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PubMed2004

Effect of mating stage on water balance, cuticular hydrocarbons and metabolism in the desert harvester ant, Pogonomyrmex barbatus.

Water-loss rates increase after mating in queens of the harvester ant Pogonomyrmex barbatus (Formicidae: Myrmicinae), then increase again after the mated queens excavate an incipient nest. We determined the mechanistic basis for these increased water-loss rates by examining cuticular permeability, respiratory water loss, metabolic rates, and cuticular hydrocarbons for queens at three stages in the mating sequence: unmated alate queens, newly mated dealate queens, and mated queens excavated from their incipient nest. Both total water loss and cuticular transpiration increased significantly following mating, with cuticular transpiration accounting for 97% of the increased water loss. In contrast, metabolic rate and respiratory water loss were unaffected by mating stage. The total quantity of cuticular hydrocarbons did not vary by mating stage. However, relative amounts of four of the most abundant cuticular hydrocarbons did vary by mating stage, as did quantities of n-alkanes and methylalkanes. The general pattern was that percent composition of n-alkanes decreased through the mating sequence, while percent composition of methylalkanes increased over the same sequence. We discuss three mechanisms that might cause these post-mating increases in cuticular permeability. Our data support the hypothesis that part of this increase results from soil particles abrading the cuticle during the process of nest excavation.

Animals↗

PubMed2004

The role of olfaction during mating in the southern temperate spiny lobster Jasus edwardsii.

Chemosensory communication may be crucial during mate choice and mating in the southern temperate spiny lobster Jasus edwardsii to ensure that females mate with large males capable of supplying adequate numbers of sperm during the short mating window. To clarify the role of pheromones during this process, three laboratory experiments were carried out. In an experiment where the output of urine, which contains sex-specific pheromones, from large and small catheterized males was switched, large post-molt females did not make a clear choice of mate. This indicates that while females distinguish among females, males, and juveniles using their chemosensory sense, they distinguish among males using visual and tactile senses in combination with olfaction. Further, two antennule-ablation experiments were carried out to determine if detection of pheromones by the antennules of females or males was critical for mate selection, courting, or mating. In both cases, we observed a (nonsignificant) trend of slightly delayed mating of treatment females. We found that disruption of female olfaction causes less impact on courtship or mating than ablation of male antennules which increased the variance in the length of the period between molting and mating and resulted in a systematic reduction in clutch size. This lesser impact of female ablation may be because females can still respond to their own internal cues about egg ripeness whereas males cannot. In J. edwardsii, unlike the American clawed lobster, Homarus americanus, one fully functional partner of either sex appears sufficient to initiate mating.

Animals↗

PubMed2003

Evolution of disassortative and assortative mating preferences based on imprinting.

A two-locus haploid model of sexual selection is investigated to explore evolution of disassortative and assortative mating preferences based on imprinting. In this model, individuals imprint on a genetically transmitted trait during early ontogeny and choosy females later use those parental images as a criterion of mate choice. It is assumed that the presence or absence of the female preference is determined by a genetic locus. In order to incorporate such mechanisms as inbreeding depression and heterozygous advantage into our haploid framework, we assume that same-type matings are less fertile than different-type mating. The model suggests that: if all the females have a disassortative mating preference a viability-reducing trait may be maintained even without the fertility cost of same-type matings; a disassortative mating preference can be established even if it is initially rare, when there is a fertility cost of same-type matings. Further, an assortative mating preference is less likely to evolve than a disassortative mating preference. The model may be applicable to the evolution of MHC-disassortative mating preferences documented in house mice and humans.

Animals↗

PubMed2003

Self, friends, and lovers: structural relations among Beck Depression Inventory scores and perceived mate values.

BACKGROUND: We used an economic model based on evolutionary theory to guide an examination of relations among self-reported depressive symptoms and ratings of mate values of self, social, and sexual partners. This model treats assortative mating as a form of social exchange between partners of socially and sexually desirable traits. METHODS: Two studies used variants of the Mate Value Inventory (MVI), a multivariate assessment of attributes desired in social or sexual partners. For study 1, 115 male and 124 female undergraduates provided self reports on four forms of the MVI-11 and on the Beck Depression Inventory (BDI); for study 2, 208 male and 277 female undergraduates provided self reports on seven forms of the MVI-7 and on the BDI-II. RESULTS: Both multisample structural equations models indicated that the parameters were statistically equivalent between female and male subsamples and provided an adequate fit to the data. The models revealed significant relations between the mate values ascribed to the self and those ascribed to short- and long-term partners as well as best friends. Furthermore, greater BDI scores significantly predicted lesser ratings of mate value for the self, and hence indirectly predicted lesser ratings of mate value for all types of partners evaluated. LIMITATIONS: Although the data obtained from the MVI demonstrated good psychometric validity, external validity has not yet been established. CONCLUSIONS: The results are consistent with models predicting: (1) assortative mating by mate value, (2) differential exchange rates of mate value for different types of partners, (3) a negative relation between depressive symptoms and assessment of one's own mate value, and (4) a possibly consequential mismatch of mate values when one partner exhibits or recovers from significant depressive symptoms. The results are inconsistent with models predicting (5) a generalized negativity bias due to depression.

Adolescent↗

PubMed2005

The effect of an inversion system and the time interval between matings on postcopulatory sexual selection in the seaweed fly, Coelopa frigida.

The seaweed fly, Coelopa frigida, exhibits LMSP. A large chromosomal inversion system affects many traits including egg-to-adult viability via heterosis. Consequently, there is also considerable potential for cryptic female mate choice to operate on the basis of sperm karyotype. Here, we investigated the effect of time interval and chromosomal inversion karyotype on postcopulatory sexual selection. Homokaryotypic females were mated with a male of the same and a male of the opposite homokaryotype. The order of the matings was varied so cryptic female mate choice could operate either in concert or antagonistically with LMSP. LMSP was found when there was a 24 h time interval between matings, irrespective of the order in which the males were mated. However, when the males were mated in quick succession the order of mating was important. When LMSP and cryptic female mate choice work in concert a high level of LMSP was found. However, when the male of opposite homokaryotype mated first, then first male sperm precedence was observed. This suggests that polyandrous females might be able to bias paternity but only when matings occur in quick succession. Consequently, population density is likely to affect the operation of postcopulatory sexual selection.

Animals↗

PubMedDate not supplied

Assortative mating in the affective disorders: a systematic review and meta-analysis.

Assortative mating, or the tendency for individuals with similar phenotypes to mate more frequently than expected by chance, has been reported for a variety of complex traits, including many neuropsychiatric disorders. Although assortative mating has been reported in affective disorders, the studies done to date have been inconclusive. This study attempts to assess the degree of assortative mating in individuals with affective disorders using systematic review and meta-analytic techniques. Studies on assortative mating in affective disorders were identified by a computerized literature search and by bibliographic assessment of published studies and reviews. Studies were selected if they had a case-control design and if they reported rates of affective disorders in the spouses of probands and controls. Of the 17 studies reviewed, six were selected for meta-analysis. All studies were blinded. Details of study design, patient characteristics, and rates of affective disorders were assessed by two independent reviewers. Twelve of the 17 studies assessed reported an increase in assortative mating. Results of the meta-analysis supported these findings, and indicated that assortative mating occurs in both bipolar disorder and major depression. Although most studies examined reported an increase in assortative mating among individuals with affective disorders, the degree of assortative mating reported varied widely. Meta-analysis with six controlled studies showed evidence for assortative mating, and suggested that the degree of assortative mating is higher for individuals with bipolar disorder than for those with major depression. These results support the previously reported findings, and may have important implications for genetic studies.

Adult↗

PubMed2003

The sex peptide of Drosophila melanogaster: female post-mating responses analyzed by using RNA interference.

Mating induces profound changes in female insect behavior and physiology. In Drosophila melanogaster, mating causes a reduction in sexual receptivity and an elevation in egg production for at least 5 days. Injection of the seminal fluid sex peptide (SP) induces both responses in virgin females, but only for 1-2 days. The role of SP in eliciting the responses to mating remains to be elucidated. Functional redundancy between seminal fluid components may occur. In addition, mating with spermless males results in brief (1- to 2-day) post-mating responses, indicating either that there is a "sperm effect" or that sperm act as carriers for SP or other seminal fluid components. Here we used RNA interference to suppress SP expression, to determine whether SP is required to elicit full post-mating responses, the magnitude of responses due to other seminal fluid components, and whether SP accounts for the "sperm effect." Receptivity was higher and egg production lower in females mated to SP knock-down males than in controls. Comparison with virgins showed that the responses were brief. SP is therefore required for normal magnitude and persistence of postmating responses. Sperm transfer and use were normal in mates of SP knock-down males, yet their post-mating responses were briefer than after normal matings, and similar to those reported in mates of spermless son-of-tudor males. The prolonged "sperm effect" on female receptivity and egg production is therefore entirely attributable to SP, but sperm are necessary for its occurrence.

Animals↗

PubMed2004

Effect of liveweight and condition score of ewes at mating, and shearing mid-pregnancy, on birthweights and growth rates of twin lambs to weaning.

AIMS: To determine the effects of liveweight and condition score of ewes at mating, and shearing mid-pregnancy, on birthweights and growth rates of twin lambs from birth to the time of weaning, and; to determine whether any effect of condition score is independent of liveweight. METHODS: Romney ewes (n=435) which conceived within a 17-day mating period and successfully gave birth to and reared twin lambs to weaning were used. Ewes were managed during pregnancy so that their total liveweight increased at a level equivalent to the expected growth of the conceptuses. Approximately half of the ewes were shorn 70 days after the mid-point of mating, and the remainder were left unshorn, at which time they had 6-months' wool growth. All lambs were weighed within 12 h of birth and again at weaning. RESULTS: There was a significant linear relationship (R2=0.99) between mean group liveweight and condition score of ewes at mating (difference of 7.3 kg per 1.0 unit condition score). Liveweight of ewes at mating had small but significant (p<0.05) positive effects on both birthweights and growth rates of twin lambs to weaning. Ewes that had condition scores of 3.5-4.0 (scale 0-5) at mating gave birth to significantly (p<0.05) lighter lambs than ewes that had condition scores <3.5. The condition score of ewes at mating was positively associated with growth rates of lambs, although this effect was largely explained by variation in the liveweight of ewes at mating. Twin lambs born to ewes shorn mid-pregnancy were significantly (p<0.05) heavier at birth (by 0.4 kg) and at weaning (p<0.05) than those born to unshorn ewes. The heavier weaning weights of lambs born to ewes shorn mid-pregnancy were due to a heavier birthweights rather than increased growth rate. CONCLUSIONS: Liveweight and condition score of ewes at mating had small positive effects on growth rates to weaning of twin lambs. Shearing mid-pregnancy increased birthweights and weaning weights of twin lambs. To achieve high weaning weights of twin lambs, farmers should ensure ewes attain high liveweights and condition scores at mating and shear mid-pregnancy. It is speculated that the effects of liveweight and condition score of ewes at mating on weaning weights of twin lambs would be greater than those observed in the present study under conditions in which nutrition of the dam is below optimum.

Journal Article↗

PubMed1995

Saccharomyces cerevisiae cells execute a default pathway to select a mate in the absence of pheromone gradients.

During conjugation, haploid S. cerevisiae cells find one another by polarizing their growth toward each other along gradients of pheromone (chemotropism). We demonstrate that yeast cells exhibit a second mating behavior: when their receptors are saturated with pheromone, wild-type a cells execute a default pathway and select a mate at random. These matings are less efficient than chemotropic matings, are induced by the same dose of pheromone that induces shmoo formation, and appear to use a site near the incipient bud site for polarization. We show that the SPA2 gene is specifically required for the default pathway: spa2 delta mutants cannot mate if pheromone concentrations are high and gradients are absent, but can mate if gradients are present. ste2 delta, sst2 delta, and far1 delta mutants are chemotropism-defective and therefore must choose a mate by using a default pathway; consistent with this deduction, these strains require SPA2 to mate. In addition, our results suggest that far1 mutants are chemotropism-defective because their mating polarity is fixed at the incipient bud site, suggesting that the FAR1 gene is required for inhibiting the use of the incipient bud site during chemotropic mating. These observations reveal a molecular relationship between the mating and budding polarity pathways.

Cell Cycle↗

PubMed1997

Genetic analysis of default mating behavior in Saccharomyces cerevisiae.

Haploid Saccharomyces cerevisiae cells find each other during conjugation by orienting their growth toward each other along pheromone gradients (chemotropism). However, when their receptors are saturated for pheromone binding, yeast cells must select a mate by executing a default pathway in which they choose a mating partner at random. We previously demonstrated that this default pathway requires the SPA2 gene. In this report we show that the default mating pathway also requires the AXL1, FUS1, FUS2, FUS3, PEA2, RVS161, and BNI1 genes. These genes, including SPA2, are also important for efficient cell fusion during chemotropic mating. Cells containing null mutations in these genes display defects in cell fusion that subtly affect mating efficiency. In addition, we found that the defect in default mating caused by mutations in SPA2 is partially suppressed by multiple copies of two genes, FUS2 and MFA2. These findings uncover a molecular relationship between default mating and cell fusion. Moreover, because axl1 mutants secrete reduced levels of a-factor and are defective at both cell fusion and default mating, these results reveal an important role for a-factor in cell fusion and default mating. We suggest that default mating places a more stringent requirement on some aspects of cell fusion than does chemotropic mating.

DNA-Binding Proteins↗

PubMed1992

Mating stimulates estradiol production by ovaries of the musk shrew (Suncus murinus).

Asian musk shrews (Suncus murinus) are induced ovulators, but exhibit no cyclic changes in reproductive structures or in sexual behavior. Mating behavior is induced by contact with a male. To determine if mating induces changes in ovarian steroidogenesis, ovaries removed from unmated animals and at 3, 10, 15, and 36 h after mating were cultured for 4 h in the presence or absence of gonadotropins (LH + FSH, 1 microgram/ml). Histological analysis revealed no obvious changes in follicular size or appearance at the end of culture in ovaries cultured at 3 and 10 h post-mating, as compared with ovaries from unmated shrews, and mating did not stimulate any discernable changes in steroid secretion in these two groups. However, at the end of the culture period, ovulation had occurred or was occurring in ovaries from 35% of the animals ovariectomized at 15 h after mating, and corpora lutea (CLs) were present in 39% of ovarian pairs obtained 36 h after mating. At 15 h post-mating, ovaries with ovulations secreted three times more estradiol than did ovaries that showed no evidence of stimulation by mating, but there were no differences in testosterone or progesterone production. In contrast, ovaries isolated 36 h post-mating with CLs secreted dramatically more of all three steroids than ovaries without CLs (23, 13, and 52 times more estradiol, testosterone, and progesterone, respectively). These data are consistent with plasma concentrations of estradiol at the time of ovariectomy, which were twice as high at both 15 and 36 h after mating, in animals whose ovaries showed evidence of ovarian stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Mating induces puberty in the female musk shrew.

Female musk shrews (Suncus murinus), lacking a behavioral estrous cycle, engage in copulatory behavior whenever tested; even during pregnancy, sexual activity can be displayed. Studies suggest that protracted sexual behavior has a functional significance in this species. Virgin females receiving a series of ejaculations over the course of several days are more likely to ovulate and subsequently deliver than animals given the same number of ejaculations over an interval of a few hours. After the virgin mating only one third of the ovaries placed in culture exhibit increased steroidogenesis. In the present set of studies, the hypothesis that the virgin mating induces the onset of puberty, in a manner similar to that in which male-related pheromones induce estrous in rodents, was tested. On the basis of gestational lengths it is evident that females mated three times (on Days 0, 4, and 8) became pregnant in the vast majority of cases as a result of the second and third matings. When the first and second matings were separated by 25 days, 82% of females ovulated in response to the second mating; less than one third of females mated only once ovulated. Finally females were housed across a screen from males, exposed to male urine, or housed alone prior to the virgin mating. In none of these cases did pre-exposure to male-related cues increase ovulation rates in response to the virgin mating. The results show that the virgin mating primes the neuroendocrine system in such a way that the pubertal ovulation can occur in response to subsequent mating.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2006

Sperm numbers vary between inter- and intra-population matings of the grasshopper Chorthippus parallelus.

Comparing the reproductive output of intra- and inter-population matings is the most common way to assess whether post-mating reproductive isolation is caused by genetic incompatibilities. Such genetic incompatibility can however, only assume that the quantity of the post-mating signals involved does not differ between intra- and inter-population matings. This assumption may not be true because sexual selection predicts reduced mating effort towards low-quality mates and in many circumstances, allopatric partners are low-quality mates. Post-mating efforts may, therefore, be reduced in inter- compared to intra-population matings. Here, I test this crucial assumption by studying variation in one post-mating trait, sperm number, in crosses of two parapatric grasshopper populations. In both populations, males transferred fewer sperm to allopatric than sympatric females. If such plasticity with respect to population is common in other post-mating traits, differences between inter- and intra-population crosses may be more frequently caused by differences in sperm number rather than gamete incompatibility. Additionally, I found that sperm numbers declined less rapidly in the female storage organ of allopatric than sympatric females but its rate differed markedly between populations. This is discussed with respect to female adaptations to male traits.

Animals↗

PubMed2002

Mating system and sex ratios of a pollinating fig wasp with dispersing males.

Recent studies have used sex ratios to quantify the mating systems of organisms, the argument behind it being that more female-biased sex ratios are an indication of higher local mate competition, which goes hand-in-hand with higher levels of inbreeding. Although qualitative tests of the effects of mating systems on sex ratios abound, there is a dearth of studies that quantify both the mating system and the sex ratio. I use a colour dimorphism with a simple Mendelian inheritance to quantify the mating system of an unusual fig-pollinating wasp in which males disperse to obtain matings on non-natal mating patches. In qualitative agreement with initial expectations, the sex ratios of single foundresses are found to be higher than those of regular species. However, by quantifying the mating system, it is shown that the initial expectation is incorrect and this species' sex ratio is a poor predictor of its mating system (it underestimates the frequency of sib-mating). The species has a very high variance in sex ratio suggesting that excess males can simply avoid local mate competition (and hence a lowered fitness to their mother) by dispersing to other patches.

Animals↗

PubMed1975

Morphological change in the early stages of the mating process of Rhodosporidium toruloides.

The events which occur in the early stages of the mating process of the yeast Rhodosporidium toruloides between strains M-919 (mating type A) and M-1057 (mating type a) were investigated. In preliminary experiments we determined the frequency of mating by two newly designed methods: the liquid culture method and the membrane-filter microculture method. The mating frequencies of strains M-919 and M-1057 were 89% in the liquid culture method and 62% in the membrane-filter microculture method. The early stages in the mating process included the following events: (i) M-919 cells produce constitutively the extracellular inducing substance (A factor), (ii) M-1057 cells receive A factor, and in response to it they form mating tubes and secrete another inducing substance (a factor), (iii) M-919 cells receive a factor, and in response to it they form mating tubes, (iv) mating tubes elongate to the cells or the tubes of mating partner, (v) tips of the growing tubes recognize the opposite mating type cells or their tubes, followed by cell-to-cell fusion.

Basidiomycota↗

PubMed1975

Mating aggregates in Escherichia coli conjugation.

Mating mixtures of Escherichia coli cells were shown to contain mating aggregates of two to 20 cells each rather than only mating pairs of two cells each. The mating aggregate size distribution shows two broad peaks, at two to four cells and at eight to 13 cells. The quantitative mating aggregate size distribution and the proportion of male cells in mating aggregates are dependent on the input ratio of male to female cells. At an input ratio of one to one, the average mating aggregate contains equal proportions of male and female cells and most of the cells involved in mating are in large aggregates of seven or more cells each. The deoxyribonucleic acid (DNA) transfer efficiency per mating aggregate cell was constant regardless of average aggregate size or of the ratio of male to female cells in the aggregate. Under optimal conditions essentially every male cell or every female cell in a mating aggregate can be involved in DNA transfer. A comparison of light microscopy, sucrose gradient centrifugation, and analysis with a modified Coulter counter indicated that the number of cells in mating aggregates is best equantitated using a modified Coulter counter.

Cell Aggregation↗

PubMed2003

Effect of adrenalectomy on mating-induced prolactin surges and pseudopregnancy in the female rat.

In the estrous female rat, mating stimulation induces an acute surge of prolactin (PRL) within 20 min after mating followed by the onset of twice-daily PRL surges which persist for an 8- to 13-day period of acyclicity called pseudopregnancy. In Experiment 1, we examined whether the release of adrenal hormones after mating modulates mating-induced PRL secretion during the first 38 h after mating. Ovariectomized females were adrenalectomized (Adx) or sham-operated (Sham) and were implanted with jugular vein catheters 2 days later. They were given estrogen and progesterone and mated 6 days after the last surgery until they received 15 intromissions or 15 mounts-without-intromission from a male. Blood samples were collected beginning 20 min before mating at 23:00 h and continuing for 38 h. Plasma PRL concentrations were measured using radioimmunoassay. Mating that included intromissions induced an acute (20-min) PRL response which was higher in Adx than in Sham animals, and advanced in the Adx animals in the onset of the first daily PRL surge to 10:00 h, some 18 h before the surge was observed at 04:00 h in the Sham-mated animals. A small but measurable nocturnal surge was observed in Adx and Sham groups 18-24 h later at 04:00-10:00 h. In Experiment 2, Adx- and Sham-cycling animals received 5 (5I) or 7 (7I) intromissions from a male 12-16 days after surgery. Adx animals receiving 5I showed a significantly higher incidence of pregnancy or pseudopregnancy (%P/PSP) than did Sham 5I animals, while there was no difference in %P/PSP in the 7I groups. We conclude that adrenal gland secretions normally suppress plasma PRL concentrations immediately post-mating and before the onset of the nocturnal mating-induced PRL surge and also inhibit pseudopregnancy when females receive a subthreshold number of intromissions normally required for its induction.

Adrenal Glands↗

PubMed1998

Diurnal fluctuations in mating-induced oxytocinergic activity within the paraventricular and supraoptic nuclei do not influence prolactin secretion.

Previous studies have implicated oxytocin (OT) in the control of surge-type PRL secretion in the pregnant and pseudopregnant rat. The present studies examined the relationship between mating-induced activation of OT neurons in the paraventricular (PVN), supraoptic (SON), and anterior commissural (ACN) nuclei and PRL secretion. Activity within OTergic neurons, as measured by increased c-fos expression, was examined immediately and 5 days following mating in ovariectomized, estrogen-plus-progesterone-treated rats at the time when nocturnal PRL surges are expressed (0600 h) and at an intersurge time (2400 h). Females received fifteen intromissions (15I), 15 mounts-without-intromission (MO), or no stimulation (homecage, HC) from a sexually experienced male. Receipt of 15I at 0600 h induced significantly higher numbers of OT immunoreactive (OT-IR) cells and FOS/OT-IR double-labeled cells in the parvocellular division of the PVN (PVNparv) and in the SON than did 15I at 2400 h. Numbers of OT-IR and FOS/OT-IR cells in the ACN and in the magnocellular compartment of the PVN (PVNmag) were not influenced by mating at either time. In contrast, acute PRL secretion induced within 5-30 min by 15I was not influenced by whether mating occurred at 1800 h (diurnal surge), 2400 h, or 0600 h, nor were plasma OT levels elevated during the 1 h following 15I or MO at these times. Examination of FOS-IR cells throughout the hypothalamus across the two times of day revealed previously unreported differences between 15I and control MO treatments in the PVN, SON, and the ventrolateral part of the arcuate nucleus (ARCvl). On day 5 post mating, numbers of OT-IR and FOS/OT-IR cells in the PVN, SON, and ACN were very low and were similar between 0600 h and 2400 h and between females that showed (15I) or did not show (MO) mating-induced PRL surges characteristic of pregnancy. The results of these studies demonstrate that intromissive but not mounts-only stimulation from males induces a rapid increase in OT-IR staining and OT neuron activation in the PVNparv and the SON. These mating-induced responses in OT neurons occurred within 1 h after mating only at 0600 h, suggesting a diurnal fluctuation in sensitivity to intromissive stimulation. Changes in OTergic function were not seen in response to mating at other times of day, nor at the time of the nocturnal PRL surge 5 days after mating. We conclude that OT activity induced by mating does not act to stimulate PRL secretion directly, but may be involved in the process(es) by which genitosensory stimulation initiates surge-type PRL secretion.

Animals↗