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1.
In ants, winged queens that are specialized for independent colony foundation can be replaced by wingless reproductives better
adapted for colony fission. We studied this shift in reproductive strategy by comparing two Mystrium species from Madagascar using morphometry, allometry and dissections. Mystrium rogeri has a single dealate queen in each colony with a larger thorax than workers and similar mandibles that allow these queens
to hunt during non-claustral foundation. In contrast, Mystrium ‘red’ lacks winged queens and half of the female adults belong to a wingless ‘intermorph’ caste smaller and allometrically distinct
from the workers. Intermorphs have functional ovaries and spermatheca while those of workers are degenerate. Intermorphs care
for brood and a few mate and reproduce making them an all-purpose caste that takes charge of both work and reproduction. However,
their mandibles are reduced and inappropriate for hunting centipedes, unlike the workers’ mandibles. This together with their
small thorax disallow them to perform independent colony foundation, and colonies reproduce by fission. M. rogeri workers have mandibles polymorphic in size and shape, which allow for all tasks from brood care to hunting. In M. ‘red’, colonial investment in reproduction has shifted from producing expensive winged queens to more numerous helpers. M. ‘red’ intermorphs are the first case of reproductives smaller than workers in ants and illustrate their potential to diversify
their caste system for better colonial economy. 相似文献
2.
With the exception of several species, bumblebees are monandrous. We examined mating frequency in feral colonies of the introduced bumblebee Bombus terrestris in Japan. Using microsatellite markers, genotyping of sperm DNA stored in the spermatheca of nine queens detected multiple insemination paternities in one queen; the others were singly mated. The average effective paternity frequency estimated from the genotypes of queens and workers was 1.23; that estimated from the workers’ genotype alone was 2.12. These values were greater than those of laboratory-reared colonies in the native ranges of B. terrestris. The genotypes of one or two workers did not match those of their queens or showed paternities different from those of their nestmates; this may have arisen from either queen takeover or drifting of workers. These alien workers were responsible for the heterogeneous genotype distribution within each B. terrestris colony, resulting in higher estimates of paternity frequency than of insemination frequency. The high mating frequency of introduced B. terrestris may have occurred by artificial selection through mass breeding for commercialization. Moreover, polyandrous queens may be selectively advantageous, because reproduction by such queens is less likely to be disturbed by interspecific mating than that by monandrous queens. 相似文献
3.
Dynamics of sperm transfer in the ant Leptothorax gredleri 总被引:1,自引:1,他引:0
Mating tactics differ remarkably between and within species of social Hymenoptera (bees, wasps, ants) concerning, e.g., mating
frequencies, sperm competition, and the degree of male sperm limitation. Although social Hymenoptera might, therefore, potentially
be ideal model systems for testing sexual selection theory, the dynamics of mating and sperm transfer have rarely been studied
in species other than social bees, and basic information needed to draw conclusions about possible sperm competition and female
choice is lacking. We investigated sperm transfer in the ant Leptothorax gredleri, a species in which female sexuals attract males by “female calling.” The analysis of 38 female sexuals fixed immediately
or up to 7 days after copulation with a single male each revealed that the sperm is transferred into the female bursa copulatrix
embedded in a gelatinous mass, presumably a spermatophore. Sperm cells rapidly start to migrate from the tip of the spermatophore
towards the spermatheca, but transfer is drastically slowed down by an extreme constriction of the spermathecal duct, through
which sperm cells have to pass virtually one by one. This results in the spermatheca being filled only between one and several
hours after mating. During this time, the posterior part of the spermatophore seals the junction between bursa copulatrix
and spermathecal duct and prevents sperm loss. The prolonged duration of sperm transfer might allow female sexuals to chose
between ejaculates and explain previously reported patterns of single paternity of the offspring of multiply mated queens.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Most studies on insect sperm motility have been conducted in vitro using artificial environments outside the animal’s body.
Only little is known about the function of motile insect sperm at different sites within the male or female genital tracts.
We dissected genital tracts of female rove beetles (Drusilla canaliculata) to show that spermatozoa use their own motility to migrate from the spermatophore into the spermatheca. Our dissection method
allowed direct observation and filming of the spermathecal filling process inside the female’s genital tract. Spermatozoa
were found to enter the spermatheca individually, sometimes in groups of two or three. Although exhibiting only weak motility
and no progressive motion in buffer solution, the spermatozoa inside the female show vigorous lashing and reach an average
velocity of 47.5 μm s−1. To gain mobility and speed, the spermatozoa likely utilize the relatively small diameter of the spermathecal duct to push
themselves off the duct walls, rather than swimming freely in seminal fluid. The spermatozoa (approximately 1,250 μm) are
considerably longer than the distance they have to travel along the spermathecal duct (approximately 800 μm). Our study provides
the first direct observation of active sperm migration within the female of an insect stressing the importance of the genital
tract as a prerequisite for functional sperm motility. 相似文献
5.
A reassessment of the mating system characteristics of the army ant Eciton burchellii 总被引:1,自引:0,他引:1
Kronauer DJ Berghoff SM Powell S Denny AJ Edwards KJ Franks NR Boomsma JJ 《Die Naturwissenschaften》2006,93(8):402-406
In a recent study, Denny et al. (2004a) showed that queens of the army ant, Eciton burchellii, mate with multiple males and presented estimates suggesting that they mate with more males than queens of any other ant species so far investigated. They also inferred that data were consistent with queens being inseminated repeatedly throughout their life, which would be exceptional among the social Hymenoptera and contradictory to predictions from kin selection theory. In the present study, we reanalyze these data using new software and supplement them with similar microsatellite data from other colonies of the same species. Mating frequencies in E. burchellii are indeed very high (mean observed and effective queen-mating frequencies of 12.9 each) but considerably lower than the previous estimates. We show that the number of patrilines represented in the first worker offspring of a young queen is lower than in older queens but suggest that this may be due to initial sperm clumping in the queen’s sperm storage organ, rather than to repeated inseminations. Moreover, we found no evidence for repeated mating by genotyping sequential worker generations produced by a single old queen, showing that she did not obtain new inseminations despite ample opportunities for mating. 相似文献
6.
The potential for reproductive conflict among colony members exists in all social insect societies. For example, queens and
workers may be in conflict over the production of males within colonies. Kin selection theory predicts that in a colony headed
by a multiply-mated queen, worker reproduction is prevented by worker policing in the form of differential oophagy. However,
few studies have demonstrated that workers actually lay eggs within queenright colonies. The purpose of this study was to
determine if workers laid male eggs within unmanipulated queen-right colonies of the polyandrous social wasps Vespula maculifrons and V. squamosa. We focused our analysis on an unusual brood pattern within colonies, multiple egg cells. We were primarily interested in
determining if individuals reared in these irregular circumstances were queen or worker offspring. To address this question,
we genotyped 318 eggs from eight V. maculifrons and two V. squamosa colonies. No worker‑reproduction was detected in any of the queenright colonies; all of the eggs found in multiple egg cells were consistent
with being queen‑produced. However, the frequency of multiple egg cells differed among colonies, suggesting that queens vary
in the frequency of errors they make when laying eggs within cells. Finally, we suggest that workers may not be laying eggs
within queenright colonies and that worker reproduction may be controlled through mechanisms other than differential oophagy
in polyandrous Vespula wasps. 相似文献
7.
Ants inhabit diverse terrestrial biomes from the Sahara Desert to the Arctic tundra. One factor contributing to the ants’
successful colonization of diverse geographical regions is their ability to manipulate objects when excavating nests, capturing,
transporting and rendering prey or grooming, feeding and transporting helpless brood. This paper is the first to report the
form and function of opposable spines on the foretarsi of queens and workers used during fine motor and gross motor object
manipulation in the fire ant, Solenopsis invicta. In conjunction with their mandibles, queens and workers used their foretarsi to grasp and rotate eggs, push or pull thread-like
objects out of their way or push excavated soil pellets behind them for disposal by other workers. Opposable spines were found
on the foretarsi of workers from seven of eight other ant species suggesting that they might be a common feature in the Formicidae. 相似文献
8.
Caste-specific pheromone biosynthesis is a prerequisite for reproductive skew in the honeybee. Nonetheless, this process is
not hardwired but plastic, in that egg-laying workers produce a queen-like pheromone. Studies with Dufour’s gland pheromone
revealed that, in vivo, workers’ gland biosynthesis matches the social status of the worker, i.e., sterile workers showed
a worker-like pattern whereas fertile workers showed a queen-like pattern (production of the queen-specific esters). However,
when incubated in vitro, the gland spontaneously exhibits the queen-like pattern, irrespective of its original worker type,
prompting the notion that ester production in workers is under inhibitory control that is queen-dependent. We tested this
hypothesis by exposing queen or worker Dufour’s glands in vitro to brain extracts of queens, queenright (sterile) workers
and males. Unexpectedly, worker brain extracts activated the queen-like esters biosynthesis in workers’ Dufour’s gland. This
stimulation was gender-specific; queen or worker brains demonstrated a stimulatory activity, but male brains did not. Queen
gland could not be further stimulated. Bioassays with heated and filtered extracts indicate that the stimulatory brain factor
is below 3,000 Da. We suggest that pheromone production in Dufour’s gland is under dual, negative–positive control. Under
queenright conditions, the inhibitor is released and blocks ester biosynthesis, whereas under queenless conditions, the activator
is released, activating ester biosynthesis in the gland. This is consistent with the hypothesis that queenright workers are
unequivocally recognized as non-fertile, whereas queenless workers try to become “false queens” as part of the reproductive
competition. 相似文献
9.
Ropalidia marginata and Ropalidia cyathiformis are sympatric, primitively eusocial paper wasps widely distributed in peninsular India. We compare the two species, especially their queens, in an attempt to begin to understand the role of the power of queens over their workers, in social organisation and evolution. Queens of R. marginata have lower levels of activity, rates of interactions and dominance behaviour, compared with queens of R. cyathiformis. For the same variables, R. marginata queens are either indistinguishable from or have lower values than their workers, while R. cyathiformis queens have higher values than their workers. R. marginata queens never occupy the top rank while R. cyathiformis queens are always at the top of the behavioural dominance hierarchies of their colonies. R. marginata queens thus do not appear to use dominance behaviour to suppress reproduction by their workers, while R. cyathiformis queens appear to do so. These different mechanisms used by the two queens to regulate worker reproduction give them different powers over their workers, because R. marginata queens are completely successful in suppressing reproduction by their nestmates while in R. cyathiformis colonies, other individuals also sometimes lay eggs. There is also some evidence that the different powers of the queens result in different mechanisms of regulation of worker foraging in the two species--decentralised, self-regulation in R. marginata and relatively more centralised regulation by the queen in R. cyathiformis. Thus we show here, perhaps for the first time, that the power of the queens over their workers can have important consequences for social organisation and evolution. 相似文献
10.
Kin selection theory predicts that in colonies of social Hymenoptera with multiply mated queens, workers should mutually inhibit (“police”) worker reproduction, but that in colonies with singly mated queens, workers should favor rearing workers’ sons instead of queens’ sons. In line with these predictions, Mattila et al. (Curr Biol 22:2027–2031, 2012) documented increased ovary development among workers in colonies of honey bees with singly mated queens, suggesting that workers can detect and respond adaptively to queen mating frequency and raising the possibility that they facultative police. In a follow-up experiment, we test and reject the hypothesis that workers in single-patriline colonies prefer worker-derived males and are able to reproduce directly; we show that their eggs are policed as strongly as those of workers in colonies with multiply mated queens. Evidently, workers do not respond facultatively to a kin structure that favors relaxed policing and increased direct reproduction. These workers may instead be responding to a poor queen or preparing for possible queen loss. 相似文献
11.
Christopher D. Pull William O. H. Hughes Mark J. F. Brown 《Die Naturwissenschaften》2013,100(12):1125-1136
Pathogens exert a strong selection pressure on organisms to evolve effective immune defences. In addition to individual immunity, social organisms can act cooperatively to produce collective defences. In many ant species, queens have the option to found a colony alone or in groups with other, often unrelated, conspecifics. These associations are transient, usually lasting only as long as each queen benefits from the presence of others. In fact, once the first workers emerge, queens fight to the death for dominance. One potential advantage of co-founding may be that queens benefit from collective disease defences, such as mutual grooming, that act against common soil pathogens. We test this hypothesis by exposing single and co-founding queens to a fungal parasite, in order to assess whether queens in co-founding associations have improved survival. Surprisingly, co-foundresses exposed to the entomopathogenic fungus Metarhizium did not engage in cooperative disease defences, and consequently, we find no direct benefit of multiple queens on survival. However, an indirect benefit was observed, with parasite-exposed queens producing more brood when they co-founded, than when they were alone. We suggest this is due to a trade-off between reproduction and immunity. Additionally, we report an extraordinary ability of the queens to tolerate an infection for long periods after parasite exposure. Our study suggests that there are no social immunity benefits for co-founding ant queens, but that in parasite-rich environments, the presence of additional queens may nevertheless improve the chances of colony founding success. 相似文献
12.
Kikuchi T Miyazaki S Ohnishi H Takahashi J Nakajima Y Tsuji K 《Die Naturwissenschaften》2008,95(10):963-968
Evolution of caste is a central issue in the biology of social insects. Comparative studies on their morphology so far suggest
the following three patterns: (1) a positive correlation between queen–worker size dimorphism and the divergence in reproductive
ability between castes, (2) a negative correlation among workers between morphological diversity and reproductive ability,
and (3) a positive correlation between queen–worker body shape difference and the diversity in worker morphology. We conducted
morphological comparisons between castes in Pachycondyla luteipes, workers of which are monomorphic and lack their reproductive ability. Although the size distribution broadly overlapped,
mean head width, head length, and scape length were significantly different between queens and workers. Conversely, in eye
length, petiole width, and Weber’s length, the size differences were reversed. The allometries (head length/head width, scape
length/head width, and Weber’s length/head width) were also significantly different between queens and workers. Morphological
examinations showed that the body shape was different between queens and workers, and the head part of workers was disproportionately
larger than that of queens. This pattern of queen–worker dimorphism is novel in ants with monomorphic workers and a clear
exception to the last pattern. This study suggests that it is possible that the loss of individual-level selection, the lack
of reproductive ability, influences morphological modification in ants. 相似文献
13.
Rare royal families in honeybees, Apis mellifera 总被引:1,自引:0,他引:1
Moritz RF Lattorff HM Neumann P Kraus FB Radloff SE Hepburn HR 《Die Naturwissenschaften》2005,92(10):488-491
The queen is the dominant female in the honeybee colony, Apis mellifera, and controls reproduction. Queen larvae are selected by the workers and are fed a special diet (royal jelly), which determines
caste. Because queens mate with many males a large number of subfamilies coexist in the colony. As a consequence, there is
a considerable potential for conflict among the subfamilies over queen rearing. Here we show that honeybee queens are not
reared at random but are preferentially reared from rare “royal” subfamilies, which have extremely low frequencies in the
colony's worker force but a high frequency in the queens reared. 相似文献
14.
In many social taxa, reproductively dominant individuals sometimes use aggression to secure and maintain reproductive status.
In the social insects, queen aggression towards subordinate individuals or workers has been documented and is predicted to
occur only in species with a small colony size and a low level of queen–worker dimorphism. We report queen aggression towards
reproductive workers in the ant species Aphaenogaster cockerelli, a species with a relatively large colony size and a high level of reproductive dimorphism. Through analysis of cuticular
hydrocarbon profiles, we show that queens are aggressive only to reproductively active workers. Non-reproductive workers treated
with a hydrocarbon typical for reproductives are attacked by workers but not by queens, which suggests different ways of recognition.
We provide possible explanations of why queen aggression is observed in this species. 相似文献
15.
Under complementary sex determination (CSD), females of Hymenoptera arise from diploid, fertilized eggs and males from haploid,
unfertilized eggs. Incidentally, fertilized eggs that inherit two identical alleles at the CSD locus will develop into diploid
males. Diploid males are usually unviable or sterile. In a few species, however, they produce diploid sperm and father a triploid
female progeny. Diploid males have been reported in a number of social Hymenoptera, but the occurrence of triploid females
has hardly ever been documented. Here, we report the presence of triploid females, diploid males, and diploid sperm (produced
by diploid males and stored in queen spermathecae) in the ant Tapinoma erraticum. Moreover, we show variations in the frequency of triploids among female castes: Triploid females are more frequent among
workers than virgin queens; they are absent among mated, reproductive queens. The frequency of triploid workers also varies
between populations and between nests within populations. 相似文献
16.
The use of species distribution models (SDMs) to predict potential distributions of species is steadily increasing. A necessary
assumption when projecting models throughout space or time is that climatic niches are conservative, but recent findings of
niche shifts during biological invasion of particular plant and animal species have indicated that this assumption is not
categorically valid. One reason for observed shifts may relate to variable selection for modelling. In this study, we assess
differences in climatic niches in the native and invasive ranges of the Greenhouse frog (Eleutherodactylus planirostris). We analyze which variables are more ‘conserved’ in comparison to more ‘relaxed’ variables (i.e. subject to niche shift)
and how they influence transferability of SDMs developed with Maxent on the basis of ten bioclimatic layers best describing
the climatic requirements of the target species. We focus on degrees of niche similarity and conservatism using Schoener's
index and Hellinger distance. Significance of results are tested with null models. Results indicate that the degrees of niche
similarity and conservatism vary greatly among the predictive variables. Some shifts can be attributed to active habitat selection,
whereas others apparently reflect variation in the availability of climate conditions or biotic interactions between the frogs'
native and invasive ranges. Patterns suggesting active habitat selection also vary among variables. Our findings evoke considerable
implications on the transferability of SDMs over space and time, which is strongly affected by the choice and number of predictors.
The incorporation of ‘relaxed’ predictors not or only indirectly correlated with biologically meaningful predictors may lead
to erroneous predictions when projecting SDMs. We recommend thorough assessments of invasive species' ecology for the identification
biologically meaningful predictors facilitating transferability. 相似文献
17.
Sperm number is often a good predictor of success in sperm competition; however, it has become increasingly clear that, for
some species, variation in probability of paternity cannot be explained by sperm number alone. Intraspecific variation in
ejaculate characteristics, such as the number of viable sperm and sperm longevity, may play an equally important role in determining
fertilization success. Here, we assess variation among ejaculates in three factors that may contribute to fertilization success
(number of sperm per ejaculate, viability, and longevity), in a population of Peron’s tree frog (Litoria peronii). We detected large variation among males in the number of sperm per ejaculate and the proportion of viable sperm within
ejaculates, which could not be explained by variation in either male size or body condition. However, the proportion of viable
sperm released by males increased over the season. Finally, we assessed sperm longevity (proportion viable sperm determined
using a dual-fluorochrome vital dye) at two different temperatures. At 23°C, on average, 75% of sperm remained viable after
2 h, but there were significant differences amongst males with the percentage of viable sperm ranging from 43% to 95%. For
sperm incubated at 4°C, ejaculates varied fivefold in sperm longevity with some males having 50% viable sperm after 5 days.
Our data suggest that ejaculate characteristics (sperm number, viability, and longevity) vary widely in Peron’s tree frog
and may therefore play an important role in determining siring success both in the presence and absence of sperm competition.
We discuss the results in relation to selection on ejaculate traits via natural and sexual selection in this and other amphibians. 相似文献
18.
19.
Fuminori Ito Yoshifumi Touyama Ayako Gotoh Shungo Kitahiro Johan Billen 《Die Naturwissenschaften》2010,97(8):725-728
Thelytokous parthenogenesis in which diploid females are produced from unfertilized eggs, was recently reported for some ant
species. Here, we document thelytokous reproduction by queens in the polygynous species Pyramica membranifera. Queens that emerged in the laboratory were kept with or without workers under laboratory conditions. Independent colony
founding was successful for a few queens if prey was provided. All artificial colonies, which started with a newly emerged
queen and workers produced new workers and some of the colonies also produced female sexuals. Some of the female sexuals shed
their wings in the laboratory and started formation of new polygynous colonies. Workers had no ovaries and thus, were obligatorily
sterile. 相似文献
20.
Dietrich Neumann 《Die Naturwissenschaften》1995,82(7):310-320
Physiological clocks have been selected in various eukaryotic organisms in relation to daily, tidal, lunar and annual cycles of the environment. Insect species are appropriate experimental objects for the analysis of biological timing mechanisms and their evolutionary adaptation to the local environment. The most complex periodic environment occurs in the interface between the land and the sea, i.e., in the range of spring and neap tides. By the combination of ’circadian‘ and ’circalunar‘ clocks and their reliably perceptible ’zeitgeber‘ conditions, a few marine insects can temporally program their development to distinct tidal situations that occur only on distinct lunar days and at a distinct time of day every 14–15 days. 相似文献