Richard H. Lewis

STRESS, GENES, AND GENERALIZABILITY ACROSS GENDER: EFFECTS OF MAOA AND STRESS SENSITIVITY ON CRIME AND DELINQUENCY*

In the current study, we extend the gene-by-environment interaction (cGxE) literature by examining how a widely studied polymorphism, the MAOA upstream variable number tandem repeat (MAOA-uVNTR) interacts with distal and proximal stressors to explain variation in crime and delinquency. Prior research findings have revealed that MAOA-uVNTR interacts with single indicators of environmental adversity to explain criminal behavior in general-population and incarcerated samples. Nevertheless, the genetically moderated stress sensitivity hypothesis suggests that increased risk for criminal behavior associated with variation in the MAOA-uVNTR can be best understood in the context of both distal stress during childhood and proximal stress in adulthood. Therefore, we employed Tobit regression analyses to examine a gene–distal–proximal environment (CGxExE) interaction across gender in a sample of university students (n = 267) and with data from the National Longitudinal Study of Adolescent to Adult Health (Add Health; n = 1,294). The results across both sets of analyses demonstrate that variation in the MAOA-uVNTR interacts with distal and proximal stress to lead to increased risk for criminal behavior in males. Although proximal life stress is associated with an increase in crime and delinquency, this effect is more pronounced among MAOA-L allele carriers that have experienced distal stress.

The Effect of Socioeconomic Status on Delinquency Across Urban and Rural Contexts: Using a Genetically Informed Design to Identify Environmental Risk

An extensive line of research has demonstrated that low socioeconomic status (SES) is a risk factor for adolescent delinquent behavior. The possibility that low SES affects adolescent’s risk for engaging in delinquent behavior has garnered a significant amount of empirical and public attention, given its implications for delinquency prevention. However, few studies have examined the association between low SES and delinquent behavior across urban and rural contexts in the United States. Moreover, much is unknown about the strength of the association between low SES and delinquency across urban and rural context after controlling for common genetic liabilities that often cluster within different levels of SES. The present study aimed to address these existing gaps in the literature by conducting a genetically informed analysis of sibling pairs from a nationally representative sample of U.S. youth. The results revealed that shared environmental factors accounted for 17% of the population variation in adolescent delinquent behavior among adolescents growing up in urban contexts, and 3% of this family-wide environmental effect was accounted for by SES. No evidence of a family-wide environmental effect on population variation in delinquent behavior was found among adolescents from rural contexts. Findings from the present study suggest that the association between low SES and delinquency in urban contexts in the United States may be a true environmental effect and highlight the utility of using genetically informed research designs to better understand the extent to which social contexts influence adolescent delinquent behavior.

Current Distribution of the Introduced Largespring Gambusia, Gambusia geiseri, In Texas

Abstract The largespring gambusia (Gambusia geiseri) is a livebearing fish likely endemic to the headwaters of the San Marcos River. This species thrives in cool headwater springs and, as a result of introductions for mosquito control, may now be invasive in many springs throughout Texas. Gambusia geiseri is believed to be outcompeting its endangered congener, G. nobilis, in the San Solomon Spring in western Texas and may be a threat to other endemic, spring-dwelling Gambusia. Thus, it is important to understand its current distribution. Approximately 15 years ago, the distribution of G. geiseri was documented through much of its range; however, many sites where G. geiseri occurs presently were not explored or were previously unknown. Therefore, to update the current distribution of this species in Texas, all sites previously documented, in addition to several other sites where G. geiseri now persists, were revisited. We present updated results for the distribution of G. geiseri in Texas and also provide estimates of the size of the population at each locale.

Status of the Endangered Pecos Gambusia (Gambusia nobilis) and Comanche Springs Pupfish (Cyprinodon elegans) in Phantom Lake Spring, Texas

Abstract The Pecos gambusia (Gambusia nobilis) and the Comanche Springs pupfish (Cyprinodon elegans) are federally listed as endangered, and they inhabit Phantom Lake Spring, the headwaters of the Balmorhea Springs Complex in western Texas. We censused both species to update their current status within Phantom Lake Spring, and we sought to determine whether the introduced largespring gambusia (G. geiseri) or any G. nobilis-G. geiseri hybrids were present in the spring. Resumen La gambusia de Pecos (Gambusia nobilis) y el cachorrito del manantial Comanche (Cyprinodon elegans) son enlistados por el gobierno federal como en peligro de extinción. Estas especies habitan el manantial Phantom Lake, el cual es la cabecera del complejo de Balmorhea Springs en el oeste de Texas. Muestreamos ambas especies para actualizar su estado vigente en el manantial Phantom Lake y buscamos la presencia de la introducida G. geiseri) o cualquier G. nobilis-G. geiseri híbrido en el manantial.

Low Resting Heart Rate and Stalking Perpetration

There is consistent evidence to suggest that individuals with low resting heart rate are more likely to engage in a variety of antisocial behaviors. The present study examines whether this finding can be extended to stalking perpetration. Drawing from fearlessness theory and stimulation-seeking theory, as well as conceptual work of Meloy and Fisher, we find that individuals with low resting heart rates had significantly greater odds of engaging in stalking behavior, net of controls for sex, age, race, self-control, parental affection, delinquent peers, attitudes/beliefs toward crime, and aggression. When disaggregated by sex, the heart rate–stalking relationship was found to be significant for males, but not for females. The implications of these findings are discussed from a biosocial perspective.

The relationship between the MAOA-uVNTR polymorphism, delinquent peer affiliation, and antisocial behavior with a consideration of sex differences

With the advent of new and more readily usable gene sequencing techniques, researchers have been able to examine the interactions between genes and the environment (G X E) within a multitude of scientific perspectives. One area that G X E interactions have been implicated in is the development of antisocial behavior (ASB). Antisocial behavior consists of a wide range of maladaptive behaviors and has been at the forefront of public health and mental health concerns for decades. One genetic polymorphism that has been associated with ASB is MAOA-uVNTR. Meta-analytic studies have found the low-activity MAOA-uVNTR polymorphism to be associated with ASB from early childhood through adulthood. Recently, studies have begun to examine the independent and interactive G X E relationship between MAOA-uVNTR and deviant peer affiliation on ASB. Inconsistent with the broader literature, these findings suggest an interaction between high-activity MAOA-uVNTR and deviant peer affiliation on ASB in a mixed sex sample. The current study re-examines the relationship between MAOA-uVNTR, peer delinquency, and ASB with a consideration of sex differences in 291 college participants. Findings indicate an interaction between the low-activity allele of the MAOA-uVNTR and peer delinquency in predicting ASB. Results are also specific to differences between the sexes. Implications and future research are discussed.

Reproductive characteristics of two Gambusia congeners in west Texas

Abstract The Pecos gambusia (Gambusia nobilis) is an endangered poeciliid native to western Texas and eastern New Mexico. The decline of G. nobilis in Texas is likely the result of habitat alteration and introduction of potentially invasive congeners (e.g., the introduced largespring gambusia, Gambusia geiseri). In the East Sandia Cienega, observers have noted mating between G. geiseri and G. nobilis. Because potential hybridization between native and introduced species could have detrimental effects on reproductive fitness, we compare mean brood size, gonadosomatic indices, and standard length of both G. geiseri and G. nobilis as a first step in assessing the impacts of G. geiseri introduction in this area.