in annual plants SULTAN, S. E. ; Wesleyan University email@example.com
An intriguing aspect of plasticity that has recently been documented in both animals and plants is the capacity for environmentally stressed parental (generally maternal) individuals to alter traits of their offspring in specific ways that enhance offspring success under those same stresses. This transgenerational aspect of plasticity constitutes a developmentally based mode of inherited adaptation that influences individual fitness, population dynamics, and species distribution. A case study is presented based on multi-generation norm of reaction experiments with naturally evolved genotypes from two well-studied annual plant species. Drought-stressed parent plants of the ecological generalist Polygonum persicaria produced seedling offspring with longer, more rapidly extending root systems and significantly greater seedling growth in dry soil, compared with the offspring of genetically identical parents that had been given ample water. In contrast, the closely related, ecologically restricted species P. hydropiper expressed maladaptive plasticity: in this species, drought-stressed parents simply produced smaller seedlings with correspondingly slower-extending root systems. Further studies with P. persicaria revealed that adaptive transgenerational drought plasticity persisted over two generations. When both parent and grandparent plants were drought-stressed, offspring size and root extension increased significantly. These seedlings also had lower mortality in very dry soil than genetically identical seedlings whose parent and/or grandparent had been amply watered, confirming the fitness impact of these inherited environmental effects. Variation in transgenerational plasticity across genotypes, taxa, environmental factors, and seed architectural position are discussed in evolutionary terms.