Our understanding of how novel warning color traits evolve in natural populations is largely based on studies of reproductive stages and organisms with endogenously produced pigmentation. In these systems, genetic drift is often required for novel alleles to overcome strong purifying selection stemming from frequency-dependent predation and positive assortative mating. Here, we integrate data from field surveys, predation experiments, population genomics, and phenotypic correlations to explain the origin and maintenance of geographic variation in a diet-based larval pigmentation trait in the redheaded pine sawfly (Neodiprion lecontei), a pine-feeding hymenopteran. Although our experiments confirm that N. lecontei larvae are indeed aposematic—and therefore likely to experience frequency-dependent predation—our genomic data do not support a historical demographic scenario that would have facilitated the spread of an initially deleterious allele via drift. Additionally, significantly elevated differentiation at a known color locus suggests that geographic variation in larval color is currently maintained by selection. Together, these data suggest that the novel white morph likely spread via selection. However, white body color does not enhance aposematic displays, nor is it correlated with enhanced chemical defense or immune function. Instead, the derived white-bodied morph is disproportionately abundant on a pine species with a reduced carotenoid content relative to other pine hosts, suggesting that bottom-up selection via host plants may have driven divergence among populations. Overall, our results suggest that life stage and pigment source can have a substantial impact the evolution of novel warning signals, highlighting the need to investigate diverse aposematic taxa to develop a comprehensive understanding of color variation in nature. This article is protected by copyright. All rights reserved

Preprints are manuscripts posted on a public server that do not yet have formal certification of peer review from a scholarly journal. The increasingly prominent online repositories for these preprints provide a means of rapidly making scientific results accessible to all with an Internet connection. We here describe the catalysis and subsequent development of a successful new process to solicit preprints for consideration for publication inProceedings B.We present preliminary comparisons between the focal topics and geographic origin of submitting authors of papers submitted in the traditional (non-solicited) route versus solicited preprints. This analysis suggests that the solicitation process seems to be achieving one of the primary goals of the preprint solicitation endeavour: broadening the scope of the papers featured inProceedings B. We also use an informal survey of the early-career scientists that are or have been involved with the Preprint Editorial Team to find that these scientists view their participation positively with respect to career development and knowledge in their field. The inclusion of early-career researchers from across the world in the preprint solicitation process could also translate into social justice benefits by providing a career-building opportunity and a window into the publishing process for young scientists.

Background: We challenge the oft-repeated claim that the beetles (Coleoptera) are the most species-rich order of animals. Instead, we assert that another order of insects, the Hymenoptera, are more speciose, due in large part to the massively diverse but relatively poorly known parasitoid wasps. The idea that the beetles have more species than other orders is primarily based on their respective collection histories and the relative availability of taxonomic resources, which both disfavor parasitoid wasps. Though it is unreasonable to directly compare numbers of described species in each order, the ecology of parasitic wasps – specifically, their intimate interactions with their hosts – allows for estimation of relative richness. We present a simple logical model that shows how the specialization of many parasitic wasps on their hosts suggests few scenarios in which there would be more beetle species than parasitic wasp species. We couple this model with an accounting of what we call the “genus-specific parasitoid-host ratio” from four well-studied genera of insect hosts, a metric by which to generate extremely conservative estimates of the average number of parasitic wasp species attacking a given beetle or other insect host species. Synthesis of our model with data from real host systems suggests that the Hymenoptera may have 2.5 - 3.2× more species than the Coleoptera. While there are more described species of beetles than all other animals, the Hymenoptera are almost certainly the larger order.