No abstract

Genitalia are among the fastest evolving morphological traits in arthropods. Among the many hypotheses aimed at explaining this observation, some explicitly or implicitly predict concomitant male and female changes of genital traits that interact during copulation (i.e., lock and key, sexual conflict, cryptic female choice and pleiotropy). Testing these hypotheses requires insights into whether male and female copulatory structures that physically interact during mating also affect each other's evolution and patterns of diversification. Here we compare and contrast size and shape evolution of male and female structures that are known to interact tightly during copulation using two model systems: (a) the sister species O. taurus (1 native, 3 recently established populations) and O. illyricus, and (b) the species-complex O. fracticornis-similis-opacicollis. Partial Least Squares analyses indicated very little to no correlation between size and shape of copulatory structures, both in males and females. Accordingly, comparing shape and size diversification patterns of genitalia within each sex showed that the two components diversify readily - though largely independently of each other - within and between species. Similarly, comparing patterns of divergence across sexes showed that relative sizes of male and female copulatory organs diversify largely independent of each other. However, performing this analysis for genital shape revealed a signature of parallel divergence. Our results therefore suggest that male and female copulatory structures that are linked mechanically during copulation may diverge in concert with respect to their shapes. Furthermore, our results suggest that genital divergence in general, and co-divergence of male and female genital shape in particular, can evolve over an extraordinarily short time frame. Results are discussed in the framework of the hypotheses that assume or predict concomitant evolutionary changes in male and female copulatory organs.

Insects show relatively little genital variation within species compared to extraordinary and often rapid diversification among species. It has been suggested that selection for reproductive isolation through differences in genital shape might explain this phenomenon. This hypothesis predicts that populations diverge faster in genital shape than in genital size. We tested this prediction in males from 10 dung beetle species with known phylogenetic relationships from the genus Onthophagus (Coleoptera: Scarabaeidae), including four species for which we were able to sample multiple populations. Specifically, we compared intra- and interspecific differentiation in shape and relative sizes of genitalia and calculated their respective evolutionary rates. We compared these rates to two similarly sized non-genital traits, the head and the fore-tibia. We found significant intraspecific variation in genital shape in all four species for which multiple populations were sampled, but for three of them we also identified significant relative size variation. We also found that genital shape evolved at higher rates than relative genital size. Genital shape evolved faster than head shape, but not fore-tibia shape. However, shapes of all measured structures evolved faster than their relative size. We discuss the functional constraints that may bias the developmental evolution of relative size and shape of genitalia and other morphological traits.

Female eastern tiger swallowtails (Papilio glaucus) are well-known wing coloration mimics of the toxic pipevine swallowtail (Battus philenor). Given that forewing shape is an important component of butterfly flight behaviour found in unpalatable species, we hypothesized that the mimicking females also mimic the forewing shape of their poisonous model. Thus, we predicted that mimicking eastern tiger swallowtails have a more similar wing shape to their model compared with their non-mimicking conspecific morphs. In order to test this, we compared the forewing of the model with mimicking and non-mimicking eastern tiger swallowtail morphs using a standard geometric morphometrics approach. Contrary to our hypothesis, we found significant differences of forewing shape between the two species, with no overlap, regardless of the morph. However, mimicking and non-mimicking female eastern tiger swallowtails were significantly different from each other in wing shape. This indicates that either pleiotropic effects, possibly owing to wing coloration mimicry, or selection for different flight patterns in mimics informed the evolution of forewings in this species. Additionally, we found sexual dimorphism in forewing shape within each species, which supports research indicating that both sexual selection and sex-specific natural selection are important drivers in wing shape evolution.

Evolutionary developmental biology (evo-devo) is a recently established discipline that connects evolutionary theory with developmental biology. However, despite evo-devo's integral use of diverse insect taxa as model systems and its interdisciplinary approach, current introductory entomology textbooks fail to fully integrate evo-devo into the undergraduate curriculum. We argue that an evo-devo case-study-based approach, focused on adult development, will not only familiarize students with exciting findings in this field, but will also help them deepen their understanding of basic entomological concepts. After a short background of the most important findings and methods currently used in evo-devo, we outline five case vignettes that span a variety of insect groups and entomological topics, including morphology and sexual selection.

It has been demonstrated that context is critical for meaning making and that understanding is enhanced with authentic, interactive problem‐solving opportunities. Learning theory and evidence of student learning assert that student learning outcomes in undergraduate courses should be in part predicted by years of college study. Undergraduates enrolling in introductory non‐majors biology courses come from all class levels as well as diverse academic majors. Do different class levels and academic majors predict learning outcomes in non‐majors biology courses and are these differences associated with pedagogy? This study examined final grade outcomes by class level and other relevant student demographic factors in two introductory non‐major biology courses with similar course content focus, yet different pedagogical approaches. Students randomly enrolled in either a traditional lecture course (content‐centered, CC) or a highly interactive team and case based course (student‐centered, SC). Results showed an effect of class level and academic major on final grade outcome in the CC learning environment but not in the SC learning environment. Student attitudes towards team and case based learning can partially explain student performance in the SC course. The implications of this study for the structuring of courses and curricula and evidence‐based teaching practice will be discussed.