共查询到20条相似文献,搜索用时 625 毫秒
1.
Detailed knowledge of the mating system in specific social insect populations is essential for testing general evolutionary
hypotheses of multiple paternity in eusocial Hymenoptera. We have studied the mating frequency of queens in a polygynous population
of the red ant Myrmica sulcinodis. Genetic mother-offspring analysis showed that double mating occurred at a considerable frequency, but that the effective
number of queen-mates remained close to one. After quantifying the effects of multiple maternity (polygyny) and multiple paternity
(polyandry) on the genetic diversity of workers, we conclude that multiple paternity in M. sulcinodis did not evolve as an adaptation to increase genetic variation within colonies. Contrary to the predictions from `genetic
variability' hypotheses, we found a positive correlation between colony-specific queen number and the average number of mates
per queen. Such positive association of queen number and frequency of multiple mating was also found after analysing comparative
data across six species of Myrmica ants. These results suggest that resticted dispersal of young queens may be a common factor promoting both polygyny and polyandry
at the same time, and that moderate degrees of multiple mating may be an unselected consequence of (1) mating at low cost
when mating occurs close to the nest and (2) mating in swarms with a highly male biased operational sex ratio. Future comparative
tests of genetic-variability hypotheses should therefore not include species with such evolutionary derived mating system
characteristics.
Received: 30 April 1998 / Accepted after revision: 19 August 1998 相似文献
2.
Liselotte Sundström 《Behavioral ecology and sociobiology》1993,33(5):345-354
Summary The genetic population structure and the sociogenetic organization of the red wood ant Formica truncorum were compared in two populations with monogynous colonies and two populations with polygynous colonies. The genetic population structure was analysed by measuring allele frequency differences among local subsets of the main study populations. The analysis of sociogenetic organisation included estimates of nestmate queen and nestmate worker relatedness, effective number of queens, effective number of matings per queen, relatedness among male mates of nestmate queens and relatedness between queens and their male mates. The monogynous populations showed no differentiation between subpopulations, whereas there were significant allele frequency differences among the subpopulations in the polygynous population. Workers, queens and males showed the same genetical population structure. The relatedness among nestmate workers and among nestmate queens was identical in the polygynous societies. In three of the four populations there was a significant heterozygote excess among queens. The queens were related to their male mates in the polygynous population analysed, but not in the monogynous ones. The data suggest limited dispersal and partial intranidal mating in the populations with polygynous colonies and outbreeding in the populations having monogynous colonies. Polyandry was common in both population types; about 50% of the females had mated at least twice. The males contributed unequally to the progeny, one male fathering on average 75% of the offspring with double mating and 45–80% with three or more matings.
Correspondence to: L. Sundström 相似文献
3.
In populations of various ant species, many queens reproduce in the same nest (polygyny), and colony boundaries appear to
be absent with individuals able to move freely between nests (unicoloniality). Such societies depart strongly from a simple
family structure and pose a potential challenge to kin selection theory, because high queen number coupled with unrestricted
gene flow among nests should result in levels of relatedness among nestmates close to zero. This study investigated the breeding
system and genetic structure of a highly polygynous and largely unicolonial population of the wood ant Formica paralugubris. A microsatellite analysis revealed that nestmate workers, reproductive queens and reproductive males (the queens' mates)
are all equally related to each other, with relatedness estimates centring around 0.14. This suggests that most of the queens
and males reproducing in the study population had mated within or close to their natal nest, and that the queens did not disperse
far after mating. We developed a theoretical model to investigate how the breeding system affects the relatedness structure
of polygynous colonies. By combining the model and our empirical data, it was estimated that about 99.8% of the reproducing
queens and males originated from within the nest, or from a nearby nest. This high rate of local mating and the rarity of
long-distance dispersal maintain significant relatedness among nestmates, and contrast with the common view that unicoloniality
is coupled with unrestricted gene flow among nests.
Received: 8 February 1999 / Received in revised form: 15 June 1999 / Accepted: 19 June 1999 相似文献
4.
Kevin R. Foster Perttu Seppä Francis L. W. Ratnieks Peter A. Thorén 《Behavioral ecology and sociobiology》1999,46(4):252-257
Queen mating frequency was studied in the European hornet, Vespa crabro, by analyzing four DNA microsatellite loci in 20 workers from each of 14 nests. Queens were found to be predominantly singly
mated (9/14), although double (4/14) and triple mating (1/14) also occurred. For most multiply mated queens, paternity was
significantly biased with the majority male fathering on average 80% of the female offspring. The population-wide effective
mating frequency was therefore low (1.11), and sister-sister relatedness high (0.701 ± 0.023 SE). Low effective mating frequency
in Vespa, in combination with data from other vespines, suggests that high paternity frequency is derived in the group. Some problems
with the non-detection of fathers, where the queen was not sampled or shared alleles with males, are analyzed.
Received: 16 November 1998 / Received in revised form: 29 March 1999 / Accepted: 12 April 1999 相似文献
5.
Ignacio Fernández-Escudero Pekka Pamilo Perttu Seppä 《Behavioral ecology and sociobiology》2002,51(3):207-213
The occurrence and genetic effects of polyandry were studied in the ant Proformica longiseta using three microsatellite markers. The average queen mating frequency (QMF) estimated from the sperm dissected from the spermathecae of 61 queens was 2.4 with 69% of the queens being multiply mated. QMF estimated from worker offspring in a subsample of eight monogynous colonies was 3.5, but the effective paternity (me,p) was only 1.23. The difference between these values reflected unequal sperm use by the queens. Most colonies of P. longiseta were polygynous and the average relatedness among workers was 0.35. Polyandry thus added only marginally to the genetic diversity of colonies, and our results gave little support to the genetic-variability hypothesis for explaining polyandry. Diploid male load was low, as only 1% of males were diploid. A large majority (92%) of nests produced one sex only, with males produced in colonies that had higher than average worker relatedness. This contradicted the predictions derived from worker control of sex ratios. Males produced enough sperm to fill the spermathecae of several queens. Thus, the results indicated that diploid male load, sperm limitation and sex ratio conflict are also unlikely explanations of polyandry. Plausible hypotheses for polyandry include mating by convenience, as the sex ratio is male biased and the mating costs to a female can be low because the females are wingless and have no mating flight. The observed unequal sperm use furthermore points to sperm choice and sperm competition as important factors in the evolution of polyandry. 相似文献
6.
Knowledge of the sociogenetic organization determining the kin structure of social insect colonies is the basis for understanding
the evolution of insect sociality. Kin structure is determined by the number and relatedness of queens and males reproducing
in the colonies, and partitioning of reproduction among them. This study shows extreme flexibility in these traits in the
facultatively polygynous red ant Myrmica rubra. Relatedness among worker nestmates varied from 0 to 0.82. The most important reason for this variation was the extensive
variation in the queen number among populations. Most populations were moderately or highly polygynous resulting in low relatedness
among worker nestmates, but effectively monogynous populations were also found. Polygynous populations also often tend to
be polydomous, which is another reason for low relatedness. Coexisting queens were positively related in two populations out
of five and relatedness was usually similar among workers in the same colonies. Due to the polydomous colony organization
and short life span of queens, it was not possible to conclusively determine the importance of unequal reproduction among
coexisting queens, but it did not seem to be important in determining the relatedness among worker nestmates. The estimates
of the mating frequency by queens remained ambiguous, which may be due to variation among populations. In some populations
relatedness among worker nestmates was high, suggesting monogyny and single mating by queens, but in single-queen laboratory
nests relatedness among the worker offspring was lower, suggesting that multiple mating was common. The data on males were
sparse, but indicated sperm precedence and no relatedness among males breeding in the same colony. A comparison of social
organizations and habitat requirements of M. rubra and closely related M. ruginodis suggested that habitat longevity and patchiness may be important ecological factors promoting polygyny in Myrmica.
Received: 15 May 1995/Accepted after revision: 17 October 1995 相似文献
7.
C. Tate Holbrook Christoph-Peter Strehl Robert A. Johnson Jürgen Gadau 《Behavioral ecology and sociobiology》2007,62(2):229-236
The evolution of polyandry is a central problem in the study of insect mating systems, and both material and genetic benefits
have been proposed to offset the presumed costs of multiple mating. Although most eusocial Hymenoptera queens mate with just
one or occasionally two males, high levels of polyandry are exhibited by several taxa, including seed-harvester ants of the
genus Pogonomyrmex. Previous studies of queen mating frequency in Pogonomyrmex have focused on monogynous (one queen per colony) species in the subgenus Pogonomyrmex. We performed a genetic mother–offspring analysis of mating frequency in Pogonomyrmex (Ephebomyrmex) pima, a queen-dimorphic species with dealate and intermorph queens that differ in colony structure (intermorph colonies contain
multiple queens). Our results demonstrate that both dealate and intermorph queens of P. (E.) pima are typically single maters, unlike their congeners analyzed thus far. Polyandry appears to be a derived trait in Pogonomyrmex, but comparative tests between P. (E.) pima queen morphs and across the genus provide no evidence that it evolved as an adaptation to increase genetic diversity within
colonies or to obtain more sperm, respectively. 相似文献
8.
Sigal Lahav Victoria Soroker Robert K. Vander Meer Abraham Hefetz 《Behavioral ecology and sociobiology》1998,43(3):203-212
This study compares two basic models for the origin and maintenance of colony gestalt odor in the polygynous ant species
Cataglyphis niger. In the first model, queens are centers of de novo biosynthesis and distribution of recognition odors (“queen-centered” model);
in the second, colony odors are primarily synthesized and distributed by workers (“worker-centered” model). We tested the
behavioral patterns that are predicted from each model, and verified by biochemical means the distributional directionality
of these signals. Encounters between nestmates originating from split colonies were as amicable as between nestmates from
non-split colonies; queenless ants were as aggressive as their queenright nestmates, and both were equally aggressed by alien
ants. These results indicate that queens have little impact on the recognition system of this species, and lend credence to
the worker-centered model. The queen-centered model predicts that unique queen substances should be produced in appreciable
quantities and that, in this respect, queens should be more metabolically active than workers. Analysis of the chemical composition
of postpharyngeal glands (PPGs) or cuticular extracts of queens and workers revealed high similarity. Quantitatively, queens
possessed significantly greater amounts of hydrocarbons in the PPG than workers, but the amount on the thoracic epicuticle
was the same. Queens, however, possess a lower hydrocarbon biosynthesis capability than workers. The biochemical evidence
thus refutes the queen-centered model and supports a worker-centered model. To elucidate the directionality of cue distribution,
we investigated exchange of hydrocarbons between the castes in dyadic or group encounters in which selective participants
were prelabeled. Queens tended to receive more and give less PPG content, whereas transfer to the epicuticle was low and similar
in all encounters, as predicted from the worker-centered hypothesis. In the group encounters, workers transferred, in most
cases, more hydrocarbons to the queen than to a worker. This slight preference for the queen is presumably amplified in a
whole colony and can explain their copious PPG content. We hypothesize that preferential transfer to the queen may reflect
selection to maintain her individual odor as close to the average colony odor as possible.
Received: 4 November 1997 / Accepted after revision: 5 February 1998 相似文献
9.
Multiple mating is likely to be costly for ant queens and yet it is common. Whether multiple mating brings benefits to queens
that outweigh the costs has, therefore, received considerable theoretical attention. Empirical tests of hypotheses have been
scarce and no clear evidence has been reported. We tested the “multiple-mating-for-more-sperm” hypothesis on individual young
queens in a natural population of the leafcutter ant Atta colombica, a monogynous ant characterised by very large colonies and high colony longevity. We found that the number of sperm stored
by queens was positively correlated with the number of mates per queen estimated through mother-offspring analysis with microsatellite
DNA markers. Queen sperm stores increased on average by 30 million sperm for each additional mate. Life-history information
for Atta indicate that the number of stored sperm observed is likely to constrain the reproductive lifespan of queens in nature. Multiple
mating, despite costs, may therefore enhance the fitness of Atta queens because it enables them to store more sperm.
Received: 19 September 1997 / Accepted after revision: 7 December 1997 相似文献
10.
Jay D. Evans 《Behavioral ecology and sociobiology》1998,44(1):35-42
Most social groups have the potential for reproductive conflict among group members. Within insect societies, reproduction
can be divided among multiple fertile individuals, leading to potential conflicts between these individuals over the parentage
of sexual offspring. Colonies of the facultatively polygynous ant Myrmicatahoensis contain from one to several mated queens. In this species, female sexuals were produced almost exclusively by one queen.
The parentage of male sexuals was more complex. In accordance with predictions based on worker sex-allocation preferences,
male-producing colonies tended to have low levels of genetic relatedness (i.e., high queen numbers). Correspondingly, males
were often reared from the eggs of two or more queens in the nest. Further, over half of the males produced appeared to be
the progeny of fertile workers, not of queens. Overall investment ratios were substantially more male biased than those predicted
by genetic relatedness, suggesting hidden costs associated with the production of female sexuals. These costs are likely to
include local resource competition among females, most notably when these individuals are adopted by their maternal nest.
Received: 3 March 1998 / Accepted after revision: 20 June 1998 相似文献
11.
Sex ratios were bimodally distributed in a population of the monogynous and monandrous ant Leptothorax nylanderi during each of 3 study years. The population-wide investment ratios suggested worker control of sex allocation. Nest-level
variation in the proportional investment in virgin queens was not affected by the presence or absence of a queen and only
slightly by collecting year, but was correlated with nest size, total sexual investment and, unexpectedly, with differences
in nestmate relatedness: small, low-investment nests and nests with several worker lineages produced male-biased sex ratios.
Colonies containing several worker lineages arise from usurpation of mature colonies by unrelated founding queens and the
fusion of unrelated colonies under strong nest site limitation. In contrast to facultatively polygynous and polyandrous species
of social insects, where workers can maximize their inclusive fitness by adjusting sex ratios according to the degree of relatedness
asymmetry, workers in mixed colonies of L. nylanderi do not benefit from manipulating sex allocation, as here relatedness asymmetries appear to be the same as in homogeneous
colonies.
Received: 7 December 1999 / Received in revised form: 29 February 2000 / Accepted: 13 March 2000 相似文献
12.
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.
Received: 16 November 1998 / Received in revised form: 9 February 1999 / Accepted: 21 February 1999 相似文献
13.
T. Giraud R. Blatrix C. Poteaux M. Solignac P. Jaisson 《Behavioral ecology and sociobiology》2001,49(2-3):128-134
Gnamptogenys striatula is a polygynous ant species, in which all workers are potentially able to mate. The reproductive status, relatedness and
pedigree relationships among nestmate queens and winged females in a Brazilian population were investigated. We collected
all the sexual females of 12 colonies (2–44 queens per colony, plus 2–18 winged females in 3 colonies). Dissections revealed
that 98% of the queens were inseminated and that the queens in the most polygynous colonies did not lay equal numbers of eggs.
The sexual females and a sample of the population were genotyped using eight microsatellite markers. Relatedness among nestmate
queens was among the highest recorded to date (0.65±0.25), and tests of pedigree relationship showed that they were likely
to be full-sisters, and sometimes cousins. Mated winged females were always full-sisters, the estimated genetically effective
queen numbers were low and tests of pedigree relationship showed that only a few queens in the colony could be the mothers.
These results suggest that the high queen-queen relatedness in polygynous colonies of G. striatula is maintained by an unusual mechanism: winged females are mostly produced by only one or a few queens, and these groups of
full-sisters are recruited back into their original nest after mating.
Received: 26 November 1999 / Revised: 7 September 2000 / Accepted: 7 September 2000 相似文献
14.
Ludivine de Menten Denis Fournier Colin Brent Luc Passera Edward L. Vargo Serge Aron 《Behavioral ecology and sociobiology》2005,58(6):527-533
Social Hymenoptera are general models for the study of parent-offspring conflict over sex ratio, because queens and workers frequently have different reproductive optima. The ant Pheidole pallidula shows a split distribution of sex ratios with most of the colonies producing reproductives of a single sex. Sex ratio specialization is tightly associated with the breeding system, with single-queen (monogynous) colonies producing male-biased brood and multiple-queen (polygynous) colonies female-biased brood. Here, we show that this sex specialization is primarily determined by the queens influence over colony sex ratio. Queens from monogynous colonies produce a significantly more male-biased primary sex ratio than queens from polygynous colonies. Moreover, queens from monogynous colonies produce a significantly lower proportion of diploid eggs that develop into queens and this is associated with lower rate of juvenile hormone (JH) production compared to queens from polygynous colonies. These results indicate that queens regulate colony sex ratio in two complementary ways: by determining the proportion of female eggs laid and by hormonally biasing the development of female eggs into either a worker or reproductive form. This is the first time that such a dual system of queen influence over colony sex ratio is identified in an ant. 相似文献
15.
Jürgen Gadau Pia J. Gertsch Jürgen Heinze Pekka Pamilo Bert Hölldobler 《Behavioral ecology and sociobiology》1998,44(1):23-33
Multilocus DNA fingerprinting and microsatellite analysis were used to determine the number of queens and their mating frequencies
in colonies of the carpenter ant, Camponotus ligniperdus (Hymenoptera: Formicidae). Only 1 of 61 analyzed queens was found to be double-mated and the population-wide effective mating
frequency was therefore 1.02. In the studied population, 8 of 21 mature field colonies (38%) contained worker, male, or virgin
queen genotypes which were not compatible with presumed monogyny and therefore suggested oligogyny, i.e., the cooccurrence
of several mutually intolerant queens within one colony. Estimated queen numbers in oligogynous colonies ranged between two
and five. According to the results of the genetic analysis, most of the queens coexisting in oligogynous colonies were not
closely related. Pleometrosis is very rare and queenless colonies adopt mated queens both in the laboratory and field. Therefore,
the most plausible explanation for the origin of oligogynous colonies in C. ligniperdus is the adoption of unrelated queens by orphaned mature colonies. The coexistence of unrelated, but mutually intolerant queens
in C. ligniperdus colonies demonstrates that oligogyny should be considered as a phenomenon distinct from polygyny.
Received: 18 December 1997 / Accepted after revision: 20 June 1998 相似文献
16.
Lack of kin recognition in swarming honeybees ( Apis mellifera ) 总被引:2,自引:0,他引:2
Honeybee colonies reproduce by colony fission and swarming. The primary swarm leaves the nest with the mated mother queen.
Further “after-swarms” can leave the nest. These are composed of virgin queens and sister workers. Since all workers in the
primary swarm have the same relationship to the mother queen, kin recognition cannot have any effect on the worker distribution
in the swarm. Because of polyandry of the mother queen, the after-swarm is composed of super- and halfsister workers of the
virgin queen. In this case kin recognition might affect swarm composition if workers increase their inclusive fitness by preferentially
investing in a supersister queen. The distribution of workers in the mother colony, the primary and the after-swarm was analyzed
using single-locus DNA fingerprinting in two colonies of the honeybee (Apis mellifera). The colonies were composed of 21 and 24 worker subfamilies because of multiple mating of the queen. The subfamily distribution
in the mother colonies before swarming was significantly different from the subfamily frequencies in the primary swarm. This
indicates different propensities for swarming in the various subfamilies. The subfamily distribution was also significantly
different between the mother colony and the after-swarm. There was however no significant difference between the subfamily
composition of the primary and the after-swarm. The average effects of kin recognition on the distribution of the subfamilies
in the two after-swarms were less than 2%. We conclude that colony-level selection sets the evolutionary framework for swarming
behaviour.
Received: 22 May 1996 / Accepted after revision: 2 November 1996 相似文献
17.
Barbara L. Thorne 《Behavioral ecology and sociobiology》1984,14(2):117-136
Summary ecological aspects of monogyny and polygyny in social insect colonies are important in comparing individual queen reproductive success. Inseminated, fecund, multiple foundresses are common in some groups of ants and eusocial wasps, but true polygyny in termites has not previously been studied. One third of Nasutitermes corniger (Isoptera: Termitidae) colonies sampled in areas of young second growth in Panama contained from 2–33 primary queens (not supplementary or neotenic reproductives). All queens in polygynous associations were fully pigmented, physogastric egg layers within a single royal cell. Multiple kings were found less frequently; true polyandry is apparently restricted to immature polygynous colonies.Data on queen weight and morphological features, and on colony composition, show that queens in polygynous nests are young and that a transition from polygyny to monogyny probably occurs after several years. The escalated growth rate of multiple queen colonies removes them from the vulnerable incipient colony size class more rapidly than colonies initiated by a single foundress, and gives them sufficient neuter support staff (workers and soldiers) to enable earlier production of fertile alates. Using a population model (Leslie matrix) I construct isoclines of equal population growth which show values of early age class probability of survival and reproductive output favoring monogyny or polygyny under individual selection. This model of queen mutualism accounts for the risk of a female in a polygynous group not succeeding as the final surviving queen.Multiple primary queens are considered rare in termites, but a review of the literature demonstrates that they may be more widespread than is currently recognized. Polygyny in termites has received scant attention but is of significance as an example of a further ecological and evolutionary convergence between the phylogenetically independent orders Isoptera and Hymenoptera. 相似文献
18.
Summary There is high within-nest relatedness for functional queens (with corpora lutea), nonfunctional queens (without corpora lutea), and workers in polygynous nests of Leptothorax acervorum. The high functional queen relatedness suggests that young mated queens are adopted back to their mother nest. Functional queen relatedness does not change with the number of queens present in the nest, suggesting that the number of generations of queens, on average two to three, is rather stable. Worker relatedness decreases with increasing number of functional queens per nest (Tables 5, 6). The number of queens contributing offspring to the nest (mothers), estimated from worker and functional queen relatedness, is lower than the number of functional queens, particularly in highly polygynous nests. Estimates of number of mothers in monogynous nests indicate that these nests previously were polygynous (Table 7). There is no correlation between nest relatedness and distance between nests, and budding-off, if present, thus appears to be a rare mode of nest founding (Table 8). There are no indications of inbreeding in the two populations studied since the frequency of heterozygotes is as high as expected from random mating (Table 4). Most likely, polygyny is the rule in L. acervorum and serves to secure the presence of queens in the nest. 相似文献
19.
Reproductive skew among cooperatively breeding animals has recently attracted considerable interest. In social insects reproductive
skew has been studied in females but not in males. However, cooperative breeding of males occurs when two males mate with
the same queen and father offspring. Here we present the first analysis of comparative data on paternity skew in ants. We
show that, across seven species of Formica ants, the average skew in paternity among worker offspring of doubly mated queens is negatively correlated with the population-wide
frequency of multiple (mostly double) mating. We also demonstrate that this trend is relatively robust in additional analyses
taking phylogenetic relationships between species into account. The observed trend is opposite to the one normally found in
non-social insects with second-male precedence through sperm displacement, but agrees with predictions based on queen-male
conflict over sperm allocation as a consequence of facultative, worker controlled, sex allocation – an interpretation which
assumes first-male precedence. However, alternative (but not mutually exclusive) explanations are possible and further studies
will be needed to discriminate between these alternatives.
Received: 16 May 1997 / Accepted after revision: 26 September 1997 相似文献
20.
Pekka Pamilo 《Behavioral ecology and sociobiology》1990,27(1):31-36
Summary Sex allocation theory is developed for polygynous eusocial Hymenoptera in which nests recruit their own daughters as new reproductive queens. Such restricted dispersal of females leads to the expectation of male-biased investment ratios. The expectation depends on the parameter q telling what proportion of the total contribution in the gene pool by all new queens is due to those dispersing. Under queen control the expected sex allocation, expressed as the proportion of resources invested in males, is IM =1/(1 + q). Under worker control, IM depends on the relatedness of old queens, on the number of males they have mated with, and on the proportion of males produced by workers. With single mating and no worker reproduction, the approximate predictions for IM are 1/(1 + q) when the nests have many highly related queens, 1/(1 + 2 q) when the old queens are as related as average worker nest mates, and 1/(1 + 3q) when the old queens are not related to each other at all. The observed investment ratios in polygynous ants would, on average, match values of the parameter q between 0.4 and 0.5. Values of q have not been estimated in nature. If q is smaller than 0.4, which may well be true, the observed sex allocation in polygynous ants is in fact more female-biased than predicted by the theory. This indicates that the female bias found in monogynous ants may not be exceptional and could be due to factors other than worker control of sex allocation. Because the value of q is likely to vary among species, testing the predictions of the theory requires thorough single-species studies. 相似文献