How does the timing of weapon loss influence reproductive traits and trade-offs in the insect Narnia femorata?

A longstanding goal of evolutionary biology is to understand among-individual variation in resource allocation decisions and the timing of these decisions. Recent studies have shown that investment in elaborate and costly weapons can result in trade-offs with investment in testes. In this study, we ask the following questions: At what point plasticity in resource allocation to these different structures ceases during development, if at all? Furthermore, can individuals tailor their reproductive behavior to accompany structural changes? We experimentally addressed these questions in the insect Narnia femorata, quantifying resource reallocation across development for the first time, using a phenotypic engineering approach. To investigate whether allocation plasticity diminishes throughout ontogeny, we induced weapon loss at a range of different developmental stages and examined subsequent testes mass and reproductive behavior. We found that relative testes mass increased as weapon investment decreased, implying a direct trade-off between testes and weapon investment. However, autotomy postadulthood ceased to induce larger testes mass. Intriguingly, losing a weapon while young was associated with extended adult mating duration, potentially enabling compensation for reduced fighting ability. Our results highlight the importance of examining the ontogeny of trade-offs between reproductive traits and the flexibility of the relationship between reproductive morphology and behavior.

A tangled web: Comparing inter- and intraspecific mating dynamics in Anasa squash bugs.

Reproductive interference, reproductive interactions between heterospecific individuals including mating, is commonly reported across taxa, but its drivers are still unclear. Studying interspecific matings in the context of their conspecific mating system-by relating an individual's conspecific mating behaviour to its heterospecific interactions-offers a powerful approach to address this uncertainty. Here, we compare inter- and intraspecific mating dynamics in the squash bug Anasa tristis and its close relative Anasa andresii under semi-natural conditions. Using replicated enclosures, we surveyed the mating behaviour of individually marked A. tristis and A. andresii (five males and five females of each species per trial) at hourly intervals using a robotic camera system over a 14-day period. We uncovered high levels of reproductive interference (19% of individuals engaged in interspecific matings), but the majority of mating activity took place between conspecifics. A. tristis females which engaged in interspecific matings had comparable hatching success with those which did not. Therefore, in this system, relatively high levels of reproductive interference may emerge under semi-natural conditions as a by-product of limited intraspecific pre-copulatory choice paired with limited fitness penalties for at least one of the species involved.

Expanding the landscape of opportunity: Professional societies support early-career researchers through community programming and peer coaching.

Weaving the future of the field of comparative psychology is dependent on the career advancement of early-career scientists. Despite concerted efforts to increase diversity in science, technology, engineering, and mathematics, scholars from marginalized groups are disproportionately underrepresented in the field-especially at advanced career stages. New approaches to sponsorship, mentoring, and community building are necessary to retain talent from marginalized communities and to create a culture and a system where all individuals can thrive. We describe the unique and supportive role of senior women scientists united through a professional society in initiating peer coaching circles to facilitate the success of a diverse cohort of early-career women scientists. We offer our experiences with the Weaving the Future of Animal Behavior program as a case study that illustrates the cascading impacts of professional societies investing in the success and career development of marginalized scholars. We focus on our peer coaching circle experience and share the products and outcomes after 2 years of meeting. Peer coaching transformed us from a group of loosely organized, anxious individuals into a collective of empowered agents of change with an enhanced sense of belonging. We end by presenting recommendations to institutions seeking to expand the landscape of opportunities to other marginalized scholars. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Long-term reproductive success is predicted by sexual behavior and impaired by temporary nutritional stress during sexual maturation.

Nutritional stress during the earliest stages of an animal's life can have long-term effects on its behavior and reproductive performance, but the effects of brief periods of nutritional stress later in life are less well-studied. We manipulated female diet in Narnia femorata (Hemiptera: Coreidae) and investigated to what extent nutritional stress during sexual maturation affects subsequent sexual behavior and long-term offspring production. We show that nutritional stress at this key point during early adulthood can have lasting effects on reproduction, impairing long-term offspring production despite the subsequent return of good nutrition. These results demonstrate that nutritional availability during late stages of development, in young adults, can be crucial to future fitness. We found no effect of temporary nutritional stress on female receptivity to mating or attractiveness to males; although females that were less receptive also produced fewer offspring in the next month. Overall, we demonstrate that even brief periods of nutritional deprivation late in development can have drastic long-term effects, apparently beyond compensation, and despite a good early nutritional environment.

Extreme variation in testes size in an insect is linked to recent mating activity.

Ample sperm production is essential for successful male reproduction in many species. The amount of sperm a male can produce is typically constrained by the size of his testes, which can be energetically expensive to grow and maintain. Although the economics of ejaculate allocation has been the focus of much theoretical and empirical literature, relatively little attention has been paid to individual adult variation and plasticity at the source of sperm production, the testes themselves. We experimentally address this issue using the insect Narnia femorata Stål (Hemiptera: Coreidae). We established the metabolic cost of testicular tissue and then quantified variation in individual testes mass in response to multiple mate quality and quantity treatments. We uncovered extreme variation across individuals and considerable short-term effects of mating activity on testes dry mass. Importantly, the observed variation in testes mass was associated with notable fitness consequences; females paired with males with larger testes had greater hatching success. Overall, pairing with a female resulted in a 11% reduction in dry testes mass. Despite this apparent considerable mating investment, we found no evidence of strategic allocation to higher quality females or longer-term changes in testes mass. The dynamic nature of testes mass and its metabolic cost is vital to consider in the context of re-mating rates, polyandry benefits and general mating system dynamics both in this species and more broadly.

Mating failure.

Greenway et al. introduce the concept of mating failure, the failure to produce offspring.

The repeatability of mating failure in a polyandrous bug.

Mating failure, characterized by the lack of production of offspring following copulation, is relatively common across taxa yet is little understood. It is unclear whether mating failures are stochastic occurrences between incompatible mating partners or represent a persistent, meaningful phenotype on the part of one or other sex. Here we test this in the seed bug Lygaeus simulans, by sequentially mating families of males with randomly allocated unrelated females and calculating the repeatability of mating outcome for each individual male and family. Mating outcome is significantly repeatable within individual males but not across full-sib brothers. We conclude that mating failure represents a consistent male-associated phenotype with low heritability in this species, affected by as yet undetermined environmental influences on males.

Experimental reduction of intromittent organ length reduces male reproductive success in a bug.

It is now clear in many species that male and female genital evolution has been shaped by sexual selection. However, it has historically been difficult to confirm correlations between morphology and fitness, as genital traits are complex and manipulation tends to impair function significantly. In this study, we investigate the functional morphology of the elongate male intromittent organ (or processus) of the seed bug Lygaeus simulans, in two ways. We first use micro-computed tomography (micro-CT) and flash-freezing to reconstruct in high resolution the interaction between the male intromittent organ and the female internal reproductive anatomy during mating. We successfully trace the path of the male processus inside the female reproductive tract. We then confirm that male processus length influences sperm transfer by experimental ablation and show that males with shortened processi have significantly reduced post-copulatory reproductive success. Importantly, male insemination function is not affected by this manipulation per se. We thus present rare, direct experimental evidence that an internal genital trait functions to increase reproductive success and show that, with appropriate staining, micro-CT is an excellent tool for investigating the functional morphology of insect genitalia during copulation.