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Circadian rhythms drive many biological patterns, such as activity periods. The temporal partitioning that results can reduce predation, minimize competition, or enable new resource utilization. It can also drive the evolution of sensory systems, such as the highly specialized antennae with which male moths find mates, and the visual specializations with which butterflies escape from birds. However, the mechanisms that underlie such niche-shift adaptations are poorly understood. Many model organisms in circadian biology are too distantly related from one another to elucidate the genetic drivers of diel-niche transitions. To address this, we examined gene expression patterns between two closely related wild silk moth species (Saturniidae), that utilize similar host plants and habitats, but have undergone temporal niche divergence. We found 200-700 differentially expressed genes, including day upregulation in eye development and visual processing genes, and night upregulation of antennal and olfactory brain development genes. We also found clusters of circadian, sensory, and brain development genes co-expressing with diel-activity. Eight genes showed a clear and statistically significant correlation between expression and diel activity in both species, and were involved in vision, olfaction, brain development, neural plasticity, energy utilization, and cellular maintenance. Disconnected (disco), a zinc-finger transcription factor involved in antennal development, circadian activity, and optic lobe brain development in flies, was repeatedly recovered in multiple analyses. Whilediscomutants have circadian arrhythmia, most studies have attributed this to improper clock neuron development, and not directly to adult circadian maintenance. Comparing predicted 3D protein structure across moth (Bombyx mori)and fly (Drosophila melanogaster)genetic models revealeddiscohas likely retained its developmental function with a conserved zinc finger domain, but it has also likely gained novel functional zinc finger domains, highly conserved in moths, but absent inD. melanogaster.These regions had several mutations between nocturnal and diurnal study species that co-occur with higher levels of predicted phosphorylation sites. Together, robust circadian gene expression, functional nocturnal and diurnal mutations with high phosphorylation, structural and sequence conservation, leads us to hypothesize thatdiscomay be a master regulator contributing to the diversification of adult diel activity patterns in adult moths.SignificanceInsects have been longstanding models for understanding circadian and sensory biology. The diversity of diel-activity patterns of insects is tremendous, yet our understanding of the genetic and evolutionary processes leading to this diversity is limited. Light environment is a powerful circadian entrainer that drives diel-niche and sensory evolution. To investigate the evolutionary impact of highly shifted light environments on animals with otherwise similar ecologies, we compared gene expression in closely related day- and night-active wild silkmoths.Genes linked to eye development, neural plasticity and energy cellular maintenance showed expression patterns linked to diel activity. Notably,disco, a gene encoding a zinc finger transcription factor involved in fly (Drosophila melanogaster)optic lobe and antennal development in the pupa, shows robust adult circadian mRNA cycling in moth heads, is highly conserved in moths, and has additional zinc-finger domains with specific nocturnal and diurnal mutations. We hypothesize thatdiscomay contribute to diversification of adult diel-activity patterns in moths.

Plants inhabit spatially and temporally heterogeneous habitat with various landscape characteristics influencing growth, survival and reproduction. Utilizing microhabitat variables such as slope, elevation and aspect can allow for a spatially explicit approach to understand the important ecological drivers of population persistence. By applying knowledge about individual plant demographics and their response to microhabitat variables, inferences into how the entire population responds over time are made possible. We used a spatially-explicit individual based modeling (SEIBM) approach to model the population demographics and distribution of a restored population of Cirsium pitcheri in Illinois. Using regression analysis, we estimated model parameters for survival, growth and reproduction which were subsequently chosen by comparing observed and projected abundances. Projected population abundances followed the same trajectory as the observed abundances for our chosen model. Using that model, 100-year projections revealed that this Illinois Beach population has a median time to extinction (MTE) of 16 years, presenting a comparable outlook for C. pitcheri as compared to traditional matrix modeling approaches. We then analyzed how landscape characteristics influenced plant occupancy via hotspot analysis to determine optimum locations. Optimum plant habitat include those on low slopes and higher elevations. This approach presents a formal modeling exercise for using spatially explicit, individual-based models to conduct population viability analysis. By comparing this SEIBM approach to matrix modeling methods, we affirm that SEIBM are a valid tool for population viability analysis while also having the ability to include information that is spatially explicit to the habitat upon which C. pitcheri occupies.

Predators can induce extreme stress and profound physiological responses in prey. Insects are the most dominant animal group on Earth and serve as prey for many different predators. Although insects have an extraordinary diversity of anti-predator behavioral and physiological responses, predator-induced stress has not been studied extensively in insects, especially at the molecular level. Here, we review the existing literature on physiological predator-induced stress responses in insects and compare what is known about insect stress to vertebrate stress systems. We conclude that many unrelated insects share a baseline pathway of predator-induced stress responses that we refer to as the octopamine-adipokinetic hormone (OAH) axis. We also present best practices for studying predator-induced stress responses in prey insects. We encourage investigators to compare neurophysiological responses to predator-related stress at the organismal, neurohormonal, tissue, and cellular levels within and across taxonomic groups. Studying stress-response variation between ecological contexts and across taxonomic levels will enable the field to build a holistic understanding of, and distinction between, taxon- and stimulus-specific responses relative to universal stress responses.

Butterflies and moths (Lepidoptera) are one of the most ecologically diverse and speciose insect orders. With recent advances in genomics, new Lepidoptera genomes are regularly being sequenced, and many of them are playing principal roles in genomics studies, particularly in the fields of phylo-genomics and functional genomics. Thus far, assembled genomes are only available for