Differential effects of mate competition and mate choice on eastern tiger salamanders

Male tiger salamanders, Ambystoma tigrinum tigrinumare slightly larger in body size and have considerably higher and longer tails than females. To determine how these dimorphic traits affected reproductive performance and success, we conducted breeding trials using 12 males and six females per trial and monitored male-female and male-male interactions. Larger males had an advantage in most aspects of mate competition investigated. Males with higher tails had no advantage in either mate competition or mate choice. Males with longer tails also had no advantage in mate competition but were preferred as mates by females. Larger males interrupted courting males more often than smaller males did. The form of male-male interference was conditional on body size and not on either tail dimension. If the intruder was larger than the courting male, it would shove the female away from the courting male and initiate courtship; if the intruder was smaller, it adopted a female mimicry tactic in which it positioned itself between the courting male and female and performed female behaviours to the courting male while simultaneously courting the female. Our trials indicated that the two components of sexual selection may influence the evolution of different male morphological traits in tiger salamanders. Mate competition may favour increased male body length; mate choice may select for greater male tail length.     

Fluctuating asymmetry, mate choice and experimental designs

No Abstract Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour     

Local mate competition, variable fecundity and information use in a parasitoid

A 30-bp deletion in the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) gene has been reported in nasopharyngeal carcinoma and EBV-associated malignant lymphomas. Information on this deletion in EBV-associated gastric carcinoma (EBVaGC) is limited. The association of gastric carcinoma (GC) with EBV was examined by EBV-encoded RNA (EBER) in situ hybridization in 510 patients from Japan and 80 patients from Brazil. We studied the prevalence of 30-bp LMP1 gene deletion in EBVaGC in Japan (29 cases) and Brazil (four cases) in comparison with the corresponding EBER1-positive metastatic lesions in lymph nodes (10 cases) and EBV-infected reactive lymphocytes from dissected nonmetastatic lymph nodes (22 cases), microdissected non-neoplastic gastric mucosa of EBVaGC (five cases), and EBV-nonassociated GC (25 cases). We studied the status of the LMP1 gene by Southern blot hybridization of polymerase chain reaction products obtained after amplification with primers flanking the site of the deletion. We also performed EBV typing and LMP1 protein immunohistochemistry. EBV DNA was amplified by polymerase chain reaction in 30 of 33 EBVaGC cases, 8 of 10 metastatic carcinomas, 14 non-neoplastic tissues from 27 EBVaGC cases, and 12 of 25 non-EBV-associated GC cases with EBER1-positive lymphocytes. The 30-bp LMP1 gene deletion was observed in 23 of 26 (88.5%) cases of EBVaGC from Japan and two of four (50%) cases of Brazilian EBVaGC as compared with EBER1-positive reactive lymphocytes from 11 of 14 (78.6%) EBVaGC cases and 9 of 12 (75%) cases of non-EBV-associated GC. The variant type (the 30-bp deletion variant or nondeleted wild type) of LMP1 gene was the same among reactive lymphocytes, primary and secondary lesions of EBVaGC in all cases for which all three tissue types were studied (six of six). There was no correlation between the presence of the 30-bp deletion with depth of cancer invasion or presence of metastasis. Type A was detected in all available EBV-positive cases. The similar high incidence of 30-bp deletion in LMP1 gene in both carcinoma cells and reactive lymphocytes in EBVaGC cases suggests that this deletion may not be relevant to the pathogenesis of EBVaGC.     

Female mate choice and male behaviour in domestic fowl

An F2 intercross derived from C57BL/6 and DBA/2 progenitor inbred strains was used to test for replication of quantitative trait loci (QTLs) for alcohol preference nominated by a previous study using BXD recombinant inbred (RI) strains (Rodriguez et al., Alcohol. Clin. Exp. Res. 19:367-379, 1995). Fourteen provisional QTLs were nominated in the original RI study with a p < 0.05 criterion. In the present study, a genome scan (101 microsatellite markers) was conducted on an F2 population (n = 218). Three significant QTLs were detected on chromosomes 1, 4, and 9, and three suggestive QTLs were detected on chromosomes 2, 3, and 10. Of these six QTLs, four were consistent with the previous RI nominations. The replication rate of 28.6% (4 of 14) is in agreement with the results of simulation studies performed by Belknap et al. (Behav. Genet. 26:149-160, 1996) and supports the methodological argument for a multistage research design for nominating and replicating QTLs.     

Interspecific mate choice in sailfin and shortfin species of mollies

I examined interspecific patterns of female choice for three species of mollies: the 'sailfin' species, P. latipinna and two 'shortfin' species, P. orri and P. mexicana. Females of the sailfin species consistently preferred conspecific males across all male treatment combinations containing conspecifics. Females of the two shortfin species had lower levels of female preference and spent less time interacting with males during trials. The only consistent pattern of female choice in either shortfin species was a preference for the sailfin P. latipinna males over heterospecific shortfin males, but not over conspecifics. This finding suggests a potential bias by shortfin females for the sailfin male phenotype. Males of the three species differed in both behaviour and morphology. Length and relative position of the dorsal fin reliably separated P. latipinna from the two shortfin species. Body depth and shape distinguished males of the two shortfin species. Dorsal fin height was not a reliable cue for distinguishing sailfin males from males of either shortfin species. Males from different populations of the sailfin species P. latipinna differ in both size-specific behavioural rates and size-specific morphometry, particularly in the overall size-adjusted area of the dorsal fin. Increased rates of courtship displays and increased area of the dorsal fin separate males of P. latipinna from males of the two shortfin species as well. If the same traits used by females of P. latipinna for intraspecific discrimination are also important species-recognition signals, this suggests a potential role for sexual selection in contributing to the divergence of male phenotype during speciation of sailfin mollies. Copyright 1998 The Association for the Study of Animal Behaviour.     

Clinical electives: the challenges and benefits of student choice

Traditionally, students have not had the opportunity to exercise choice over the specialty and location of their clinical placements. This is now changing but it requires the wholehearted commitment of students, their lecturers and all those in the institutions concerned. The innovation has to sit coherently within the largely externally prescribed curricula approved by the National Boards, the professional arm of conjoint validation processes. The challenges are many, but the benefits can be immeasurable. This article describes the experiences of one university in managing and planning these initiatives and examines students' responses to them. Significant questions are raised about developments for the future.     

Mate choice and mate competition influence male body size in Japanese medaka

A sexual size dimorphism usually occurs when size-dependent reproductive advantages exist in only one sex. Studies on Japanese medaka, Oryzias latipes, have demonstrated reproductive size advantages in females but not in males, even though males and females are similar in body size. We conducted mate-choice and mate-copying tests in which a female could first associate with, then mate with, either a large (>/=1 sd+X standard length) or a small male (相似文献   

Age preferences and mate choice among homosexuals and heterosexuals: A case for modular psychological mechanisms.

Age preferences expressed by homosexuals and heterosexuals in 783 singles ads were compared. In line with earlier cross-cultural findings, heterosexual women at all ages tend to prefer men from their own age to several years older. Heterosexual men change with age; young men show an interest in both older and younger women, but older men express progressively stronger interest in women younger than themselves. Homosexual men's preferences were very similar to those of heterosexual men and homosexual women showed a pattern somewhat between that of heterosexual women and men. Results combine with previous literature to suggest that homosexual choice is not a simple and general reversal of heterosexual roles, and fit with an emerging view that sexual behavior is controlled by a number of independently evolved psychological mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parent-Adolescent Relationship program (PARD): Relationship enhancement therapy with adolescents and their families (fathers and sons).

Parent–Adolescent Relationship Development (PARD), a relationship enhancement therapy program, was created as a way to improve the relationship between fathers and sons. Fathers and their adolescent sons are brought together in small groups to learn communication and relationship skills. This 10-session program helps fathers and sons remain engaged, improve acknowledgment of their positive feelings toward each other, and feel better about themselves. An excerpt from a PARD group with fathers and sons is presented to exemplify the process and value of this method. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hormonal dynamics during mate choice in the northern pintail: a test of the 'challenge' hypothesis

In previous mate choice experiments, we found no relationship between dominance rank and pairing success in male northern pintails, Anas acutaOnce chosen by a female, however, males became aggressive, initiated fights with higher-ranked males and quickly established dominance. In the present study, we tested a variation of the 'challenge' hypothesis, that the behavioural stimuli associated with acquiring and defending a mate induce an increase in testosterone level, which in turn facilitates aggressive behaviours required for males to establish dominance. We measured plasma hormone levels (testosterone, dihydrotestosterone, luteinizing hormone and corticosterone) before and after mate choice in two experiments in which males competed for a single female (experiments 1 and 2) and in a control experiment in which no female was introduced (experiment 3). We used groups of either three adult males (experiment 1) or one adult and two yearling males (experiments 2 and 3). Contrary to expectation, in experiment 1, plasma levels of corticosterone increased significantly and testosterone levels decreased in chosen males following mate choice. The magnitude of change in corticosterone was positively correlated with the rate of aggression by males. Chosen adult males in experiment 2 showed similar patterns of hormone change (corticosterone increase and testosterone decrease), although not all changes were significant. Hormone levels of unchosen yearlings in experiment 2 and control adults and yearlings in experiment 3 showed no changes. The results are consistent with the hypothesis that behavioural stimuli associated with successful pair formation induce a transitory increase in circulating levels of corticosterone, which in turn mediates the behavioural response of increased aggression leading to the establishment of dominance following mate choice. A short-term increase in corticosterone may be adaptive in this situation because it would mobilize energy stores needed by the male to defend the new pair bond and establish dominance.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour     

Interests of fathers and sons.

"Estimation of 'true' resemblance must represent resemblance between fathers and sons, as such, and not resemblance between all men, or even the general resemblance between men in any two samples under consideration. Correlations between chance pairs have been deducted from correlations between true pairs to provide a more accurate measure of resemblance. Father-son resemblance must be construed to mean resemblance in certain respects but not in all respects… . An interest profile should express a pattern of interests even better than a single scale. On such a basis one may explain the higher resemblance between profiles (.40) than between scores on interest scales (.30 to .35) and the definitely higher correlation between profiles than between items (.27)." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Meditations on the hunt: A reexamination of the issue of choice in the process of mate selection and its implications for psychotherapy.

Describes choice in mate selection as derived less from underlying psychodynamic factors and more from what is available in the marketplace. The factors (biographical, personality, and selectivity) that reduce choice in mate selection are examined. The implications of the availability model on mate selection and psychotherapy with the nonmarried are discussed. It is contended that the choice becomes less a statement of the unconscious and conscious needs of the S and more a reflection of the state of the marketplace. It is suggested that availablity factors be explored in therapy before factors within the individual are addressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is human mating adventitious or the result of lawful choice? A twin study of mate selection.

Pairs of middle-aged twins and their spouses provided data on 74 mainly psychological variables. Neither spousal similarity nor idiosyncratic criteria could account for specific mate selection in these 738 couples. Of the twins (and their spouses), 547 independently rated their initial attraction to their twin's mate (or to their spouse's twin). Findings suggest that characteristics both of the chooser and the chosen constrain mate selection only weakly. This article proposes that it is romantic infatuation that commonly determines the final choice from a broad field of potential eligibles and that this phenomenon is inherently random, in the same sense as is imprinting in precocial birds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alcohol challenge with sons of alcoholics: A critical review and analysis.

Studies are reviewed in which response to acute administration of alcohol was compared between individuals with and without family histories of alcoholism (FH+, FH–). This research represents a search for a psychobiological marker for alcoholism. A methodological critique of the procedures reported in this literature is then presented. Finally, a conceptual model is suggested in which differences in the response to alcohol between FH+ individuals and FH– individuals must be understood in relation to time after drinking alcohol. This Newtonian differentiator model proposes that sons of alcoholics exhibit acute sensitization as blood alcohol level rises and acute tolerance as blood alcohol level falls, compared with sons of nonalcoholics. Therefore, FH+ Ss find alcohol more rewarding because they accentuate the pleasurable, excitatory aspects of initial intoxication and attenuate the feelings of anxiety and depression that predominate as blood alcohol levels drop. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inherited predisposition to alcoholism: Characteristics of sons of male alcoholics.

Sons of male alcoholics (SOMAs) are at markedly heightened genetic risk for the development of alcohol abuse. Study of SOMAs could therefore conceivably increase the efficiency of research aimed at uncovering those heritable factors that predispose to alcoholism. SOMAs manifest observable behavioral, cognitive, and psychophysiological abnormalities while sober and react idiosyncratically to alcohol intoxication. They are most commonly described as conduct disordered and hyperactive, appear heir to a variety of deficits in verbal and abstract cognition, and perform more poorly in the academic environment. SOMAs are characterized by abnormal patterns of cued psychophysiological response, and appear more sensitive to the putatively reinforcing aspects of alcohol intoxication. Various methodological weaknesses permeate the relevant literature. Some straightforward improvements are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pregnancy block in house mice (Mus domesticus) as a function of t-complex genotype: Examination of the mate choice and male infanticide hypotheses.

Pregnancy block, whereby recently mated female mice abort their pregnancies when exposed to novel (strange) males, was studied in house mice (Mus domesticus) differing in t-complex genotype; t-mutations are deleterious and +/t females avoid +/t males as mates. The results of Experiment 1, in which the genotype of the female, stud male, and strange male was systematically varied, showed that pregnancy block was most frequent when the strange male was +/+. Because this effect was not enhanced among +/t females when stud males were +/t, the results cannot clearly be explained by the hypothesis that pregnancy block is a manifestation of mate choice. Moreover, the "strange male" effect in Experiment 1 is unlikely to be a female response correlated with the risk of male infanticide, as +/+ and +/t males did not differ in their infanticidal tendencies (Experiments 2 & 3). Alternative hypotheses, including a modified version of the male choice hypothesis, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anticoagulation: assessment of benefits and risks

Thromboembolism is a frequent complication of atrial fibrillation. As could be demonstrated by several placebo-controlled prospective studies in the recent years the rate of thromboembolism was reduced significantly by anticoagulation of nearly all kinds of atrial fibrillation. These results are challenging to weigh risks and benefits in every patient. The principles which have to consider in this calculation are discussed with regard to the knowledge derived from the controlled studies.     

The necessities and luxuries of mate preferences: Testing the tradeoffs.

Social exchange and evolutionary models of mate selection incorporate economic assumptions but have not considered a key distinction between necessities and luxuries. This distinction can clarify an apparent paradox: Status and attractiveness, though emphasized by many researchers, are not typically rated highly by research participants. Three studies supported the hypothesis that women and men first ensure sufficient levels of necessities in potential mates before considering many other characteristics rated as more important in prior surveys. In Studies 1 and 2, participants designed ideal long-term mates, purchasing various characteristics with 3 different budgets. Study 3 used a mate-screening paradigm and showed that people inquire 1st about hypothesized necessities. Physical attractiveness was a necessity to men, status and resources were necessities to women, and kindness and intelligence were necessities to both. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chronic tolerance and sensitization to alcohol in sons of alcoholics: II. Replication and reanalysis.

Data from D. B. Newlin and J. B. Thomson (1991) were reanalyzed, and data from an independent replication study were analyzed, relative to tonic (baseline) and phasic (response to alcohol challenge) aspects of drinking alcohol administered at the same dose on several occasions. Among the high-risk men (sons of alcoholic fathers), linear trends across days for resting (predrinking) baselines were opposite to alcohol-evoked changes for finger pulse amplitude, finger temperature, and skin conductance in Study 1 and for pulse transit time and body sway (static ataxia) in Study 2. In contrast, the structure of the low-risk men's (sons of nonalcoholic parents) data was precisely the opposite. Results are discussed in terms of sensitization as a potential mechanism that relates vulnerability to final manifestation of addictive behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive and motoric functioning of sons of alcoholic fathers and controls: The early childhood years.

Compared cognitive and motoric abilities of male preschoolers with alcoholic fathers with matched community comparison boys. Despite meticulous neighborhood searches, socioeconomic status (SES) and Home Observation for Measurement of the Environment (HOME) scores of control families were significantly higher than alcoholic families. Among high-risk boys, overall developmental quotient, fine motor, and personal/social development were significantly less advanced than for controls when SES and HOME scores were not considered. In analyses of developmental data when HOME scores were considered as a covariate, only personal/social development remained significantly different. Findings suggest that paternal alcohol problems are related to cognitive development of their preschool sons, primarily if they impact on aspects of family environment related to intellectual abilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)