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1.
In facultatively eusocial hover wasps, some females leave their natal nests while others choose to stay and become helpers.
We tested whether the decisions of 126 newly emerged females to stay or leave depended on group size: the number of females
already resident on their natal nests. We predicted that females would be less likely to stay in larger groups, where the
benefits of helping are probably smaller and there is a smaller chance of inheriting the dominant position. We also predicted
that unrelated females would be less likely to join larger groups. We manipulated group size by removing residents from nests.
Newly emerged females disappeared from their natal nests at a rate of 2.5% per day, but did not disappear from manipulated
nests at higher rates than controls. Experimentally reducing group size also did not increase the frequency of joiners. Newly
emerged females disappeared at twice the rate of older subordinate females, suggesting the existence of a `leaving window'
early in life. One problem is the difficulty of distinguishing between leaving and death.
Received: 7 July 1998 / Accepted after revision: 25 October 1998 相似文献
2.
Sabra L. Klein H. Ray Gamble Randy J. Nelson 《Behavioral ecology and sociobiology》1999,45(5):323-329
Females may choose mates based on secondary sex traits that reflect disease resistance. Accordingly, females should be able
to distinguish between unparasitized and parasitized males, and should prefer to mate with unparasitized individuals. Mate
and odor preferences for uninfected males or males infected with the nematode, Trichinella spiralis, were examined among prairie voles (Microtus ochrogaster) and meadow voles (M. pennsylvanicus). In a 15-min odor preference test, only female meadow voles distinguished between bedding from parasitized and unparasitized
conspecific males, and preferred to spend time with bedding from unparasitized males. Although T. spiralis infection influenced odor preference in female meadow voles, there was no effect of infection status on mate preference among
either species. Testosterone and corticosterone concentrations were not different between parasitized and unparasitized males.
However, among prairie voles, males that spent an increased amount of time with females during the mate preference test had
elevated testosterone concentrations. Taken together, these data suggest that (1) female meadow voles can discriminate between
unparasitized and parasitized males, (2) the effects of infection on steroid hormone concentrations may be masked by the effects
of social interactions, and (3) parasites may represent a selective constraint on partner preference in voles; however, the
life cycle of parasites may influence female preference and should be considered in studies of female preference.
Received: 23 April 1998 / Accepted after revision: 25 October 1998 相似文献
3.
Frank Rosell Gry Gundersen Jean-François Le Galliard 《Behavioral ecology and sociobiology》2008,62(10):1559-1568
Neighbour–stranger discrimination occurs when individuals respond with more aggression to strangers than to territorial neighbours—a
phenomenon termed the “dear enemy phenomenon” (DEP). We investigated the DEP with male and female root voles (Microtus oeconomus Pallas 1776) using field dyadic arena tests conducted in enclosures where we could test for the effects of familiarity (familiar
versus stranger), ownership (resident versus intruder status) and resource-holding potential (body mass) on territorial behaviours.
The results showed that males put more effort into territorial defence than females, and males could discriminate between
neighbours and strangers. In males, aggressiveness was influenced by a significant two-way interaction between treatment and
ownership. Male residents were more aggressive towards stranger intruders than towards neighbour intruders, while male intruders
were less aggressive towards stranger residents than towards neighbour residents. In females, neither treatment nor ownership
status had a significant effect on aggressiveness. Familiar males performed more social behaviours but less non-social behaviours
than stranger males. Furthermore, there was a clear dominance hierarchy between residents and intruders in stranger dyads,
with the male territory holders dominating the intruder in pairwise interactions. To our knowledge, these results demonstrate
for the first time DEP in a small mammal with a known pedigree and present the first evidence for “prior resident advantage”
in voles. We argue that both ownership status and familiarity status affect how much an individual invests in territory defence.
The benefits of neighbour–stranger discrimination for male root voles and the absence of neighbour–stranger discrimination
in female root voles are discussed. 相似文献
4.
Brian Keane Sara Parsons Byran J. Smucker Nancy G. Solomon 《Behavioral ecology and sociobiology》2014,68(12):1951-1964
Laboratory studies have shown that vasopressin can influence sociosexual behavior through its action on the vasopressin 1a receptor (V1aR). There is substantial evidence that the length of a microsatellite in the gene (avpr1a) encoding for the V1aR can affect social attachment to females and paternal behavior in male prairie voles under laboratory conditions. However, previous field studies of prairie voles have failed to detect a strong effect of the length of a male’s avpr1a allele on their sociosexual behavior, but these studies are typically much shorter than the average prairie vole breeding lifespan. We examined the relationship between male avpr1a microsatellite allele length and sociosexual behavior in a natural population of prairie voles for 15 weeks, closer to the lifespan of prairie voles in nature. Contrary to predictions, we found that males with the longest avpr1a microsatellite alleles were significantly more likely to sire offspring with more than one female and to sire offspring that survived until trappable age than males with the shortest avpr1a microsatellite allele lengths. This relationship was the strongest for males with the longest tenure on the study site. As in previous field studies, we did not find evidence of a relationship between a male’s avpr1a genotype and any index of social behavior including male residency status or the number of females with which males associate. This is the first study to support the hypothesis that a male’s avpr1a genotype is a factor underlying variation in the genetic mating system of prairie voles under natural conditions. 相似文献
5.
Donald G. Miller III. 《Behavioral ecology and sociobiology》1998,43(2):95-103
This study investigated the consequences of communal gall induction on individual and group fitness in the aphid Tamaliacoweni. The possibilities that kin discrimination and foundress density are factors favoring communal gall occupation were examined.
Clonally produced aphid foundresses were collected to create two treatments: clonal groups and groups of less closely related
individuals. These were confined on suitable host plant tissue to compare their respective propensities towards communal behavior.
There were no significant differences in the frequencies of communal gall occupation; therefore, active kin discrimination
by T.coweni foundresses apparently does not play a role in their communal behavior, within the context of this experiment. In a second
experiment, aphid foundress density on the host plant was manipulated in three treatments and was correlated with the frequency
of communal gall occupation. Individual fitness was inversely related to the mean number of foundresses per gall. These results
suggest that communal gall occupation does not necessarily represent mutual cooperation but may instead be the outcome of
competition for limited gall sites on the host plant. However, natural selection at the clonal level may favor communal gall
occupation under the conditions of resource limitation and high within-group relatedness.
Received: 26 September 1997 / Accepted after revision: 28 March 1998 相似文献
6.
Summary Breeding units (occupants of a nest including at least one reproductive female) within two free-living populations of the prairie vole, Microtus ochrogaster, were monitored by live-trapping at nest during two 28-h periods each week from October 1980 to March 1984. Data are presented for 281 breeding units from all seasons, at high and low population densities and during breeding and nonbreeding periods. Fifty percent of the breeding units were monogamous (single resident reproductive male and female), 27% consisted of a single reproductive female with no resident adult male and 23% included more than one resident adult male and/or female (complex units). Monogamous units were present in the same proportions during breeding and nonbreeding periods. The number of monogamous units was significantly greater at low population densities than at high densities. During winter there were relatively more complex units and fewer single female units than during the rest of the year. Monogamous pairs remained together for an average of 42 days. Seventy-eight percent of these pairs were disbanded by the death of one or both members. There were few overlaps of the home ranges of adjacent breeding units. Significantly more nests were visited by nonresident males than by females, and the intervals between visits by males were significantly shorter than those for visits by females. Males visited single female units significantly more often than units with one or more resident males. Survival of juveniles was generally very low; 38% and 34% of young males and females, respectively, that were trapped survived until 30 days of age. Of young females remaining at the natal nest at low population densities, only 17.6% were reproductively activated; 77.1% of such females became reproductively activated at high densities. All young females that dispersed from the natal nest became reproductive. 相似文献
7.
Effects of Habitat Loss and Fragmentation on the Behavior and Demography of Gray-Tailed Voles 总被引:6,自引:0,他引:6
We monitored the short term behavioral and demographic responses of gray-tailed voles (Microtus canicaudus) to the reduction and fragmentation of their habitat. Our objectives were (1) to test whether animals perished or moved into remaining fragments after 70% of their habitat was removed; and (2) to test the null hypothesis that the social structure and demography of animals would not differ between habitats consisting of one large continuous fragment (625 m2), a mosaic of 25 small fragments (each 25 m2) separated by 4 m of bare ground, and control, unmanipulated habitats (1850 m2). We conducted the experiment in 12, 0.2-ha enclosures planted with alfalfa with four replicates for each of two manipulated treatments and a control. A 70% reduction in habitat did not adversely affect adult survival, reproductive rate, juvenile recruitment, or population size. However, an influx of unrelated females into habitat fragments resulted in decreased juvenile recruitment in those fragments. Voles from cleared habitat moved into the remaining habitat and did not measurably affect the resident population. Similarly, the demography of voles did not differ significantly among the large-fragment, small-fragment, and control enclosures. Peak density estimates based on the amount of habitat in each enclosure were 545 animals per hectare in control, 1056 in large-fragment, and 2880 in small-fragment enclosures. Reduced movement of animals among the small fragments was the most obvious effect of habitat fragmentation. Six percent of females and 15% of males moved among small fragments within a week compared to approximately 60% moving comparable distances in large-fragment and control enclosures. Rates of juvenile dispersal and sexual maturation declined throughout the summer on all treatments, were associated with season and density, and were only marginally associated with habitat loss and fragmentation. We conclude that at the time of habitat removal and fragmentation, populations were small enough to accommodate a 70% reduction in habitat and still continue to increase in numbers. The social system of gray-tailed voles was sufficiently flexible to accommodate an influx of animals to withstand densities> 1000 voles per ha. The behavioral and demographic features of gray-tailed voles are similar to those reported for other small mammals, thus confirming the use of voles for ecological model systems in habitat fragmentation studies. 相似文献
8.
Betty McGuire Lowell L. Getz Joyce E. Hofmann Theresa Pizzuto Barbara Frase 《Behavioral ecology and sociobiology》1993,32(5):293-302
Summary We used intensive livetrapping to examine natal dispersal and philopatry in prairie voles (Microtus ochrogaster). The majority of male (70.0%) and female prairie voles (75.1 %) remained at the natal nest until death. Those males and females that did disperse left home at about the same age (45–55 days) and moved similar distances (28–33 m). Dispersal was more common (1) from small natal groups than from large natal groups, (2) following disappearance of parents, (3) during the breeding period than during the nonbreeding period, and (4) at low population densities than at high densities. Dispersal was not associated with level of competition for mates within natal groups, and dispersers did not differ from nondispersers in body weight. Our data do not support competition for mates or resources as important factors influencing natal dispersal in prairie voles. The absence of sex differences in dispersal tendency or distance, and our fording that more than half of dispersers had become reproductive before leaving the natal nest, lead us to suggest that inbreeding avoidance is not a primary function of dispersal in this species. Dispersal was, however, more common when potential mates within the natal group were relatives than when they were nonrelatives. Although not tested here, if family members avoid mating with one another through patterns of mate choice, then some animals may leave home in search of mates. The precise benefits associated with philopatry in prairie voles remain to be identified.
Correspondence to: B. McGuire at her present address 相似文献
9.
Inbreeding depression is a well-documented phenomenon. In animals, one means of avoiding the costs of inbreeding is through
the recognition and avoidance of kin as mates. Prairie voles (Microtus ochrogaster) are short-lived, socially monogamous rodents that demonstrate inbreeding depression in the laboratory. Field data indicate
that pair formation in nature is opportunistic but pairing among close relatives seems uncommon. We examined the role of relatedness
and familiarity on prairie vole social associations and reproduction by placing adult voles into 0.1-ha enclosures with familiar
siblings, unfamiliar siblings, and unrelated, unfamiliar conspecifics. Live-trapping data indicated that indices of social
pair bonding were random with respect to relatedness and familiarity. Among females whose litters were sired by a single male,
litters were significantly more likely to be sired by unfamiliar than familiar males, but the number of litters sired by males
that were unrelated to their partner was not different from the number of litters sired by males that were related to their
partner. Additionally, females that produced offspring with familiar siblings were significantly more likely to have litters
with multiple paternity than females not producing offspring with familiar siblings. However, multiple paternity was not influenced
by relatedness of sires. Finally, older individuals were more likely to produce offspring with each other than with younger
individuals. Our findings suggest that prior association is a more important mechanism of inbreeding avoidance than phenotype
matching for prairie voles mating under ecologically relevant conditions. 相似文献
10.
Sperm competition and sexual selection: a meta-analysis of paternity studies of birds 总被引:8,自引:0,他引:8
Sperm competition (the competition among the sperm of different males for fertilization of the eggs of a female) has been
suggested to be an important component of sexual selection, but no general assessment has been made of this proposition. We
used a meta-analytic approach to assess the extensive literature on paternity (the proportion of offspring in a focal nest
sired by an attending male) in birds based on allozyme and molecular techniques. The relative variance in male mating success
was on average increased by a factor of 4.6 over the variance in apparent male success. Males with more extravagant secondary
sexual characters had higher paternity in their own nests than less adorned males. There was a weak effect of male age being
positively associated with paternity in own nests. Male body size measured as the length of wing and tarsus was weakly positively
associated with paternity in own nests. Male survival prospect was positively associated with paternity in own nests. Polygynous
males generally had decreased paternity of their broods compared to monogamous males. Paternity of the resident male decreased
with increasing population density and breeding asynchrony. The intensity of paternity guards such as within-pair copulation
rate and mate guarding were not significantly related to extra-pair paternity. Sperm competition was thus an important component
of sexual selection by increasing the variance in male mating success, and by being associated with the expression of secondary
sexual characters, in particular in dense and asynchronously breeding populations of birds.
Received: 12 February 1998 / Accepted after revision: 31 May 1998 相似文献
11.
Summary Within a natural population of blacktailed prairie dogs (Cynomys ludovicianus), 68% of sampled juveniles received milk from foster mothers via communal nursing (Table 1). In proximate terms, communal nursing may result because prairie dog mothers seem unable to discriminate between their own and others' offspring. In ultimate terms, both indirect selection and reduced predation on juveniles resulting from the formation of multilitter groupings have probably been important in the evolution of communal nursing. 相似文献
12.
Wiebke Schuett Jesse Laaksonen Toni Laaksonen 《Behavioral ecology and sociobiology》2012,66(9):1341-1350
Consistent behavioural differences between individuals of the same population (“personality” variation) might arise if individuals follow different life-history strategies. Thus, it would be important to determine how personality variation relates to behaviours potentially associated with life-history strategies, such as those related to the use of information about the state of the environment. Little is, however, known about how personality is associated with information use and reproductive success. We tested whether wild social jackdaws, Corvus monedula, show consistent behavioural differences in their exploratory behaviour (in a novel environment in the lab and in their reaction towards a novel object in the wild) and prospecting behaviour (number of visits to conspecific nests). We furthermore examined whether these behavioural traits are linked with each other and predictors of reproductive success. Breeding jackdaws were consistent in their exploratory behaviour within, and in their prospecting behaviour between, years. Exploratory behaviour in the novel environment was correlated with the latency to approach a novel object in the wild but not with the frequency of prospecting at conspecific nests. Highly exploratory males and females and frequently prospecting males produced fewer fledglings than less exploratory individuals or less prospecting males, respectively. We discuss the importance of consistent individual differences in exploration and information sampling on individual fitness. 相似文献
13.
Most studies of social polygyny in birds have examined male provisioning on the basis of the number of feeding visits. This
may be misleading if males compensate for infrequent visits by bringing larger prey at each visit. We investigated nestling
provisioning in the socially polygynous great reed warbler, Acrocephalus arundinaceus, in south Central Sweden in 1996–1997. We collected data on rate of feeding visits, prey size and the amount of biomass delivered
by males and females. Males had lower rates of feeding visits and provided smaller prey to nestlings in secondary than in
monogamous and primary nests. Secondary females had higher rates of feeding visits and brought larger prey than monogamous
and primary females. These results confirm that secondary females face a potential cost of polygyny through a lower rate of
male feeding, and that this cost was reinforced by the significantly lower male provisioning rate (biomass h–1) at secondary nests. Secondary females compensated for the lack of male assistance by increasing their rate of feeding and
bringing larger prey. As a result, offspring in nests of secondary females received as much food as did those in nests of
primary females. Prey load size increased with the parent’s proportion of feeding visits, suggesting that parents use different
feeding strategies depending on their amount of responsibility for nestling provisioning. We suggest that parents which take
the main responsibility for nestling feeding have to forage further away from the nest, and based on optimal-foraging theory,
they should then on average bring larger prey to their nest.
Received: 4 April 1999 / Received in revised form: 12 October 1999 / Accepted: 23 October 1999 相似文献
14.
Christopher E. Hill S. Elizabeth Campbell J. Cully Nordby John M. Burt Michael D. Beecher 《Behavioral ecology and sociobiology》1999,46(5):341-349
Sharing song types with immediate neighbors is widespread in birds with song repertoires, and sharing songs may confer a
selective advantage in some cases. Levels of song sharing vary between different geographical populations of several bird
species, and ecological differences often correlate with differences in singing behavior; in particular, males in migratory
subspecies often share fewer songs than males in resident subspecies. The song sparrow (Melospiza melodia) appears to fit this pattern: resident song sparrows in western North America generally share 20–40% of their repertoire
(of about eight songs) with each neighbor, while migratory subspecies from eastern North America often share 10% or less.
We compared song sharing in two populations within a single subspecies of song sparrow (M. m. morphna) in Washington State. These populations, separated by only 120 km, nonetheless differ in migratory tendencies and several
other ecological and life history variables. We recorded complete song repertoires from 11 male song sparrows in a high-elevation,
migrating population at Gold Creek in west-central Washington, and compared them to two samples (n = 15 and n = 36) from a coastal, resident population at Discovery Park, Seattle, Washington. Despite major differences in habitat, population
density, and migratory tendencies, song sharing among Gold Creek males was as high as that among Discovery Park males. In
both populations, sharing was highest between immediate neighbors, and declined with distance. We conclude that at the within-subspecies
level, neither migration nor population density affect song sharing in song sparrows, a song repertoire species.
Received: 26 November 1998 / Received in revised form: 1 May 1999 / Accepted: 29 May 1999 相似文献
15.
Carola Borries Kristin Launhardt Cornelia Epplen Jörg T. Epplen Paul Winkler 《Behavioral ecology and sociobiology》1999,46(5):350-356
Hypotheses about the evolution of gregariousness and social organisation in primates are based on ecological explanations
as well as on social factors such as conspecific threat (especially infanticide by males). The social explanation fits well
with the conditions found in strepsirrhine primates and furthermore explains why infanticide in anthropoid primates living
in one-male groups mainly occurs when the resident male (protector) is replaced. However, whether it likewise fits to the
conditions in multimale groups will depend on the role of resident males as infant protectors, which has rarely been examined.
We investigated long-term data of wild Hanuman langurs (Presbytis entellus) inhabiting a forest near the village of Ramnagar (southern Nepal). Twenty-two eye-witnessed attacks on infants by males
were analysed in connection with male residency, paternity (DNA analyses) and sexual behaviour. Adult males played a major
role in infant defence (65%). Only the genetic father or males who had been residents when the infant was conceived were observed
to protect infants. Males who immigrated after a female had conceived may later attack her infant and were never observed
to defend it. lt seems that the males took only copulations with potentially fertile females but not with pregnant females
as clues for paternity. In the light of these results it seems likely that the risk of infanticide is an important determinant
in female-male associations even in anthropoid primate multimale groups.
Received: 22 December 1998 / Received in revised form: 30 April 1999 / Accepted: 1 May 1999 相似文献
16.
The persistence of narrowly adapted species under climate change will depend on their ability to migrate apace with their historical climatic envelope or to adapt in place to maintain fitness. This second path to persistence can only occur if there is sufficient genetic variance for response to new selection regimes. Inadequate levels of genetic variation can be remedied through assisted gene flow (AGF), that is the intentional introduction of individuals genetically adapted to localities with historic climates similar to the current or future climate experienced by the resident population. However, the timing of reproduction is frequently adapted to local conditions. Phenological mismatch between residents and migrants can reduce resident × migrant mating frequencies, slowing the introgression of migrant alleles into the resident genetic background and impeding evolutionary rescue efforts. Focusing on plants, we devised a method to estimate the frequency of resident × migrant matings based on flowering schedules and applied it in an experiment that mimicked the first generation of an AGF program with Chamaecrista fasciculata, a prairie annual, under current and expected future temperature regimes. Phenological mismatch reduced the potential for resident × migrant matings by 40–90%, regardless of thermal treatment. The most successful migrant sires were the most resident like in their flowering time, further biasing the genetic admixture between resident and migrant populations. Other loci contributing to local adaptation—heat‐tolerance genes, for instance—may be in linkage disequilibrium with phenology when residents and migrants are combined into a single mating pool. Thus, introgression of potentially adaptive migrant alleles into the resident genetic background is slowed when selection acts against migrant phenology. Successful AGF programs may require sustained high immigration rates or preliminary breeding programs when phenologically matched migrant source populations are unavailable. 相似文献
17.
Tuan T. Cao 《Behavioral ecology and sociobiology》2013,67(11):1799-1807
Many organisms live in crowded groups where social density affects behavior and fitness. Social insects inhabit nests that contain many individuals where physical interactions facilitate information flow and organize collective behaviors such as foraging, colony defense, and nest emigration. Changes in nest space and intranidal crowding can alter social interactions and affect worker behavior. Here, I examined the effects of social density on foraging, scouting, and polydomy behavior in ant colonies—using the species Temnothorax rugatulus. First, I analyzed field colonies and determined that nest area scaled isometrically with colony mass—this indicates that nest area changes proportionally with colony size and suggests that ants actively control intranidal density. Second, laboratory experiments showed that colonies maintained under crowded conditions had greater foraging and scouting activities compared to the same colonies maintained at a lower density. Moreover, crowded colonies were significantly more likely to become polydomous. Polydomous colonies divided evenly based on mass between two nests but distributed fewer, heavier workers and brood to the new nests. Polydomous colonies also showed different foraging and scouting rates compared to the same colonies under monodomous conditions. Combined, the results indicate that social density is an important colony phenotype that affects individual and collective behavior in ants. I discuss the function of social density in affecting communication and the organization of labor in social insects and hypothesize that the collective management of social density is a group level adaptation in social insects. 相似文献
18.
Communal rearing of offspring may help mothers maximize their investment in offspring at a reduced cost to their own bodily condition, thus maximizing their potential for reproductive success. The objective of this study was to quantify the costs and benefits of communal rearing to prairie vole (Microtus ochrogaster) pups and mothers. Mothers were assigned to one of three social units: solitary mothers, singularly breeding groups (i.e. one mother and one non-reproductive sister) and plurally breeding groups (i.e. two lactating sisters). For each type of social unit, some replicates were provided with food ad libitum, while others were provided with limited food. The body mass of focal mothers (i.e. the first mother to produce a litter) was a significant predictor of pup growth. Regardless of food availability, litters of focal mothers in plurally breeding groups gained more weight than litters reared by solitary mothers. Pups reared in singularly breeding groups were intermediate in weight gain, but did not gain significantly more weight than solitary offspring. There was no difference in the body mass of focal mothers from each type of social unit, regardless of food availability. Within plurally breeding groups, the weight gain of the two litters and body mass of focal and second mothers did not differ. However, focal mothers from plurally breeding groups nursed fewer pups than solitary mothers and also fewer pups than their nestmates when food was limited. Our results suggest that plural breeding results in greater fitness to mothers than solitary and singular breeding.Communicated by E. Korpimäki 相似文献
19.
Do female black-capped chickadees prefer high-ranking males as extra-pair partners? 总被引:14,自引:0,他引:14
Ken Otter Laurene Ratcliffe Denise Michaud Peter T. Boag 《Behavioral ecology and sociobiology》1998,43(1):25-36
Previous studies have shown that some female black-capped chickadees (Poecile atricapillus) solicit copulations from males that rank higher in winter flocks than their social mates, and extra-pair paternity in nests
occurs commonly enough to be considered a potential female mating tactic. This study uses blood samples collected in 1992–1995
from 58 families of black-capped chickadees to test whether females with extra-pair offspring have chosen extra-pair sires
higher in social rank than their mates. Paternity was assessed with multilocus DNA fingerprinting in 1992–1994 nests and with
microsatellite and single-locus minisatellite DNA typing in 1995 nests. Seventeen of 58 nests (29.3%) contained young genetically
mismatched with their social father. In 11 of 15 cases where the identity of the extra-pair male was known, the extra-pair
male was dominant to the social father. Using data from 29 nests located in 1994 and 1995 for which we had the most data on
relative ranks of males, high-ranking males had greater realized reproductive success than low-ranking males as a result of
extra-pair fertilizations. There was no significant difference between the number of nests containing extra-pair young of
females mated to low-ranked versus high-ranked males. Two nests in 1995 contained young either genetically mismatched with
both social parents (intraspecific brood parasitism) or, in one nest, genetically mismatched with the social mother but not
the social father (quasi-parasitism). The implications of female strategies acquiring genetic benefits through extra-pair
copulations are discussed.
Received: 7 July 1997 / Accepted after revision: 14 March 1998 相似文献
20.
For primitively eusocial insects in which a single foundress establishes a nest at the start of the colony cycle, the solitary provisioning phase before first worker emergence represents a risky period when other, nestless foundresses may attempt to usurp the nest. In the primitively eusocial sweat bee Lasioglossum malachurum (Hymenoptera, Halictidae), spring foundresses compete for nests which are dug into hard soil. Nest-searching foundresses (‘floaters’) frequently inspected nests during this solitary phase and thereby exerted a usurpation pressure on resident queens. Usurpation has been hypothesised to increase across the solitary provisioning phase and favour closure of nests at an aggregation, marking the termination of the solitary provisioning phase by foundresses, before worker emergence. However, our experimental and observational data suggest that usurpation pressure may remain constant or even decrease across the solitary provisioning phase and therefore cannot explain nest closure before first worker emergence. Levels of aggression during encounters between residents and floaters were surprisingly low (9% of encounters across 2 years), and the outcome of confrontations was in favour of residents (resident maintains residency in 94% of encounters across 2 years). Residents were significantly larger than floaters. However, the relationship between queen size and offspring production, though positive, was not statistically significant. Size therefore seems to confer a considerable advantage to a queen during the solitary provisioning phase in terms of nest residency, but its importance in terms of worker production appears marginal. Factors other than intraspecific usurpation need to be invoked to explain the break in provisioning activity of a foundress before first worker emergence. 相似文献