Recent studies showed that alternative splicing (AS) is much more prevalent in plants than previously thought. Both genome-wide analyses and cases studies of AS in response to abiotic stresses indicate the importance of AS for plant adaptation in a changing environment. However, how plants regulate their AS in response to herbivore attack, one of major biotic stresses that threaten plant fitness, remains unknown. The tight association between AS and environmental stresses also points to the rapid evolution of AS. However, the underlying mechanisms for this rapid evolution are unknown in plants. In this thesis, I aimed to address these two main questions by investigating the genome-wide insect herbivore-induced AS alteration in wild tobacco (Nicotiana attenuata) and by systematically studying the mechanisms that contributed to the evolution of AS among six plant species.