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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 34 (1994), S. 157-167 
    ISSN: 1432-0762
    Keywords: Key words: Sex ratio variation – Ants – Wing polymorphism – Polygyny – Polydomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary. The colony-level sex allocation pattern of eusocial Hymenoptera has attracted much attention in recent studies of evolutionary biology. We conducted a theoretical and empirical study on this subject using the dolichoderine ant Technomyrmex albipes. This ant is unusual in having a dispersal polymorphism in both males and females. New colonies are founded by an alate female after mating with one or more alate males in the nuptial flight. In mature colonies, the reproductive role of the foundress queen is taken over by wingless offspring (supplementary reproductives). Mature colonies are extremely polygynous, with many wingless queens reproducing through intra-colonial mating with wingless males (inbreeding), and producing both alate and wingless sexuals. The population sex ratio of wingless sexuals was found to be extremely female-biased, while the population allocation ratio of alates was almost 1: 1. This result suggests that there is local mate competition among wingless sexuals. A specific model for this extraordinary life cycle predicted that the asymmetry of ”regression relatedness” (b f/b m) will disappear during the first few generations of wingless reproductives after the foundress dies. If colonies begin to produce alates after several wingless generations, this undermines the hypotheses for inter-colonial sex ratio variation based on the relatedness asymmetry. We compared the magnitude of variation in sex ratios and other characteristics between two levels (within-colony-inter-nest and between-colony). Although there was considerable within-colony variation in all the examined characteristics, between-colony variances were always larger. This means that allocation is important at the whole-colony level, not that of the nest. There was no apparent correlation between the sex ratio of alates and colony size. Furthermore, partial correlation analysis indicated that neither the number of workers nor investment in alates explained the variation in the sex ratio of alates. The only factor which was significantly correlated with the sex ratio of alates was the sex ratio of wingless sexuals (a positive correlation). We conclude that both the alate and wingless sex ratios may be influenced by a common primary sex ratio at the egg stage, the variance of which may have genetic components. In the wingless sexuals, partial correlation analysis indicated that colony size and the number of workers explained the sex allocation ratio. The number of wingless females was strongly (positively) correlated with the total investment in wingless sexuals, while the number of males showed no such correlation. There is, however, no convincing explanation for the variation in sex allocation ratio of wingless sexuals, because the estimates of investment in wingless males may have a large sampling error.
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  • 2
    ISSN: 1572-8889
    Keywords: metatibial gland ; calling behavior ; sexual pheromone ; ponerine ; Diacamma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several species of the ant genus Diacamma reproduce through mated workers (gamergates). Such gamergates have no wings and therefore are unable to conduct nuptial flight. Instead they perform a sexual calling behavior by standing outside the nest and rubbing the tibiae of their hindleg over the surface of the arched gaster. In a series of exclusion experiments we demonstrate that secretions from the metatibial gland are the most important component in making the virgin female attractive to the males.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 35 (1994), S. 109-113 
    ISSN: 1432-0762
    Keywords: Maintenance of cooperation ; Division of labor ; Interdemic selection ; Proportion of forager ; Behavioral flexibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The queenless ant Pristomyrmex pungens has an unusual social structure, in which all workers reproduce parthenogenetically and help others. Laboratory experiments manipulating the proportion of post-reproductive foragers in the colony at various rates suggested that colonies with 5–10% forager ratios had the maximum efficiency per-worker. This result suggests that the cooperative colonies may be maintained by colony-level natural selection. Non-cooperative mutants that oviposit but do not forage should increase in relative frequency in the colony in the short term. However, decreased colony productivity and the resulting competition among colonies might eliminate colonies dominated by such mutants in the long term. P. pungens has a viscous population without migration between colonies, which may facilitate this process.
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  • 4
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Technomyrmex albipes makes huge polydomous colonies which consist of up to several millions of adults. In field colonies, dealate queens are rare or absent, though winged males and winged females emerge annually (synchronously) in large numbers from late may to mid June. Field and laboratory observations showed that the reproduction of established colonies was performed by wingless females inseminated by wingless males from the same colony. Dissections and morphological examinations revealed that wingless females are workers with no spermatheca and intercastes with a spermatheca. Most intercastes were inseminated, had developed ovaries, and seemed to reproduce, while workers did not seem to reproduce. Extranidal tasks were performed only by workers. Approximately half of the adult population were intercastes, and wingless males represented only a small portion of all adults, the rest being nonreproductive workers. Intercastes and wingless males were produced throughout the year except in winter. The winged females and males copulate outside the nest only after the nuptial flight and the dealate females are able to perform independent founding, but they are also eventually supplanted by intercastes. The adoption of dealate queens by an established natal colony did not seem to occur. Thus we infer that in this species the winged reproductives disperse and found new colonies, while inbred wingless reproductives allow the enlargement and budding of colonies. This species has a special trophic-flow system. There is no trophallaxis among adults, and nutrient transfer from adults to other colony members is achieved exclusively by specialized trophic eggs. All females (dealate queens, intercastes, and workers) seem to produce trophic eggs. This aphid-like life cycle, i.e., the occurrence of both winged and wingless reproductive forms, may have evolved as an adaptation supporting the development of secondary polygyny and polydomy.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 34 (1994), S. 157-167 
    ISSN: 1432-0762
    Keywords: Sex ratio variation ; Ants ; Wing polymorphism ; Polygyny ; Polydomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The colony-level sex allocation pattern of eusocial Hymenoptera has attracted much attention in recent studies of evolutionary biology. We conducted a theoretical and empirical study on this subject using the dolichoderine ant Technomyrmex albipes. This ant is unusual in having a dispersal polymorphism in both males and females. New colonies are founded by an alate female after mating with one or more alate males in the nuptial flight. In mature colonies, the reproductive role of the foundress queen is taken over by wingless offspring (supplementary reproductives). Mature colonies are extremely polygynous, with many wingless queens reproducing through intea-colonial mating with wingless males (inbreeding), and producing both alate and wingless sexuals. The population sex ratio of wingless sexuals was found to be extremely female-biased, while the population allocation ratio of alates was almost 1:1. This result suggests that there is local mate competition among wingless sexuals. A specific model for this extraordinary life cycle predicted that the asymmetry of “regression relatedness” (b f/b m) will disappear during the first few generations of wingless reproductives after the foundress dies. If colonies begin to produce alates after several wingless generations, this undermines the hypotheses for intercolonial sex ratio variation based on the relatedness asymmetry. We compared the magnitude of variation in sex ratios and other characteristics between two levels (within-colony-inter-nest and between-colony). Although there was considerable within-colony variation in all the examined characteristics, between-colony variances were always larger. This means that allocation is important at the whole-colony level, not that of the nest. There was no apparent correlation between the sex ratio of alates and colony size. Furthermore, partial correlation analysis indicated that neither the number of workers nor investment in alates explained the variation in the sex ratio of alates. The only factor which was significantly correlated with the sex ratio of alates was the sex ratio of wingless sexuals (a positive correlation). We conclude that both the alate and wingless sex ratios may be influenced by a common primary sex ratio at the egg stage, the variance of which may have genetic components. In the wingless sexuals, partial correlation analysis indicated that colony size and the number of workers explained the sex allocation ratio. The number of wingless females was strongly (positively) correlated with the total investment in wingless sexuals, while the number of males showed no such correlation. There is, however, no convincing explanation for the variation in sex allocation ratio of wingless sexuals, because the estimates of investment in wingless males may have a large sampling error.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 46 (1999), S. 180-189 
    ISSN: 1432-0762
    Keywords: Key words Policing ; Worker reproduction ; Behavioral dominance ; Monandry ; Diacamma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Policing behavior that prevents workers from laying male eggs was examined in the monogynous and monandrous ponerine ant Diacamma sp. from Japan, in which a singly mated worker called a “gamergate” reproduces as the functional queen in each colony. Since oviposition by virgin workers is rare in the presence of a gamergate, we separated a portion of workers from the gamergates and induced their oviposition experimentally. When orphaned workers had started to oviposit, they were returned to the original colonies, where they continued to lay eggs for a while. The gamergates and other workers interfered with the laying workers by aggressively taking and finally eating the eggs. In total, 60% and 29% of the worker-derived eggs were eaten by gamergates and non-mother workers, respectively. The observed worker-worker interactions were not driven simply by competition to leave own sons, because non-laying non-orphaned workers interfered with worker reproduction. Furthermore, orphaned workers were usually attacked by non-orphaned workers soon after colony reunification. These results indicate that both queen policing by gamergates and worker policing in this species are mechanisms inhibiting worker oviposition. The gamergate contribution to policing was proportionately larger than that of workers, but among virgin workers, the relationship between dominance rank and contribution to policing was not clear. But about 11% of the eggs were not policed and were added to egg piles, especially in large colonies. Worker policing in a monandrous and monogynous eusocial Hymenoptera contrasts to other recent findings, and possible genetic, social, and ecological factors for its evolution in Diacamma sp. are discussed.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Evolutionary ecology 12 (1998), S. 141-152 
    ISSN: 1573-8477
    Keywords: average reproductive success ; Morisita's index ; reproductive skew ; sampling error ; special dispersion index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several indices of reproductive skew, which quantify the degree of unequal partitioning of reproductive output among members in an animal society, have been proposed. Here we point out the drawbacks of these indices. The most serious problem is the dependence of the indices on mean reproductive success: skew values tend to be larger, as average numbers of offspring decrease, due to random sampling error in numbers of offspring. Thus it is difficult to compare societies with different average lifetime reproductive success using these indices, even though we have presented methods to calculate the expected reproductive skew caused by random sampling error, especially when average numbers of offspring are small, as is often the case with cooperatively breeding vertebrates. As an alternative, we propose using the spatial dispersion indices of population ecology (Morisita's index or its standardized version) for the measurement of reproductive skew. These indices are almost independent of average fecundity and have their own method of testing for random variation in offspring numbers.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of ethology 6 (1988), S. 77-81 
    ISSN: 1439-5444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous workers (Tsuji & Itô 1986) have presented evidence that suggests individuals of the Japanese queenless ant,Pristomyrmex pungens (Formicidae, Myrmicinae) which is an obligatorily thelytokous species, can recognize individuals of “home” and those of “other” colonies. The data presented here are derived from an improved experimental set (transfer between foraging areas) and support the existence of colony recognition mechanisms. I also present some data on “natural” inter-colony interactions observed in the field. The studied population was divided into many distinct colonies (they were not unicolonial) and inter-colonial exchange was considered to be inhibited by aggressive interactions during inter-colonial encouters. During encounters between individuals from different colonies, fighting was often observed, and sometimes resulted in the death of combatants. Dead or wounded combatants were never carried into the nest of the winner's colony.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 23 (1997), S. 1025-1034 
    ISSN: 1573-1561
    Keywords: Ants ; Myrmicinae ; poison gland ; trail pheromone ; 6-n-pentyl-2-pyrone ; monoterpenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The myrmicine ant Pristomyrmex pungens marks recruitment trails with poison gland secretions. The effective trail pheromone compound is 6-n-pentyl-2-pyrone. Poison gland components were identified by means of gas chromatographic coupled mass spectrometry. The biological activity was examined in trail-following experiments as well as in gas chromatographic coupled electroantennograms. In addition to 6-n-pentyl-2-pyrone, a number of monoterpenes were found in the poison gland secretion, i.e., α-pinene, camphene, β-pinene, myrcene, α-phellandrene, α-terpinene, and limonene. The terpenoid compounds increased the trail-following response only slightly when offered together with 6-n-pentyl-2-pyrone. In contrast to the latter component, synthetic monoterpenes elicited no orientation behavior in trail-following bioassays.
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  • 10
    Publication Date: 2015-10-01
    Print ISSN: 1438-3896
    Electronic ISSN: 1438-390X
    Topics: Biology
    Published by Springer
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