The Role of Female Behavior in Maintaining Monogamy of a Coral-Reef Filefish

The corallivorous filefish Oxymonacanthus longirostris is a predominantly monogamous species without parental care. Polygyny reduces female fitness because monogamous females benefit from male assistance with feeding–territory defense that secures both a feeding area and time to feed. I studied the strategy of females to prevent polygyny, with the help of field observations and manipulative field experiments. Monogamous females always behaved aggressively towards intruding floater females. When a caged male or female was placed within the territory of a monogamous pair, the resident female was more likely to pay attention to the caged female than to the caged male. Experimentally transplanted floater females succeeded in settling as secondary females in the monogamous territory more frequently when the resident female was caged. These results suggest that monogamous females behave aggressively towards floater females to defend their mating status; such aggressive behavior is successful in preventing polygyny. Furthermore, the removal experiment showed that polygynous (especially secondary) females moved to territories of widowed males located near them more frequently than monogamous females did. This outcome indicates that polygynous females can change their mating status and escape polygyny by moving to another territory if the opportunity occurs. Thus, female behavior can play an important role in the maintenance of monogamy and in lowering the level of polygyny within populations of this species.     

Virgin females compete for mates in the male lekking species Ceratitis capitata

Abstract. Aggressive behaviour occurring in intrasexual competition is an important trait for animal fitness. Although female intrasexual aggression is reported in several insect species, little is known about female competition and aggressive interactions in polygynous male lekking species. The interactions of female Mediterranean fruit flies, Ceratitis capitata (a male lekking species), with other females and mating pairs under laboratory conditions are investigated. Mature, unmated (virgin) females are aggressive against each other and against mating pairs, whereas immature females are not. Female aggression against other females decreases dramatically after mating; however, mated females maintain aggression against mating pairs. In addition, higher intrasexual aggression rates are observed for mature, virgin females than for virgin males of the same age. The results show that female aggressiveness is virginity related, suggesting female competition for mates. These findings have important implications for understanding the physiological aspects of a complex social behaviour such as aggression and should stimulate further research on female agonistic behaviour in male lekking mating systems.     

Impaired sperm quality,delayed mating but no costs for offspring fitness in crickets winning a fight

The outcome of male–male contest competition is known to affect male mating success and is believed to confer fitness benefits to females through preference for dominant males. However, by mating with contest winners, females can incur significant costs spanning from decreased fecundity to negative effects on offspring. Hence, identifying costs and benefits of male dominance on female fitness is crucial to unravel the potential for a conflict of interests between the sexes. Here, we investigated males' pre‐ and post‐copulatory reproductive investment and its effect on female fitness after a single contest a using the field cricket Gryllus bimaculatus. We allowed males to fight and immediately measured their mating behaviour, sperm quality and offspring viability. We found that males experiencing a fight, independently of the outcome, delayed matings, but their courtship effort was not affected. However, winners produced sperm of lower quality (viability) compared to losers and to males that did not experience fighting. Results suggest a trade‐off in resource allocation between pre‐ and post‐mating episodes of sexual selection. Despite lower ejaculate quality, we found no fitness costs (fecundity and viability of offspring) for females mated to winners. Overall, our findings highlight the importance of considering fighting ability when assessing male reproductive success, as winners may be impaired in their competitiveness at a post‐mating level.     

The evolution of repeated mating under sexual conflict

In insects, repeated mating by females may have direct effects on female fecundity, fertility, and longevity. In addition, a female's remating rate affects her fitness through mortality costs of male harassment and ecological risks of mating such as predation. We analyse a model where these female fitness factors are put into their life-history context, and traded against each other, while accounting for limitations because of mate availability. We solve analytically for the condition when female multiple mating will evolve. We show that the probability that a female mates with a courting male decreases with increases in population density. The extent of conflict between the sexes thus automatically becomes larger at higher densities. However, because at higher densities females meet males at a higher rate, the resulting ESS female remating rate is independent of population density. The female remating probability is in conflict with male adaptations that increase male mating rate by persuading or forcing females to mate, and also in conflict with male adaptations for protecting the own sperm from being removed by future female mates. We show that the relative importance of these conflicts depends on population density.     

Maternal investment and male reproductive success in angiosperms: parent-offspring conflict or sexual selection?

It is possible to interpret components of seed development in angiosperms from the perspective of parent-offspring conflict (a special case of kin selection) or sexual selection. Available parent-offspring conflict models predict the evolution of traits determining the outcome of competition among related individuals soliciting maternal resources. In such models, ‘selfishness’ may spread even if it reduces female fecundity and thus population mean fitness may decline. These models are limited, however, because most of them do not simultaneously consider selection among maternal genotypes varying in the tendency to respond to their offspring. Available sexual selection models, in contrast, do consider the joint evolution of polygenic male traits (influencing viability, mating success and fecundity) and female preferences (influencing the mating success of different male phenotypes). These models have shown that male traits may evolve that are non-optimal with respect to viability. Only one recent sexual selection model explicitly incorporates direct fecundity selection upon females; this model concludes that fecundity will be maximized at equilibrium. Hence population mean fitness may decline due to reduced male viability but not due to diminished female fecundity. Available sexual selection models, however, are limited because they do not consider the effects of interactions among relatives. The assumptions and qualitative results of the two types of models are compared and discussed in the context of seed development. Differential allocation of maternal resources among genetically distinct developing seeds may be viewed from the perspective of either. Because the results of the available models of parent-offspring conflict and sexual selection are not wholly consistent and because data confirming the genetic basis of maternal patterns of investment or differential male reproductive success are scant, it is not clear which set of conclusions is most appropriate to apply to plants. To achieve the generality towards which mathematical approaches aspire, new models concerning the evolution of traits influencing resource allocation in plants must incorporate the components of both parent-offspring conflict and sexual selection.     

Reproductive strategies of Aphidius ervi Haliday (Hymenoptera: Aphidiidae)

Hymenopteran parasitoids are usually arrhenotokous parthenogenetic, where females arise from fertilized and males from unfertilized eggs. Therefore, the reproductive fitness of females is a function of egg production and furthermore affected by mating, whereas that of males is mainly determined by the number of daughters they father. Aphidius ervi Haliday is a quasi-gregarious parasitoid of a number of aphid pests on economically important crops such as legumes and cereals. Females are monandrous whereas males are polygynous. Here, we tested how parental age at mating and male mating history affected mating success, fecundity and daughter production in this species. Once-mated males perform significantly better than naïve males with regard to mating success, suggesting that males learn from previous matings. The fecundity of virgin females is not significantly different from that of mated females regardless of parental age at mating and male mating history, indicating that mating does not stimulate egg production or contribute to female nutrient supply. Males can replenish sperm supply after mating, implying that they are at least moderately synspermatogenic. Preference for young over old mates for mating by both sexes may be explained by the fact that aging of both sexes contributes to the reduction of daughter production. Rather than sperm depletion, the reduced daughter production may be attributed to diminishing sperm viability and mobility in aging males and increasing constraints in fertilization process in aging females. Our results also show that female age has a stronger impact on the production of daughters, suggesting that fertilization process in females is more sensitive to aging than sperm vigor in males.     

Experimental confirmation of the polygyny threshold model for red-winged blackbirds

The polygyny threshold model assumes that polygynous mating is costly to females and proposes that females pay the cost of polygyny only when compensated by obtaining a superior territory or male. We present, to the authors' knowledge, the first experimental field test to demonstrate that females trade mating status against territory quality as proposed by this hypothesis. Previous work has shown that female red-winged blackbirds (Agelaius phoeniceus) in Ontario prefer settling with unmated males and that this preference is adaptive because polygynous mating status lowers female reproductive success. Other evidence suggests that nesting over water increases the reproductive success of female red-winged blackbirds. Here we describe an experiment in which females were given choices between two adjacent territories, one owned by an unmated male without any over-water nesting sites and the other by an already-mated male with over-water sites. Females overwhelmingly preferred the already-mated males, demonstrating that superior territory quality can reverse preferences based on mating status and supporting the polygyny threshold model as the explanation for polygyny in this population.     

Experimentally-elevated testosterone, female parental care, and reproductive success in a songbird, the Dark-eyed Junco (Junco hyemalis)

In male dark-eyed juncos (Junco hyemalis), experimentally elevated testosterone (T) decreases male parental care and offspring survival, but results in higher overall fitness through greater mating success. To help address the ensuing question of what prevents selection from favoring higher levels of T in male juncos, we manipulated T in female juncos. A previous study demonstrated no effect of experimentally elevated T on female incubation behavior, suggesting that female parental behavior might be insensitive to T. In this study we asked whether experimentally elevated T mediates other female parental behaviors and whether variation in T-mediated parental behavior might influence reproductive success. We videotaped free-living control- and T-females during nesting to quantify brooding behavior when young were 3 days old and provisioning behavior when young were 6 days old. Nest defense was measured by quantifying responses to a mounted predator placed near the nest. Reproductive success was assessed via fecundity, nestling quality, and nest survival. T-females spent less time than control females brooding but did not differ in provisioning rate. T-females performed fewer dives at the predator mount and, unlike controls, failed to increase defense as nesting progressed. T-females also had lower daily nest survival and lower nest success (odds of producing at least one fledgling). We conclude that some aspects of female parental behavior are sensitive to experimentally elevated T while others are not and consider the implications for the evolution of T-mediated characters in both sexes.     

Paternal genetic effects on offspring fitness are context dependent within the extrapair mating system of a socially monogamous passerine

Avian extrapair mating systems provide an interesting model to assess the role of genetic benefits in the evolution of female multiple mating behavior, as potentially confounding nongenetic benefits of extrapair mate choice are seen to be of minor importance. Genetic benefit models of extrapair mating behavior predict that females engage in extrapair copulations with males of higher genetic quality compared to their social mates, thereby improving offspring reproductive value. The most straightforward test of such good genes models of extrapair mating implies pairwise comparisons of maternal half-siblings raised in the same environment, which permits direct assessment of paternal genetic effects on offspring traits. But genetic benefits of mate choice may be difficult to detect. Furthermore, the extent of genetic benefits (in terms of increased offspring viability or fecundity) may depend on the environmental context such that the proposed differences between extrapair offspring (EPO) and within-pair offspring (WPO) only appear under comparatively poor environmental conditions. We tested the hypothesis that genetic benefits of female extrapair mate choice are context dependent by analyzing offspring fitness-related traits in the coal tit (Parus ater) in relation to seasonal variation in environmental conditions. Paternal genetic effects on offspring fitness were context dependent, as shown by a significant interaction effect of differential paternal genetic contribution and offspring hatching date. EPO showed a higher local recruitment probability than their maternal half-siblings if born comparatively late in the season (i.e., when overall performance had significantly declined), while WPO performed better early in the season. The same general pattern of context dependence was evident when using the number of grandchildren born to a cuckolding female via her female WPO or EPO progeny as the respective fitness measure. However, we were unable to demonstrate that cuckolding females obtained a general genetic fitness benefit from extrapair fertilizations in terms of offspring viability or fecundity. Thus, another type of benefit could be responsible for maintaining female extrapair mating preferences in the study population. Our results suggest that more than a single selective pressure may have shaped the evolution of female extrapair mating behavior in socially monogamous passerines.     

Female aggression and the maintenance of monogamy: female behaviour predicts male mating status in European starlings

Any reduction in the fitness of a breeding female induced by the settlement of additional females with her mate creates a conflict between the sexes over mating system. In birds, females are often aggressive towards other females but few studies have been able to quantify the importance of female-female aggression for the maintenance of monogamy. This study of the European starling, Sturnus vulgaris, quantifies male and female behaviour towards a potential prospecting female, presented in a cage during the pre-laying period, and relates it to the subsequent mating status of the male. A solitary breeding male was given the opportunity to attract an additional mate, which almost half of the males did. No biometric characters of the male or female were related to the subsequent mating status. Males demonstrated mate-attraction behaviour towards the caged female but the behaviour of the male did not predict the likelihood to attract an additional female. However, the proportion of time that the female spent near the potential settler was related to mating status, indicating that females that reacted more strongly towards a potential female competitor maintained their monogamous status. These results suggest that female behaviour may play an important role in shaping the mating system of facultatively polygynous species.     

Inbreeding Avoidance in Male Primates: A Response to Female Mate Choice?

Inbreeding often has negative fitness consequences for primates, which have led to the evolution of inbreeding avoidance strategies in a number of species. In polygynous primates, females may suffer a higher fitness cost from inbreeding than males and are thus expected to exhibit a lower tolerance for inbreeding. Nevertheless, it is apparent that inbreeding avoidance behaviours are common in both female and male polygynous primates. In this perspectives article, I review the evidence that female mate choice can lead to male inbreeding avoidance behaviours in polygynous primates. I conclude that male inbreeding avoidance may be strongly driven by female mate choice at both proximate and ultimate levels. To better understand the extent to which this pattern applies across the primate order, studies are needed on the separate effects of participating in inbred matings and producing inbred offspring on male and female lifetime reproductive success . It would also be useful to examine how inbreeding avoidance strategies vary across primate mating systems. Finally, measuring the covariance between female choice and male inbreeding avoidance behaviour, and between male inbreeding avoidance behaviour and male fitness, would help to clarify the role of female mate choice in the evolution of male inbreeding avoidance.     

Form,function and consequences of density dependence in a long‐distance migratory bird

The density dependence of demographic parameters and its implications for population regulation have long been recognized. Recent work has revealed potential effects of density on mating systems and sexual selection, but few studies concurrently assess the consequences of density on both demography and sexual selection. Such an approach is important because population processes and individual behaviors can interact to influence population growth and evolutionary trajectories. In this study, we tested the density dependence of breeding success, extra‐pair paternity, and the opportunity for sexual selection in a population of American redstarts Setophaga ruticilla using two different measures of density. To evaluate temporal patterns, we analyzed annual territory density, based on the total number of territories at our study site each year. To evaluate spatial patterns, we analyzed local territory density within years, based on the number of territories surrounding a focal territory. Greater annual density was associated with fewer offspring fledged per female, a reduced mean population rate of fledging success, and a lower relative contribution of extra‐pair paternity to male fitness. Greater local density was associated with fewer offspring fledged, reduced fledgling success, higher rates of nest loss, and higher rates of paternity loss on focal territories. Interestingly, greater local density was also associated with greater nestling mass on focal territories, which could imply that more densely‐packed territories contain superior resources. Overall, our results suggest that the effects of crowding via greater territory density reduce fecundity through increased nest predation, rather than reduced food availability, and increase rates of extra‐pair paternity. Thus, the selective pressures faced by individuals and their reproductive behaviors are likely to differ based on the annual and local density they experience, which may then feed back into population demography.     

Urine Marking and Territoriality in Galago alleni (Waterhouse, 1837 — Lorisoidea,Primates) — A Field Study by Radio-telemetry

Behavioral interactions among color-marked individual Vidua chalybeata that shared common song dialects were observed for 5 years in two populations at Lochinvar National Park, Zambia. Social interactions involved ♂♂ visiting and competing for mating sites and ♀♀ visiting ♂♂ in an apparent sampling of potential copulating partners. Differences in mating success among the polygynous ♂♂ were compared with male behavior and territory resources, and criteria were developed to test the importance of intrasexual male competition and female mate choice in explaining the mating system of the populations. Song behavior best explained differences in mating success of ♂♂ with lesser effects of neighboring ♂♂ and the defensible resources around the call-sites. The social organization of song populations resembles that of a dispersed lek with ♀♀ visiting many ♂♂ but mating with few ♂♂. We discuss the observations on indigobirds in relation to behavioral selection, sexual selection, and mating systems. Mating systems of certain populations and species are compared using statistics of individual mating success.     

Sexual cannibalism and population viability

Some behaviours that typically increase fitness at the individual level may reduce population persistence, particularly in the face of environmental changes. Sexual cannibalism is an extreme mating behaviour which typically involves a male being devoured by the female immediately before, during or after copulation, and is widespread amongst predatory invertebrates. Although the individual‐level effects of sexual cannibalism are reasonably well understood, very little is known about the population‐level effects. We constructed both a mathematical model and an individual‐based model to predict how sexual cannibalism might affect population growth rate and extinction risk. We found that in the absence of any cannibalism‐derived fecundity benefit, sexual cannibalism is always detrimental to population growth rate and leads to a higher population extinction risk. Increasing the fecundity benefits of sexual cannibalism leads to a consistently higher population growth rate and likely a lower extinction risk. However, even if cannibalism‐derived fecundity benefits are large, very high rates of sexual cannibalism (>70%) can still drive the population to negative growth and potential extinction. Pre‐copulatory cannibalism was particularly damaging for population growth rates and was the main predictor of growth declining below the replacement rate. Surprisingly, post‐copulatory cannibalism had a largely positive effect on population growth rate when fecundity benefits were present. This study is the first to formally estimate the population‐level effects of sexual cannibalism. We highlight the detrimental effect sexual cannibalism may have on population viability if (1) cannibalism rates become high, and/or (2) cannibalism‐derived fecundity benefits become low. Decreased food availability could plausibly both increase the frequency of cannibalism, and reduce the fecundity benefit of cannibalism, suggesting that sexual cannibalism may increase the risk of population collapse in the face of environmental change.     

Fitness components and ecological risk of transgenic release: a model using Japanese medaka (Oryzias latipes)

Any release of transgenic organisms into nature is a concern because ecological relationships between genetically engineered organisms and other organisms (including their wild-type conspecifics) are unknown. To address this concern, we developed a method to evaluate risk in which we input estimates of fitness parameters from a founder population into a recurrence model to predict changes in transgene frequency after a simulated transgenic release. With this method, we grouped various aspects of an organism's life cycle into six net fitness components: juvenile viability, adult viability, age at sexual maturity, female fecundity, male fertility, and mating advantage. We estimated these components for wild-type and transgenic individuals using the fish, Japanese medaka (Oryzias latipes). We generalized our model's predictions using various combinations of fitness component values in addition to our experimentally derived estimates. Our model predicted that, for a wide range of parameter values, transgenes could spread in populations despite high juvenile viability costs if transgenes also have sufficiently high positive effects on other fitness components. Sensitivity analyses indicated that transgene effects on age at sexual maturity should have the greatest impact on transgene frequency, followed by juvenile viability, mating advantage, female fecundity, and male fertility, with changes in adult viability, resulting in the least impact.     

Female aggression predicts mode of paternity acquisition in a social lizard

Individual differences in behaviour are ubiquitous in nature. Despite the likely role of selection in maintaining these differences, there are few demonstrations of their fitness consequences in wild populations and, consequently, the mechanisms that link behavioural variation to variation in fitness are poorly understood. Specifically, the consequences of consistent individual differences in behaviour for the evolution of social and mating strategies have rarely been considered. We examined the functional links between variation in female aggression and her social and mating strategies in a wild population of the social lizard Egernia whitii. We show that female Egernia exhibit temporally consistent aggressive phenotypes, which are unrelated to body size, territory size or social density. A female''s aggressive phenotype, however, has strong links to her mode of paternity acquisition (within- versus extra-pair paternity), with more aggressive females having more offspring sired by extra-pair males than less aggressive females. We discuss the potential mechanisms by which female aggression could underpin mating strategies, such as the pursuit/acceptance of extra-pair copulations. We propose that a deeper understanding of the evolution and maintenance of social and mating systems may result from an explicit focus on individual-level female behavioural phenotypes and their relationship with key reproductive strategies.     

SEXUAL SELECTION AND MALE CHARACTERISTICS IN THE BLUEHEAD WRASSE,THALASSOMA BIFASCIATUM: MATING SITE ACQUISITION,MATING SITE DEFENSE,AND FEMALE CHOICE

Through a series of replacement experiments with the bluehead wrasse, Thalassoma bifasciatum, we have identified male morphological characteristics that appear to be under phenotypic sexual selection. We were particularly interested in whether the various sources of sexual selection (male-male competition for unoccupied mating sites, defense of mating sites against small males, and female choice of males) were (1) independently associated with different phenotypic characteristics; (2) jointly affected the same characteristic in the same way; or (3) jointly affected the same characteristic in an antagonistic fashion. We replaced the resident large, brightly colored Terminal Phase (TP) males on a reef with the same number of TP males from other reefs. When transplanted, these males contest with each other to take over mating sites. The transplanted group of males were then scored for three components of fitness: (1) the quality of the site obtained through competition with other large males; (2) the male's ability to defend arriving females from small intruding males; and (3) changes in female visits to the site once the new male takes over. The first and second components are part of intrasexual selection; the third represents intersexual selection. We measured the opportunity for selection by partitioning variance in mating success, and measured the direct effects of sexual selection by estimating the covariance between morphology and fitness components. Opportunities for selection: Because females generally remain faithful to particular mating sites, most (54%) of the explainable variation in male mating success is due to the acquisition of a particular mating territory, which is the outcome of competition among TP males. There was less variation in mating success due to shifts in site use by females and defense of females against the intrusions of smaller males, but all components were significant. Effects of selection: Success in male–male competition among TP males, estimated by the quality of the territory acquired, was positively associated with body length and the relative length of the pectoral fin. Success in territorial defense against small males was primarily related to body length, with lesser contributions from body depth and the area of a white band on the flank. Contribution to fitness through female choice of males was positively associated with white band area. In the two instances where a character was associated with two fitness components, the direction of selection was the same. While body length was positively associated with winning intrasexual contests, it was not correlated to any behavioral measures of aggression. Similarly, the white band associated with attractiveness was not correlated with any aspect of courtship or aggression. Parasite load was uncorrelated with other morphological characters, and did not appear to affect any aspect of sexual selection. There was no evidence for stabilizing selection or significant additional contributions from second-order effects to the fitness surfaces. Fitness functions calculated using cubic splines were generally linear except for body length, which appeared sigmoid in its effect on site acquisition ability; this same feature tended to plateau in its effect on site defense. Analyses of the interactions of selection gradients with reef or experiment indicated that the effect of particular male characters on estimates of fitness was generally homogeneous in both time and space.     

The evolution of male mate choice in insects: a synthesis of ideas and evidence

Mate choice by males has been recognized at least since Darwin's time, but its phylogenetic distribution and effect on the evolution of female phenotypes remain poorly known. Moreover, the relative importance of factors thought to underlie the evolution of male mate choice (especially parental investment and mate quality variance) is still unresolved. Here I synthesize the empirical evidence and theory pertaining to the evolution of male mate choice and sex role reversal in insects, and examine the potential for male mating preferences to generate sexual selection on female phenotypes. Although male mate choice has received relatively little empirical study, the available evidence suggests that it is widespread among insects (and other animals). In addition to 'precopulatory' male mate choice, some insects exhibit 'cryptic' male mate choice, varying the amount of resources allocated to mating on the basis of female mate quality. As predicted by theory, the most commonly observed male mating preferences are those that tend to maximize a male's expected fertilization success from each mating. Such preferences tend to favour female phenotypes associated with high fecundity or reduced sperm competition intensity. Among insect species there is wide variation in mechanisms used by males to assess female mate quality, some of which (e.g. probing, antennating or repeatedly mounting the female) may be difficult to distinguish from copulatory courtship. According to theory, selection for male choosiness is an increasing function of mate quality variance and those reproductive costs that reduce, with each mating, the number of subsequent matings that a male can perform ('mating investment') Conversely, choosiness is constrained by the costs of mate search and assessment, in combination with the accuracy of assessment of potential mates and of the distribution of mate qualities. Stronger selection for male choosiness may also be expected in systems where female fitness increases with each copulation than in systems where female fitness peaks at a small number of matings. This theoretical framework is consistent with most of the empirical evidence. Furthermore, a variety of observed male mating preferences have the potential to exert sexual selection on female phenotypes. However, because male insects typically choose females based on phenotypic indicators of fecundity such as body size, and these are usually amenable to direct visual or tactile assessment, male mate choice often tends to reinforce stronger vectors of fecundity or viability selection, and seldom results in the evolution of female display traits. Research on orthopterans has shown that complete sex role reversal (i.e. males choosy, females competitive) can occur when male parental investment limits female fecundity and reduces the potential rate of reproduction of males sufficiently to produce a female-biased operational sex ratio. By contrast, many systems exhibiting partial sex role reversal (i.e. males choosy and competitive) are not associated with elevated levels of male parental investment, reduced male reproductive rates, or reduced male bias in the operational sex ratio. Instead, large female mate quality variance resulting from factors such as strong last-male sperm precedence or large variance in female fecundity may select for both male choosiness and competitiveness in such systems. Thus, partial and complete sex role reversal do not merely represent different points along a continuum of increasing male parental investment, but may evolve via different evolutionary pathways.     

Intraspecific competition and the maintenance of monogamy in tree swallows

Intraspecific competition for access to breeding resources maylimit male mating success typically monogamous birds. We examinedthe potential for intraspecific competition to limit polygynyin tree swallows at Beaverhill Lake, Alberta, Canada. In thispopulation, polygynous males raisedmore fledglings than monogamousmales, and there was little or no cost to females from nestingpolygynously. Under these conditions one might expect polygynyto be more common than that observed(8% of males). We foundthat females were most aggressive toward conspecific intrudersearly in the breeding season. This aggression was associatedwith (1) females settling farther apart than expected underrandom settlement, (2) later settlement by secondary than bymonogamous females, and (3) no relationship between female settlementdate and male territory size instead of the negative correlationexpected if females settled randomly without competition. Earlyin the season, males also settled farther apart than expectedif they had settled randomly, and among males with two or morenest boxes on their territory, males with widely separated nestboxes were more likely to be polygynous. Monogamy is probablythe most common pairing association in this population becauseintraspecific competition for nest sites prevents most malesfrom gaining a territory with nest sites far enough apart topermit two females to breed without one female excluding theother. Females appeared to be defending an area surroundingtheir nest box to limit nest usurpation or intraspecific broodparasitism, rather than to limit any loss of male parental carefrom polygyny.     

Male mate choice in a sexually cannibalistic species: male escapes from hungry females in the praying mantid <Emphasis Type="Italic">Tenodera angustipennis</Emphasis>

While competing males and choosy females may be common in animal mating systems, male choice can evolve under certain conditions. Sexual cannibalism is such a condition because of the high mortality risk for males. In mantids, female body condition is associated with male mate preference, with fat females preferred, due to at least two reasons: females in poor nutritional condition are likely to attack and predate males, and fat females can potentially increase the number of offspring. Thus, the risk of cannibalism and female fecundity can influence male mating behavior. In this study, we attempted to separate these factors by using the praying mantid Tenodera angustipennis to examine whether male preference for fat female mantids was based on avoiding sexual cannibalism (cannibalism avoidance hypothesis) or preference for female fecundity (fecundity preference hypothesis). The feeding regimes were experimentally manipulated to discriminate between the effects of female fecundity and female hunger status on male and female mating behaviors. We found that recently starved females more frequently locomoted toward the male, and that male abdominal bending was less intensive and escape was sooner from recently starved females. These female and male behavioral responses to female hunger condition may reveal male avoidance of dangerous females in this mantid.