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1.
Reproduction in birds requires the input of time and energy during discrete breeding phases leading to investment trade-offs
between laying date, clutch size, body mass, and incubation constancy. We investigated costs during incubation by experimentally
enlarging 25 clutches of white-tailed ptarmigan Lagopus leucurus. The experiment was conducted in 2 years, one with harsh weather that forced a natural delay in reproduction. When forced
to delay egg-laying, females began incubation with poorer body condition and foraged more during incubation. Rates of mass
loss during incubation were not affected by clutch enlargement, and did not differ between harsh and benign years; however,
females that were heavier at the start of incubation lost more mass than lighter females. Clutch-enlarged females had reduced
nest attendance compared to control birds in both years and incubation periods increased by up to 2 days relative to controls.
In the harsh year, there was a trend for clutch-enlarged females to have lower nest success, but there was no effect on overwinter
survival. Different behavioral responses by females in the 2 years showed that incubation costs may depend on other factors
such as female quality, food supply, or weather conditions. Incubation is a dynamic period during which birds may adjust energy
balances by varying body condition and food intake.
Received: 28 March 2000 / Received in revised form: 18 August 2000 / Accepted: 2 July 2000 相似文献
2.
Life history costs of olfactory status signalling in mice 总被引:4,自引:0,他引:4
L. M. Gosling S. C. Roberts E. A. Thornton M. J. Andrew 《Behavioral ecology and sociobiology》2000,48(4):328-332
Large body size confers a competitive advantage in animal contests but does not always determine the outcome. Here we explore
the trade-off between short-term achievement of high social status and longer-term life history costs in animals which vary
in competitive ability. Using laboratory mice, Mus musculus, as a model system, we show that small competitors can initially maintain dominance over larger males by increasing investment
in olfactory status signalling (scent-marking), but only at the cost of reduced growth rate and body size. As a result they
become more vulnerable to dominance reversals later in life. Our results also provide the first empirical information about
life history costs of olfactory status signals.
Received: 15 December 1999 / Revised: 6 June 2000 / Accepted: 24 June 2000 相似文献
3.
Threat-sensitive decision-making might be changed in response to a parasitic infection that impairs future reproduction. Infected
animals should take more risk to gain energy to speed up their growth to achieve early reproduction and/or to strengthen their
immune response. To avoid correlational evidence, we experimentally infected and sham-infected randomly selected immature
three-spined sticklebacks with the cestode Schistocephalus solidus. For 7 weeks we determined the threat-sensitive foraging decisions and growth of individual sticklebacks in the presence
of a live pike (Esox lucius). The experimenters were blind with respect to the infection status of the fish. In contrast to previous studies, our recently
infected fish should have been almost unconstrained by the parasite and thus have been able to adopt an appropriate life history
strategy. We found a strong predator effect for both infected and uninfected fish: the sticklebacks’ risk-sensitive foraging
strategy resulted in significantly reduced growth under predation risk. Infected fish did not grow significantly faster under
predation risk than uninfected fish. Since infected fish consumed much less prey in the presence of the predator than did
infected fish in its absence, they obviously did not use the opportunity to maximize their growth rate to reach reproduction
before the parasite impairs it.
Received: 21 June 1999 / Revised: 27 November 1999 / Accepted: 5 September 2000 相似文献
4.
We investigated the fledging probability of oystercatcher, Haematopus ostralegus, chicks as a function of hatching order, brood size, territory quality and food availability. Sibling dominance was related
to the hatching order in both low- (’leapfrogs’) and high-quality (’residents’) territories. Differences in hatchling mass
might have aided the establishment of a dominance hierarchy, since breeders produced small late eggs and hatchlings. These
mass differences were most pronounced in leapfrogs, and in large broods in years with lower food availability (’poor’ years).
Late hatchlings fledged less often and with lower body masses compared to early hatchlings in all situations. Leapfrogs produced
smaller broods and hatched their broods more asynchronously in poor years than leapfrogs breeding in years with more available
food (’good’ years) and residents breeding in both poor and good years. Large brood sizes resulted in lower survival of hatchlings
in poor years. These results favour the ’brood reduction’ hypothesis. However, contrary to the expectations of this hypothesis,
hatching order also affected fledging success in residents. Moreover, large brood size resulted in higher survival of hatchlings
in good years, particularly in residents. Thus, although large broods experienced losses due to sibling competition in some
years, they nevertheless consistently produced more fledglings per brood in all years, both as leapfrogs and residents. We
believe this effect is due to parental quality correlating with initial brood size. Most leapfrogs, at best, fledged one chick
successfully each year, losing chicks due to starvation. Nevertheless, leapfrog broods were reduced in size after hatching
significantly less quickly than resident broods. These results suggest that breeders lay and hatch insurance eggs to compensate
for unpredictable losses due to the high predation rates on both nests (ca 50%) and chicks (ca 90%), in accordance with the
’nest failure’ hypothesis.
Received: 14 February 2000 / Revised: 27 September 2000 / Accepted: 10 June 2000 相似文献
5.
We used data from a long-term study (15 years) of fallow deer to report for the first time the lifetime mating success, overall
variance in lifetime mating success, and age-specific mortality levels of males. Fallow bucks that gain matings have higher
social dominance rank, higher rates of fighting, and invest more in vocal display during the breeding season than unsuccessful
males. Therefore, we examined if mating was associated with trade-offs in terms of survival, lifespan, and mating potential.
We found that the variance in lifetime mating success was very high: 34 (10.7%) males mated, and of those, the 10 most successful
males gained 73% of all matings (n=934). Mortality rates were generally high and only 22.3% (71/318) of males reached social maturity, i.e., 4 years. The oldest
male was 13 years old. We found that fallow bucks that mated were not more likely to die during the following year, did not
suffer from a reduction in lifespan, and did not incur lower mating success later in life as a result of mating during the
early years of social maturity. Our results show that mating males at age 5 years (and possibly 9 years) may be more likely
to survive than non-mating males. Additionally, the number of matings gained by males during the first years of social maturity
was positively correlated with lifespan. We suggest that mating males are of higher quality than non-mating males because
they are not more likely to incur trade-offs as a result of their increased reproductive efforts.
Received: 9 November 1999 / Revised: 30 April 2000 / Accepted: 27 May 2000 相似文献
6.
L. Hughes B. Siew-Woon Chang D. Wagner N. E. Pierce 《Behavioral ecology and sociobiology》2000,47(3):119-128
The mating system of the Australian lycaenid butterfly, Jalmenus evagoras, is highly unusual compared to most other Lepidoptera. Characteristics of this system, which has been termed an ’explosive
mating strategy,’ include the formation of an intensely competitive mating aggregation of males, a highly male biased operational
sex ratio, a lack of discrimination and mate choice by both sexes, a high variance in male mating success, and female monogamy.
In this study, we tested the hypothesis that multiple mating by males imposes physiological costs resulting in smaller spermatophores,
and that this results in a fitness cost to females. We found that male J. evagoras transferred only 2.2% of their eclosion weight during their first mating, consistent with the hypothesis that males of monandrous
species produce a relatively small investment. The wet weight of the ejaculate declined by an average of 27% at the second
mating and the dry weight by 29%, and an intermating interval of 5–9 days was needed for the ejaculate to return to the size
at the first mating, regardless of male size or age. Wet ejaculate mass increased proportionally with male size, though dry
mass was proportionally larger in smaller males. Ejaculate mass tended to increase with male age at both first and second
matings. Female characteristics, in general, did not affect ejaculate mass, although the wet weight of the ejaculate was positively
associated with female weight at the second mating. Copulation duration increased from 2.4 h to approximately 3 h at the second
mating, and to over 4 h at the third and fourth matings. Fecundity was positively correlated with female size but not with
mating history, copulation duration, or any other characteristics measured for either males or females. Female longevity declined
significantly as the number of times the male partner had previously mated increased. We conclude that despite the small male
investment in ejaculate, the costs of multiple mating may nonetheless be significant, as indicated by the reduction in ejaculate
mass, an increase in copulation duration, and reduction in female lifespan with increasing mating number.
Received: 22 January 1999 / Received in revised form: 28 July 1999 / Accepted: 18 September 1999 相似文献
7.
Indriķis Krams 《Behavioral ecology and sociobiology》2000,48(2):147-153
The risk of predation may influence the acquisition of energy and the feeding activity of animals. Feeding activity and body
reserves of wintering great tits Parus major in response to the priority to food access were studied in two areas differing in incidence of predators. The one-predator
area contained sparrowhawks Accipiter nisus only, whereas the two-predator area contained both sparrowhawks and pygmy owls Glaucidium passerinum, whose hunting periods overlap at dawn and dusk. In the two-predator area dominant great tits arrived at feeders significantly
later in the morning, and left earlier in the evening, than their subordinate flock-mates. Hence, feeding day length of dominants
was found to be significantly shorter. The reverse was true for the one-predator area. In addition, dominants carried significantly
greater reserves than subordinates in the area inhabited by two predators. Factors constraining subcutaneous energy reserves
were also studied in removal experiments. After the removal of dominant individuals, subordinate great tits did not reduce
their body reserves in the two predator area. In contrast, subordinate great tits significantly reduced evening body reserves
in the single-predator area. I concluded that the presence of the two predators increases unpredictability in feeding conditions
for great tits. Dominant individuals responded to this by shortening their feeding day and increasing body reserves at dusk.
Received: 8 December 1999 / Received in revised form: 15 March 2000 / Accepted: 31 March 2000 相似文献
8.
Divorce and extrapair mating in female black-capped chickadees (Parus atricapillus): separate strategies with a common target 总被引:1,自引:0,他引:1
S. M. Ramsay K. A. Otter D. J. Mennill L. M. Ratcliffe P. T. Boag 《Behavioral ecology and sociobiology》2000,49(1):18-23
Patterns of divorce and extrapair mating can provide insights into the targets of female choice in free-living birds. In resident,
site-faithful species with continuous partnerships, the better options and the incompatibility hypotheses provide the most
likely explanations for divorce. Extrapair mating can be explained by a number of hypotheses often making similar predictions.
For example, the good genes and future partnerships hypo- theses predict similar patterns if males with good genes also make
the best future partners. By considering both divorce and extrapair mating, it may be possible to distinguish between these
comparable hypotheses. We examined natural patterns of divorce and extrapair mating in a long-term study of black-capped chickadees
(Parus atricapillus). Out of 144 partnerships over 8 years, we observed 11 divorces and 38 faithful pairs between seasons. Females usually divorced
between their first and second breeding seasons for males of higher social rank than their previous partners, had similar
reproductive success prior to divorce as females who retained their previous partners, and did not divorce on the basis of
previous reproductive success. These results confirm earlier experimental evidence that females divorce for better options.
Females who divorced were significantly more likely to have had mixed-paternity broods prior to divorce than females who stayed
with their previous partners. There was no evidence that females divorced in favour of previous extrapair partners. These
results support the good genes hypothesis for extrapair mating, suggesting that female chickadees use divorce and multiple
mating as separate strategies sharing a common target.
Received: 4 February 2000 / Revised: 20 July 2000 / Accepted: 4 September 2000 相似文献
9.
Food distribution is hypothesized to be important in determining the nature of female relationships within social groups of
primates. When food limits female reproductive success, spatially clumped foods are expected to produce strong, linear dominance
hierarchies within groups, whereas more spatially dispersed foods are expected to produce weaker or non-existent dominance
hierarchies. The association between food distribution and competitive relationships presumably occurs because clumped foods
are usurpable but dispersed foods are not. We examined the spatial distribution of food patches (trees) and patch size relative
to feeding behavior and agonistic interactions in vervets and patas monkeys, two closely related and sympatric species that
nonetheless differ in the strength of the female dominance hierarchy. Food patches of both patas monkeys and vervets were
small in size and randomly distributed in Acacia drepanolobium habitat. In contrast, in A. xanthophloea woodland, the habitat type that was exclusively used by vervets, food patches were larger and more spatially clumped. These
similarities and differences between and within species were correlated with similarities and differences in the strength
and linearity of their dominance hierarchies. Patas monkeys and vervets in A. drepanolobium habitat had dominance hierarchies that were weakly defined because there were relatively few agonistic interactions between
females. By contrast, in A. xanthophloea habitat, vervets had a stronger, linear dominance hierarchy characterized by a higher rate of agonistic interactions over
food. The covariation of agonistic interactions with patch size is discussed in relation to depletion time, another characteristic
that may covary with food distribution, and resource renewal rate, an important determinant of agonistic interactions in insectivorous
birds, fishes, insects, and mammals.
Received: 18 February 2000 / Revised: 5 September 2000 / Accepted: 26 September 2000 相似文献
10.
Ectoparasites of house sparrows (Passer domesticus): an experimental test of the immunocompetence handicap hypothesis and a new model 总被引:2,自引:0,他引:2
Conspicuous secondary sexual traits may have evolved as handicap-revealing signals or as badges of status. We present results
of an experiment using males of the sexually dimorphic house sparrow (Passer domesticus), that support the idea that the male-specific bib can be both a handicap-revealing signal and a reliable badge indicating
the physical condition of the bird. In a test of the immunocompetence handicap hypothesis, wild-caught adult male house sparrows
were studied in captivity. Birds implanted with elevated doses of testosterone were more dominant, had higher circulating
levels of both testosterone and corticosterone and they also harboured relatively larger ectoparasite loads. Higher parasite
loads were also associated with individuals showing lower immunocompetence and larger changes in bib size. A new model for
immunocompetence effects in sexual selection is introduced, integrating actions that the hypothalamopituitary axis exerts
on gonads, adrenals and the thyroid gland. The ”integrated immunocompetence model” synthesizes both the ”handicap” (i.e. survival-decreasing)
and ”badge of status” (i.e. survival- enhancing) models for evolution of secondary sexual traits.
Received: 15 May 1999 / Received in revised form: 2 November 1999 / Accepted: 6 November 1999 相似文献
11.
Multiple-queen (polygyne) colonies of the introduced fire ant Solenopsis invicta present a paradox for kin selection theory. Egg-laying queens within these societies are, on average, unrelated to one another,
and the numbers of queens per colony are high, so that workers appear to raise new sexuals that are no more closely related
to them than are random individuals in the population. This paradox could be resolved if workers discriminate between related
and unrelated nestmate sexuals in important fitness-related contexts. This study examines the possibility of such nepotism
using methods that combine the following features: (1) multiple relevant behavioral assays, (2) colonies with an unmanipulated
family structure, (3) multiple genetic markers with no known phenotypic effects, and (4) a statistical technique for distinguishing
between nepotism and potentially confounding phenomena. We estimated relatedness between interactants in polygyne S. invicta colonies in two situations, workers tending egg-laying queens and workers feeding maturing winged queens. In neither case
did we detect a significant positive value of relatedness that would implicate nepotism. We argue that the non-nepotistic
strategies displayed by these ants reflect historical selection pressures experienced by native populations, in which nestmate
queens are highly related to one another. The markedly different genetic structure in native populations may favor the operation
of stronger higher-level selection that effectively opposes weaker individual-level selection for nepotistic interactions
within nests.
Received: 28 June 1996 / Accepted after revision: 6 October 1996 相似文献
12.
K. W. Kim 《Behavioral ecology and sociobiology》2000,48(3):182-187
This study investigates proximate factors influencing dispersal behaviour in the subsocial spider Amaurobius ferox. Dispersal of spiderlings from the natal web occurred as a progressive sigmoidal function (mean duration of dispersal period=31
days), with considerable individual variability in developmental instar and body mass within the clutch at the time of dispersal.
The spiderlings showed a significant decrease in group cohesion on the 6th day after their second moult, which corresponded
to the beginning of the dispersal period. Mutual aggressiveness appeared when the spiderlings began to show predatory behaviour
(4th day post-second moult) and increased over the course of the dispersal period. While lack of prey in the maternal nest
accelerated dispersal behaviour, the addition of prey items lengthened the dispersal period in previously non-fed clutches.
Individuals that dispersed were smaller than the remaining individuals when measured on the day 50% of the clutch had dispersed.
Timing of the appearance of the developmental characters (second moult, predation activity, agonistic behaviour against siblings,
reduction of group cohesion, dispersal) suggests that the dispersal trait might have evolved in consequence of these different
functional behaviours.
Received: 10 August 1999 / Received in revised form: 15 March 2000 / Accepted: 1 April 2000 相似文献
13.
Frank Götmark 《Behavioral ecology and sociobiology》1997,40(1):41-49
Conspicuous color patterns in birds may lead to increased risk of predation. Alternatively, bright birds may be aposematic
or unprofitable prey, which leads to decreased predation. During four autumns, I examined whether the black-and-white plumage
of (stuffed) magpies Pica pica increases or reduces the risk of attack by migrating goshawks Accipiter gentilis. Attack risk was higher for normal magpies than for cryptic, brown magpies whether the mounts were placed near one another
or far apart. However, the brown magpie may have been avoided because of its novelty. For magpies and cryptic jays Garrulus glandarius exposed together, the attack risk was similar. In 2 years, magpie and jay mounts were also exposed far apart. In 1994, with
an invasion of migrating jays, attack risk was much higher for jays than for magpies. In 1995, with a normal density of jays,
hawks attacked the magpies more often. The results demonstrate frequency-dependent prey selection by goshawks, which would
influence any predation cost of bright plumage. The attacks on normally colored magpie mounts suggest that magpies are not
aposematic. Trials with photographs and human observers indicated that normal magpies were somewhat easier to detect than
jays. The plumage of the magpie possibly increases the risk of predation, but may be favoured by sexual or social selection.
Received: 18 January 1996 / Accepted after revision: 6 October 1996 相似文献
14.
Environmental and genetic determinants of the male forceps length dimorphism in the European earwig Forficula auricularia L. 总被引:1,自引:0,他引:1
J. L. Tomkins 《Behavioral ecology and sociobiology》1999,47(1-2):1-8
Male dimorphisms are particularly conspicuous examples of alternative reproductive strategies. The male forceps length dimorphism
in the European earwig Forficula auricularia has long been considered an example of a status- (body size) dependent male dimorphism. In this paper, I test three hypotheses
relating to the dimorphism of F. auricularia. First, that the dimorphism is status dependent and determined by nutrition. Second, that the dimorphism is a density-dependent
adaptation. Third, that there is a genetic basis to population differences in morph frequency seen in the field. These hypotheses
were tested by rearing two populations in a split-family rearing design with two diets and two densities. Populations of male
earwigs reared in the common garden differed in forceps length and relative forceps length. The populations also differed
in the morph frequencies, with 40 versus 26% long-forceped males. These results confirm the notion that there is a genotype-by-environment
interaction that determines the morph frequency in a population. There were only minor effects of density on male forceps
length and no influence of density on the male dimorphism. In accordance with the hypothesis that the morphs are status-dependent
alternatives, large-forceped males only arose on the high-protein diet that produced earwigs of a large body size. However,
not all large males produced the long-forceped phenotype. I put forward an extension of the status-dependent dimorphism model
that may account for the pattern of forceps dimorphism in this species.
Received: 18 November 1998 / Received in revised form: 14 May 1999 / Accepted: 25 July 1999 相似文献
15.
Of the three species of hirundine that breed sympatrically across the U.K., one, the barn swallow, has outer tail feathers
elongated into streamers, whereas the other two species, the house martin and the sand martin, do not. The tail streamer of
the barn swallow is regarded as a classic example of a sexually selected trait. Recent evidence, however, has suggested that
streamers may have evolved largely through natural selection for enhanced flight performance and increased maneuverability.
We tested the hypotheses that small streamers (1) increase performance in turning flight, but (2) decrease performance in
flight variables related to velocity. We manipulated the lengths of house martin outer tail feathers and measured changes
in their free-flight performance, using stereo-video to reconstruct the birds" three-dimensional flight paths. Five flight
variables were found to best describe individual variation in flight performance. Of these five, the three variables determining
maneuverability predicted that flight performance would be optimized by a 6- to 10-mm increase in the length of the outer
tail feathers. In contrast, for mean velocity and mean acceleration, extension of the outer tail feathers appears to have
a detrimental effect on flight performance. We suggest that the initial selection pressure for streamers in ancestral short-tailed
"barn swallows" was via natural selection for increased maneuverability. In addition, we propose that the benefits of increased
maneuverability have differed between hirundines in the past, such that the cost of increasing the length of the outer tail
feather has, to date, outweighed the benefits of doing so in streamerless hirundines.
Received: 14 February 2000 / Revised: 2 July 2000 / Accepted 18 July 2000 相似文献
16.
Aggression and resource sharing among foundresses in the social wasp Polistes dominulus: testing transactional theories of conflict 总被引:3,自引:0,他引:3
Tug-of-war models of within-group conflict predict that the frequency of conflict will be positively related to the degree
of reproductive sharing within the group; in contrast, a negative relationship supports transactional models, in which reproductive
payments among group members limit the degree of within-group selfishness. We tested predictions of the tug-of-war and transactional
models by examining cofoundress interactions during the founding (preworker) phase of colony development in 30 naturally nesting
colonies of the paper wasp Polistes dominulus. We found that the mean rate of foundress aggression and the mean probability of food sharing were significantly negatively
associated, which supports the prediction of the transactional, not the tug-of-war model. Further, cofoundress aggression
significantly increased over the founding phase (independently of temperature), while the fraction of aggression initiated
by the dominant (alpha) foundress significantly decreased over this period. We show that both of these results are predicted
by the transactional model of within-group conflict. Interestingly, the alpha’s rate of aggression was significantly positively
temperature dependent, while the beta’s was not. This indicates that the alpha’s aggression level may often be near her physiological
maximum, while the beta’s aggression is limi- ted by other factors, contradicting the prediction of the tug-of-war model.
Moreover, the alpha’s aggression was significantly positively temperature dependent only in the second half of the founding
period, as predicted by the transactional model since this is when there is least reproductive sharing. Finally, our results
indicate that the alpha’s level of aggression depends on the resources controlled by the beta.
Received: 18 January 2000 / Revised: 19 June 2000 / Accepted: 24 June 2000 相似文献
17.
Male willow warblers have song repertoires which vary in complexity along several dimensions. We examined whether female choice,
as measured by date of pairing, was based on these song characteristics in 4 different years. Pairing date was negatively
correlated with song repertoire size in 1 year, and with song versatility in another year, but there was no consistent effect
of any song characteristic on pairing throughout the years or in the pooled sample. The variable that best explained how soon
a male pairs is male arrival date (only males that had settled territories before the first female arrived were considered
in the analysis). This correlation is consistently significant in all years. This is most parsimoniously interpreted as females
choosing some habitat characteristic in the same way that males do. A small percentage of males (8.3%) attracted and paired
with a second female. The likelihood of becoming polygynous was not explained by any measured song characteristic, but it
was related to arrival date: early males were more likely to pair with two females. Males with large repertoires fledged more
young in their primary nests, and there was a trend for the offspring of these males to have a greater probability of being
recruited into the population. In conclusion, the results show that in most years there is no sexual selection by female preference
on song characteristics, although the data on reproductive success is consistent with the idea of repertoire size being an
indicator of male quality.
Received: 4 June 1999 / Received in revised form: 1 December 1999 / Accepted: 31 December 1999 相似文献
18.
Emma L. Taylor Dominique Blache David Groth John D. Wetherall Graeme B. Martin 《Behavioral ecology and sociobiology》2000,47(5):359-364
Parentage in emus (Dromaius novaehollandiae) was examined by microsatellite analysis using four independent loci. Of 106 chicks sampled in one breeding season from 18
nests, 54 (51%) were not fathered by the nesting male, 12 (11%) were not from the observed mate of the sitting male, and 9
(8%) represented intra-specific brood parasitism, having no alleles in common with either nest parent. Some males (11%) fathered
all chicks in their nests, but the majority showed high levels of cuckoldry. Those males commencing incubation earliest in
the season tended to have the highest levels of paternity in their own nests. These results reveal a high frequency of extra-pair
fertilisations and resultant cuckoldry in a predominantly socially monogamous bird and support recent reports which have described
the emu mating system as a complexity of polyandrous, promiscuous and monogamous behaviour. Parentage assignment of chicks
resulting from extra-pair fertilisations revealed an evenly scattered pattern of paternity that did not show any particular
male dominance in reproductive success. These results lead to a reassessment of behavioural observations of emus, the consequences
of parentage distribution, and theories about mating systems and sexual selection. The frequency of extra-pair copulations
and intra-specific brood parasitism suggests patterns of descent that differ greatly from those implied by social monogamy.
Received: 27 November 1999 / Received in revised form: 8 January 2000 / Accepted: 8 February 2000 相似文献
19.
We report on the genetic evaluation and behavioral study of social organization in the Asian elephant (Elephas maximus). Although Asian elephants and African elephants (Loxodonta africana) were previously thought to have similar social organizations, our results demonstrate a substantial difference in the complexity
and structure of Asian elephant social groupings from that described for African savanna elephants. Photographic cataloging
of individuals, radio telemetry, and behavioral observations in Ruhuna National Park, Sri Lanka, enabled us to assign associated
females and young to four groups with overlapping ranges. Genetic sampling of individuals from the four groups in Ruhuna National
Park and three other groups in surrounding areas, conducted through PCR amplification and sequencing of mitochondrial DNA
from dung, supported the matriarchal nature of female groups and the lack of inter-group transfer of females. Behaviorally
and genetically, the identified social groups were best described as ”family groups”. We did not find any evidence for the
existence of social groups of higher complexity than family groups.
Received: 25 March 2000 / Received in revised form: 28 March 2000 / Accepted: 1 April 2000 相似文献
20.
Leg ornamentation and the efficacy of courtship display in four species of wolf spider (Araneae: Lycosidae) 总被引:1,自引:1,他引:0
This study used both correlative and experimental video playback methods to test the hypothesis that the secondary sexual
traits of male wolf spiders act to increase the efficacy of visual courtship displays. Direct observations of courtship of
several lycosid genera and a review of the literature revealed a significant association between ornamentation and visual
courtship displays. This suggests that the ornamentation may be playing the role of amplifier for a visual display. To test
this hypothesis, male courtship behaviors of four Schizocosa species were experimentally manipulated using video-imaging techniques. Females of species with non-visually displaying,
non-ornamented males (Schizocosa duplex and S. uetzi) did not increase in frequency of receptivity when tufts were added to conspecific males. In a species with a visual display
and foreleg pigmentation (S. stridulans), the addition of foreleg tufts increased female receptivity. In a tufted species (S. crassipes), females tended to decrease their receptivity when male ornamentation was completely removed. In visually displaying species,
ornamentation acts to increase female receptivity, supporting its role as an amplifier of a visual display.
Received: 29 December 1997 / Received in revised form: 23 October 1999 / Accepted: 13 December 1999 相似文献