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1.
In Acromyrmex octospinosus leaf-cutting ants the metapleural glands produce an array of antibiotic compounds that serve as a general defence against unwanted microbes on the cuticle. Leaf-cutting ants also grow mutualistic Pseudonocardiaceae bacteria on their cuticle that produce antibiotics controlling a microfungal parasite of their fungus gardens. Interaction between this bacterium and gland secretion therefore seems unavoidable. We document the typical development of bacterial growth on the cuticle of young major workers, show that growth starts a few days after eclosion, and that the maximal cover is reached after 2–3 weeks and gradually declines when workers mature. Experimental closure of the metapleural glands had no effect on the initial exponential growth phase of the bacterium, but significantly reduced the cover during the decline phase. The age-dependent abundance of the bacterium and its partial dependence on metapleural gland secretion support the hypothesis that the abundance of this mutualist is actively regulated. 相似文献
2.
Susanne P. A. den Boer Jacobus J. Boomsma Boris Baer 《Behavioral ecology and sociobiology》2008,62(12):1843-1849
The seminal fluid that accompanies sperm in ejaculates has been shown or suggested to affect sperm competition and paternity
success of insects by preventing female remating, inducing oviposition, and forming mating plugs. In Atta leafcutter ants, queens have multiple mates but never remate later in life, although they may live and produce fertilized
eggs for several decades. The mating biology and life history of these ants therefore suggests that the major function of
seminal fluid is to maximize sperm viability during copulation, sperm transfer, and initial sperm storage. We tested this
hypothesis by comparing the viability of testis sperm and ejaculated sperm (mixed with seminal fluid) and found a significant
positive effect of seminal fluid on sperm viability. We further quantified this positive effect by adding accessory gland
secretion (a major component of seminal fluid) in a dilution series, to show that minute quantities of accessory gland secretion
achieve significant increases in sperm viability. Sperm stored by queens for 1 year benefited in a similar way from being
exposed to accessory gland compounds after dissection in control saline solution. Our results provide the first empirical
evidence that seminal fluid is important for the production of viable ejaculates and that the accessory glands of Atta males—despite their small size—are functional and produce a very potent secretion. 相似文献
3.
Duccio Lambardi Francesca R. Dani Stefano Turillazzi Jacobus J. Boomsma 《Behavioral ecology and sociobiology》2007,61(6):843-851
Some social parasites of insect societies are known to use brute force when usurping a host colony, but most use more subtle
forms of chemical cheating either by expressing as few recognition cues as possible to avoid being recognized or by producing
similar recognition cues to the host to achieve positive discrimination. The former “chemical insignificance” strategy represents
a more general adaptive syndrome than the latter “chemical mimicry” strategy and is expected to be characteristic of early
evolutionary stages of social parasitism. We tested this hypothesis by experimentally analyzing the efficiency by which Acromyrmex echinatior leaf-cutting ants recognize intruding workers of the incipient social parasite Acromyrmex insinuator. The results were consistent with the parasite being “chemically insignificant” and not with the “chemical mimicry” hypothesis.
Gas chromatography–mass spectrometry analysis of cuticular hydrocarbon profiles showed that social parasite workers produce
significantly fewer hydrocarbons overall and that their typical profiles have very low amounts of hydrocarbons in the “normal”
C29–C35 range but large quantities of unusually heavy C43–C45 hydrocarbons. This suggests that the C29–C35 hydrocarbons are
instrumental in normal host nestmate recognition and that the C43–C45 compounds, all of which are dienes and thus more fluid
than the corresponding saturated compounds, may reinforce “chemical insignificance” by blurring any remaining variation in
recognition cues. 相似文献
4.
Katja?BargumEmail author Jacobus?J.?Boomsma Liselotte?Sundstr?m 《Behavioral ecology and sociobiology》2004,57(1):9-16
The genetic basis of morphological traits in social insects remains largely unexplored. This is even true for individual body size, a key life-history trait. In the social insects, the size of reproductive individuals affects dispersal decisions, so that small size in queens is often associated with reduced dispersal, and large size with long-range dispersal and independent colony founding. Worker size is connected to division of labour when workers specialize in certain tasks according to their size. In many species, variation in worker size has been shown to increase colony performance. In this study, we present the first evidence of an additive genetic component to queen size in ants, using maternal half sib analysis. We also compared intra-colony size variation in colonies with high (queen doubly mated) versus low (queen singly mated) genetic variability. We found a high and significant heritability (h2=0.51) for queen size in one of the two study years, but not in the other. Size variation among queens was greater in colonies headed by a doubly mated queen in one of the study years, but not in the other. This indicates that genetic factors can influence queen size, but that environmental factors may override these under some circumstances. The heritability for worker size was low (h2=0.09) and non-significant. Increased genetic diversity did not increase worker size variation in the colonies. Worker size appeared largely environmentally determined, potentially allowing colonies to adjust worker size ratios to current conditions.Communicated by J. Heinze 相似文献
5.
Dorte Bekkevold Jane Frydenberg Jacobus J. Boomsma 《Behavioral ecology and sociobiology》1999,46(2):103-109
Queen mating frequency of the facultatively polygynous ant Acromyrmex echinatior was investigated by analysing genetic variation at an (AG)n repeat microsatellite locus in workers and sexuals of 20 colonies from a single Panamanian population. Thirteen colonies
were found to be monogynous, 5 colonies contained multiple queens, whereas the queen number of 2 colonies remained unresolved.
Microsatellite genotypes indicated that 12 out of 13 queens were inseminated by multiple males (polyandry). The mean queen
mating frequency was 2.53 and the mean genetically effective paternity frequency was 2.23. These values range among the highest
found in ants, and the results are in keeping with the high mating frequencies reported for other species of leafcutter ants.
Consistent skew in the proportional representation of different patrilines within colonies was found, and this remained constant
in two consecutive samples of offspring. Dissections showed that all examined queens from multiple-queen colonies were mated
egg-layers. The mean relatedness value among nestmate workers in polygynous colonies was lower than that for monogynous colonies.
No diploid males were detected in a sample of 70 genotyped males. Worker production of males was detected in one queenless
colony. We discuss our findings in relation to known patterns of multiple maternity and paternity in other eusocial Hymenoptera.
Received: 2 September 1998 / Received in revised form: 3 February 1999 / Accepted: 7 February 1999 相似文献
6.
Dóra B. Huszár Rasmus S. Larsen Sarah Carlsen Jacobus J. Boomsma Jes Søe Pedersen 《Behavioral ecology and sociobiology》2014,68(11):1859-1870
Ant supercolonies (large networks of interconnected nests) represent the most extreme form of multi-queen breeding (polygyny) and have been found across ant lineages, usually in specific long-term stable populations. Many studies on the genetic population structure and demography of ant supercolonies have been done in recent decades, but they have lacked multicolonial control patches with separated colonies headed by a single or few queens so the origin of the supercolonial trait syndrome has remained enigmatic. Here, we set out to compare sympatric supercolonial and multicolonial patches in two natural Danish populations of the common red ant Myrmica rubra. We used DNA microsatellites to reconstruct genetic colony/population structure and obtained morphological and density measurements to estimate life history and ecology covariates. We found that supercolonies in both populations completely dominated their patches whereas colonies in multicolonial patches coexisted with other ant species. Supercolony patches had very low genetic differentiation between nests, negligible relatedness within nests, and lower inbreeding than multicolonial patches, but there were no significant morphological differences. One population also had nests that approached true outbred monogyny with larger workers and males but smaller queens than in the two other social nest types. Our results suggest that once smaller colonies start to adopt additional queens, they also gain the potential to ultimately become supercolonial when the habitat allows rapid expansion through nest budding. This is relevant for understanding obligate polygyny in ants and for appreciating how and why introduced North American populations of M. rubra have recently become invasive. 相似文献
7.
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
8.
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
9.
Seirian?SumnerEmail author William?O.?H.?Hughes Jacobus?J.?Boomsma 《Behavioral ecology and sociobiology》2003,54(3):256-263
Social parasites exploit the socially managed resources of social insect colonies in order to maximise their own fitness. The inquilines are among the most specialised social parasites, because they are dependent on being fully integrated into their host's colony throughout their lives. They are usually relatives of their host and so share ancestral characteristics (Emery's rule). Closely related inquiline-host combinations offer a rare opportunity to study trade-offs in natural selection. This is because ancestral adaptations to a free-living state (e.g. the production of a worker caste) become redundant and may be replaced by novel, parasitic traits as the inquiline becomes more specialised. The dynamics of such processes are, however, unknown as virtually all extant inquiline social parasites have completely lost their worker caste. An exception is Acromyrmex insinuator, an incipient permanent social parasite of the leaf-cutting ant Acromyrmex echinatior. In the present study, we document the size distribution of parasite and host workers and infer how selection has acted on A. insinuator to reduce, but not eliminate, its investment in a worker caste. We show that the antibiotic producing metapleural glands of these parasite workers are significantly smaller than in their host counterparts and we deduce that the metapleural gland size in the host represents the ancestral state. We further show experimentally that social parasite workers are more vulnerable to the general insect pathogenic fungus Metarhizium than are host workers. Our findings suggest that costly disease resistance mechanisms are likely to have been lost early in inquiline evolution, possibly because active selection for maintaining these traits became less when parasite workers had evolved the ability to exploit the collective immune system of their host societies. 相似文献
10.
Freddie-Jeanne Richard Michael Poulsen Abraham Hefetz Christine Errard David R. Nash Jacobus J. Boomsma 《Behavioral ecology and sociobiology》2007,61(11):1637-1649
Cuticular hydrocarbon profiles are essential for nestmate recognition in insect societies, and quantitative variation in these
recognition cues is both environmentally and genetically determined. Environmental cues are normally derived from food or
nest material, but an exceptional situation may exist in the fungus-growing ants where the symbiotic fungus garden may be
an independent source of recognition compounds. To investigate this hypothesis, we quantified the chemical profiles of the
fungal symbionts of 18 sympatric colonies of Acromyrmex echinatior and Acromyrmex octospinosus and evaluated the quantitative variation of the 47 compounds in a multivariate analysis. Colony-specific chemical profiles
of fungal symbionts were highly distinct and significantly different between the two ant species. We also estimated the relative
genetic distances between the fungal symbionts using amplified fragment length polymorphism (AFLP) and correlated these with
the overall (Mahalanobis) chemical distances between the colony-specific profiles. Despite the standardized laboratory conditions,
the correlations were generally weak, but a statistically significant portion of the total variation in chemical profiles
could be explained by genetic differences between the fungal symbionts. However, there was no significant effect of ant species
in partial analyses because genetic differences between symbionts tend to coincide with being reared by different ant species.
However, compound groups differed significantly with amides, aldehydes, and methyl esters contributing to the correlations,
but acetates, alkanes, and formates being unrelated to genetic variation among symbionts. We show experimentally that workers
that are previously exposed to and fed with the fungal symbiont of another colony are met with less aggression when they are
later introduced into that colony. It appears, therefore, that fungus gardens are an independent and significant source of
chemical compounds, potentially contributing a richer and more abundant blend of recognition cues to the colony “gestalt”
than the innate chemical profile of the ants alone.
Freddie-Jeanne Richard and Michael Poulsen contributed equally to this work. 相似文献