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1.
Fluctuating asymmetry (FA) can indicate developmental instability in bilaterally symmetric organisms, and studies have shown
that the degree of asymmetry in male secondary sexual characters influences female mate choice in a number of taxa. In male
Schizocosa ocreata wolf spiders, conspicuous tufts of bristles on the forelegs are a critical component of visual courtship signals, which appear
to play a role in female mate choice. Previous studies have shown that females exhibit reduced receptivity to males with regenerative
asymmetry, a consequence of leg loss and regeneration that causes males to be grossly asymmetric with respect to this important
signaling character. We provide data on the occurrence of FA in the tufts of S. ocreata, and examine further the influence of asymmetry on female mate choice. The distribution of tuft area asymmetry values from
a sample of field-collected males was normal, with a mean value of zero, indicating true FA. For a subset of males measured
directly after field collection and prior to feeding, tuft asymmetry was significantly negatively correlated with measures
of body size (body length) and condition (abdomen volume/cephalothorax width). Receptivity responses of females to visual
signals from live males of similar size varied with the degree of asymmetry in male tufts. Since FA covaries with male body
size and condition, which may also influence behavioral vigor, we used video image manipulation to alter the degree of asymmetry
in tufts of a courting male while holding size and condition constant. Asymmetry treatments represented values within the
range of natural FA variation as well as more extreme values characteristic of regenerative asymmetry. With the confounding
effects of male size, condition, and behavior held constant, female spiders exhibited reduced receptivity responses to all
experimental asymmetric video images relative to a control video stimulus. There were no differences in the frequency of female
receptivity among the various asymmetry treatments, suggesting that discrimination against asymmetry in conspecific male signal
characters is not simply a rejection of extreme phenotypes. Results suggest that asymmetry in a key male secondary character
used in visual signaling, independent of any concomitant behavioral or size factor, is an important criterion in mate choice.
Received: 26 February 1998 / Accepted after revision: 12 September 1998 相似文献
2.
Individual variation in female preference for male traits may influence mate choice, especially if benefits and costs of choosiness
vary with the range of available males or reproductive timing. We examined variation in female preference for male leg tuft
size in Schizocosa ocreata (Hentz) wolf spiders with video playback. Dichotomous (simultaneous) choice test experiments included all possible combinations
of four stimuli (i.e., modified versions of the same video male stimulus): average tuft size (control), reduced (−25%), enlarged
(+25%), and no tufts (removed). Females exhibited a directional preference for larger tuft size independent of the nature
of the choice (except for reduced tufts vs no tufts where no difference was seen). Female preference in the short term (over
a period of 4 days) was also highly repeatable for control vs reduced tufts, but not for control vs enlarged tufts. Responses
of females in ‘no-choice’ presentations of a single (control) male stimulus varied with age post-maturity; females were less
receptive in weeks 1 and 2, highly receptive at week 3, and less thereafter. Mated females were least receptive and most aggressive
towards a male stimulus. Females offered choices repeatedly at different ages post-maturity consistently preferred the control
male vs reduced tufts over all 3 weeks but varied in their preference for enlarged tufts vs control male. In the first 2 weeks,
females preferred the enlarged tuft male stimulus, but showed no preference by the third week. Females tested in week 4 showed
no preference in either choice. Results suggest that the potential interaction between female preference for male traits and
female reproductive timing may be a critical consideration in mate choice. 相似文献
3.
Males of the brush-legged wolf spider, Schizocosa ocreata (Araneae: Lycosidae), possess a conspicuous male secondary sexual character: dark pigmentation and tufts of bristles on the
tibiae of their forelegs. We tested several hypotheses relating to the role of this conspicuous trait in sexual selection.
Triad mating experiments suggest that the tufts do not play an obvious role in the operation of sexual selection by either
male competition or female choice, as there were no significant differences in the mating success of intact and experimentally
shaved males. However, females mated more often with males that initiated courtship first, suggesting that capture of a female’s
attention by male signalling may play a critical role. In behavioral experiments that paired a single male with a female in
arenas that allowed both visual and vibratory signal transmission during courtship, female receptivity did not vary significantly
with the presence or absence of tufts. However, experiments that isolated the visual component of communication (by eliminating
vibratory communication) revealed a significant effect of the presence of tufts: females showed receptivity less often to
males with tufts removed. Female response to visual signals was much greater in S. ocreata than in its sibling congener, Schizocosa rovneri, which lacks male tufts. We hypothesize that the tufts serve to increase the efficacy of visual displays of S. ocreata, as vibratory communication is constrained by the complex leaf litter habitat of some populations. Such environmental constraints
may make visual signalling over distance a critical factor for effective courtship communication, which may in turn strongly
influence male fitness.
Received: 30 September 1994/Accepted after revision: 4 August 1995 相似文献
4.
George W. Uetz David L. Clark J. Andrew Roberts Meghan Rector 《Behavioral ecology and sociobiology》2011,65(4):753-761
For visual signaling to be effective, animal signals must be detected and discriminated by receivers, often against complex
visual backgrounds with varying light levels. Accordingly, in many species, conspicuous visual displays and ornaments have
evolved as a means to enhance background contrast and thereby increase the detection and discrimination of male courtship
signals by females. Using video playbacks, we tested the hypothesis that visual courtship displays and leg decorations of
male Schizocosa ocreata wolf spiders are more conspicuous against complex leaf-litter backgrounds. Video exemplars of courting males with manipulated
leg tufts were superimposed on different backgrounds (complex leaf litter in sun or shade, featureless gray background) and
presented to female spiders. Females were more likely to orient to males presented against lighter backgrounds (litter in
sun, gray) than the darker ones (litter—shade). Males with larger tufts were also more likely to be detected, as latency to
orient was shortest for enlarged and longest for removed tufts. Latency of females to approach was shorter against lighter
backgrounds, and approach latency was longest for males without tufts. Female receptivity scores were significantly greater
for males against lighter backgrounds, and males with larger tufts had higher scores. These results suggest that both complexity
and light level of display backgrounds affect the detection of male visual courtship signals by females and that aspects of
the male phenotype may increase chances of detection (and receptivity) against visually complex backgrounds. 相似文献
5.
Kevin J. Delaney J. Andrew Roberts George W. Uetz 《Behavioral ecology and sociobiology》2007,62(1):67-75
Male signaling behaviors are often studied in a single context but may serve multiple functions (e.g., in male–male competition
and female mate choice). We examined the issue of dual function male signals in a wolf spider species Schizocosa ocreata (Hentz) that displays the same species-specific signaling behaviors in both male–male and male–female contexts. These signaling
behaviors have been described as either aggression or courtship according to the context observed. We tested the possibility
of dual functions by comparing the relationship between behaviors and outcome of male–male contests (winner/loser) and male–female
mating encounters (mating success). Frequency, rate, and mean duration of signaling behaviors did not vary with outcome of
male–male contests, which appears instead to be based upon relative size and body mass. Winners of contests had significantly
greater body mass than losers, and greater mass relative to opponents was significantly associated with probability of winning.
Overall, signaling rates were much higher in male–female interactions than in male–male contests and were higher for males
that successfully mated than for those that did not mate. Mean duration of some male displays was also greater for males that
successfully mated. However, male size was not associated with probability of mating. Taken together, results suggest an intersexual
selection context for the current function of male signals in these wolf spiders and that increased display vigor is associated
with male mating success. 相似文献
6.
Male fitness is often determined by the ability of the male to gain access to multiple mates, although in species that exhibit
sexual cannibalism, males might increase their likelihood of being cannibalized with each encounter. This risk should create
selection for males who are able to perceive potential risks associated with mating encounters. We studied male Schizocosa ocreata wolf spiders to determine whether they use female chemotactile cues (silk, excreta) as indicators of potential risks and
how these cues affected subsequent male courtship behaviors. Female treatments included satiated females vs. starved females,
as well as a treatment where females had recently cannibalized a male S. ocreata. We performed experiments to assess (1) if males use female chemotactile cues to determine potential risks associated with
differing female feeding treatments and alter courtship investment, and 2) how male experience with female chemotactile cues
affected courtship investment in subsequent female encounters. At first encounter, males do not vary courtship investment
(number of bouts, duration, and vigor) with different female feeding treatments. However, male behaviors during subsequent
encounters with female chemotactile cues varied in complex ways, depending on female feeding treatment and male first encounter
experience. These data suggest that male experience impacts perception of female chemical cues and offers the male opportunity
to avoid sexual cannibalism in high-risk situations. 相似文献
7.
To respond appropriately to communication signals, animals must have the ability to decipher signal meaning. At a basic level,
interpreting the difference between territorial and courtship signals can be vital for the survival and reproduction of social
animals. Male and female fiddler crabs communicate with claw-waving displays, but the function of these waves remains uncertain.
Species differ in the context in which they wave: Some wave during courtship, some during territorial defence and some during
both. In this paper, we provide evidence that males of an Australian species of fiddler crab, Uca perplexa, use two different types of claw waving display, lateral and vertical. Lateral waves are employed solely in a courtship context,
whilst vertical waves are employed during courtship as well as territorial interactions. Using video recordings, we show that
lateral waves were produced spontaneously (broadcast), and their frequency increased only in the presence of female wanderers.
Vertical waves were not broadcast but were elicited by male wanderers during agonistic interactions and female wanderers during
close range courtship. Male resident U. perplexa were able to discriminate the sex of wandering crabs on the mudflat at distances of 32 cm. During all resident–wanderer interactions,
residents attempted to maintain a position directly between the wanderer and the home burrow and orient themselves to face
females and to present the major claw towards males. To our knowledge, this is the first demonstration of the multiple use
of waving displays in a fiddler crab species. 相似文献
8.
Christian C. Voigt Gerald Heckel Frieder Mayer 《Behavioral ecology and sociobiology》2005,57(5):457-464
We investigated how morphological traits of territorial males in the polygynous bat Saccopteryx bilineata were related to their reproductive success. Because of the frequency of aerial courtship displays and defence manoeuvres, and the high energetic costs of flight, we expected small and symmetric males to be better able to court females on the wing and to monopolize copulations with females in their harems. We predicted that small and symmetric males would sire more offspring within the colony and a larger portion of the young born within their harem than large or asymmetric males. We measured size and fluctuating asymmetry of 21 territorial males and analysed their reproductive success in 6 offspring cohorts (n=209 juveniles) using 11 microsatellite loci. As predicted, small and symmetric males had, on average, a higher reproductive success in the colony than large and asymmetric males. The percentage of young sired by males within their harem increased as males decreased in size, but was not influenced by fluctuating asymmetry. As fluctuating asymmetry of males correlated with their reproductive success within the colony but not within their harems, we infer that fluctuating asymmetry is probably related to female choice, whereas male size is probably important for harem defence on the wing.Communicated by G. Wilkinson 相似文献
9.
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
10.
Joanna P. Y. Chan Pei Rong Lau Ai Jie Tham Daiqin Li 《Behavioral ecology and sociobiology》2008,62(5):639-646
In experiments that comprised of three phases (fight, choice, and mating) under “seen” and “unseen” conditions, we examined
the effects of the outcomes of male–male contests and female eavesdropping on female mate choice and male mating success in
the fighting spider, Thiania bhamoensis (Salticidae). The results revealed female eavesdropping on agonistic interactions. Females that had watched an aggressive
interaction showed no distinctive preference for the winner over the loser, but they preferred the loser when they had not
observed a fight. Winners, however, achieved a greater mating success than did losers during the mating phase. Gaining access
to females was based on the insistence of the winners in courtship in terms of the number of quivers, rather than on the fighting
behavior of the males. Hence, the outcome of male–male contests may not be an important determinant of a male’s mating success
in T. bhamoensis. Instead, courtship display plays an important role in determining the success of male mating in this species. This study
also suggests that female mate preference may not be a good indicator of eventual female mate choice and male mating success.
Thus, a causal relationship between female mate preference and male mating success cannot be inferred.
Joanna P. Y. Chan, Pei Rong Lau, and Ai Jie Tham contributed equally. 相似文献
11.
Asymmetries in courtship signals can result from both developmental instability during ontogeny and from temporary or permanent
damage following mating, fighting, or interactions with predators. These two types of asymmetries, which can be divided into
fluctuating asymmetry (FA) and damage asymmetry (DA), have both been suggested to play an important role in mate choice as
potential honest indicators of phenotypic and/or genetic quality, while at the same time, DA may affect ornament asymmetry
in a random manner. Interestingly, despite the massive research effort that has been devoted to the study of asymmetry during
the past decades, very little is known about how an individual’s behaviour relates to asymmetry. Here, we measure and characterise
asymmetry in morphological courtship signals in Corynopoma riisei, a fish where males carry elaborate paddle-like appendices on each side of the body that they display in front of females
during courtship. Moreover, we investigate whether male courtship display, employing this bilateral morphological trait, reflects
trait asymmetry. Finally, we assess whether males respond to phenotypic manipulations of DA with corresponding changes in
courtship behaviour. We show that male display behaviour is asymmetric in a manner that reflects asymmetry of their morphological
courtship trait and that male display behaviour responds to manipulations of asymmetry of these paddles. Our results thus
suggest that males preferentially use their best side and, hence, that males respond adaptively to temporary changes in signal
trait asymmetry. 相似文献
12.
Condition-dependent control of paternity by female purple martins: implications for coloniality 总被引:9,自引:0,他引:9
Proposed causal links between extra-pair copulation (EPC) and colony formation in socially monogamous birds hinge on the
question of which sex controls fertilizations. We examined in colonial purple martins Progne subis (1) whether EPCs were forced or accepted by females, and (2) the degree to which apparently receptive females were able to
obtain EPCs against their mates’ paternity defenses. Paternity analyses of multilocus DNA fingerprinting confirmed previous
findings of a marked relationship between age class and extra-pair fertilizations (EPFs), with young males losing paternity
of 43% (n = 53) of their putative offspring compared to 4% (n = 85) by old males. All assignable extra-pair offspring were sired by old males, with one male obtaining most EPFs each year.
Contrary to the hypothesis that EPCs are forced, EPF frequency within age class did not increase with seasonal increases in
the number of males per fertile female. Whereas the male control hypothesis predicted that the male age class that mate-guarded
more would be cuckolded less, the reverse was true: young males guarded significantly more intensely. The male age class difference
in cuckoldry could not be explained by the possibility that young and inexperienced females (which are usually paired to young
males) were more vulnerable to forced copulation because EPFs were unrelated to female age. These findings suggest that females
(1) pair with old males and avoid EPCs, or (2) pursue a mixed mating strategy of pairing with young males and accepting EPCs
from old males. The receptivity to EPCs by females paired to young males put them in conflict with their mates. Two factors
determined the paternity achieved by young males: (1) the relative size of the male to the female, with young males achieving
much higher paternity when they were larger than their mates, and (2) the intensity of mate-guarding. Both variables together
explained 77% of the variance in paternity and are each aspects of male-female conflict. Given female receptivity to EPCs,
mate-guarding can be viewed as male interference with female mating strategies. We conclude that EPCs are rarely or never
forced, but the opportunity for females paired to young males to obtain EPCs is relative to the ability of their mates to
prevent them from encountering other males. Evidence of mixed mating strategies by females, combined with other features of
the martin mating system, is consistent with the female-driven “hidden lek hypothesis” of colony formation which predicts
that males are drawn to colonies when females seek extra-pair copulations.
Received: 23 March 1995/Accepted after revision: 14 January 1996 相似文献
13.
In mammalian polygynous mating systems, male reproductive effort consists mainly of male–male competition and courting of
females, which entail substantial somatic costs. Males are thus expected to adjust their reproductive effort according to
their age and condition. In this study, we examined how activity budgets of male mountain goats (Oreamnos americanus), a polygynous ungulate, varied with age in a marked population over two periods: (1) summers 1995–2006 and (2) ruts 2004–2006.
We then assessed if the proportions of time spent in male–male competition and courtship behaviors were influenced by age-specific
body mass and social rank during the rut. Males spent most of their time foraging and resting during summer, and rested more
and foraged less with increasing age. During the rut, pronounced shifts in activity budgets occurred as juveniles (1–2 years)
increased time spent foraging, whereas adults (≥3 years) increased standing and time spent in social interactions at the expense
of foraging. At old age, reproductive effort either stabilized or decreased slightly, providing weak support for the ‘mating
strategy–effort’ hypothesis, predicting that courtship behaviors should peak in prime-aged males. Age-specific body mass did
not affect time spent in male–male competition, but was positively related with time spent in courtship behaviors, providing
support for the ‘individual quality’ hypothesis, predicting that males with more resources at the start of the rut should
spend more time in mating-related activities. Age-specific social rank did not affect reproductive effort. Surviving to prime
age while increasing mass each year should thus allow male ungulates to gain greater ability to court estrus females. 相似文献
14.
Evolution from a solitary way of life to sociality involves changes in the modalities of within-population aggression. This
paper is concerned with environmental causes of variation in aggression within the complex of mole-rat species Spalax ehrenbergi. We focus on physiological constraints associated with aggressive behaviour, i.e. those resulting from emotional arousal
and thus stress. Aggression, social stress sensitivity and urine osmolarity were studied in males of two chromosomal species
of Spalax ehrenbergi, 2n = 52 (occurring in cool humid areas) and 2n = 60 (occurring in warm arid zones). Males with 2n = 52 reached a higher level of within-population aggression during a 3-round tournament (an average, 488 ± 140 acts) than
males with 2n = 60 (163 ± 54 acts). The species with 2n = 52 displayed a higher corticosterone response after a social encounter (in average, 5.15 ± 0.54 μg/100 ml) than that with
2n = 60 (3.0 ± 0.3 μg/100 ml) whereas resting levels of this hormone were low and not different between the two species. Urine
osmolarity was significantly higher in males with 2n = 60 (331.9 ± 18.6 mmol/kg) than males with 2n = 52 (267.3 ± 10.9 mmol/kg). Considering the overall general trend urine osmolarity tended to be negatively related to the
level of aggression, while corticosterone levels tended to vary positively with aggressiveness (Fig. 3). Our results allow
further discussion of the hypothesis that high levels of aggression could be selected against in arid habitats due to their
physiological correlates (decrease in water economy, increased corticosterone leading to potential energy mobilisation and
loss). We propose that behavioural ecophysiology could have contributed to the radiation of the S. ehrenbergi superspecies into increasingly arid environments, and may favour evolution toward social tolerance.
Received: 10 June 1995/Accepted after revision: 25 October 1995 相似文献
15.
Chad C. Smith 《Behavioral ecology and sociobiology》2007,61(9):1349-1358
Operational sex ratio (the ratio of sexually active males to fertilizable females) has a major influence on male competition
for mates and male–female interactions. The contributions of male and female density per se to mating system dynamics, however,
are rarely examined, and the fitness consequences are often inferred rather than quantified. Male mosquitofish (Gambusia affinis) compete aggressively and frequently harass females for copulations, a behavior thought to reduce female fitness. Female
fitness can also be reduced by increases in female density, which may affect food availability, cannibalism rates, and chemical
interactions between females. I manipulated male and female densities of G. affinis to measure their effects on male–male aggression, male harassment toward females, and female fitness. I found that males
chased rivals more often and attempted fewer copulations when female density decreased, but surprisingly male density had
no significant effect on the frequency of these male behaviors. In contrast, males’ agonistic displays toward other males
increased with male density, but display behavior was unaffected by female density. These results suggest that male and female
density do not always contribute equally or at all to the patterns of behavior we observe. Female fitness declined as female
density increased, the opposite pattern expected if male harassment is costly to females. This suggests that a strong, negative
effect of female density overwhelmed any potential costs of male harassment. Sources of female density dependence and the
consequences of changes in male and female density to patterns of male behavior are discussed. 相似文献
16.
Effect of female molt stage and sex ratio on courtship behavior of the blue crab Callinectes sapidus
In many species, males and females actively participate in courtship, and the outcome of pre-mating interactions influences
the mating success of both sexes. Female blue crabs, Callinectes sapidus, mate soon after their final molt to maturity; thus female molt stage dictates the timing of mating. In a field experiment,
we manipulated female molt stage and sex ratio to test their effects on the courtship behavior of both sexes, if female behavior
influences the behavior and pairing success of males, and if male courtship influences male pairing-success. Early-molt-stage
females avoided males during courtship, whereas late-molt-stage females sought out males. As a result, males had to pursue
and capture early-molt-stage females whereas males displayed to late-molt-stage females and more easily physically controlled
them. Males sometimes abandoned late-molt-stage females, but this occurred more often when females were abundant. The rate
at which females avoided males was positively correlated with that of males abandoning females, and males that were unsuccessful
at pairing met with higher rates of female resistance than successful males, suggesting that female behavior influences male
pairing-success. Unlike unsuccessful males, successful males more often made the transition between display and maintaining
physical control of the female. At high male sex ratios, males initiated courtship more readily; thus both sexual competition
and female behavior influence male courtship in this species.
Received: 7 July 1996 / Accepted: 10 January 1998 相似文献
17.
Effects of male dominance and courtship display on female choice in the ring-necked pheasant 总被引:7,自引:0,他引:7
Male traits and behaviours acting in mate choice and intrasexual competition are expected to be congruent. When studying
their evolution, this often makes it difficult to differentiate between these two components of sexual selection. Studies
are therefore needed on mate choice in conjunction with the role of displays and dominance. We present the results from two
experiments conducted to investigate the effects of male dominance and courtship displays on female choice in the ring-necked
pheasant, Phasianus colchicus, controlling for differences in morphological male traits. We found: (1) different courtship behaviours had different effects
on female choice: females were mainly attracted by the feeding courtship behaviour, while another courtship display (the lateral
display) was effective in producing the copulation-acceptance response by the females; (2) subordinate males performed the
courtship behaviour before females less frequently than dominant males, and females reinforced intrasexual selection by choosing
dominant males, and (3) subordinate males in visual contact with a dominant became less attractive to females. The results
support the idea (armament-ornament model) that female pheasants may benefit from using traits selected in male-male competition
as clues for mate choice.
Received: 23 October 1997 / Accepted after revision: 7 October 1998 相似文献
18.
Changes in male guppy courting distance in response to a fluctuating light environment 总被引:1,自引:0,他引:1
In the guppy (Poecilia reticulata), effective courting by a male requires visual contact with the female. Therefore, environmental light intensity may affect
male display behavior, particularly initial courtship distance. We found that male guppies courted at exact and predictable
distances from the female given a particular light level, both in field and laboratory studies. In lower light levels (<0.1 μmol m−2 s−1), for example at dawn, dusk, or under heavy canopy, males court females at closer and less variable distances (<3 cm). At
higher light levels, which occur during most of the day and with less canopy cover, males often court from twice or three
times further out. Light levels over guppy streams change over relatively short time periods and ranges, correlating with
variation in courtship distances. Laboratory manipulations of irradiance confirmed that courtship distance depends on illumination.
Hence, courtship distances may be set by the effect of lighting on signal efficiency, minimization of energy or time expenditures,
or predation risk.
Received: 16 December 1997 / Accepted after revision: 8 August 1998 相似文献
19.
Yvonne Zimmermann David W. Roubik Thomas Eltz 《Behavioral ecology and sociobiology》2006,60(6):833-843
Male orchid bees (Euglossini) collect fragrances from flowers and other natural sources, a behaviour that has shaped the euglossine pollination syndrome. Males store such chemicals in hind leg pouches and later expose them during courtship display. In the present study, we show that complex bouquets of two sympatric species of Eulaema, E. meriana and E. bombiformis, are chemically distinct. When exposed during bioassays at display perches individual hind leg extracts rapidly and consistently attracted other males of the correct species, even if derived from males of disparate localities (French Guiana and Panama). Conspecific males as well as females of E. bombiformis arrived at natural perch sites only from downwind, and two copulations were observed. Our findings demonstrate that acquired odours mediate exclusive attraction within species and support the idea that such fragrances are pheromone analogues. Their role in acquiring matings and during male–male interaction is discussed. 相似文献
20.
Two species of seed-eating true bugs, Neacoryphus bicrucis (Heteroptera: Lygaeidae) and Margus obscurator (Heteroptera: Coreidae) co-occur on ragwort, Senecio tomentosus, in southern Georgia, USA. Males of both species sometimes engage in chases and protracted grappling with females that flee
initial mountings. Sometimes genital coupling occurs while the wriggling female is restrained in the male's grasp. Chases,
grappling, and mounting attempts are misdirected toward heterospecific females, heterospecific males, or conspecific males.
In a laboratory study, confinement of mated N. bicrucis females with either conspecific or heterospecific males reduced fecundity by approximately one-half relative to mated females
confined only with other females. Perhaps as a consequence of this, N. bicrucis females frequently leave areas of high host plant density, where they prefer to oviposit, when males are abundant. The abundance
of each species is positively correlated with host plant density but the two species rarely occur together on the same plants.
This may be an effect of heterospecific courtship which induces the flight of N. bicrucis more than the flight of M. obscurator. The laboratory results suggest that copulations following chases and grappling represent sexual harassment, not a mechanism
of active female choice for a vigorous mate. As sexual harassment imposes high fitness costs that favor abandonment of host
plants, it may, when misdirected, incidentally limit habitat use by ecologically similar species.
Received: 3 October 1998 / Received in revised form: 21 January 1999 / Accepted: 14 February 1999 相似文献