A Naupactus Cervinus weevil, which is a common yet invasive species in many areas of the globe, is seen chewing a leaf. Credit: Analia Lanteri/Facultad de Ciencias Naturales y Museo de La Plata, ArgentinaHow can an asexual invasive species survive in a changing environment without the evolutionary genetic variation that comes with meiotic reproduction? The surprising discovery that all-female weevils can transmit gene regulation changes to future generations has led to the surprise discovery that they can produce female offspring only from unfertilized eggs.Wellesley College's new research has shown that two types of beetles, which are common but invasive in many parts the world, use epigenetic changes in order to adapt to and respond to different toxins in their plants. These findings were published in PLOS One under the title "Host Specific Gene Expression as A Tool for Introduction Success In Naupactus Parthenogenetic Beetles." They have implications for how we view asexual invaders, and how successful they may be due to gene regulation.Andrea Sequeira, Wellesley College Gordon, and Althea Lang'26 Professor of Biology Sciences were the researchers. They collected samples from parthenogenetic, invading, and polyphagous weevils (Naupactus cerevinus and N. Leucoloma) from Florida, California, Argentina, over five years that began in 2015. The weevils, although they are from different parts of the United States, many times through commerce, are identical genetically and sexually. The team discovered that they are able to produce proteins that can be used to digest different plants, including those that produce toxic chemicals.Sequeira collaborated with a talented group: Ava Mackay Smith, Mary Kate Dornon and Rosalind Lucier from Wellesley College and Marcela Rodriguero and Viviana Confalonieri from the University of Buenos Aires. They analyzed gene expression patterns in three gene categories that could mediate weevil–host plant interactions. This included identification of suitable host plants and short-term adaptation to host-plant defenses.Sequeira stated that weevils respond differently to certain host plants, such as legumes. Sequeira said that although weevil responses to taxing host plants share many differentially expressed genes with other stressful circumstances, such as transition to new hosts and organic cultivation conditions, it suggests that there is an evolutionary-friendly shared gene expression system for different types of stressful situations.Ava Mackay Smith, 2020 Wellesley College alumna and lead author of the study, said that "we also found that mothers can 'prime" their young with these epigenetic modifications." We initially thought these changes would be visible in one generation. We found evidence that larvae have the same adaptations and proteins as their mothers when we examined them.Sequeira pointed out that this finding is particularly important because the classic understanding of sexual and asexual reproduction has been that all epigenetic markers are erased between generations, and each generation begins over.These mothers give their children a pep talk and prepare them for the harsh reality of the herbivorous insects world by passing on these gene regulation tips from generation to generation.Mackay-Smith believes having a better understanding about epigenetic changes in invasive, sexual species could eventually help to regulate or mitigate their potential adverse impact on the environment, native plants, and crops. You could think that knowing what's in the insect's repertoire could help you target specific proteins and create a pesticide that only kills that particular species of weevil.Both Mackay-Smith and Sequeira are excited to see that perhaps genetic variation is not the only form of heritable variation for natural selection to act upon and that epigenetic processes may increase the evolutionary potential of organisms in response to stress and other environmental challengesadaptations that could be relevant in the context of climate change.More information: Ava Mackay Smith et al., Host-specific gene transcription as a tool to introduce success in Naupactus partshenogenetic weevils. PLOS ONE (2021). Information from the Journal: PLoS One Ava Mackay Smith et al., Host-specific genes expression as a tool to introduce success in Naupactus partshenogenetic weevils. (2021). DOI: 10.1371/journal.pone.0248202
