Mate attraction by females in a sexually cannibalistic praying mantis

We studied mate attraction by females of the praying mantid, Tenodera aridifolia sinensis, testing honest signaling of mate availability versus deceptive signaling to attract males for sexual cannibalism. We experimentally varied female diet and mating history and measured the rate of attraction of a wild population of males to caged females. Honest signaling theory predicts that virgin females will attract males at the greatest rate whereas deceptive signaling predicts that hungry females (which are more likely to cannibalize males) will attract more males, particularly among non-virgin females. Our results show that hungry females did not attract more males than well-fed females. Indeed, the opposite was true: hungry females attracted significantly fewer males. Moreover, hungry females were no more likely than well-fed females to attract males subsequent to mating, and mated females attracted males at a lower rate than did virgin females. We also observed female T. aridifolia sinensis and male Mantis religiosa arriving at the caged females and we discuss the significance of these observations. The results refute the hypothesis of deceptive signaling and show that mate attraction signals of female T. aridifolia sinensis are honest indicators of female mate availability and a lower risk of sexual cannibalism.     

Sexual signalling and viability in a wolf spider (Hygrolycosa rubrofasciata): measurements under laboratory and field conditions

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     

Prey vulnerability in relation to sexual coloration of prey

Sexual selection that results in the evolution of exaggerated secondary sexual characters has been hypothesized to impose production and maintenance costs of such traits on their bearers. Costs arising from sexual selection could increase the intensity of predator-mediated natural selection, leading to the prediction that species with exaggerated secondary sexual characters should be particularly susceptible to predation. We tested this prediction in a comparative analysis based on 31,745 prey individuals belonging to 66 species of birds collected from a total of 937 breeding events by 33 to 66 different pairs of European sparrowhawks Accipiter nisus annually during a period of 21 years. To assess vulnerability of different species we estimated a prey vulnerability index based on the difference in the logarithmically transformed absolute abundance of prey minus the logarithmically transformed expected abundance as determined by population density of breeding birds. The prey vulnerability index was predicted by sexual dichromatism, accounting for 23% of the variance in risk of predation among species, even when considering similarity in phenotype among species due to common descent (in the latter case explaining 12% of the variance). This finding suggests that sexual selection is an important evolutionary force-affecting predator–prey interactions.Electronic Supplementary Material Supplementary material is available for this article at     

Pair and extra-pair mating success relative to male quality in red-winged blackbirds

We tested whether the reproductive success of male red-winged blackbirds (Agelaius phoeniceus) varied with male secondary sexual traits or with haematozoa prevalence, and whether these patterns were consistent with females preferring genetically superior males. We also determined whether the traits that correlated with male success on their own territories were also correlated with male success at siring young on other males territories. Our analysis included data from a 6-year study involving 617 nestlings for which paternity was determined by DNA profiling. Larger males sired more young on their territories, principally because they obtained larger harems. The success of larger males at acquiring more mates did not appear to be a consequence of larger males holding larger or better-quality territories. Older and longer-lived males sired more young by extra-pair fertilizations. Larger males sired the most offspring overall (on territory + off territory). Variation in epaulet size and color, responses to male and female models, nest defence and parasitism was not correlated with male success either on or off their territories or overall. Male success in a given year was significantly correlated with success the previous year, as expected if females were selecting genetically superior males. The male that was by far the most successful individual in this study was highly consistent from year to year. Because male body size is positively correlated with survival in this population (although not within the sample of males included in this study), female preference for larger males may have reflected a general preference for males with superior Survival ability. We propose that the direct advantage realized by older males in extra-pair matings might indicate that experience is important, such that experienced males are better at creating or exploiting the opportunities for extra-pair mating. This hypothesis is consistent with a pairwise analysis of cuckoldry that showed that cuckolders were most often older than the males they cuckolded.     

Current analyses do not resolve whether extra-pair paternity is male or female driven

Recent studies question the importance of indirect genetic effects in explaining female benefits of extra-pair matings in socially monogamous species. Compiling data on 14 wild bird species, Arnqvist and Kirkpatrick (Am Nat 165:S26–S37, 2005) estimated the average direct cost in terms or reduced parental care to be an order of magnitude larger than the potential effect of genetic benefits. This study has sparked a debate regarding potential confounding factors but no consensus appears to have been reached. Here we focus on the implicit assumption that all individuals face the same selective pressures and argue that this assumption is probably too strong in most cases. Using a theoretical model we show that when the amount of resources that a male provides depends on territory quality, his physical condition or prospects for alternative breeding opportunities, a female may respond to such differences by altering her mating behaviour. Such confounding factors may lead to direct fitness effects that result in negative correlations between paternal care and paternity even if females that produce extra-pair young experience a net benefit. Negative correlations can also result when males forcefully seek copulations and females resist them. We discuss the studies included in the analysis in this light, and conclude that current analyses on the net selective pressures remain uninformative. In addition to considering average effects across individuals and species we suggest giving attention to individual differences and the influence of ecological factors such as territory quality and predation pressures on female mating behaviour.     

Female ornamentation and territorial conflicts in collared flycatchers (Ficedula albicollis)

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.     

Male coloration and chick condition in blue-footed booby: a cross-fostering experiment

Sexual selection models suggest that female choice is based on male traits that indicate their genetic or environmental condition, consequently enhancing her reproductive success by direct or indirect benefits. We investigated the relationship between male foot colour and offspring condition in the blue-footed booby, a socially monogamous seabird, with conspicuous and variably condition-dependent coloured feet that are selected by females. In a cross-fostering experiment, we found that chick condition was related to the foot colour of the foster father and, to some extent, to the foot colour of the genetic father; thus overall, the fathers sexual ornamentation (genetic and foster) explained 32% of variance of chick condition. These data suggest that foot colour, a dynamic sexually selected trait, is mostly a signal of parental contribution. In species in which males provide parental care, females may choose mates with higher parental ability. Overall, our data suggest that colourful integuments are honest signals of parental ability.Communicated by J. Graves     

Black spots and female association preferences in a sexual/asexual mating complex (Poecilia, Poeciliidae, Teleostei)

We investigated whether female association preferences for males are influenced by black spot disease (BSD), a parasite induced change of the host phenotype. We compared three different species of fish: a gynogenetic hybrid species, Poecilia formosa (amazon molly) and two sexual species (Poecilia latipinna and Poecilia mexicana), which were involved in the natural hybridisation leading to the amazon molly. Contrary to their sexual relatives, asexual amazon mollies significantly avoided images of males infected with black spot disease. We propose that amazon molly females have direct fitness benefits from choosing healthy males. The adaptive significance of the preference for BSD-uninfected males in the asexual amazon molly is yet unclear but may involve avoidance of predation or parasite infection as well as increased sperm availability.     

Phenotypic manipulation reveals sexual conflict over precopula duration

Sexual conflict is common in nature, but detailed behavioral studies on the role female resistance behavior plays in shaping mating patterns are rare. I manipulated female resistance to examine its effects on pairing dynamics in two ecologically different freshwater amphipods. I found evidence for female behavior playing a role in both the outcome of pre-pairing interactions and the initiation of pairing in both species. In these species, the male optimum pairing duration is greater than the value preferred by females or compromised pairing durations observed under natural conditions, thus indicating sexual conflict. Furthermore, the proportion of male–female encounters producing male grasping was greater and the duration of such interactions was longer when female resistance was reduced. Thus, sexual conflict over pairing duration may select simultaneously for female resistance and for male persistence both of which mediate the outcome of pre-pairing interactions in Hyalella. Contact precopulatory mate guarding and the interactions that precede it are common components of crustacean and insect mating systems, suggesting that such conflicts may play an important role in the evolution of mating traits in many taxa.     

Potential direct fitness consequences of ornament-based mate choice in a butterfly

Female mate choice has been shown to provide direct mating benefits in several animal groups. In butterflies, for which there are increasing reports of fine-scale color-based mate choice, the evolutionary benefits that accrue from such mating biases, if any, are largely unknown. We addressed this issue in the butterfly Colias eurytheme, a species in which females choose mates on the basis of iridescent ultraviolet (UV) wing ornamentation and in which males donate reproductively beneficial nuptial gifts. In the first experiment, we assessed the mass of gifts donated to 77 virgin females by males sampled directly from a field encounter site. Despite large variance in the male adult phenotype and ejaculate, no single aspect of dorsal wing coloration, including UV brightness, chroma, or hue, was related to ejaculate mass. There was, however, an interesting interaction between the effects of male body size and copula duration upon ejaculate mass, with size scaling positively with ejaculate mass among males involved in shorter copulations (those lasting <70 min) but negatively among males in longer copulations. In the second experiment, we assessed the lifetime fecundity, fertility, and longevity of 85 females mated under similar circumstances to free-flying wild males. Although several wing color parameters proved subtly informative in more sophisticated multivariable models, no model predicted more than about 20% of the variation in any single female fitness parameter. The duration of copulation, which ranged from 35 min to over 16 h and which carries putative costs for females, was, again, only very weakly predicted by male wing color parameters (i.e., R ² = 0.089). Given the overall minor predictive power of male wing coloration in general and of UV brightness in particular, our results do not strongly support the hypothesis that female C. eurytheme prefer bright UV males to obtain direct benefits or to minimize the costs associated with lengthy copulations.