Genetics of divergence in male wing pigmentation and courtship behavior between Drosophila elegans and D. gunungcola.
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Many sex-specific traits involved in mating consist of functionally coordinated morphologies and behaviors. How the components of these complex traits evolve and become coordinated during evolution is unknown. In order to understand how such trait complexes evolve and diversify, we must decipher the genetic underpinnings of their components. In this study, we begin to elucidate the genetic architecture underlying differences in functionally related male pigmentation and behavior between two Asian Drosophila melanogaster group species, D. elegans and D. gunungcola. D. elegans possesses a male-specific wing melanin spot and a stereotypical wing display element in male courtship, whereas D. gunungcola lacks both of these traits. Using reciprocal F1 male hybrids, we demonstrate that the X-chromosome contains a major locus or loci required for wing spot formation and that autosomal loci largely determine the male courtship display. Using phenotypic and genetic analysis of backcross progeny, we further demonstrate that both the wing spot and courtship differences between the two species are polygenic and both depend at least in small part on genetic factors on both the X and the autosomes. Finally, we find that male wing spot size and courtship wing display are highly correlated in backcross progeny, suggesting that linkage or pleiotropy may have been involved in their coordinated evolution. (+info)
Physical dating violence among high school students--United States, 2003.
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Dating violence is defined as physical, sexual, or psychological violence within a dating relationship. In a study of dating violence victimization among students in grades 7-12 during 1994-1995, the 18-month prevalence of victimization from physical and psychological dating violence was estimated at 12% and 20%, respectively. In addition to the risk for injury and death, victims of dating violence are more likely to engage in risky sexual behavior, unhealthy dieting behaviors, substance use, and suicidal ideation/attempts. Dating violence victimization can be a precursor for intimate partner violence (IPV) victimization in adulthood, most notably among women. Among adult women in the United States, an estimated 5.3 million IPV incidents occur each year, resulting in approximately 2 million injuries and 1,300 deaths. By using data from the 2003 Youth Risk Behavior Survey (YRBS), CDC analyzed the prevalence of physical dating violence (PDV) victimization among high school students and its association with five risk behaviors. The results indicated that 8.9% of students (8.9% of males and 8.8% of females) reported PDV victimization during the 12 months preceding the survey and that students reporting PDV victimization were more likely to engage in four of the five risk behaviors (i.e., sexual intercourse, attempted suicide, episodic heavy drinking, and physical fighting). Primary prevention programs are needed to educate high school students about healthy dating relationship behaviors, and secondary prevention programs should address risk behaviors associated with dating violence victimization. (+info)
No evidence for learned mating discrimination in male Drosophila pseudoobscura.
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BACKGROUND: Since females often pay a higher cost for heterospecific matings, mate discrimination and species recognition are driven primarily by female choice. In contrast, frequent indiscriminate matings are hypothesized to maximize male fitness. However, recent studies show that previously indiscriminate males (e.g., Drosophila melanogaster and Poecilia reticulata) can learn to avoid heterospecific courtship. This ability of males to discriminate against heterospecific courtship may be advantageous in populations where two species co-occur if courtship or mating is costly. RESULTS: Here, we tested whether Drosophila pseudoobscura males learn to discriminate against heterospecific females after being exposed to and rejected by D. persimilis females. In most of our assays, we failed to observe differences in D. pseudoobscura courtship intensity of heterospecific females by males that had previously courted heterospecific females vs. males that had been maintained in isolation. CONCLUSION: We conclude that learning to avoid heterospecific courtship may not be universal, even within the genus Drosophila, and may possibly be dependent on the natural history of the species. (+info)
Social norms and beliefs regarding sexual risk and pregnancy involvement among adolescent males treated for dating violence perpetration.
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The present study explored perceived sexual norms and behaviors related to sexual risk and pregnancy involvement among adolescent males (ages 13 to 20) participating in programs for perpetrators of dating violence. The purpose of this study was to generate hypotheses regarding the contexts and mechanisms underlying the intersection of adolescent dating violence, sexual risk and pregnancy. Six focus groups were conducted (N = 34 participants). A number of major themes emerged: 1) male norm of multiple partnering, 2) perceived gain of male social status from claims of sexual activity, 3) perception that rape is uncommon combined with belief that girls claiming to be raped are liars, 4) perception that men rationalize rapes to avoid responsibility, 5) condom non-use in the context of rape and sex involving substance use, 6) beliefs that girls lie and manipulate boys in order to become pregnant and trap them into relationships, and 7) male avoidance of responsibility and negative responses to pregnancy. The combination of peer-supported norms of male multiple partnering and adversarial sexual beliefs appear to support increased male sexual risk, lack of accountability for sexual risk, and rationalization of rape and negative responses to pregnancy. Further research focused on the context of male sexual risk and abusive relationship behaviors is needed to inform intervention with young men to promote sexual health and prevent rape, dating violence, and adolescent pregnancy. (+info)
The relationship between watching professional wrestling on television and engaging in date fighting among high school students.
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CONTEXT: Previous research has found that exposure to violence in the home, community, and electronic media are associated with children's and adolescents' normative expectations concerning the use of violence and with other indicators of the violent behaviors by youth. OBJECTIVE: Our purpose with this study was to examine the relationships between the frequency that high school students reported watching wrestling on television and engaging in date fighting, weapon carrying, and other fighting behaviors. DESIGN: The initial analysis consisted of a cross-sectional study of a simple random sample of high school students, which was followed by a longitudinal analysis of these students over a 6- to 7-month period. SETTING: The setting was all public high schools in 1 city/county system. PARTICIPANTS: We used a simple random sample (N = 2228) of students. MAIN OUTCOME MEASURES: The primary outcome variables included the frequency of date fighting during the previous 12 months and alcohol or other drug involvement associated with the last date fight. RESULTS: There were significant correlations between frequency of watching wrestling on television during the previous 2 weeks and engaging in date fighting, fighting in general, and weapon carrying for both males and females, although the relationships were stronger among females than among males. The frequency of watching wrestling was highest among students reporting date fighting when either the victim or perpetrator had been drinking alcohol or using illegal drugs. When analyzed using logistic regression, the strongest relationships were observed between the frequency of watching wrestling and date-fight perpetration among females in cross-sectional and longitudinal analyses. These findings persisted after adjusting for multiple other factors. CONCLUSIONS: For males and females, the frequency of watching wrestling was highest among students who fought with their dates when alcohol or other drugs were involved. The association between watching wrestling and date fighting was stronger among females than males. The relationship between watching wrestling on television and being the perpetrator of dating violence was also stronger among females and remained consistent over a 6- to 7-month time period. (+info)
Exposure to degrading versus nondegrading music lyrics and sexual behavior among youth.
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BACKGROUND: Early sexual activity is a significant problem in the United States. A recent survey suggested that most sexually experienced teens wish they had waited longer to have intercourse; other data indicate that unplanned pregnancy and sexually transmitted diseases are more common among those who begin sexual activity earlier. Popular music may contribute to early sex. Music is an integral part of teens' lives. The average youth listens to music 1.5 to 2.5 hours per day. Sexual themes are common in much of this music and range from romantic and playful to degrading and hostile. Although a previous longitudinal study has linked music video consumption and sexual risk behavior, no previous study has tested longitudinal associations between the content of music lyrics and subsequent changes in sexual experience, such as intercourse initiation, nor has any study explored whether exposure to different kinds of portrayals of sex has different effects. DESIGN AND PARTICIPANTS: We conducted a national longitudinal telephone survey of 1461 adolescents. Participants were interviewed at baseline (T1), when they were 12 to 17 years old, and again 1 and 3 years later (T2 and T3). At all of the interviews, participants reported their sexual experience and responded to measures of more than a dozen factors known to be associated with adolescent sexual initiation. A total of 1242 participants reported on their sexual behavior at all 3 time points; a subsample of 938 were identified as virgins before music exposure for certain analyses. Participants also indicated how frequently they listened to each of more than a dozen musical artists representing a variety of musical genres. Data on listening habits were combined with results of an analysis of the sexual content of each artist's songs to create measures of exposure to 2 kinds of sexual content: degrading and nondegrading. OUTCOME MEASURES: We measured initiation of intercourse and advancement in noncoital sexual activity level over a 2-year period. RESULTS: Multivariate regression analyses indicated that youth who listened to more degrading sexual content at T2 were more likely to subsequently initiate intercourse and to progress to more advanced levels of noncoital sexual activity, even after controlling for 18 respondent characteristics that might otherwise explain these relationships. In contrast, exposure to nondegrading sexual content was unrelated to changes in participants' sexual behavior. CONCLUSION: Listening to music with degrading sexual lyrics is related to advances in a range of sexual activities among adolescents, whereas this does not seem to be true of other sexual lyrics. This result is consistent with sexual-script theory and suggests that cultural messages about expected sexual behavior among males and females may underlie the effect. Reducing the amount of degrading sexual content in popular music or reducing young people's exposure to music with this type of content could help delay the onset of sexual behavior. (+info)
Before first sex: gender differences in emotional relationships and physical behaviors among adolescents in the Philippines.
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CONTEXT: Early age at first sex has been identified as a risk factor for unplanned pregnancy and HIV infection. However, the emotional relationships and physical behaviors that precede first intercourse, and how they differ by sex, also may provide important cues about how to prevent sexual risk behavior. METHODS: The precoital activities of 2,051 adolescents aged 17-19 in Cebu, Philippines, are examined using 1998-2000 and 2002 data from the Cebu Longitudinal Health and Nutrition Survey. The timing and tempo of emotional relationships and physical behaviors for males and females are described. Cox proportional hazards models are used to identify the characteristics associated with age at first sex. RESULTS: Males engage in precoital physical behaviors and first sex at younger ages than females. Although the standard order in which the two sexes engage in emotional relationships for the first time is the same, males progress through the sequence more quickly than females. After adolescents have progressed through the sequence of emotional relationships, there is a gap of a least a year before they begin to have sex. In the multivariate analysis, rapid progression through the sequence of emotional relationships was associated with initiating sex at a younger age for females (hazard ratio, 1.5), but not for males. CONCLUSION: The period between first date and first sex experienced by both males and females provides an opportunity to ensure that adolescents have access to the information and services that will allow them to make informed choices about sexual behavior. (+info)
Evaluating the risk and attractiveness of romantic partners when confronted with contradictory cues.
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Research shows that people engage in "risky" sex with "safe" partners and in "safer" sex with "riskier" partners. How is the determination of "risky" or "safe" status made? Factorial survey methodology was used to randomly construct descriptions of romantic partners based on attractive and/or risky characteristics. Respondents evaluated 20 descriptions for attractiveness, health risk, likelihood of going on a date, likelihood of unprotected sex, and likelihood of STD/HIV infection. Respondents were most attracted to and perceived the least risk from attractive descriptions and were least attracted to and perceived the most risk from the risky descriptions. The differences between the "conflicting information" descriptions are attributable to a primacy effect: descriptions that began with attractiveness information but end with risk information were evaluated more positively than those that began with risk and ended with attractive information. (+info)