Spatial phylogenomics and diet evolution of the megadiverse plant bugs (Hemiptera: Miridae)
Plant bugs (Miridae; Fig. 1) are a megadiverse insect family (>11,350 described species; Cassis & Schuh, 2012) that ranks among the 20 most species-rich families of insects (Wang et al., 2014). The group includes crop pests and beneficial predatory insects used in integrated pest management and is of major economic importance (Ferreira et al., 2015; Wheeler Jr., 2001). Although most species are phytophagous, Miridae include lineages that are predatory on other insects, mycetophagous, or zoophytophagous. About 60% of phytophagous species with known host associations occur on a single host plant species (Cassis & Schuh, 2012), suggesting that their diversification has been closely associated with the evolution of land plants. Plant bugs occur in all biogeographic regions and most biomes but are particularly diverse in Mediterranean scrubs and woodlands, a biome that is acutely threatened by habitat loss (Slingsby et al., 2017). Most mirid species have limited endemic ranges, typically smaller than their host plants, making them ideal for biogeographic research. Recent federal funding has generated a vast body of biodiversity data for plant bugs, with emphasis on the >2,000 Nearctic species, that can now be used to test hypotheses on co-diversification with plants, biogeographic history, and phylogenetic diversity in Mediterranean biomes such as the California Floristic Province (CA-FP), one of only two biodiversity hotspots that reside almost entirely within the continental USA (Cassis & Schuh, 2012; Mittermeier et al., 2011; Schuh, 2013; Weirauch et al., 2017) Research in these areas has remained largely nonexistent because of the lack of robust phylogenetic hypotheses for plant bugs at appropriate taxonomic levels.
Main objectives:
A. Phylogeny: Generate a worldwide phylogeny of plant bugs (~930 taxa/>50% of genera) based on ultraconserved element (UCE) data to accurately reconstruct tribal and subtribal-level relationships and investigate the temporal and diet evolution of the group.
B. Biogeography and host evolution: Focusing on 12 important clades, determine the origin of taxa in the CA-FP and investigate the biogeographic history and host plant evolution of Nearctic Miridae. C. Phylogenetic diversity in a biodiversity hotspot: Test if phylogenetic diversity patterns of Miridae in the CA-FP hotspot correspond to those documented for plants and other animals. 3. Background.
Why Miridae? Miridae are the second-largest family of the 5th largest insect order (Hemiptera) and comprise 7 subfamilies, about 35 tribes, and >1,550 genera (Schuh, 2013). The described and undescribed species diversity together is estimated to exceed 20,000 species. The worldwide taxonomic community on Miridae is very active (>300 taxonomic publications during the past decade), but current classifications only partially reflect the phylogeny of plant bugs, mostly because phylogenetic research on much of the group is in its infancy. Plant bugs are part of the Miroidea that also include Tingidae (lace bugs; ~2,500 spp.) and Thaumastocoridae (palm and bronze bugs; ~30 spp.), which are two strictly phytophagous lineages that include pests of crops and ornamental plants. Relationships among the three families remain ambiguous (Weirauch et al., 2019; Standring et al., in prep.; Fig. 2b).