Benefit to male sailfin mollies of mating with heterospecific females

Female gynogens reproduce clonally but rely on sperm from heterospecific males to initiate embryogenesis. It has been assumed that males gain no benefit from such matings; thus, selection should favor males that avoid them. Here it is shown that males gain a benefit by mating with female gynogens in an asexual-sexual complex of fish. The sexual females increase their preference for males whom they observe consorting with female gynogens. Thus, gynogenetic species might persist because selection favors males to be sexually parasitized.     

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.     

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.     

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     

Non-genetic benefits of mate choice: fecundity enhancement and sexy sons

I compared reproductive success (lifetime number of fertilized eggs) as a function of mate choice among females of the stink bug, Nezara viridula L. (Hemiptera: Pentatomidae). 'Choosing' (C) females were placed with one of two males on alternate days. CI females chose between inexperienced males while CR females chose between males previously rejected by CI females. 'Non-choosing' (N) females were placed with the same male every day. Non-choosing NI, NR and NA females encountered, respectively, inexperienced males, previously rejected males, or previously accepted and mated males. Reproductive success was highest for CI females, showing direct selection on mate preferences. Reproductive success did not differ between CR and NR females, indicating that male quality, not the act of choosing a mate, affects fitness. CI females preferred males with longer antennae and their fecundity (lifetime number of eggs) was correlated with male antenna length, consistent with antenna length as an indicator of male ability to transfer nutritive sperm produced in paired harlequin lobes of the testes. Harlequin lobes were smaller in rejected than chosen males. In second-generation mate choice trials, sons of NR females competed well against sons of NA females but not against sons of CI females. This suggests that non-genetic paternal contributions that decline with prior mating account for the attractiveness of sons because sons of CI and NA females shared the same fathers. Sons experiencing mating success came from larger eggs and egg size was greatest for CI females, perhaps as a consequence of paternal nutritional contributions. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.     

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   

Three experiments on mate choice in meadow voles (Microtus pennsylvanicus).

Species differences in selectivity with respect to mate choice have been hypothesized to be related to mating systems. Procedures used in 3 previous experiments on monogamous prairie voles (Microtus ochrogaster) and polygamous montane voles (M. montanus) were used with polygamous meadow voles (M. pennsylvanicus). The expectation was that meadow voles would show few preferences. Female meadow voles preferred mating with familiar versus unfamiliar males but displayed no preference for unmated versus mated males. Male meadow voles displayed no preference for unmated versus mated females. The results are partially consistent with the hypothesis that relates mate choice to social and mating system, as this polygamous species resembles polygamous montane voles species in 2 situations but is similar to monogamous prairie voles in the 3rd. (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     

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)     

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)     

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)     

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)     

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.     

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)     

Sex differences in perceived controllability of mate value: an evolutionary perspective

Men and women value different characteristics in potential partners. It was hypothesized that women feel they have less control over traits relevant to their desirability than men feel they have over traits related to male desirability. In Study 1, undergraduates (N = 150) completed questionnaires measuring (a) the importance they attributed to 64 characteristics when choosing a mate and (b) their perceived control over these traits. Men selected partners on the basis of traits that are relatively uncontrollable (e.g., youth, attractiveness), whereas women selected partners on the basis of traits that are more controllable (e.g., status, industriousness; d = 1.75). In Study 2, these findings were replicated in an older, representative community sample (N = 301; d = 1.03). Greater uncontrollability of traits relevant to female mate value may place women at elevated risk for negative affect, depression, low self-esteem, and body dissatisfaction.     

Hormonal responses of male gerbils to stimuli from their mate and pups

Following copulation and cohabitation with a pregnant female, male gerbils show high levels of parental behavior toward their pups. The initiation of male parental behavior may be the result of neuroendocrine changes induced by cohabiting with the pregnant female or by pup stimuli. Experiment 1 examines the changes in androgen and prolactin levels in male gerbils cohabiting with females over the reproductive cycle. Gerbils were mated and blood samples taken from males for hormone analysis 1, 10, and 20 days after pairing and 3, 10, and 20 days after pups were born. A group of unmated male gerbils served as controls. Plasma prolactin levels of males were elevated throughout the female's pregnancy and lactation periods, but were only statistically significantly higher than those of unmated males 20 days after pups were born. Androgen levels rose during pregnancy and dropped significantly after the birth of the pups. These hormonal changes are similar to those found in males of monogamous birds and differ from those found in males of polygynous rodents such as the rat. Experiment 2 examined the hormonal responses of male and female gerbils to pup replacement after 4 hr of parent-pup separation. Female gerbils showed a significant elevation of prolactin levels 1 hr after pup replacement, but males did not. Males with pups returned showed no difference in androgen levels from males who did not have pups returned. Thus, male gerbils show neuroendocrine changes following long-term cohabitation with their mate and pups, but do not show acute hormone responses to pup removal and replacement. These results indicate that parental males have neuroendocrine changes associated with parental behavior and these differ from the neuroendocrine changes underlying female parental behavior.     

Contingent weighting in judgment and choice.

Preference can be inferred from direct choice between options or from a matching procedure in which the decision maker adjusts one option to match another. Studies of preferences between two-dimensional options (e.g., public policies, job applicants, benefit plans) show that the more prominent dimension looms larger in choice than in matching. Thus, choice is more lexicographic than matching. This finding is viewed as an instance of a general principle of compatibility: The weighting of inputs is enhanced by their compatibility with the output. To account for such effects, we develop a hierarchy of models in which the trade-off between attributes is contingent on the nature of the response. The simplest theory of this type, called the contingent weighting model, is applied to the analysis of various compatibility effects, including the choice-matching discrepancy and the preference-reversal phenomenon. These results raise both conceptual and practical questions concerning the nature, the meaning and the assessment of preference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conceptual perspective and lexical choice in acquisition

Adult speakers choose among perspectives when they talk, with different words picking out different perspectives (e.g., the dog, our pet, that animal). The many-perspectives account of lexical acquisition proposes that children learn to take alternative perspectives along with the words they acquire, and, therefore, from the first, readily apply multiple terms to the same objects or events. And adults offer children pragmatic directions about the meanings of new words and hence about new perspectives. In contrast, the one-perspective account proposes that children are able, at first, to use only one term to talk about an object or event. Evidence for the many-perspectives account comes from a range of sources: children spontaneously use more than one term for the same object (horse and chair for a toy horse); they construct novel words to mark alternate perspectives (Dalmation-dog vs. dog); they shift perspective when asked (from cat to animal, or sailor to bear for anthropomorphic characters); and they readily learn new terms for talking about already-labelled kinds. Children sometimes fail to learn new words or fail to relate them to words already known, but only in situations that lack adequate pragmatic directions.