Warning Behaviors

The typology of eight proximal warning behaviors for targeted violence was first introduced a decade ago. Since that time, a number of studies have continued to support its interrater reliability and its criterion, discriminant, and predictive validity. Among the warning behaviors, the three most validated in discriminating between attackers and nonattackers are pathway, identification, and last resort. All of the other warning behaviors—fixation, novel aggression, energy burst, leakage, and directly communicated threat—are found at various frequencies throughout all the samples tested to date, including intimate partner homicide perpetrators, school shooters, adult mass murderers, public figure attackers, and lone actor terrorists.

Adolescent and Adult Mass Shooters

Understanding why people commit mass shootings in the United States is perplexing and discerning perpetrators' motivations is difficult because there have been a fairly limited number of shootings. In addition, there is incomplete research on mitigating historical evidence about the perpetrators. Thus, this chapter takes a broader approach to understanding why these shootings may have happened by reviewing the empirical literature to identify possible correlations from childhood and adolescent trauma experiences (and subsequent mental health problems) to later adult violence. This review supports a hypothesis that these experiences are potential links to explaining mass shooting outcomes. The trauma experiences that are identified to be most impactful include maltreatment, poverty, witnessing violence, domestic violence, deaths (violent and non-violent) of family and friends, and adolescent bullying.

Parental Photoperiod Affects Egg Diapause in a Montane Population of Mormon Crickets (Orthoptera: Tettigoniidae)

Insect diapause is a state of arrested development persisting when conditions are favorable for growth. Prolonged diapause, which occurs when insects remain in diapause for multiple years, is uncommon. Mormon crickets Anabrus simplex Haldane, a katydid and pest of rangeland forage and crops, were thought to be biennial in the Bighorn Mountains of Wyoming, but they are able to prolong diapause in the egg stage for multiple years. To test whether parental photoperiod serves as a cue to prolong diapause, mating pairs from the Bighorn Mountains were set in the same daily temperature and humidity profiles with 20 pairs on short daylength (12:12 [L:D] h) and 20 on long daylength (15:9 [L:D] h). Almost every parental pair had some undeveloped eggs after two warm periods. Females in short daylength were not more likely to have eggs with a biennial life cycle, but they were more likely than those in long daylength to lay eggs with multi-annual life cycles. Parents on short daylength were more likely to lay inviable eggs. Other fitness measures, such as hatchling mass, nymphal survivorship, and adult mass were not different between parental treatments. Diapause termination distributed over multiple years probably constitutes a bet-hedging strategy in an unpredictable environment.

Adolescent and Adult Mass Shooters

Understanding why people commit mass shootings in the United States is perplexing and discerning perpetrators' motivations is difficult because there have been a fairly limited number of shootings. In addition, there is incomplete research on mitigating historical evidence about the perpetrators. Thus, this chapter takes a broader approach to understanding why these shootings may have happened by reviewing the empirical literature to identify possible correlations from childhood and adolescent trauma experiences (and subsequent mental health problems) to later adult violence. This review supports a hypothesis that these experiences are potential links to explaining mass shooting outcomes. The trauma experiences that are identified to be most impactful include maltreatment, poverty, witnessing violence, domestic violence, deaths (violent and non-violent) of family and friends, and adolescent bullying.

Life history responses of meerkats to seasonal changes in extreme environments

Species in extreme habitats increasingly face changes in seasonal climate, but the demographic mechanisms through which these changes affect population persistence remain unknown. We investigated how changes in seasonal rainfall and temperature influence vital rates and viability of an arid environment specialist, the Kalahari meerkat, through effects on body mass. We show that climate change–induced reduction in adult mass in the prebreeding season would decrease fecundity during the breeding season and increase extinction risk, particularly at low population densities. In contrast, a warmer nonbreeding season resulting in increased mass and survival would buffer negative effects of reduced rainfall during the breeding season, ensuring persistence. Because most ecosystems undergo seasonal climate variations, a full understanding of species vulnerability to global change relies on linking seasonal trait and population dynamics.

Hybridization affects life-history traits and host specificity in Diorhabda spp

Hybridization is an influential evolutionary process that has been viewed alternatively as an evolutionary dead-end or as an important creative evolutionary force. In colonizing species, such as introduced biological control agents, hybridization can negate the effects of bottlenecks and genetic drift through increasing genetic variation. Such changes could be beneficial to a biological control program by increasing the chances of establishment success. However, hybridization can also lead to the emergence of transgressive phenotypes that could alter host specificity; an important consideration when assessing potential non-target impacts of planned agents. In a series of lab experiments, we investigated the effects of hybridization between three species of Diorhabda released to control invasive Tamarix (saltcedar) on life history traits through two generations, and through the third generation for one cross. Depending on the cross, hybridization had either a positive or neutral impact on development time, adult mass, and fecundity. We evaluated preference for the target (saltcedar) relative to a non-target host Tamarixaphylla (athel), and found host specificity patterns varied in two of the three hybrids, demonstrating the possibility for hybridization to alter host preference. Importantly, the overall effects of hybridization were inconsistent by cross, leading to unpredictability in the outcome of using hybrids in biological control.