Inter-Cohort Competition Drives Density Dependence and Selective Mortality in a Marine Fish

For organisms with complex life cycles, the transition between life stages and between habitats can act as a significant demographic and selective bottleneck. In particular, competition with older and larger conspecifics and heterospecifics may influence the number and characteristics of individuals successfully making the transition. We investigated whether the availability of enemy-free space mediated the interaction between adult goldspot gobies (Gnatholepis thompsoni), a. common tropical reef fish, and juvenile conspecifics that had recently settled from the plankton. We added rocks, which provide refuge from predators, to one-half of each of five entire coral reefs in the Bahamas and measured the survival and growth of recent settlers in relation to adult goby densities. We also evaluated whether mortality was selective with respect to three larval traits (age at settlement, size at settlement, and presettlement growth rate) and measured the influence of refuge availability and adult goby density on selection intensity. Selective mortality was measured by comparing larval traits of newly settled gobies (≤ 5 postsettlement) with those of survivors (2-3 week postsettlement juveniles). We detected a negative relationship between juvenile survival and adult goby density in both low- and high-refuge habitats, though experimental refuge addition reduced the intensity of this density dependence. Juvenile growth also declined with increasing adult goby density, but this effect was similar in both low- and high-refuge habitats. Refuge availability had no consistent effect on selective mortality, but adult goby density was significantly related to the intensity of size-selective mortality: bigger juveniles were favored where adults were abundant, and smaller juveniles were favored where adults were rare. Given the typically large difference in sizes of juveniles and adults, similar stage-structured interactions may be common but underappreciated in many marine species

Larval exposure to predator cues alters immune function and response to a fungal pathogen in post-metamorphic wood frogs

For the past several decades, amphibian populations have been decreasing around the globe at an unprecedented rate. Batrachochytrium dendrobatidis (Bd), the fungal pathogen that causes chytridiomycosis in amphibians, is contributing to amphibian declines. Natural and anthropogenic environmental factors are hypothesized to contribute to these declines by reducing the immunocompetence of amphibian hosts, making them more susceptible to infection. Antimicrobial peptides (AMPs) produced in the granular glands of a frog’s skin are thought to be a key defense against Bd infection. These peptides may be a critical immune defense during metamorphosis because many acquired immune functions are suppressed during this time. To test if stressors alter AMP production and survival of frogs exposed to Bd, we exposed wood frog (Lithobates sylvaticus) tadpoles to the presence or absence of dragonfly predator cues crossed with a single exposure to three nominal concentrations of the insecticide malathion (0, 10, or 100 parts per billion [ppb]). We then exposed a subset of post-metamorphic frogs to the presence or absence of Bd zoospores and measured frog survival. Although predator cues and malathion had no effect on survival or size at metamorphosis, predator cues increased the time to metamorphosis by 1.5 days and caused a trend of a 20% decrease in hydrophobic skin peptides. Despite this decrease in peptides determined shortly after metamorphosis, previous exposure to predator cues increased survival in both Bd-exposed and unexposed frogs several weeks after metamorphosis. These results suggest that exposing tadpoles to predator cues confers fitness benefits later in life.Keywords: immunosuppression, AchE inhibitor, chytridiomycosis, disease ecology, brevinin, emerging infectious disease, Batrachochytrium dendrobatidis, temporin, Lithobates sylvaticus, indirect effect

The Effect of School Rape-Supportive Norms on Rape Proclivity

Rape prevention programs have recently begun using social norms interventions in addition to, or in lieu of, individual-level interventions. These programs assume that rape-supportive social norms influence the likelihood of rape. The current study tests that assumption by analyzing how school-level aggregates of men‘s rape myth acceptance (RMA) and hostile masculinity affect rape proclivity. Data for this study come from 1326 male students in 11 high schools throughout Illinois. At the individual level, risk and protective factors were similar to past studies: higher RMA and hostile masculinity were associated with increases in rape proclivity. Conversely, believing men have a responsibility to prevent rape, that they would personally intervene to prevent assault, and that there are negative consequences for perpetrating rape were all associated with decreased rape proclivity. After controlling for these individual factors, results indicate that higher school social norms for hostile masculinity increase the odds of reporting some likelihood of sexual assault. Against hypotheses, school social norms for RMA did not have a direct negative effect on proclivity; however, these results were partially qualified by interactions. School social norms for RMA appear to affect students differently depending on their own RMA. Results support efforts to target both individual and community-level factors. Implications for prevention programs are discussed

Encouraging Bystanders to Intervene: A Test of Normative Influence in an Online Training

Bystander programs on college campuses encourage community members to respond to interpersonal violence through intervening, challenging harmful social norms, and supporting survivors (Banyard, 2015). Such programs often use social norms tactics to normalize and promote intervening. Because recent federal law requires that universities offer prevention programs with bystander components to all new students and target social norms (Campus SaVE, 2013), many schools have begun using online trainings to ease compliance with that goal. While online trainings carry the advantages of personalized feedback and reaching a large number of students quickly, few have been robustly evaluated. Furthermore, the literature provides little guidance as few studies have evaluated online bystander programs, examined whether normative tactics affect bystanders’ likelihood of intervening, or examined the relationship between bystander norms and behaviors. This study addresses these gaps by comparing two common social norm tactics (injunctive messages and normative feedback) to alter perceptions of social norms and increase intentions to intervene as a bystander. Injunctive messages create an impression that others think participants should intervene whereas normative feedback provides data to show intervening is common. Together they try to make intervening seem socially desirable and normal. A randomized 2 X 2 full factorial design was used to assess the individual and interactive effects of these tactics on perceptions of social norms. Finally, the Theory of Normative Social Behavior (Rimal & Real, 2005) was applied to assess how bystander social norms relate to intentions to intervene. At a large Midwestern urban university, 218 student volunteers were randomly assigned to one of four versions of an online training: a control condition (information only),normative feedback, injunctive messages, or feedback plus injunctive messages. ANCOVAs revealed that feedback made intervening seem more common and socially accepted while injunctive messages had no effect on perceived social norms. An interaction revealed that injunctive messages and possibly feedback reduce intentions to intervene when administered alone yet have no overall impact when combined relative to control. A regression showed that norms positively relate to intentions and that the effects of social norm tactics on intentions to intervene were partly mediated by norms. Results suggest that altering perceptions of social norms may have mixed effects on intentions to intervene. Implications for bystander intervention are discussed in the context of social norms theory and reactance theory

Coordinating women\u27s preventive health care for rural veterans

PURPOSE: As the number of women veterans receiving care from the Veterans Health Administration (VHA) continues to increase, so does the need to access gender-specific preventive health care services through the VHA. In rural areas, women veterans are the numeric minority, so many preventive screenings are performed outside of the VA by community providers. As the numbers of veterans utilizing both VHA and non-VHA providers for their preventive care continue to increase, so does the need to coordinate this care. This research examines the role of the Women Veterans\u27 Care Coordinator (WVCC) at rural facilities and their perceptions of coordinating preventive care. METHODS: Between March and July 2019, semi-structured telephone interviews were conducted with WVCCs at 26 rural VA facilities. Each interview was digitally recorded and transcribed verbatim. Transcripts were loaded into Atlas.ti for further analysis. Once the codes were refined, the investigators coded the 26 interviews independently and conferred to achieve consensus on the underlying themes. FINDINGS: Five themes arose from the WVCC interviews: (1) Rural women veterans have varying needs of coordination; (2) Fragmented communication between the VA and non-VA care settings hinders effective coordination; (3) Difficulties in prioritizing rural care coordination; (4) Care coordination impacts patient care; and (5) WVCC recommendations to improve rural care coordination. CONCLUSIONS: The recent addition of WVCCs to rural facilities has expanded the VA\u27s reach to veterans living in the most rural areas. As a result, many of these women are now receiving timely, quality, and coordinated health care

Range position and climate sensitivity: The structure of among‐population demographic responses to climatic variation

Species’ distributions will respond to climate change based on the relationship between local demographic processes and climate and how this relationship varies based on range position. A rarely tested demographic prediction is that populations at the extremes of a species’ climate envelope (e.g., populations in areas with the highest mean annual temperature) will be most sensitive to local shifts in climate (i.e., warming). We tested this prediction using a dynamic species distribution model linking demographic rates to variation in temperature and precipitation for wood frogs (Lithobates sylvaticus) in North America. Using long‐term monitoring data from 746 populations in 27 study areas, we determined how climatic variation affected population growth rates and how these relationships varied with respect to long‐term climate. Some models supported the predicted pattern, with negative effects of extreme summer temperatures in hotter areas and positive effects on recruitment for summer water availability in drier areas. We also found evidence of interacting temperature and precipitation influencing population size, such as extreme heat having less of a negative effect in wetter areas. Other results were contrary to predictions, such as positive effects of summer water availability in wetter parts of the range and positive responses to winter warming especially in milder areas. In general, we found wood frogs were more sensitive to changes in temperature or temperature interacting with precipitation than to changes in precipitation alone. Our results suggest that sensitivity to changes in climate cannot be predicted simply by knowing locations within the species’ climate envelope. Many climate processes did not affect population growth rates in the predicted direction based on range position. Processes such as species‐interactions, local adaptation, and interactions with the physical landscape likely affect the responses we observed. Our work highlights the need to measure demographic responses to changing climate.Demographic processes and climate interact and vary across a species’ range to determine how species’ distributions will respond to climate change. We predicted that populations at the extremes of a species’ climate envelope are most sensitive to climate shifts. We tested this using a dynamic species distribution model linking demographic rates to variation in climate for wood frogs (Lithobates sylvaticus) in North America. Sensitivity to changes in climate cannot be predicted simply by knowing locations within the species’ climate envelope.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142087/1/gcb13817.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142087/2/gcb13817_am.pd