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101.
Models of parasite-mediated sexual selection have thus far overlooked the potential effects of parasites of females on their
hosts’ ability to choose mates. A set of models addressing this issue is developed, each building on the previous one to add
complexity and realism to the framework. The selection coefficient for parasite immunity and brightness is estimated using
the ratio of the fitness of susceptible males to the fitness of immune males. Parasite-induced reduction in female choosiness
can substantially relax the selection for bright, immune males, especially when: (1) immunity to parasites is rare in the
population, (2) parasites are not highly aggregated within the host population, (3) parasites are abundant, and (4) the effects
of parasites on male brightness or female choosiness are severe. Parasite-induced variability in male brightness is most likely
to occur in populations in which parasites are abundant and not aggregated; if females in those populations show a reduced
preference for bright males, sexual selection for brightness (and parasite immunity) will still operate but exert a weaker
selective pressure.
Received: 4 November 1994/Accepted after revision: 9 September 1995 相似文献
102.
Animal colour signals serve important functions in intraspecific interactions, including species recognition, mate choice and agonistic behaviour. An increasing interest concerns ultraviolet (UV) wavelengths, for instance studies on the effect of UV in mating decisions. More recently, some studies also established that UV signals affect intrasexual interactions. We studied the role of UV during aggressive encounters between male three-spined sticklebacks (Gasterosteus aculeatus), a species in which UV has an effect on female and male mate choice and shoaling behaviour. To that aim, we compared the aggressive response of a territorial male to male intruders, either seen in UV-including (UV+) or UV-lacking (UV-) conditions. Our prediction was that, if UV wavelengths are used in male-male competition, a territorial male should show less competitive behaviour towards an intruder representing a lower threat, i.e. the one presented without UV light. Male sticklebacks showed significantly lower levels of aggression towards male opponents lacking an UV component to their coloration than male opponents possessing this colour component. Discrimination was not influenced by a difference in brightness between the UV+ and UV- stimuli. Finally, we present some reflectance-spectrophotometrical data of two skin regions (cheek and abdomen) of the experimental males and analysed relationships between colorimetric variables, body variables and behaviour. Our study emphasises that UV visual cues are of importance in different communicational tasks in the three-spined stickleback. 相似文献
103.
Female ornaments in species with conventional sex roles often indicate individual quality, but the evolutionary forces maintaining
them are less clear. Sexual competition for breeding opportunities may represent an important role for female signals, especially
in polygynous species, but there is little experimental evidence for this. The wing patch size (WPS) of female collared flycatchers
indicates age and body condition and predicts social mating patterns. We challenged nest-building females with decoy females
of varying WPS and found that the aggressive response of residents increased with decoy WPS, suggesting a role for this female
ornament in territorial competition. Our results explain why female WPS predicts territorial distances when mated to a polygynous
male and indicate that the role of WPS in female competitive interactions is similar to that in males of the same population. 相似文献
104.
Males often use elaborate courtship displays to attract females for mating. Much attention, in this regard, has been focused
on trying to understand the causes and consequences of signal variation among males. Far less, by contrast, is known about
within-individual variation in signal expression and, in particular, the extent to which males may be able to strategically
adjust their signalling output to try to maximise their reproductive returns. Here, we experimentally investigated male courtship
effort in a fish, the Australian desert goby, Chlamydogobius eremius. When offered a simultaneous choice between a large and a small female, male gobies spent significantly more time associating
with, and courting, the former, probably because larger females are also more fecund. Male signalling patterns were also investigated
under a sequential choice scenario, with females presented one at a time. When first offered a female, male courtship was
not affected by female size. However, males adjusted their courtship effort towards a second female depending on the size
of the female encountered previously. In particular, males that were first offered a large female significantly reduced their
courtship effort when presented with a subsequent, smaller, female. Our findings suggest that males may be able to respond
adaptively to differences in female quality, and strategically adjust their signalling effort accordingly. 相似文献
105.
Joah R. Madden Hans-Joerg P. Kunc Sinead English Marta B. Manser Tim H. Clutton-Brock 《Behavioral ecology and sociobiology》2009,63(9):1259-1268
Adults vary in their generosity in provisioning the young and their sensitivity to the need of the young. Do the young modulate their behaviour so as to specifically target more high-provisioning adults? This is especially likely in situations with mobile, nutritionally dependent young. We studied cooperatively breeding meerkats Suricata suricatta, in which pups beg to parents and other adults in the group. We found that the young begged differently when next to different adults and that they are consistent in how they beg when next to each adult. Pups next to adults that provision at high rates beg at higher rates and spend longer with them, and these adults are generally more sensitive to increases in begging rate. Such behaviour has adaptive benefits to offspring in terms of increased likelihood of being fed. However, offspring do not appear to be actively seeking out high-provisioning adults or increasing their begging behaviour when they encounter one. Pups did not appear to actively discriminate between adults in their association or begging behaviour. We suggest instead that the relationship between an adult's relative contribution to pup feeding and the behaviour of its accompanying pup is driven by adult behaviour, with responsive adults that feed pups at a relatively higher rate preferentially associating with fast-begging hungry pups. 相似文献
106.
Martin Plath Katja Kromuszczynski Ralph Tiedemann 《Behavioral ecology and sociobiology》2009,63(3):381-390
Males often face strong mating competition by neighboring males in their social environment. A recent study by Plath et al.
(Anim Behav 75:21–29, 2008a) has demonstrated that the visual presence of a male competitor (i.e., an audience male) affects
the expression of male mating preferences in a poeciliid fish (Poecilia mexicana) with a weaker expression of mating preferences when an audience male observed the focal male. This may be a tactic to reduce
sperm competition, since surrounding males likely share intrinsic preferences for female traits or copy mate choice decisions.
Here, we examined the hypothesis that a same-sex audience would affect female mate preferences less than male mating preferences. Our hypothesis was based on the assumptions that (1) competition for
mates in a fashion that would be comparable in strength to sperm competition or overt male–male aggression is absent among
Poecilia females, and (2) P. mexicana females typically form female-biased shoals, such that almost any female mate choice in nature occurs in front of a female
audience. Poecilia females (P. mexicana, surface and cave form, and the closely related gynogenetic Poecilia formosa) were given a choice between a large and a small male, and the tests were repeated while a conspecific, a heterospecific,
or no audience female (control) was presented. Females spent more time in the neutral zone and, thus, less time near the males
during the second part of a trial when an audience was presented, but—consistent with predictions—females showed only slightly
weaker expression of mate preferences during the second part of the tests. This decline was not specific to the treatment
involving an audience and was significantly weaker than the effect seen in the male sex. 相似文献
107.
David J. Able 《Behavioral ecology and sociobiology》1999,46(6):423-428
Darwin predicted that scramble competition for access to reproductive females would result in sexual dimorphism of locomotory
structures, but direct evidence for this is extremely rare. I examined the relationship between variation in tailfin size
and mating success in a field and laboratory study of red-spotted newts, Notophthalmus viridescens. Over three breeding seasons, male tailfin size was positively correlated with variation in male amplexus frequency, and
indirectly correlated with male insemination frequency. In a laboratory study, I confirmed that males' ability to capture
females is affected by variation in tailfin size. This is the first study to show that naturally occurring variation in male
locomotory structures affects male mating success. It corroborates the prediction that scramble competition leads to sexual
selection on locomotory structures and, potentially, to dimorphism in these structures.
Received: 16 April 1999 / Received in revised form: 16 May 1999 / Accepted: 12 June 1999 相似文献
108.
Sexual signalling and viability in a wolf spider (Hygrolycosa rubrofasciata): measurements under laboratory and field conditions 总被引:4,自引:0,他引:4
Janne S. Kotiaho Rauno V. Alatalo Johanna Mappes Silja Parri 《Behavioral ecology and sociobiology》1999,46(2):123-128
This study examined the crucial prediction of the conditional-handicap theory, the relationship between male sexual trait
size and male viability, in the wolf spider Hygrolycosa rubrofasciata. In this species, males court females by drumming dry leaves with their abdomen, and males with the highest drumming rate
enjoy highest mating success. We determined male drumming rate, body mass, and mobility, which reflects mate-searching activity,
in relation to male survival. Because it is often difficult to know how results obtained from laboratory studies reflect the
natural world, particularly when the measured variable is survival, we repeated our study in both laboratory and field conditions.
Males drumming at the highest rate survived better than males drumming at a lower rate in both laboratory and field conditions.
These results are in accordance with the predictions of conditional-handicap models of sexual selection. Survival was independent
of male body mass and there was no significant correlation between male drumming activity and body mass. However, large males
moved further than smaller males, and males moving longer distances lost less mass than those moving shorter distances. These
results suggest that, moving, and consequently mate-searching activity, may be a condition-dependent trait and that there
may be a advantage for large males in mate searching.
Received: 22 October 1998 / Received in revised form: 28 January 1999 / Accepted: 14 February 1999 相似文献
109.
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
110.
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