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1.
The gregarious parasitoid Cotesia glomerata (L.) is often presumed to possess the characteristic attributes of a species that manifests local mate competition (LMC), as it commonly produces female-biased broods. However, our field surveys of sex ratio and laboratory observations of adult behaviour showed that this species is subject to partial local mate competition caused by natal dispersal. On average, 30% of males left their natal patch before mating, with the proportion of dispersing males increasing with an increase in the patch's sex ratio (i.e. proportion of males). Over 50% of females left their natal patch before mating, and only 27.5% of females mated with males emerging from the same natal patch. Although females showed no preference between males that were and were not their siblings, broods from females that mated with siblings had a significantly higher mean brood sex ratio (0.56) than broods from females that mated with nonsiblings (0.39). Furthermore, brood sex ratios increased as inbreeding was intensified over four generations. A field population of this wasp had a mean brood sex ratio of 0.35 over 3 years, which conformed well to the evolutionarily stable strategy sex ratio (r=0.34) predicted by Taylor's partial sibmating model for haplodiploid species. These results suggest that the sex allocation strategy of C. glomerata is based on both partial local mate competition in males and inbreeding avoidance in females. In turn, this mating system plays a role in the evolution of natal dispersal behaviour in this species.Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. 相似文献
2.
The social aphid Astegopteryx spinocephala forms a banana-bunch shaped gall, consisting of several subgalls, on Styrax benzoides in northern Thailand. The aphid’s life cycle is non-host alternating. Alates (sexuparae) containing both male and female
embryos appear near the end of the dry season, when many sexuals and eggs are found in subgalls guarded by sterile soldiers.
Our experiments revealed that these alates give birth to almost all (99%) females within the natal subgall before flying but
most (73–86%) males on leaves of the host tree after flying, and that these first-instar males intrude into live subgalls
for mating. The fact that some (14–27%) males are deposited in the natal subgall indicates the occurrence of both outbreeding
and inbreeding, or some level of local mate competition (LMC), in this mating system. However, the primary (investment) sex
ratio was estimated to be near 0.5. This suggests that factors other than LMC, a candidate for which is local resource competition,
might also affect the sex ratio in A. spinocephala.
Received 19 March 2007; revised 12 July 2007; accepted 13 August 2007. 相似文献
3.
MHC-associated mating strategies and the importance of overall genetic diversity in an obligate pair-living primate 总被引:1,自引:0,他引:1
Mate choice is one of the most important evolutionary mechanisms. Females can improve their fitness by selectively mating
with certain males. We studied possible genetic benefits in the obligate pair-living fat-tailed dwarf lemur (Cheirogaleus medius) which maintains life-long pair bonds but has an extremely high rate of extra-pair paternity. Possible mechanisms of female
mate choice were investigated by analyzing overall genetic variability (neutral microsatellite marker) as well as a marker
of adaptive significance (major histocompatibility complex, MHC-DRB exon 2). As in human medical studies, MHC-alleles were
grouped to MHC-supertypes based on similarities in their functional important antigen binding sites. The study indicated that
females preferred males both as social and as genetic fathers for their offspring having a higher number of MHC-alleles and
MHC-supertypes, a lower overlap with female’s MHC-supertypes as well as a higher genome wide heterozygosity than randomly
assigned males. Mutual relatedness had no influence on mate choice. Females engaged in extra-pair mating shared a significant
higher number of MHC-supertypes with their social partner than faithful females. As no genetic differences between extra-pair
young (EPY) and intra-pair young (IPY) were found, females might engage in extra-pair mating to ‘correct’ for genetic incompatibility.
Thus, we found evidence that mate choice is predicted in the first place by the ‘good-genes-as-heterozygosity hypothesis’
whereas the occurrence of extra-pair matings supports the ‘dissassortative mating hypothesis’. To the best of our knowledge
this study represents the first investigation of the potential roles of MHC-genes and overall genetic diversity in mate choice
and extra-pair partner selection in a natural, free-living population of non-human primates. 相似文献
4.
Split sex ratios in the social Hymenoptera: a meta-analysis 总被引:1,自引:0,他引:1
The study of sex allocation in social Hymenoptera (ants, bees,and wasps) provides an excellent opportunity for testing kin-selectiontheory and studying conflict resolution. A queen–workerconflict over sex allocation is expected because workers aremore related to sisters than to brothers, whereas queens areequally related to daughters and sons. If workers fully controlsex allocation, split sex ratio theory predicts that colonieswith relatively high or low relatedness asymmetry (the relatednessof workers to females divided by the relatedness of workersto males) should specialize in females or males, respectively.We performed a meta-analysis to assess the magnitude of adaptivesex allocation biasing by workers and degree of support forsplit sex ratio theory in the social Hymenoptera. Overall, variationin relatedness asymmetry (due to mate number or queen replacement)and variation in queen number (which also affects relatednessasymmetry in some conditions) explained 20.9% and 5% of thevariance in sex allocation among colonies, respectively. Theseresults show that workers often bias colony sex allocation intheir favor as predicted by split sex ratio theory, even iftheir control is incomplete and a large part of the variationamong colonies has other causes. The explanatory power of splitsex ratio theory was close to that of local mate competitionand local resource competition in the few species of socialHymenoptera where these factors apply. Hence, three of the mostsuccessful theories explaining quantitative variation in sexallocation are based on kin selection. 相似文献
5.
G. H. Walter K. Ruohomki E. Haukioja E. Vainio 《Entomologia Experimentalis et Applicata》1994,70(1):83-90
Sex ratios of the arrhenotokous sawflyDineura virididorsata Retz. (Hymenoptera: Tenthredinidae) are variable among populations in the field, but are biased in favour of females. We
have concluded elsewhere that the sex ratios of this species cannot be satisfactorily explained by any general sex ratio model
that is available. Here we present data on the different behavioural traits that are relevant to interpretation of the evolution
of female-biased sex ratios under local mate competition. We report on oviposition behaviour, mating behaviour and the patterns
of movement of ovipositing virgin and mated females. Our results show that adult emergence is synchronous and females will
mate daily with different males (in the laboratory, at least). This would decrease the relatedness of offspring should it
also take place in the field. In addition, ovipositing females (mated and virgin) leave their site of release in a relatively
short time and deposit few eggs relative to their capabilities, so siblings are unlikely to be clumped. The time that virgins
spend in deposition of an egg is not different from that spent by mated females, so there is no differential ‘investment’
in this regard. These behavioural observations agree with our previous conclusion that the preconditions of current sex ratio
theories are not met byD. virididorsata. 相似文献
6.
Multiple mating (i.e., polyandry) by queens in social Hymenoptera is expected to weaken social cohesion since it lowers within-colony relatedness,
and hence, indirect fitness benefits from kin selection. Yet, there are many species where queens mate multiply. Several hypotheses
have been put forward to explain the evolution and maintenance of polyandry. Here,we investigated the ‘sperm limitation’ and
the ‘diploid male load’ hypotheses in the ant Cataglyphis cursor. Genetic analyses of mother-offspring combinations showed that queens mate with up to 8 males, with an effective mating frequency
of 3.79. Significant paternity skew (unequal contribution of the fathers) was detected in 1 out of 5 colonies. The amount
of sperm stored in the spermatheca was not correlated with the queen mating frequency, and males carry on average enough sperm
in their seminal vesicles to fill one queen’s spermatheca. Analyses of the nuclear DNA-content of males also revealed that
all were haploid. These results suggest that the ‘sperm limitation’ and the ‘diploid male load’ hypotheses are unlikely to
account for the queen mating frequency reported in this ant. In light of our results and the life-history traits of C. cursor, we discuss alternative hypotheses to account for the adaptive significance of multiple mating by queens in this species.
Received 13 August 2008; revised 19 November 2008; accepted 21 November 2008. 相似文献
7.
Joseph Soltis 《Primates; journal of primatology》1999,40(3):453-467
Heterosexual relationships during one mating season were examined in a wild troop of Japanese macaques (Macaca fuscata yakui) on Yakushima Island, Japan. Validation tests of putative mate choice behaviors demonstrated that female initiation and maintenance
of proximity, female lookback at the male, and sexual presents to the male, were associated with increased mating. Male grooming
the female was also associated with increased mating. Ten dyadic social behaviors were subject to principal components analysis
to empirically define behavioral dimensions of male-female relationships. The analysis yielded four relationship dimensions:
‘Mutual Choice and Male Coercion,’ ‘Female Choice’ (two types), and ‘Mutual Choice’ Dyads tended to be characterized by more
than one dimension. The results suggested that females sought matings with multiple males of various dominance ranks. Female
relationships with high ranking males contained elements of male coercion and mate guarding, however, because these males
attempted to inhibit females from mating with lower ranking males. The correlation between each relationship dimension and
mating success depended, in part, on the dominance rank of males. Relationships involving high ranking males, which were most
likely to contain elements of male coercion and mate guarding, were associated with mating success. Relationships involving
low ranking males, which usually lacked such coercive elements. were less strongly correlated with mating success. These results,
obtained from a wild troop, are compared to those previously obtained in captive and provisioned groups of Japanese macaques. 相似文献
8.
Divergence in male mating tactics between two populations of the soapberry bug: I. Guarding versus nonguarding 总被引:5,自引:3,他引:2
I compared male allocation to prolonged mate guarding versusnot guarding between two populations of the soapberry bug (Jaderahaematoloma) that differ in adult sex ratio: Oklahoma, USA (mean± SD adult sex ratio, 2.70 ± 0.95 males per female),and Florida, USA (1.09 ± 0.26 males per female). To predictthe reproductive performance of each mating tactic in each population,I collected data on search time per mating, time required forguarding to be effective, sperm competition, female rematingpropensity, and female resistance to guarding. Search time alonediffered significantly between the populations, being much greaterin Oklahoma (estimated as 26.2 h per mate) than in Florida (estimatedas 9.6 h per mate). For males in each region, these data wereused to model the costs and benefits of guarding for differentnumbers of oviposition bouts versus not guarding. The reproductiverate of nonguarders in Oklahoma is exceeded by that of guarderswho remain with a female for more than one oviposition bout,but in Florida, the reproductive rate of nonguarders is onlyexceeded by that of guarders who remain with a female for atleast three ovipositions. Consistent with the model, Oklahomamales in field arenas guarded more frequently than did Floridamales. However, nonguarding was common in both populations,and guarding durations were highly variable. 相似文献
9.
10.
Ian C. W. Hardy Stinne Stokkebo Jesper Bønløkke-Pedersen & Mikael K. Sejr 《Ethology : formerly Zeitschrift fur Tierpsychologie》2000,106(11):1021-1032
Models considering sex ratio optima under single foundress strict local mate competition predict that female bias will be reduced by stochasticity in sex allocation, developmental mortality of males and limited insemination capacity of males. In all three cases the number of males per brood is expected to increase with brood size. Sex ratio optima may also be less female biased when several mothers contribute offspring to local mating groups or if non‐local mating occurs between members of different broods; again more males are expected in larger broods. In the parasitoid wasp Goniozus legneri (Hymenoptera: Bethylidae), sex allocation has only a small stochastic component, developmental mortality is low and non‐siblings are unlikely to develop in the same brood. However, the number of males per brood increases with the size of the brood (produced by a single mother). We investigated the further possibilities of limited insemination capacity and non‐local mating using a naturalistic experimental protocol. We found that limited insemination capacity is an unlikely general explanation for the increase in number of males with brood size. All males and females dispersed from both mixed and single sex broods. Although most females in mixed sex broods mated prior to dispersal, these data suggest that non‐local mating is possible, for instance via male immigration to broods containing virgin females. This may influence sex ratio optima and account for the trend in male number. 相似文献
11.
Adaptive production of fighter males: queens of the ant Cardiocondyla adjust the sex ratio under local mate competition 总被引:1,自引:0,他引:1
Hamilton's concept of local mate competition (LMC) is the standard model to explain female-biased sex ratios in solitary Hymenoptera. In social Hymenoptera, however, LMC has remained controversial, mainly because manipulation of sex allocation by workers in response to relatedness asymmetries is an additional powerful mechanism of female bias. Furthermore, the predominant mating systems in the social insects are thought to make LMC unlikely. Nevertheless, several species exist in which dispersal of males is limited and mating occurs in the nest. Some of these species, such as the ant Cardiocondyla obscurior, have evolved dimorphic males, with one morph being specialized for dispersal and the other for fighting with nest-mate males over access to females. Such life history, combining sociality and alternative reproductive tactics in males, provides a unique opportunity to test the power of LMC as a selective force leading to female-biased sex ratios in social Hymenoptera. We show that, in concordance with LMC predictions, an experimental increase in queen number leads to a shift in sex allocation in favour of non-dispersing males, but does not influence the proportion of disperser males. Furthermore, we can assign this change in sex allocation at the colony level to the queens and rule out worker manipulation. 相似文献
12.
The study of social behaviour can give us important insights into the social and mating system of a species or population.
We investigated male–female interactions in captive bushveld gerbils, Gerbilliscus leucogaster, to gain insight into the social behaviour and mating structure. We conducted two experiments. In experiment 1, we studied
the interactions between two strangers for a week in a three-tank setup, which tested behavioural variation spatially and
temporally. Although tolerance between strange males and females increased with time, it remained generally low throughout
the experiment. Females appeared to be cautious of males initially, but they later became aggressive towards them. Males showed
an increase in submissive behaviour over time. The ‘home’ cage did not appear to be defended by either sex. In experiment
2, we investigated the social interactions of male–female pairs during pregnancy and lactation. Aggression persisted throughout
the study and amicable behaviour was low; females were much more aggressive than males. We did not detect changes in social
behaviour with the progression of pregnancy and lactation. We suggest that pair bonding is unlikely and that promiscuity is
the most probable mating system. Female aggression may be related to mate choice prior to mating and mate exclusion thereafter,
while it may be a response to infanticide risk during pregnancy and lactation. 相似文献
13.
Elizabeth Le Roux C. H. Scholtz A. A. Kinahan P. W. Bateman 《Journal of Insect Behavior》2008,21(3):111-122
Females of most taxa mate selectively. Mate selection may be: (1) pre-copulatory, involving active female choice and male-male
competition, and (2) post-copulatory, with cryptic female choice and sperm competition. Because female dung beetles (Circellium bacchus) invest heavily in parental care by ball-rolling and remaining with developing larva they are, therefore, expected to be
highly selective when mating. Mate choice in this species was investigated via behavioral observations and investigations of genital allometry of both sexes, leading to conclusions about the mechanisms
of, and male characteristics important in, female choice. Male–male competition seems to be crucial in mate selection of C. bacchus, although the females appeared to show no active mate choice. There is a negative allometric relationship between genital
size and body size of males as predicted by the ‘one size fits all’ hypothesis (where males have genitalia that fit average-sized
females). For the females, no relationship was found between genital size and body size. This might be as a result of the
non-sclerotized nature of female genitalia, which may allow for greater morphological plasticity. 相似文献
14.
The directional orientation of female presents in a captive group of long-tailed macaques (Macaca fascicularis) is markedly dependent upon the sex of the potential recipient. Females present in the ‘standard’ mode significantly more
often than in the ‘sideways’ mode to males, with the opposite pattern prevailing to other females. 相似文献
15.
16.
The evolution of secondary sexual characters is the subject of controversial debate between those defending their role as
‘viability indicators’ and those arguing that ornaments are purely ‘attractive traits’ selected by females. Recent theoretical
studies suggest that these hypotheses are not mutually exclusive, as both viability and attractiveness can contribute to improve
the reproductive success of progeny and could thus simultaneously underlie female choices. If that is the case, strategies
of cheaper advertisement, allowing the expression of larger ornaments for the same cost, could proliferate even in species
in which honest signalling of viability prevails. Under this scenario, different males could invest a different amount of
resources per ornament unit of expression, thus using different signalling rules. We studied the relationship between tail
feather length (a trait that is the subject of a female mate preference) and feather mass (a measure of investment in feather
production) in a barn swallow Hirundo rustica population. Different males used different and consistent signalling rules when developing ornamental feathers. That is,
to produce a feather of a given length, each male used a constant amount of resources across different years, but this amount
varied between males. Although the amount of material invested in feathers (feather mass) is a condition-dependent trait,
the organization of this material in ornamental feathers (i.e. the signalling rules) was not. Neither survival nor risk of
feather breakage was related to the signalling rules. Thus, these results suggest that both ‘viability’ and ‘runaway’ mechanisms
are independent determinants of the evolution of ornamental sexual feathers in the barn swallow. A preference for long tails
will ensure that females either obtain a sire with high viability, or one transferring the capability to produce longer and
more attractive tails at a lower cost of production to its offspring. 相似文献
17.
The sex allocation strategy of the parasitoid Laelius pedatus (Hymenoptera: Bethylidae) on different-sized hosts was investigated. The wasp lays from one to five eggs, and clutch size
increases with host size. On the smallest hosts, single male eggs are laid, while on slightly larger hosts single female eggs
are laid. On still larger hosts, gregarious clutches are laid which nearly always consist of a single male and one or more
female eggs. The sex ratio strategy of the wasp appears to be influenced by a combination of local mate competition and conditional
sex expression based on host quality.
Received: 6 June 1996 / Accepted: 13 October 1996 相似文献
18.
Fig‐pollinating wasps (Agaonidae) only reproduce within fig tree inflorescences (figs). Agaonid offspring sex ratios are usually female‐biased and often concur with local mate competition theory (LMC). LMC predicts less female‐bias when several foundresses reproduce in a fig due to reduced relatedness among intra‐sexually competing male offspring. Clutch size, the offspring produced by each foundress, is a strong predictor of agaonid sex ratios and correlates negatively with foundress number. However, clutch size variation can result from several processes including egg load (eggs within a foundress), competition among foundresses and oviposition site limitation, each of which can be used as a sex allocation cue. We introduced into individual Ficus racemosa figs single Ceratosolen fusciceps foundresses and allowed each to oviposit from zero to five hours thus variably reducing their eggs‐loads and then introduced each wasp individually into a second fig. Offspring sex ratio (proportion males) in second figs correlated negatively with clutch size, with males produced even in very small clutches. Ceratosolen fusciceps lay mainly male eggs first and then female eggs. Our results demonstrate that foundresses do not generally lay or attempt to lay a ‘fixed’ number of males, but do ‘reset to zero’ their sex allocation strategy on entering a second fig. With decreasing clutch size, gall failure increased, probably due to reduced pollen. We conclude that C. fusciceps foundresses can use their own egg loads as a cue to facultatively adjust their offspring sex ratios and that foundresses may also produce more ‘insurance’ males when they can predict increasing rates of offspring mortality. 相似文献
19.
D. Waynforth 《Human nature (Hawthorne, N.Y.)》2007,18(3):264-271
There is substantial evidence that in human mate choice, females directly select males based on male display of both physical
and behavioral traits. In non-humans, there is additionally a growing literature on indirect mate choice, such as choice through
observing and subsequently copying the mating preferences of conspecifics (mate choice copying). Given that humans are a social
species with a high degree of sharing information, long-term pair bonds, and high parental care, it is likely that human females
could avoid substantial costs associated with directly searching for information about potential males by mate choice copying.
The present study was a test of whether women perceived men to be more attractive when men were presented with a female date
or consort than when they were presented alone, and whether the physical attractiveness of the female consort affected women’s
copying decisions. The results suggested that women’s mate choice decision rule is to copy only if a man’s female consort
is physically attractive. Further analyses implied that copying may be a conditional female mating tactic aimed at solving
the problem of informational constraints on assessing male suitability for long-term sexual relationships, and that lack of
mate choice experience, measured as reported lifetime number of sex partners, is also an important determinant of copying. 相似文献
20.
Various aspects were studied of the brood size and sex allocation strategies, and of size-fitness relationships in Parallorhogas pyralophagus (Marsh), a gregarious ectoparasitoid of Eoreuma loftini Dyar. Brood size was significantly correlated with host size; larger hosts were allocated larger broods. Brood sex ratios were fixed precisely at 1 male per 4 females, and eggs were likely to be deposited in that order; differential mortality did not contribute to this precise sex ratio. The sex allocation strategy of P. pyralophagus is likely to conform to strict, i.e. single foundress, local mate competition. Adoption of this strategy is probably influenced by a limited insemination capacity of males; a smaller proportion of females (0.09 vs. 0.21) remained virgin in broods with precise or higher sex ratios (> or = 0.20 males) relative to broods with lower than precise sex ratios (< 0.20 males). Moreover, all females were inseminated in most broods (60%) with precise or higher sex ratios, whereas this did not occur in broods with lower than precise sex ratios. The hypothesized occurrence of strict local mate competition in P. pyralophagus was supported also by observations that: (i) offspring brood sex ratios were independent of maternal brood sex ratios and number of parental females concurrently allocating offspring to a group of hosts, and; (ii) the rate of superparasitism under no-choice conditions was low (approximately 20%), suggesting that rates of outbreeding in the field are low. Other results suggested that fitness in P. pyralophagus was correlated with adult size; longevity and reproductive capacity both increased with adult size in males and females. However, adult size may be more important for females than for males because the differences in reproductive capacity between the largest and smallest individuals was up to 7.3 times greater in females versus < 2 times in males. 相似文献