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1.
Hannon Susan J. Mumme Ronald L. Koenig Walter D. Pitelka Frank A. 《Behavioral ecology and sociobiology》1985,17(4):303-312
Summary Breeding males or females were removed from groups of the cooperatively breeding acorn woodpecker to study (1) competition among individuals from different groups to fill the breeding vancancies, (2) conflict between parents and offspring within groups over replacement of the removed bird, and (3) conflict between parents and offspring for breeding status. Intense fights (power struggles) among nonbreeders from other groups to fill the breeding vacancies developed after the removals. In groups containing only helpers of the opposite sex as the removed bird, replacement was rapid, but in groups containing helpers of the same sex as the removed bird replacement was delayed substantially. In these latter groups parent-offspring conflict developed: helpers could not breed because their parent of the opposite sex was present, and they attacked potential replacements, while their remaining parent advertised for a new mate by calling. Once replacement had occurred, dominance interactions between parents and offspring and among siblings appeared to prevent some individuals from breeding. We conclude that the potential for competition among close kin is high in cooperative species because breeding opportunities are limited. 相似文献
2.
The small cichlid fish Neolamprologus multifasciatus is endemic to Lake Tanganyika and is unique among fish because it lives in complex social groups with several reproductive
males and females, all of which participate in defending their territory against neighbors and intruders. Individuals use
empty snail shells for breeding and shelter. Previous parentage analysis using microsatellites suggested occasional exchange
of individuals between groups. In field experiments, we found that females showed a higher tendency than males to migrate
into territories already occupied by a resident pair. The phenomenon and causes of female-biased immigration were further
investigated in aquarium experiments: Nine of 15 females, but only 2 of 15 equally sized males, settled in territories of
established pairs. Territorial males exhibited more aggression toward strange males (potential reproductive competitors) than
toward strange females (potential additional mates); their females were more aggressive toward strange females (probably competitors
for shells) than toward strange males. Apparently, a conflict exists between the sexes regarding the immigration of additional
females. This conflict seems to be the selective basis for observed active male interference in aggressive disputes between
females in the territory. Interfemale tolerance in a group was greater in the male’s presence than in his absence.
Received: 1 February 2000 / Received in revised form: 2 May 2000 / Accepted: 5 May 2000 相似文献
3.
J. Haydock Patricia G. Parker Kerry N. Rabenold 《Behavioral ecology and sociobiology》1996,38(1):1-16
We investigated parentage using multilocus DNA fingerprinting for 222 juveniles produced during 99 group-years in the bicolored
wren Campylorhynchus griseus, a cooperatively breeding bird of the Venezuelan savanna. Young adult bicolored wrens (auxiliaries) remain in their natal
territories and substantially enhance the production of young there. We have previously used behavioral indicators of dominance
by a single male/female pair (principals) to infer breeding status, resulting in the commonly applied model of helping in
which current fitness accrues to auxiliaries only indirectly, in proportion to their relatedness to the principals and the
effect of their assistance on breeding success. Our parentage analysis has demonstrated that 8.6% of the juveniles found on
territories were not produced by the principal pair. Parentage of 4.1% of the juveniles was completely outside the social
group; these appear to result from early dispersal of juveniles rather than from brood parasitism, most likely resulting from
breakup of nearby groups. Principal females mated outside of their group (2.3%), or with an auxiliary male (2.3%), in the
remaining cases of parentage outside the principal pair. No matings were detected between close relatives (e.g. mother-son);
matings detected between the principal female and an auxiliary male followed a typical replacement of the principal female
by an unrelated immigrant female. Our finger-printing results indicate that: (1) current fitness benefits accruing to most
auxiliaries do not exceed their likely reproductive success had they dispersed successfully to a breeding position; (2) nearly
all wren mating is monogamous and (3) behavioral dominants (especially females) can monopolize breeding.
Received: 23 September 1994/Accepted after revision: 10 June 1995 相似文献
4.
In cooperative breeders, mature males may compete for fertilizations. In this study, we measured the degree of multiple paternity
in a natural population of a cooperatively breeding fish. Neolamprologus pulcher (Perciformes: Cichlidae) is a highly social cichlid endemic to Lake Tanganyika. We used highly variable microsatellite loci
to survey 12 groups with an average number of 10.6 brood care helpers per group and a total of 43 offspring (mean 3.6 per
brood). In 11 of 12 groups, all young were assigned to the dominant female. The dominant male sired all offspring in three
groups, part of the offspring in four groups, and in five groups, he had no paternity at all. In total, 44.2% of young were
not fathered by the current male territory owner. Multiple paternity was found in 5 of 12 broods (41.7 %), with 8 of 35 young
(22.9 %) being sired by males other than the respective territory owners. This is an exceptionally high rate of extra-pair
paternity among cooperatively breeding vertebrates. Neither helpers present in these territories during collection nor neighbouring
males were unequivocally assigned to have sired these extra-pair young. However, behavioural observations suggest that male
helpers may have produced these young before being expelled from the territory in response to this reproductive parasitism.
We discuss these results in the light of reproductive skew theory, cooperative breeding in vertebrates and alternative reproductive
tactics in fish. 相似文献
5.
Reproduction by subordinates in cooperatively breeding Arabian babblers is uncommon but predictable 总被引:4,自引:0,他引:4
In a genetic analysis of the mating system of cooperatively breeding Arabian babblers (Timalidae: Turdoides squamiceps), we identified which individuals in the population are breeding, and how reproductive success was distributed among group
members with respect to their dominance rank, for both males and females. The population was characterized by an asymmetrical
distribution of reproductive success; behaviorally dominant males produced 176 of 186 (95%) of the offspring in 44 social
groups analyzed, and alpha females produced 185 of 186 (99.5%). We evaluated models of reproductive skew by examining genetic
and demographic correlates of reproduction by␣subordinates. Subordinate (beta) males that sired young were more likely to
be recent dispersers from their natal groups or members of newly formed groups than betas that did not reproduce. Breeding
beta males had spent smaller proportions of their lives with the current alpha male and female as alphas than had beta males
that did not sire young. One consequence of the linkage of dispersal with breeding in newly formed, nonnatal groups is that
beta males that sired young had significantly lower genetic similarity to the alpha males in their groups (based on band-sharing
coefficients using multilocus minisatellite DNA fingerprinting) than those that did not sire young. This pattern may occur
generally in species in which group membership accrues both through nondispersal of young (forming groups of relatives) as
well as through dispersal involving coalitions that sometimes include nonrelatives.
Received: 22 July 1997 / Accepted after revision: 5 February 1998 相似文献
6.
Sexual conflict in the snake den 总被引:3,自引:0,他引:3
Red-sided garter snakes (Thamnophis sirtalis parietalis) court and mate in spring, soon after they emerge from large communal overwintering dens in south-central Manitoba. Because
of a massive bias in the operational sex ratio, every female attracts intense courtship from dozens to hundreds of males.
We suggest that this courtship constitutes significant ”harassment,” because it delays the females’ dispersal from the den
and hence increases their vulnerability to predation. Small females may face the greatest costs, because they are less able
to escape from amorous males (who court all females, even juvenile animals). Our measurements show that males are stronger
and faster than females. Experimental trials confirm that the locomotor ability of females (especially small females) is greatly
reduced by the weight of a courting male. Arena trials show that intense courtship stimulates females to attempt to escape.
Remarkably, some females that are too small to produce offspring may nonetheless copulate. This precocious sexual receptivity
may benefit juvenile females because copulation renders them unattractive to males, and thus allows them to escape more easily
from the den. Female ”tactics” to escape male harassment may explain other puzzling aspects of garter snake biology including
size-assortative mating, temporal patterns in dispersal from the den, avoidance of communal dens by young-of-the-year snakes,
and female mimicry. Hence, sexual conflict may have influenced important features of the mating system and behavioral ecology
of these animals.
Received: 8 May 2000 / Revised: 28 July 2000 / Accepted: 30 July 2000 相似文献
7.
We report a long-term study of offspring sex ratios in the cooperatively breeding superb fairy-wren Malurus cyaneus. Detailed study of this species had revealed a suite of potentially strong selection pressures on the sex ratio. First, females
gain substantial fitness benefits from the presence of helpers; so females without male helpers would benefit from any strategy
that increased the probability of recruiting help, such as overproduction of sons (local resource enhancement hypothesis),
but large numbers of helper males compete among themselves, favouring the production of daughters (local resource competition).
Second, daughters fledged early in the season have far greater chances of recruitment to the breeding population than late-fledged
daughters, so mothers would benefit from production of daughters early in the breeding season (early bird hypothesis). Third,
extra-group mate choice imposes strong sexual selection on males, suggesting that females mating with attractive sires could
benefit from investing in sons (sexual selection hypothesis). However, the predictions from these and other sex ratio hypotheses
were rejected. The only convincing evidence for manipulation of the sex ratio was a slight bias towards sons (11 sons to 10
daughters) that occurred regardless of context. This result does not support current theory. 相似文献
8.
Reproductive success in a low skew, communal breeding mammal: the banded mongoose, Mungos mungo 总被引:1,自引:1,他引:0
Jason S. Gilchrist 《Behavioral ecology and sociobiology》2006,60(6):854-863
In most cooperatively breeding species, reproduction is monopolised by a subset of group members. However, in some species
most or all individuals breed. The factors that affect reproductive success in such species are vital to understanding why
multiple females breed. A key issue is whether or not the presence of other breeders is costly to an individual’s reproductive
success. This study examines the factors that affect the post-parturition component of reproductive success in groups of communal-breeding
banded mongoose (Mungos mungo), where up to ten females breed together. Per-litter reproductive success was low (only 18% of pups survived from birth to
independence). Whilst singular breeding was wholly unsuccessful, there were costs associated with breeding in the presence
of increasing numbers of other females and in large groups. Synchronisation of parturition increased litter success, probably
because it minimises the opportunity for infanticide or decreases competitive asymmetry between pups born to different females.
There was no evidence of inbreeding depression, and reproductive success was generally higher in litters where females only
had access to related males within their group. I conclude that communal breeding in female banded mongooses represents a
compromise between the benefits of group-living and communal pup care on the one hand, and competition between females to
maximise their personal reproductive success on the other. Such conflicts are likely to occur in most communal breeding species.
Whilst communal breeding systems are generally considered egalitarian, negative effects of co-breeders on individual reproductive
success is still an issue. 相似文献
9.
Anne Peters Lee B. Astheimer Andrew Cockburn 《Behavioral ecology and sociobiology》2001,50(6):519-527
Superb fairy-wrens are cooperatively breeding birds that combine stable, socially monogamous pair bonds and high levels of paternal care, with extreme levels of extra-pair mating and high levels of sexual competition. Our aim was to determine which testosterone correlates would prevail in such a life history that combines features that are conventionally associated with divergent hormone profiles. Unlike the situation in other species with monogamous pair bonds and high levels of paternal care, testosterone was elevated for a very long period of several months. During breeding there was a broad peak in testosterone followed by a gradual decline: this resembles the profile found in polygynous and promiscuous species. We found that three factors correlated with testosterone: development of the sexually selected nuptial plumage, social status and extra-group mating opportunities. Testosterone started increasing months prior to breeding, when the males that are later preferred as extra-group sires develop their nuptial plumage. Although these males did not have higher testosterone levels during breeding, they sustained high testosterone for much longer, and this might lend reliability to this sexual signal. Dominant males in groups had higher testosterone than pair-dwelling males and subordinate helpers. This was not due to differences in age, reproductive capability or mating opportunities, but was presumably associated with the assertion of dominance. In contrast to findings in other species, male testosterone level was not correlated with whether the resident female was fertile or had dependent nestlings. However, testosterone was strongly correlated with the total number of fertile females in the population, and hence with the opportunities for extra-group mating. 相似文献
10.
Sjouke A. Kingma Michelle L. Hall Anne Peters 《Behavioral ecology and sociobiology》2011,65(6):1203-1213
When fitness returns or production costs vary between male and female offspring, selection is expected to favor females that
adjust offspring sex ratio accordingly. However, to what extent vertebrates can do so is the subject of ongoing debate. Here,
we explore primary sex ratios in 125 broods of cooperatively breeding purple-crowned fairy-wrens Malurus coronatus. We expected that females might adjust offspring sex ratio because this passerine species experiences considerable variation
in social and environmental conditions. (1) However, although helpers substantially increase parental fitness, females (particularly
in pairs and small groups) did not overproduce philopatric males (helper-repayment hypothesis). (2) Sex-ratio adjustment based on competition among individuals (helper-competition hypothesis) did not conceal helper-repayment effects or drive sex allocation on its own: while high-quality territories can accommodate
more birds, brood sex ratios were independent of territory quality, alone or in interaction with group size. (3) Additionally,
males are larger than females and are possibly more costly to produce (costly sex hypothesis), and (4) female offspring may benefit more from long-term effects of favorable conditions early in life (Trivers–Willard hypothesis). Nonetheless, large seasonal variation in food abundance was not associated with a consistent skew in primary sex ratios.
Thus, overall, our results did not support the main hypotheses of adaptive sex-ratio adjustment in M. coronatus. We discuss that long-term differential costs and benefits may be insufficient to drive evolution of primary sex-ratio manipulation
by M. coronatus females. More investigation is therefore needed to determine the general required sex differences in long-term fitness returns
for mechanisms of primary sex-ratio manipulation to evolve. 相似文献
11.
Summary This paper reports on 5 years of observatiors of individually marked saddle-backed tamarins (Saguinus fuscicollis, Callitrichidae). Although callitrichids have long been presumed to have a monogamous social system, this study shows that the breeding structure of saddle-back tamarin groups is highly variable. Groups most commonly include two or more adult males and a single reproductive female, but occasionally contain only a single pair of adults, or less often, two reproductively active females and one or more males. Data on group compositions, group formations, intergroup movements and copulations show that the social and mating systems of this species are more flexible than those of any other non-human primate yet studied. Infants (usually twins) were cared for by all group members. There were two classes of helpers: young, nonreproductive individuals who helped to care for full or half siblings, and cooperatively polyandrous males who cared for infants whom they may have fathered. The observations suggest that non-reproductive helpers may benefit from their helping behavior through a combination of inclusive fitness gains, reciprocal altruism, and the value of gaining experience at parental care. 相似文献
12.
M. J. O’Riain N. C. Bennett P. N. M. Brotherton G. McIlrath T. H. Clutton-Brock 《Behavioral ecology and sociobiology》2000,48(6):471-477
Meerkats live in co-operatively breeding familial groups in which reproduction is monopolised by a dominant pair of breeders.
Offspring of the breeders are behaviourally subordinate, and typically remain in their natal group as sexually mature, non-breeding
helpers. In this study, we investigated the proximate factors limiting subordinate reproduction. Evidence for reproductive
suppression by dominants was investigated by comparing life history, behaviour and hormonal profiles of dominants and subordinates.
Baseline levels of plasma luteinising hormone (LH) were significantly higher in dominant than in subordinate females. However,
following an exogenous injection of gonadotrophin-releasing hormone (GnRH), both categories had comparable concentrations
of circulating LH. There were no significant differences in pre- or post-GnRH challenge LH levels in dominant or subordinate
males. Reproduction in both dominant and subordinate females rarely occurred in the absence of unrelated males. Given that
groups typically comprise parents and offspring, lack of suitable mates emerged as the primary constraint on subordinate reproduction.
When this constraint was removed, subordinates typically bred but at a lower rate than dominants. This difference in reproduction
may be attributed to intrasexual competition manifested through direct interference by dominant females through subordinate
evictions, infanticide and the abandoning of subordinate litters. We argue that differences in reproductive regulation within
mammalian co-operative breeding systems may be explained by differences in the mating strategy (inbreeding versus outbreeding)
and the probability that subordinates in obligate outbreeding species will encounter unrelated opposite-sex partners.
Received: 19 April 2000 / Accepted: 17 July 2000 相似文献
13.
Post-mating odor in females of the solitary bee, Andrena nigroaenea (Apoidea, Andrenidae), inhibits male mating behavior 总被引:3,自引:0,他引:3
We investigated odor changes and their behavioral significance in the solitary, ground-nesting bee Andrena nigroaenea. We used gas chromatography with electroantennographic detection and performed behavioral tests with males in the field using
natural odor samples and synthetic compounds. We found that only cuticle extracts of young females elicited copulation attempts
in the males. We demonstrated that among the 17 compounds which triggered electroantennographic responses, all-trans-farnesyl hexanoate and all-trans-farnesol were significantly more abundant in unattractive cuticle extracts of A. nigroaenea females. Dufour’s gland extracts of these females also contained greater amounts of both compounds. In bioassays using synthetic
farnesyl hexanoate and farnesol we found that these compounds inhibit copulation behavior in the males. Farnesyl hexanoate
is probably synthesized in Dufour’s gland and used by females for lining brood cells. We interpret the semiochemical function
of farnesyl hexanoate and its precursor farnesol to have evolved secondarily. As an outcome of sexual selection, it facilitates
the discrimination by males of receptive females from nesting and thus already mated individuals. The dual function of these
compounds represents an elegant parsimony in the chemical communication system of this insect.
Received: 19 January 2000 / Revised: 29 May 2000 / Accepted: 24 June 2000 相似文献
14.
The evolution of male breeding aggregations is difficult to explain because males may reduce their reproductive success by
associating with their closest competitors. We examined aggregative behavior by male New Mexico spadefoot toads, Spea multiplicata, which form breeding choruses in rain-filled pools. We specifically asked whether males are attracted to conspecific calls
and, if so, whether they preferentially associate with those male calls that are also attractive to females. Field observations
revealed that males showed significant clustering with conspecifics within breeding ponds, whereas laboratory phonotaxis experiments
revealed that males preferentially associated with conspecific male calls. Moreover, when males were presented with conspecific
calls that differed in call rate, smaller males associated with the stimulus preferred by females (average call rate). Thus,
males appear to evaluate the attractiveness of competitors using the same trait employed by females to assess potential mates,
and males adjust their positions relative to competitors depending on their size. We discuss these results in the light of
several current hypotheses on the adaptive significance of male breeding aggregations.
Received: 20 December 1999 / Accepted: 18 March 2000 相似文献
15.
R. G. Harcourt J. J. Kingston M. F. Cameron J. R. Waas M. A. Hindell 《Behavioral ecology and sociobiology》2007,61(4):643-652
For polygynous mammals with no paternal care, the number of offspring sired is often the sole measure of male reproductive
success. The potential for polygyny is highest when resources or other environmental factors such as restricted breeding sites
force females to aggregate. In these circumstances, males compete intensely for females and mating success may vary greatly
among males, further intensifying selection for those traits that confer an advantage in reproduction. Hence, determinants
of male success in competition for females are likely to be under strong sexual selection. Paternity analysis was used in
conjunction with measures of age, site fidelity, and behavior during the breeding season to assess variance in male breeding
success in Weddell seals (Leptonychotes weddellii) breeding at Turtle Rock, McMurdo Sound (77.727S, 166.85E) between 1997 and 2000. Paternity could be assigned to 177 pups
at relaxed or 80% confidence level or 111 pups at strict or 95% confidence levels. Weddell seals at Turtle Rock show a modest
degree of polygyny with the greatest number of pups sired by any individual male in a single season equalling 5 or ∼10% of
the pups born. Over four consecutive years, most (89.2%) males sired at least one pup. In a generalized linear model (GLM),
age and the age first seen at the study site as an adult were unrelated to mating success, but adult experience, either site-specific
or elsewhere in McMurdo Sound, over the reproductive life span of males explained nearly 40% of variance in total mating success
with 80% confidence and 24% of variance at 95% confidence. While learning where females are likely to be may enhance male
reproductive success, aquatic mating reduces the ability of males to monopolize females, and thereby increases equity in mating
success. 相似文献
16.
17.
Karen J. Nutt 《Behavioral ecology and sociobiology》2007,61(11):1651-1663
Current mating system theory predicts that the number of females breeding in a group will depend on the number of females
in the group and the accessibility of unrelated males, whereas the number of males breeding in a group will depend on the
ability of males to control access to reproductive females. By combining information on group composition with genetic data,
I determined whether breeding patterns in a rock-dwelling rodent, Ctenodactylus gundi, were concordant with these expectations. C. gundi breeding patterns varied from facultative monogamy to uni-male polygyny to multi-male polygyny. The number of reproductive
individuals of each sex in a group increased with group size. Whereas communal breeding among related females tended to increase
female reproductive success, males breeding in the same group were unrelated to other group members and seemed to compete
over access to matings. While some males were assigned offspring from neighboring social groups, most group-living males successfully
monopolized the reproduction of females within their group. There was no evidence that females had multiply sired litters,
although some bred with alternative males in separate breeding attempts. Although numerous individuals were not assigned as
parents or offspring, genetic information enabled me to determine that most unassigned individuals were philopatric group
members, whereas only a few were unrelated immigrants into their current social group. Together, these results provide evidence
that C. gundi social groups represent fairly distinct reproductive units whose breeding patterns are dependent on group size and composition
in accordance with theoretical predictions.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
18.
Stephan J. Schoech Ronald L. Mumme John C. Wingfield 《Behavioral ecology and sociobiology》1996,39(2):77-90
To determine whether fundamental differences exist in the reproductive physiology of breeder and nonbreeder Florida scrub-jays
(Aphelocoma coerulescens), we compared plasma levels of testosterone (T) and luteinizing hormone (LH) in males, and estradiol (E2) and LH in females. Although male breeders had higher overall T and larger testes, nonbreeders’ T paralleled that of breeders,
and their testes were more than an order of magnitude larger than regressed testes. Breeder and nonbreeder males had equivalent
baseline LH, and equivalent changes in LH following a gonadotropin-releasing hormone (cGnRH-I) challenge. The T, LH and GnRH
challenge data indicate that nonbreeder males have functional hypothalamo-pituitary-gonadal (HPG) axes. We found no hormonal
evidence of inbreeding suppression in males: nonbreeders that did not live with their mothers and those that did had similar
T. Male nonbreeders that were exposed to E2-implanted females had higher T than did controls, suggesting that the lack of within-pair stimulation is a key factor in
whether an individual delays breeding. Female nonbreeders had E2 titres equal to or higher than breeders and neither basal LH nor LH following GnRH challenge differed by breeding status.
Nonbreeders’ ovarian follicles were smaller than breeders’, but were larger than they would be during the non-breeding season.
These data suggest that nonbreeders were primed for breeding and were simply waiting for an opportunity or a required stimulus.
Female nonbreeders that lived in a territory with an unrelated male breeder had significantly higher E2 than those that remained with their fathers. Similarly, nonbreeders that were captured away from their home territories had
elevated E2. However, nonbreeders that lived with their fathers had E2 that was equivalent to breeding females, suggesting that inbreeding avoidance may not be the primary factor leading to delayed
breeding in females.
Received: 13 June 1995 /Accepted after revision: 27 April 1996 相似文献
19.
Male-male competition ensures honest signaling of male parental ability in the three-spined stickleback (Gasterosteus aculeatus) 总被引:1,自引:0,他引:1
U. Candolin 《Behavioral ecology and sociobiology》2000,49(1):57-61
The importance of socially imposed costs for the evolution and maintenance of honest sexual signals has received less attention
than other costs. Here I show that male-male competition can increase the honesty of sexual signaling in relation to male
parental ability in a species with flexible signaling. When four three-spined stickleback (Gasterosteus aculeatus) males were allowed to court a female first separately and then in competition, red nuptial coloration under competition
reflected male parental ability more accurately than red coloration when separated. Parental ability was determined as the
ability of the male to raise a clutch of eggs to the hatching stage under interaction with other breeding and non-breeding
males. The increased honesty under competition was probably due to subordinate males of poor parental ability decreasing their
color expression under interaction to reduce the risk of fights with superior males. However, socially imposed costs of signaling
were probably not the main factors maintaining honest signaling, as red coloration reflected male parental ability also in
the absence of competition, although less accurately. Nevertheless, the small-scale differences that male-male competition
induced can significantly facilitate adaptive female choice and have large impacts on sexual selection.
Received: 7 July 2000 / Revised: 31 August 2000 / Accepted: 4 September 2000 相似文献
20.
Harri Hakkarainen Erkki Korpimäki Esa Huhta Päivi Palokangas 《Behavioral ecology and sociobiology》1993,33(4):247-251
Summary In many sexually dichromatic species, young males have female-like plumage during their first potential breeding year. The female-mimicry hypothesis (FMH) supposes that by possessing female-like plumage young males deceive older conspicuous males into believing that they are females, thus reducing competition from adult males. The status-signalling hypothesis (SSH) supposes that adult males can distinguish sex, but postulates that young males reduce competition from adult males by reliably signaling low status with their dull plumage. We tested these hypotheses in the European kestrel (Falco tinnunculus). Female-like young males settled to breed closer to adult males than did other adult males (Figs. 1a, b). By settling near adult males, young males seemed to increase their chance of mating with adult females. Adult female-young male pairs had better reproductive success than yearling-yearling pairs. These results suggest that there is an adaptive value in possessing a female-like plumage colour in the breeding season. To test the FMH, we measured sexual preference of adult males when adult females and young males were simultaneously shown in an aviary. Adult males were unable to recognize sex, because in half the cases they preferred young males (Fig. 3). However, when adult males and females were shown simultaneously, males preferred females (Fig. 2). Our results support the FMH rather than the SSH, because young males successfully deceived older males by their plumage. 相似文献