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PubMed1980

Flagellar roots, mating structure and gametic fusion in the green alga Ulva lactuca (Ulvales).

The slightly anisogamous gametes of Ulva lactuca exhibit a cruciate flagellar root system consisting of 4 microtubular roots (4-2-4-2 system) and an elaborate system of fibrous roots associated with the 2-stranded microtubular roots. Two fibres (32-nm striation periodicity; system I fibres) closely underlie each of the 2-stranded roots, while different fibres (150-nm striation periodicity; system II fibres) run parallel to the root microtubules, and are 150-200 nm more internally located. Female gametes have 4 system II fibres, 3 of which are combined into a compound fibre associated with one microtubular root, while the fourth fibre is associated with the opposite root. In male gametes only 2 system II fibres are present, each underlying one of the two 2-stranded roots. A special region of the plasmalemma of both gamete types about 0.5 mum away from the basal bodies and located between 2 adjacent microtubular roots is structurally specialized and acts as a mating structure in gametic fusion. The region is oval-shaped and up to I.I mum long with a maximum diameter of 0.7 mum. A continuous electron-dense boundary layer underlies the plasmalemma at the edges of the mating structure. In both gamete types the mating structure consists of a fuzzy layer of material underlying the plasmalemma and special granules (60 nm diameter) are associated with this layer on its cytoplasmic side. In addition diffuse material overlies the mating structure, especially in male gametes. The mating structure is connected to 3 different kinds of flagellar roots: the boundary layer is linked to a 2-stranded microtubular root and its associated system I fibre; the fuzzy layer of the mating structure is connected with a system II fibre; and in female gametes this is the compound system II fibre. The ultrastructural changes which occur after mixing the 2 gamete types have been followed. Mating structure activation involves contraction of system II fibres (change of striation periodicity to 100 nm), detachment of special granules from the fuzzy layer of the mating structure and their replacement by electron-transparent vesicles at the prospective cell fusion site. Furthermore, release of electron-dense contents from Golgi-derived vesicles in the anterior part of both gamete types precedes cell fusion. Cell fusion is exclusively initiated in a region delimited by the 2 mating structures. After partial dissolution the 2 plasma membranes unite within the mating structure regions. The ultrastructure of gametic fusion in Ulva lactuca is compared to that of other green algae and the significance of flagellar roots in the mating process of green algae is discussed.

Chlorophyta↗

PubMed1993

Prediction of fertility by mating latency and photoperiod in nulliparous and primiparous meadow voles (Microtus pennsylvanicus).

Mating behavior and litter production of female meadow voles (Microtus pennsylvanicus) housed in long (14 h light: 10 h dark; long day; LD) or short (10 h light: 14 h dark; short day; SD) photoperiods were monitored to determine whether the reduced birthrate of SD females resulted from a lack of copulation. All females mated, but fewer SD females gave birth. LD and SD females fell into three distinct groups based on mating latency. The rapid onset group (RO) mated between 7 min and 9 h after pairing, the intermediate onset group (IO) mated between 16-44 h and the late onset group (LO) mated after 58-262 h of male contact. Sixty-seven per cent of LD females were assigned to group RO, 27% to IO, and 6% to LO. In contrast, 30% of SD females were assigned to group RO, 35% to IO and 35% to LO. Fertility was predicted by mating latency. Sixty-nine per cent of RO, 93% of IO and 33% of LO animals gave birth. In a further experiment, a small-mouthed cup was added to the environment to serve as an escape for females wishing to avoid mating. Although females did not use the cup to escape male approaches, mating occurred in only 66% of SD females, but was observed in all LD females. In a final experiment, mating latency and litter production were recorded in primiparous LD and SD females initially observed in the first experiment. Group LO was eliminated in parous females; all primiparous LD and SD females mated within 48 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2002

Unassisted isolated-pair mating of Anopheles gambiae (Diptera: Culicidae) mosquitoes.

Female Anopheles mosquitoes usually mate only once, but mating is seldom seen in small containers containing only one female and male. Therefore, matings are often performed among many adults in large cages or by forced copulation. Isolated-pair mating of Anopheles gambiae G3 strain-derived mosquitoes without forced copulation in small vials is described. We observed that the experimental variables eye color and male number were significant factors in the mating frequency. Females mated more frequently when three males were present over only one male. White-eyed females were more likely to be mated than wild-eyed females, but wild males mated more frequently than did white-eyed males. Experiments were also conducted to determine when mating was occurring by using wild-eye-color mosquitoes in isolated pairs. Almost no matings were observed before day 6 rather than the frequencies typically observed after 1-2 d in standard large-cage matings among large numbers of adults.

Animals↗

PubMed2005

Evaluation of Dorset, Finnsheep, Romanov, Texel, and Montadale breeds of sheep: V. Reproduction of F1 ewes in spring mating seasons.

Objectives were to estimate effects of sire breed (Dorset, Finnsheep, Romanov, Texel, and Montadale), dam breed [Composite III (CIII) and northwestern whiteface (WF)], mating season (March and May), and their interactions on reproductive traits of mature F1 ewes in spring mating seasons. A total of 1,099 F1 ewes produced 1,754 litters of 2,995 lambs from exposures to Suffolk rams during March and May mating seasons in 1995 through 1999. Fertility rate and ewe longevity were measured. Number born and litter birth weight were recorded, and number and weight at weaning and 20 wk of age were analyzed separately for dam- and nursery-reared litter mates. Total productivity from 4 to 6 yr of age for each ewe entering the breeding flock was calculated as the sum of 20-wk weights for dam-reared lambs and separately for nursery-reared lambs. Interactions of sire breed x mating season, ewe age x mating season, and ewe age x dam breed were often significant. Interactive effects of sire breed and mating season on fertility rate (P < 0.001) were primarily due to differences in magnitude. Fertility rates of sire breeds for March and May matings, respectively, were 92 and 89% for Romanov, 91 and 72% for Finnsheep, 90 and 52% for Texel, 88 and 52% for Montadale, and 83 and 62% for Dorset. Sire breed x mating season also affected number born (P < 0.03); March and May values were 2.12 and 2.05 for Romanov, 2.00 and 1.94 for Finnsheep, 1.39 and 1.41 for Texel, 1.37 and 1.51 for Montadale, and 1.37 and 1.55 for Dorset, respectively. Interaction of sire breed x dam breed on fertility rate (P < 0.01) was due to change in rank as well as magnitude. Romanov- and Dorset-sired ewes out of CIII dams had greater fertility rates than Romanov- and Dorset-sired ewes out of WF dams. The opposite situation existed for ewes by Finnsheep, Texel, and Montadale sires. Differences between dam breeds (CIII and WF) in total productivity of dam-reared lambs were not detected, whereas ewes exposed in March (78 kg) were more productive (P < 0.01) than those exposed in May (68 kg). Means of sire breeds for total productivity of dam-reared lambs were 47, 65, 70, 70, and 111 kg for Texel, Montadale, Dorset, Finnsheep, and Romanov, respectively (P < 0.001). Superior reproduction of Romanov sired ewes was primarily due to greater fertility rate and prolificacy at each mating season and ewe age. Use of Romanov-crossbred ewes would increase fertility during spring mating, an important constraint of the sheep industry.

Aging↗

PubMed1989

Effects of Rumen-Mate on lactational performance of Holsteins fed a high grain diet.

Three Latin-square trials were conducted to determine the effects of supplementing Rumen-Mate, a commercial buffer containing KCl, NaCl, and Mg and Na carbonates, on lactation performance of Holsteins. Cows were fed a basal ration of 40% corn silage and 60% concentrate in Trials 1 and 2, and 40% corn silage, 55% concentrate, and 5% alfalfa hay in Trial 3 (DM basis). In Trial 1, treatments were: basal diet, or basal diet supplemented with either 1% NaHCO3, or 1, 3, or 4.4% Rumen-Mate. Increasing dietary Rumen-Mate resulted in a linear increase in milk fat production and concentration with no difference between 1% Rumen-Mate and 1% bicarbonate. There was a significant linear decrease in milk protein concentration, but not production, with increasing concentrations of Rumen-Mate. In Trial 2 treatments were: basal diet, or basal diet supplemented with either .8% NaHCO3, 2.6% Rumen-Mate, .5% MgO, .8% NaHCO3 plus .5% MgO, or 1.8% Rumen-Mate plus .8% NaHCO3. Organic matter and CP intakes and milk protein yield and concentration were decreased by Rumen-Mate with a nonsignificant increase in milk fat concentration. Data from Trials 1 and 2 were combined with data from Trial 3, which compared basal diet, 1% bicarbonate, and 3% Rumen-Mate. The combined data showed a larger increase over basal diet in milk fat yield and concentration for 2.6 to 3% Rumen-Mate vs. .8 to 1% bicarbonate. Rumen-Mate did not decrease DM intake or protein yield relative to basal diet but did decrease protein yield 34 g/d compared with that of bicarbonate.

Animal Feed↗

PubMed1997

Effect of excluding sib matings on inbreeding coefficient and effective size of finite diploid populations.

The effects of excluding full-sib matings, half-sib matings, or both under random selection or equal family size selection on the inbreeding coefficient and effective size in finite populations with unequal sex ratio have been studied. Recurrent equations for the inbreeding coefficient and approximate formulas for effective size are derived for different breeding systems. It is shown that avoidance of sib matings results in lower inbreeding coefficients in any generations under random selection. Under equal family size selection, however, excluding sib matings gives rise to lower inbreeding coefficients only in the first few generations and will eventually result in a higher inbreeding in later generations compared with random mating. Exclusion of sib matings increases effective size under random selection while it decreases effective size under equal family size selection. The relative effectiveness on effective size of different sib mating avoidance depends only on sex ratio of the population. The importance of full-sib mating decreases and that of half-sib mating increases with the increment of the value of sex ratio (r). When r = 3, full-sib mating has the same effect on effective size as half-sib mating.

Animals↗

PubMed2001

Mating-type genes for classical strain improvements of ascomycetes.

The ability to mate fungi in the laboratory is a valuable tool for genetic analysis and for classical strain improvement. In ascomycetous fungi, mating typically occurs between morphologically identical partners that are distinguished by their mating type. In most cases, the single mating-type locus conferring mating behavior consists of dissimilar DNA sequences (idiomorphs) in the mating partners. All ascomycete mating-type idiomorphs encode proteins with confirmed or putative DNA-binding motifs. These proteins control, as master regulatory transcription factors, pathways of cell speciation and sexual morphogenesis. Mating-type organization of four of the six classes of ascomycetes has been studied at the molecular level over the past 20 years. This review gives a short overview of the structural organization of the mating-type loci of yeasts and filamentous ascomycetes. In addition, this review describes how the availability of mating-type sequences allows the investigation of key issues concerning genetic and phylogenetic analyses of fungal species.

Amino Acid Sequence↗

PubMed2002

Influence of activated A and B mating-type pathways on developmental processes in the basidiomycete Coprinus cinereus.

The A and B mating type pathways in Coprinus cinereus monokaryons can be activated by transformation with cloned genes from strains of compatible mating types. The presence of heterologous A mating-type genes (Aon) induces production of submerged chlamydospores, hyphal knots and sclerotia in cultures kept in the dark. Upon illumination of transformants of certain strains (218), fruiting body primordia may develop that arrest before karyogamy. Furthermore, formation of aerial spores (oidia) is repressed by the action of A mating type genes in the dark, but light overrides this repression. Heterologous B mating type genes enhance the effects of the A genes on developmental processes, and partially repress the negative action of light on A-mediated regulation of development. Most notably, A-induced fruiting occurs more efficiently and earlier when the B mating type pathway is also active (Bon). However, activation of the B pathway alone is not sufficient to induce fruiting. Unlike A-activated transformants, A+ B-activated transformants of monokaryon 218 form mature fruiting bodies. Therefore, the B genes control fruiting body maturation at the stage of karyogamy. Basidia within the fruiting bodies that were analysed contained four spores in a typical post-meiotic arrangement. In the absence of an activated A mating type pathway, B mating type genes cause deformation and hyperbranching of vegetative hyphae, a reduction in aerial mycelium, and invasion of the agar substrate - a phenotype resembling the "flat" phenotype known from B-activated Schizophyllum commune strains. B-activated transformants usually show enhanced production of chlamydospores and hyphal knots, but maturation of sclerotia is variably efficient. Activation of the B mating type pathway in monokaryons blocked acceptance of nuclei, but not activation of the A mating type pathway.

Coprinus↗

PubMed2000

Comparative analysis of the mating-type loci from Neurospora crassa and Sordaria macrospora: identification of novel transcribed ORFs.

The mating-type locus controls mating and sexual development in filamentous ascomycetes. In the heterothallic ascomycete Neurospora crassa, the genes that confer mating behavior comprise dissimilar DNA sequences (idiomorphs) in the mat a and mat A mating partners. In the homothallic fungus Sordaria macrospora, sequences corresponding to both idiomorphs are located contiguously in the mating-type locus, which contains one chimeric gene, Smt A-3, that includes sequences which are similar to sequences found at the mat A and mat a mating-type idiomorphs in N. crassa. In this study, we describe the comparative transcriptional analysis of the chimeric mating-type region of S. macrospora and the corresponding region of the N. crassa mat a idiomorph. By means of RT-PCR experiments, we identified novel intervening sequences in the mating-type loci of both ascomycetes and, hence, concluded that an additional ORF, encoding a putative polypeptide of 79 amino acids, is present in the N. crassa mat a idiomorph. Furthermore, our analysis revealed co-transcription of the novel gene with the mat a-1 gene in N. crassa. The same mode of transcription was found in the corresponding mating-type region of S. macrospora, where the chimeric Smt A-3 gene is co-transcribed with the mat a-specific Smt a-1 gene. Analysis of a Smt A-3 cDNA revealed optional splicing of two introns. We believe that this is the first report of co-transcription of protein-encoding nuclear genes in filamentous fungi. Possible functions of the novel ORFs in regulating mating-type gene expression are discussed.

Alternative Splicing↗

PubMed1993

Heterologous expression of mating-type genes in filamentous fungi.

Podospora anserina and Neurospora crassa, two filamentous heterothallic ascomycetes, have a single mating-type locus with two alternate forms called mat+ and mat- and A and a, respectively. Mating type controls entry into the sexual cycle, events subsequent to fertilization, and, in N. crassa, prevents the formation of mixed mating-type heterokaryons. The mating types of these two organisms display similarity in their DNA structure and in the encoded polypeptides involved in fertilization. Here we show that this molecular similarity reflects a functional homology with respect to mating identity. Transformation experiments show that the N. crassa mating-type genes can provide the fertilization functions in P. anserina strains devoid of mating specificity as well as in mat+ and mat- strains. Reciprocally, the introduction of P. anserina mating-type genes confers mating activity in N. crassa. Functional identity between the mating types is not observed for vegetative incompatibility or for post-fertilization events such as meiosis and ascosporogenesis.

DNA-Binding Proteins↗

PubMed1992

Mating type switching in the tetrapolar basidiomycete Agrocybe aegerita.

The study of fruiting in the basidiomycete Agrocybe aegerita has shown that some haploid homokaryotic strains can spontaneously switch their mating specificities at the two unlinked A and B mating type factors. This event causes the dikaryotisation of primary homokaryons without plasmogamy and leads to the differentiation of sporulating fruit-bodies (pseudo-homokaryotic fruiting). For each mating type factor, the genetic analyses have revealed that: (1) parental and switched mating types segregate meiotically as Mendelian markers, (2) a total of six switched mating type factors (two parental and four nonparental) were obtained from a wild strain, (3) most of the nonparental factors have specificities differing from those of a large series of wild factors, (4) strains with the same expressed mating type can generate different specificities, (5) switching is always restricted to the same mating type in a homokaryon, (6) nonparental types can switch again, and (7) meiosis fixes the specificities to which switching can occur. This suggests, for the first time in filamentous fungi, the existence of a mechanism analogous to the mating type switching in yeasts. We hypothese that both A and B mating type regions in A. aegerita are constituted of three loci, one specialized in expression and two other carrying silent information. Mating type switching in homokaryotic strains would occur by copy transposition of silent A and B information into the expression loci. Moreover, we propose that during meiosis the silent loci are substituted by copies of the expressed loci.

Basidiomycota↗

PubMed1998

Molecular genetics of mating recognition in basidiomycete fungi.

The recognition of compatible mating partners in the basidiomycete fungi requires the coordinated activities of two gene complexes defined as the mating-type genes. One complex encodes members of the homeobox family of transcription factors, which heterodimerize on mating to generate an active transcription regulator. The other complex encodes peptide pheromones and 7-transmembrane receptors that permit intercellular signalling. Remarkably, a single species may have many thousands of cross-compatible mating types because the mating-type genes are multiallelic. Different alleles of both sets of genes are necessary for mating compatibility, and they trigger the initial stages of sexual development--the formation of a specialized filamentous mycelium termed the dikaryon, in which the haploid nuclei remain closely associated in each cell but do not fuse. Three species have been taken as models to describe the molecular structure and organization of the mating-type loci and the genes sequestered within them: the pathogenic smut fungus Ustilago maydis and the mushrooms Coprinus cinereus and Schizophyllum commune. Topics addressed in this review are the roles of the mating-type gene products in regulating sexual development, the molecular basis for multiple mating types, and the molecular interactions that permit different allelic products of the mating type genes to be discriminated. Attention is drawn to the remarkable conservation in the mechanisms that regulate sexual development in basidiomycetes and unicellular ascomycete yeasts, Saccharomyces cerevisiae and Schizosaccharomyces pombe, a theme which is developed in the general conclusion to include the filamentous ascomycetes Neurospora crassa and Podospora anserina.

Amino Acid Sequence↗

PubMed2003

Identification and characterization of a Candida albicans mating pheromone.

Candida albicans, the most prevalent fungal pathogen of humans, has recently been shown to undergo mating. Here we describe a mating pheromone produced by C. albicans alpha cells and show that the gene which encodes it (MFalpha) is required for alpha cells, but not a cells, to mate. We also identify the receptor for this mating pheromone as the product of the STE2 gene and show that this gene is required for the mating of a cells, but not alpha cells. Cells of the a mating type respond to the alpha mating pheromone by producing long polarized projections, similar to those observed in bona fide mating mixtures of C. albicans a and alpha cells. During this process, transcription of approximately 62 genes is induced. Although some of these genes correspond to those induced in Saccharomyces cerevisiae by S. cerevisiae alpha-factor, most are specific to the C. albicans pheromone response. The most surprising class encode cell surface and secreted proteins previously implicated in virulence of C. albicans in a mouse model of disseminated candidiasis. This observation suggests that aspects of cell-cell communication in mating may have been evolutionarily adopted for host-pathogen interactions in C. albicans.

Amino Acid Sequence↗

PubMed1999

Female mating strategy in an enclosed group of Japanese macaques.

Female Japanese macaques (Macaca fuscata) are noted for mating with multiple males and for their ability to exert mate choice. In a captive group of Japanese macaques housed at the Primate Research Institute of Kyoto University, Japan, behavioral and endocrine data were combined to examine female mating strategies. During one breeding season, daily behavioral observations were conducted on females who exhibited copulatory behavior. Blood was collected from females twice weekly and their ovulatory periods estimated by analyzing hormone profiles. Females began mating shortly before ovulation, peaked at ovulation, and continued receiving ejaculations for up to ten weeks after conception. Females were more responsible than males for inbreeding avoidance with matrilineal kin. Males sometimes approached females from their own matriline, but females avoided such males and expressed mate choice behavior preferentially toward non-matrilineal males. Over the entire mating season, females did not choose non-matrilineal males on the basis of displays, dominance rank, age, weight, or weight change during the mating season. When females were likely to conceive, however, they expressed mate choice behavior toward males who displayed most frequently. Female mating strategy may include both mate choice at ovulation and other, non-procreative functions.

Animals↗

PubMed2000

Influence of mate drinking, hot beverages and diet on esophageal cancer risk in South America.

To estimate the effects of consuming hot beverages, including mate (an infusion of the herb Ilex paraguayensis), tea, coffee and coffee with milk, and other food items on esophageal cancer risk, we analyzed data from 830 cases and 1,779 controls participating in a series of 5 hospital-based case-control studies of squamous-cell carcinoma of the esophagus conducted in high-risk areas of South America. After adjusting for the strong effects of tobacco and alcohol consumption, both heavy mate drinking (>1 l/day) and self-reported very hot mate drinking were significantly associated with esophageal cancer risk in men and women. The magnitude and strength of the association for mate amount and, to a lesser extent, mate temperature were higher for women than men. The joint effects of mate amount and mate temperature were more than multiplicative, following a statistically significant synergistic interaction (p = 0.02) which was particularly evident among heavy drinkers (>1.50 l/day) of very hot mate (odds ratio = 4.14, 95% confidence interval: 2.24-7.67) compared to light drinkers (<0.50 l/day) of cold/warm/hot mate. Consumption of other very hot beverages, such as tea and coffee with milk but not coffee alone, was also significantly associated with an increased risk, in the 2- to 4-fold range. Statistically significant protective associations were identified for high consumption of vegetables, fruits, cereals and tea. In contrast, frequent consumption of meat, animal fats and salt was associated with a moderately increased risk. This pooled analysis adds evidence for a carcinogenic effect of chronic thermal injury in the esophagus induced by the consumption of very hot drinks, including mate. Our study further confirms the protective effect of a dietary pattern characterized by daily consumption of fruits and vegetables and low consumption of meat and animal fats.

Aged↗

PubMed2004

Do males have a better chance of mating when the number of estrous females is equal to or greater than the males' ordinal rank? Testing the hypothesis in Japanese macaques.

This study was designed to test the hypothesis that male primates in multi-male/multi-female social groups with a clear male dominance hierarchy have a better chance of mating when the number of estrous females is equal to or greater than, as opposed to less than, the males' ordinal rank. I studied a Japanese macaque (Macaca fuscata fuscata) troop during mating seasons from 1992 to 1995. The mean daily operational sex ratio (OSR; the number of estrous females per troop male), which was calculated on observation days, was 0.21, 1.9, 0.48, and 3.1 in 1992-1995, respectively. Overall, focal animal sampling of males yielded 118 male-day records. The male-day records for each male were divided into the two estrous female number conditions: 1) the male-day records when the number of estrous females was equal to or greater than the male's ordinal rank, and 2) the male-day records when the number of estrous females was less than the male's ordinal rank. In the 1993 and 1995 mating seasons, when the number of estrous females was equal to or greater than the ordinal rank of each male, all of the males were observed mating. Conversely, when the number of estrous females was less than the ordinal rank of some male, they were not observed mating in the 1992 and 1994 mating seasons. The percentage for each male across each male's total mating opportunity was <20% when the number of estrous females was less than the male's ordinal rank. By contrast, the percentage for each male across each male's total mating opportunity exceeded 45% when the number of estrous females was equal to or greater than the male's ordinal rank, except for one male. Of all the male-day records for males observed mating with ejaculation, 41 were obtained when the number of estrous females was equal to or greater than the male's rank; conversely, only three records were obtained when the number of estrous females was less than the male's ordinal rank. Therefore, it appears that males have a better chance of mating when the number of estrous females is equal to or greater than the males' ordinal rank, as opposed to when the number is less than their ordinal rank.

Animals↗

PubMed1997

Sexual selection in Japanese macaques II: female mate choice and male-male competition

Mating and reproductive outcomes are the product of the potentially conficting strategies of breeding males and females. In a captive group of Japanese macaques, Macaca fuscata fuscatabehavioural, endocrine and genetic data were combined to assess the independent effects of male-male competition and female mate choice on mating and reproductive success. Males were ranked by social dominance and by their attractivity to females. Computer simulation and logistic regression analyses showed that male attractivity had a stronger effect than male dominance on both mating and reproductive outcome. Although male dominance and attractivity both significantly predicted mating success during fertile periods, only male attractivity significantly predicted actual male reproductive success. These results provide evidence that female mate choice can be a stronger determinant of mating and reproductive outcome in this species when male and female strategies are in conflict. The lack of a consistent correlation between male dominance rank and reproductive success in this species may be accounted for in part by female mate choice of socially subordinate males. Sires who were observed to mate with the mother during her fertile period were more likely to be socially dominant than sires who were not observed to do so. This observation suggests the existence of alternative mating strategies by subordinate males, which may also contribute to the lack of a consistent correlation between male dominance rank and reproductive success in this species.1997The Association for the Study of Animal Behaviour

Journal Article↗

PubMed1998

Monogyny and regulation of worker mating in the queenless ant Dinoponera quadriceps

The morphologically specialized queen caste has been lost in various ponerine ants, and mated workers ('gamergates') reproduce instead of queens. Unlike previous reports in the literature, we found only one gamergate in each colony of Dinoponera quadriceps. We documented monogyny by dissecting ovaries and spermathecae in 914 workers from 15 colonies, and by observing mating in the laboratory. In colonies without a gamergate, aggressive interactions among some of the unmated nestmates led to the behavioural differentiation of a top-ranking worker ('alpha'), which laid almost all the eggs. Only the alpha went outside the nest at night, and mated if foreign males were present (N=11 tests), thus becoming a gamergate. The alpha was sexually attractive even when her ovaries were not yet active. After intromission, the male remained linked to the alpha while she severed the end of his abdomen. Pieces of the male genitalia remained attached to her genital tract, and she removed them after 30+/-18 min (X+/-sdN=9). We interpret this to be a mating plug, preventing other males from fathering her offspring. None of these newly inseminated gamergates continued to go outside the nest, and, when tested, they never re-mated (N=4). Thus, gamergates of D. quadriceps probably mate only once. In queenless ant species, comparative evidence indicates that worker mating is often regulated in monogynous species, while unrestricted mating of young individuals is typical of polygynous species (oviposition is regulated subsequently). Furthermore, the occurrence of either monogyny or polygyny influences the mating strategies of males, and mating plugs have been reported only in some monogynous species. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗