Benefits Of Mating Research Articles

Effects of variable mating opportunity, delay, and male mating experience on the lifespan, female reproductive traits, and offspring traits of Phytoseiulus persimilis (Acari: Phytoseiidae)

The balance between mating benefits and costs shapes reproductive strategies and life history traits across animal species. For biological control programs, understanding how mating rates influence life history traits is essential for optimising population management and enhancing predator efficacy. This study investigates the impact of mating opportunity availability, delayed mating, and male mating history (copulation frequency) on the lifespan (both sexes), female reproductive traits (duration of oviposition and of pre- and post-oviposition periods, and lifetime oviposition), and offspring quality (egg size and offspring survival) of the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae), an important biological control agent against spider mites. We examined three mating treatments—no mating, limited mating opportunity (24-h access), and continuous lifetime access—to assess their effects on lifespan (both sexes), female reproductive traits, and offspring quality. Further analyses examined the impact of delayed mating and male copulation history on female reproductive success and offspring traits. Our results showed a sexually differentiated response to repeated mating: females with continuous access to mates had similar lifespans in comparison with those mated for only 24 h, while males with continuous mating access exhibited significantly shorter lifespans. Both unlimited mating and delayed mating prolonged the female pre-oviposition period. However, neither varied mating opportunities, delayed mating, nor male copulation had any significant effect on other female reproductive traits or offspring quality. This suggests that repeated mating provides no reproductive advantage and imposes no observable costs on P. persimilis females.

Costs and benefits of polyandrous mating to the female emerald treefrog (Zhangixalus prasinatus), a lek-chorusing anuran

Costs and benefits of polyandrous mating to the female emerald treefrog (Zhangixalus prasinatus), a lek-chorusing anuran

Sex-specific manipulation of sexually cannibalistic mantid mating behavior by hairworms

Abstract Changes in the morphology, physiology, and behavior of parasitized organisms provide an ideal opportunity to examine the extended phenotype of parasites. Because the quality of the host directly affects the fitness of the parasite, parasites may increase their fitness by manipulating phenotypes of low-quality hosts. Males are usually preyed on by females in sexual cannibalism. Thus, the males of sexually cannibalistic species are unsafe and low-quality hosts for parasites, whereas females may be beneficial hosts because of the chance of nutrient intake from cannibalized males. Under passive modes of transmission, parasites cannot choose the host sex. Such parasites exploiting sexually cannibalistic organisms are subjected to contrasting fitness effects and may evolve to manipulate host mating behavior in a sex-specific manner: decreasing male mating to avoid cannibalism and promoting female mating to engage in cannibalism. We examined this hypothesis by a behavioral experiment using a mantid–hairworm system. Parasitized male mantids (Tenodera angustipennis) changed their behavior as expected, exhibiting increased escapes and decreased courtships and mountings, potentially avoiding encounters with the female. Interestingly, male attack behavior was promoted, possibly decreasing contact with the encountered female. However, contrary to our prediction, parasitized females also exhibited decreased propensities of mating, suggesting costs or little benefits of host mating for parasites in the female host. This study provides novel insights into the evolution of parasite strategies in response to sexual differences in host quality.

Fake news? The impact of information mismatch on mating behaviour.

Multiple cues are often used for mate choice in complex environments, potentially entailing mismatches in the information conveyed by different sources. We address the consequences of this information mismatch for receivers using the spider mite Tetranychus urticae, in which virgin females are highly valuable mates compared to mated females, given first male sperm precedence. Accordingly, males are known to prefer virgins and distinguish them using cues from the females themselves and that they leave on the substrate. Whereas cues from females are highly reliable, those left on the substrate may not reflect the real female mating status if females move and/or mate. Here, we tested the consequences of such mismatch by exposing males to mated or virgin females on patches previously impregnated with cues deposited by females of either mating status. Male mating attempts were solely affected by substrate cues while female acceptance and the number of mating events were independently affected by both cues. Copulation duration, in contrast, depended mainly on the mating status of the female, with the number of copulations and the total time spent mating being intermediate in environments with mismatched information. We also show that males incur mating costs, reflected in reduced survival in environments with virgin cues. These results suggest that substrate cues left by females are instrumental for males to find their mates. However, in environments with mismatched information, males may pay survival costs without the associated benefit of mating with virgins, or they may lose opportunities to mate with virgins by responding to substrate cues from mated females. The benefit of using multiple cues will then hinge upon the frequency of information mismatch, which itself should vary with the dynamics of populations.

Spatial structure could explain the maintenance of alternative reproductive tactics in tree cricket males.

Trait polymorphisms are widespread in nature, and explaining their stable co-existence is a central problem in ecology and evolution. Alternative reproductive tactics, in which individuals of one or more sex exhibit discrete, discontinuous traits in response to reproductive competition, represent a special case of trait polymorphism in which the traits are often complex, behavioural, and dynamic. Thus, studying how alternative reproductive tactics are maintained may provide general insights into how complex trait polymorphisms are maintained in populations. We construct a spatially explicit individual-based model inspired from extensively collected empirical data to address the mechanisms behind the co-existence of three behavioural alternative reproductive tactics in males of a tree cricket (Oecanthus henryi). Our results show that the co-existence of these tactics over ecological time scales is facilitated by the spatial structure of the landscape they inhabit, which serves to equalise the otherwise unequal mating benefits of the three tactics. We also show that this co-existence is unlikely if spatial aspects of the system are not considered. Our findings highlight the importance of spatial dynamics in understanding ecological and evolutionary processes and underscore the power of integrative approaches that combine models with empirical data.

Little evidence for color- or size-based mating preferences by male strawberry poison frogs (Oophaga pumilio)

While there are many studies documenting female mating preferences across taxa, male mate choice remains relatively understudied. Male mate choice often develops when there is variation in female quality and thus the fitness benefits of mating with particular females. Specifically, males tend to prefer females with traits that confer direct fitness benefits such as large body size, which may be linked with high fecundity. Prior work has shown that females of the strawberry poison frog, Oophaga pumilio, prefer males bearing certain coloration (most often the female’s own color), and that this preference can be learned through maternal imprinting. Females have been shown to prefer larger males as well. Here we test whether similar mate preferences for color and size exist in males of this species using two-way choice tests on captive bred male O. pumilio. In each test focal males were placed in an arena with two stimulus females: either both of the same size but differing in color, or both of the same color but differing in size. We found only weak evidence for behavioral biases toward particular colors and no evidence for biases toward larger females, suggesting that males of O. pumilio do not predictably choose mates based on these female traits. Despite several aspects of their natural history that suggest males have reasons to be choosy, our findings suggest that the cost of mate rejection may outweigh any fitness benefits derived from being selective of mates. Studies of additional populations, ideally conducted on wild individuals, are needed to better understand the range of conditions under which males may exhibit mate choice and the types of traits on which they base these choices.Significance statementTo fully understand the fitness landscapes and evolutionary trajectories that result from sexual selection, we need to understand when and how the mate preferences of the two sexes act and interact. While female mate choice has been widely studied, male mate choice remains poorly understood. To help bridge this gap, we studied male mate preferences in the strawberry poison frog Oophaga pumilio, a small brightly colored frog for which female preferences for male color and size have been well-documented. We found no evidence that male O. pumilio exhibit mate preferences based on female size and little evidence for male mate preferences based on female color. This is surprising given that larger females are often more fecund, male O. pumilio are known to exhibit color-based behavioral biases in the context of male-male competition, and both sexes provide parental care.

Female state and condition-dependent chemical signaling revealed by male choice of silk trails

Abstract Male mate choice is predicted in systems with high costs of mating, as for those with male nuptial gifts and/or sexual cannibalism. We ask whether males of the nuptial gift-giving spider Pisaura mirabilis exert preferences for mates varying in their reproductive potential based on chemical information during mate search. Males were presented with binary trails consisting of silk lines and substrate-borne chemicals deposited while females were walking, from females varying in 1) body condition (high vs. low), 2) developmental state (subadult vs. adult), and 3) mating state (unmated vs. mated). If female chemical signaling co-varies with individual state, we expect males to choose trails of females that are 1) in higher body condition, indicating higher fecundity, 2) adults, which can successfully reproduce, and 3) unmated, to avoid sperm competition. We show that female signaling is condition-dependent, with males being more likely to follow trails of higher body condition females, but not dependent on female mating state. Males also tended to prefer trails of adults over subadults. Choice did not depend on male individual body condition. Our findings suggest costs to chemical signaling in nutritionally deprived females, often considered negligible, and their potential as reliable indicators of individual quality. Selection may favor male preferences for more fecund partners given the energetic investment nuptial gifts entail. Nutritional and reproductive benefits of multiple mating to females and high share of paternity for males, may instead select against signaling of female mating state, and/or male discrimination and choice.

The evolution of dynamic and flexible courtship displays that reveal individual quality

Sexual selection is a major force shaping morphological and behavioral diversity. Existing theory focuses on courtship display traits such as morphological ornaments whose costs and benefits are assumed be to fixed across individuals’ lifetimes. In contrast, empirically observed displays are often inherently dynamic, as vividly illustrated by the acrobatic dances, loud vocalizations, and vigorous motor displays involved in courtship behavior across a broad range of taxa. One empirically observed form of display flexibility occurs when signalers adjust their courtship investment based on the number of rival signalers. The predictions of established sexual selection theory cannot readily be extended to such displays because display expression varies between courtship events, such that any given display may not reliably reflect signaler quality. We thus lack an understanding of how dynamic displays coevolve with sexual preferences and how signalers should tactically adjust their display investment across multiple courtship opportunities. To address these questions, we extended an established model of the coevolution of a female sexual preference and a male display trait to allow for flexible, dynamic displays. We find that such a display can coevolve with a sexual preference away from their naturally selected optima, though display intensity is a weaker signal of male quality than for non-flexible displays. Furthermore, we find that males evolve to decrease their display investment when displaying alongside more rivals. This research represents a first step towards generalizing the findings of sexual selection theory to account for the ubiquitous dynamism of animal courtship.Significance statementAnimal courtship displays are typically costly for survival: songs attract predators; dances are exhausting; extravagant plumage is cumbersome. Because of the trade-off between mating benefits and survival costs, displaying individuals often vary their displays across time, courting more intensely when the potential benefit is higher or the cost is lower. Despite the ubiquity of such adjustment in nature, existing theory cannot account for how this flexibility might affect the coevolution of displays with sexual preferences, nor for the patterns of tactical display adjustment that might result, because those models treat displays as static, with fixed costs and benefits. Generalizing a well-studied model of sexual selection, we find that a static display and a flexible display can evolve under similar conditions. Our model predicts that courtship should be less intense when more competitors are present.

The use and misuse of evolutionary psychology in online manosphere communities: The case of female mating strategies.

While early evolutionary accounts of female sexuality insisted on coyness and monogamous tendencies, evidence from the field of primatology started challenging those assumptions in the 1970s. Decades later, there exist many competing and overlapping hypotheses stressing the potential fitness benefits of female short-term and extra-pair mating. Female mammals are now seen as enacting varied and flexible reproductive strategies. This is both a victory for science, with a better fit between theory and reality, and for feminism, with the downfall of narrow stereotypes about female sexuality. However, evolutionary hypotheses on female mating strategies are routinely invoked among the antifeminist online communities collectively known as 'the manosphere'. Based on extensive qualitative analysis of manosphere discourse, this study shows how these hypotheses are sometimes interpreted in misogynistic online spaces. Indeed, evolutionary scholars might be surprised to see sexist worldviews reinforced by the 'dual mating strategy' and 'sexy son' hypotheses, or by the latest research on the ovulatory cycle. The manosphere has its own version of evolutionary psychology, mingling cutting-edge scientific theories and hypotheses with personal narratives, sexual double standards and misogynistic beliefs. After analysing this phenomenon, this article suggests ways to mitigate it.

In negative life contexts men report a lower desire to end relationship if their partners are high in borderline behavioral characteristics. A quasiexperimental research

We investigated the relationship between borderline symptoms in women and their partner’s desire to continue the relationship and relationship commitment in an aversive living environment using an experimental design. We aimed to highlight the adaptive mechanisms of borderline symptoms, which may materialize in reproductive advantages for women in aversive contexts. We conducted two experiments to test the same hypotheses. In Study 1, online participants were assigned to the experimental group (N = 123). The experimental scenario hypothesized having a relationship with a woman high in borderline characteristics, during an aversive life environment. The control group (N = 118) hypothesized having a relationship with a woman high in borderline characteristics, during normal living conditions. We repeated the same experimental manipulation using a within-subjects design in Study 2 (N = 171). Environmental conditions influenced the desire to end the relationship with women characterized by borderline symptoms; men had a lower desire to end the relationship with their partner in aversive life events than in normal living conditions. Thus, women’s borderline behavioral characteristics may bring mating benefits in aversive living environments.

Concerted evolution of metabolic rate, economics of mating, ecology, and pace of life across seed beetles

Male-female coevolution has taken different paths among closely related species, but our understanding of the factors that govern its direction is limited. While it is clear that ecological factors, life history, and the economics of reproduction are connected, the divergent links are often obscure. We propose that a complete understanding requires the conceptual integration of metabolic phenotypes. Metabolic rate, a nexus of life history evolution, is constrained by ecological factors and may exert important direct and indirect effects on the evolution of sexual dimorphism. We performed standardized experiments in 12 seed beetle species to gain a rich set of sex-specific measures of metabolic phenotypes, life history traits, and the economics of mating and analyzed our multivariate data using phylogenetic comparative methods. Resting metabolic rate (RMR) showed extensive evolution and evolved more rapidly in males than in females. The evolution of RMR was tightly coupled with a suite of life history traits, describing a pace-of-life syndrome (POLS), with indirect effects on the economics of mating. As predicted, high resource competition was associated with a low RMR and a slow POLS. The cost of mating showed sexually antagonistic coevolution, a hallmark of sexual conflict. The sex-specific costs and benefits of mating were predictably related to ecology, primarily through the evolution of male ejaculate size. Overall, our results support the tenet that resource competition affects metabolic processes that, in turn, have predictable effects on both life history evolution and reproduction, such that ecology shows both direct and indirect effects on male-female coevolution.

High frequency of social polygyny reveals little costs for females in a songbird

Mating system theory predicts that social polygyny—when one male forms pair bonds with two females—may evolve by female choice in species with biparental care. Females will accept a polygynous male if the benefit of mating with a male providing high-quality genes or rearing resources outweighs the cost of sharing mate assistance in parental care. Based on this rationale, we hypothesise that the population frequency of social polygyny (FSP) varies due to changes in mate sharing costs caused by changing environmental conditions. We predicted that: (1) polygamous females (i.e. mated with a polygynous male) pay a survival cost compared to monogamous females; (2) FSP would be higher in years with better rearing conditions and (3) the difference in survival rates between monogamous and polygamous females would be small following years with higher FSP. We tested these predictions using regression and multistate analyses of capture-recapture data of pied flycatchers, Ficedula hypoleuca, in central Spain collected over 26 years (1990–2016). Monogamous females had a higher mean survival rate than polygamous females (prediction 1), but there was no difference in survival between polygynous and monogamous males. In addition, FSP was positively associated with annual reproductive success (a proxy of the quality of rearing conditions—prediction 2). Finally, following years with high FSP, the survival of polygamous females was similar to that of monogamous females (prediction 3), while the chance of breeding in a polygamous state for 2 years in a row increased for both males and females. Our findings suggest that fluctuating environmental conditions may be a necessary but neglected aspect of understanding social polygyny mechanisms.

A decade of sexual selection studies reveals patterns and processes of fitness variation in male collared lizards

Territory defence is widely assumed to be adaptive because it enhances reproductive success. However, empirical evidence for such a benefit is scarce or nonexistent for many types of territorial organisms. The roles of intraspecific aggression versus interactions with females in successful breeding by territorial males are also still poorly understood in lower tetrapods, including lizards. We address both of these important issues using 10 years of data on genetic parentage combined with field behavioural studies in collared lizards, Crotaphytus collaris . As predicted, territorial males (T-males) had more mates, sired markedly more total offspring and sired more surviving offspring with more females than did nonterritorial (NT) males. Territorial males in structurally simpler habitats sired a higher proportion of each female's offspring than their counterparts in complex habitats, indicating that the ability of T-males to accrue mating benefits is highest where topography maximizes contact with multiple females. All measures of T-male reproductive success increased with travel rate but decreased with the time spent courting individual females, suggesting a fitness trade-off between these behaviours. We found no evidence that aggressive behaviour was linked to any component of male fitness. Hence, activities of territory owners appear to be shaped by sexual selection to enhance mating opportunities rather than to aggressively dominate same-sex rivals. Our study illustrates the value of long-term research documenting behaviour and fitness of free-ranging individuals over multiple reproductive cycles in evaluating fundamental questions about the adaptive significance of social tactics. • Territorial male collared lizards had higher fitness than nonterritorial males. • Territorial tactics increased mating more effectively in simpler habitats. • Fitness of territory owners increased with travel but not with aggressive behaviour. • Limiting courtship per female promoted travel to interact with additional mates. • Male behaviour is selected to enhance interactions with multiple female mates.

Temperature impacts all behavioral interactions during insect and arachnid reproduction.

Temperature shapes the processes and outcomes of behaviors that occur throughout the progression of insect and arachnid mating interactions and reproduction. Here, we highlight how temperature impacts precopulatory activity levels, competition among rivals, communication with potential mates, and the relative costs and benefits of mating. We review how both the prevailing temperature conditions during reproductive activity and the temperatures experienced early in life influence mating-related behavior. To effectively predict the consequences of global warming for insect and arachnid mating behavior, we advocate for future work that universally integrates a function-valued approach to measuring thermal sensitivity. A function-valued approach will be especially useful for understanding how fine-scale temperature variation shapes current and future selection on mating interactions.

Lek Territory Size and the Evolution of Leks: A Model and a Test Using an Ungulate With a Flexible Mating System

Despite many decades of research, the evolution of the rare and unusual lek-mating system continues to be debated. The key question is: why do males defend tiny territories clustered together in an aggregation when the costs of doing so are so high? Theory and empirical work on lek evolution typically focus on why males cluster their territories. Surprisingly, the other characteristic feature of classical leks, which is the unusually small size of lek-territories, has received very little attention. Here, I argue that understanding the factors favoring the reduced size of lek-territories can provide fresh insights into the evolution of leks. I used the variable mating system of an Indian antelope, the blackbuck (Antilope cervicapra), to investigate lek territory size. Because there are few quantitative models of mating territory size, I first constructed a spatial simulation model of territory size based on male competition costs and on mating benefits generated by a female bias for mating on central lek-territories, the processes most likely to influence lek-territory size. The model generated much systematic variation in territory size within a territory-cluster and also across territory-clusters varying in the number of territorial males. I tested predictions from the model using comparative data on territory size from six blackbuck populations, and detailed spatial and temporal data from an intensively-studied population. Empirical analyses strongly supported model predictions and assumptions. Based on these findings, I present a novel hypothesis for the small size of classical lek-territories. I suggest that much of the variation in the size of lek-territories can be explained by the competition that arises from a female bias for mating on central territories and that is intensified by the number of territorial males in an aggregation. Thus, the reduced size of classical lek-territories is likely a consequence of a central mating advantage in large aggregations. I present a framework for the evolution of leks that explicitly incorporates the evolution of reduced territory size alongside the evolution of male clustering. This framework can also help explain other forms of mating systems that are based on the defense of mating territories by males.

Sex differences in bonobo (Pan paniscus) terrestriality: implications for human evolution.

Recent finds in hominin fossil environments place the transition to terrestriality in a wooded or forested habitat. Therefore, forest-dwelling apes can aid in understanding this important evolutionary transition. Sex differences in ape locomotion have been previously attributed to sexual dimorphism or ecological niche differences between males and females. This study examined the hypothesis that differential advantages of terrestrial travel may impact mating success in male bonobos. We examined whether males are more terrestrial when there are mating benefits for fast travel. We analyzed behavioral data on wild bonobos over a ten-month period in the Lomako Forest, DRC and examined the proportion of time spent at lower heights compared to higher heights between adult females and males relative to their location to feeding contexts with high mating frequencies. We found a significant interaction between sex and height class away from food patches (F=4.65, df =1, p <0.05) such that females were primarily arboreal whereas there was no difference between males across height classes. However, there was also a significant interaction between sex and height class (F =29.35, df =1, p <0.0001) for adults traveling near or entering a food patch. Males often arrived at food patches terrestrially and females arrived almost exclusively arboreally. We found a significant difference between the expected and observed distribution of matings by food patch context (G =114.36, df =4, p <0.0001) such that most mating occurred near or in a food patch. These results suggest that males may travel terrestrially to arrive at food patches before cohesive parties of females arrive arboreally, in order to compete with other males for mating access to these females. Such intrasexual selection for sex differences in locomotion may be important in considerations of the evolution of locomotion strategies in hominins in a forested environment.

Baffling: a condition-dependent alternative mate attraction strategy using self-made tools in tree crickets.

Intense sexual selection in the form of mate choice can facilitate the evolution of different alternative reproductive strategies, which can be condition-dependent. Tree cricket males produce long-distance acoustic signals which are used by conspecific females for mate localization and mate choice. Our study shows that baffling, an acoustic call amplification strategy employed by male tree crickets using self-made tools, is a classic example of a condition-dependent alternative strategy. We show that though most males can baffle, less preferred males, such as smaller and lower-amplitude callers, predominantly use this alternative strategy. Baffling allows these males to increase their call amplitude and advertisement range, which attracts a higher number of females. Baffling also gives these males a mating benefit because females mate for longer durations with them. Our results suggest that the advantage of baffling in terms of gain in the number of sperm cells transferred while mating is primarily limited to less preferred males, thus maintaining the polymorphism of calling strategies in the population. We summarize that baffling is a condition-dependent strategy used by less preferred tree cricket males to obtain mating benefits.

&lt;p class="Body"&gt;&lt;strong&gt;Effectiveness of second mating in sperm-depleted females in the two-spotted spider mite, &lt;em&gt;Tetranychus urticae&lt;/em&gt; (Acari: Tetranychidae)&lt;/strong&gt;&lt;/p&gt;

Conspecific males often disturb copulating mites, thus interrupting the mating and a subsequent mating may occur. However, in natural populations of Tetranychus urticae, virgin or sperm-depleted females exist (3.2% of the females in a population) and a second mating may occur when these females are placed with males of unknown age. How does multiple mating benefit the fitness of T. urticae females? To answer this question and to establish the success of re-mating, we investigated the effects of mating interruption at various time intervals after the start on the validity of fertilization. Female offspring ratios were significantly lower if mating was interrupted at 30, 60 or 90 s, compared with complete (undisturbed) mating. Females accepted the second mating if they could not obtain sufficient sperm from the first mating owing to interruption. The success of the second mating and priority of the second male’s sperm depended on how soon the interruption of the first mating occurred. Proportion of females produced female offspring of the second males when mated at 6 days after the first mating was fewer than those when mated just after the first mating. To know the effect of males of unknown age, of which some were assumed to be sperm-depleted, we used them as the first mating partner and then used virgin males as the second mating partner. Three females (6.4%, n = 47) who mated with males of unknown age at the first mating, produced female offspring of the second males, but no females produced female offspring of the second males when mated with virgin males at the first mating. These findings indicate that sperm depletion, caused by mating interruption or paternal age in the first mating, might indeed affect the fertilizing ability.

Does sexual cannibalism secure genetic benefits of polyandry in a size-dimorphic spider?

Females mate multiply despite numerous costs. It is well established that polyandry can result in sexual conflict, favoring male adaptations that prevent sperm competition often to the disadvantage of the female. Such adaptations are extreme in spiders with one-shot genitalia of which parts break off and act as mating plugs, rendering them dysfunctional. In the spider Argiope bruennichi, mating plugs effectively prevent further males from inseminating and males that inseminate and plug both genital openings of a female secure exclusive paternity. However, females frequently prevent monopolization by attacking and cannibalizing males during their first copulation, leaving their second spermatheca free for another male. Here, we test whether the high frequency of sexual cannibalism evolved as a female adaptation to resist monopolization and secure indirect benefits of polyandry. To standardize conditions, we double-mated females either with the same or two different males and prevented male consumption. Using a split-brood design, we raised offspring to maturity under poor and rich food conditions and measured their survival, duration of juvenile phase, and adult body mass. Under low food, daughters of polyandrous mothers matured later but slightly heavier than daughters of monandrous females. Since the adaptive value of this combination is unclear, these findings lend no conclusive support to our hypothesis. We discuss the stereotypic nature of the female attack in the context of antagonistic co-evolution considering previous studies that found modest direct benefits of cannibalism as well as a potential for non-additive benefits.Significance statementSexual conflict is extreme in spiders where sexual cannibalism impairs male mating rates. Males of the spider Argiope bruennichi possess one-shot genitalia which they break off to plug female genital openings. They gain exclusive paternity with a female if two copulations are achieved and both genital openings plugged. Females, however, stereotypically attack every male at the onset of copulation, limiting most males to single copulation but retaining the option to secure potential benefits of polyandry. Previous studies revealed weak direct and non-additive indirect benefits of multiple mating. In this study, we tested for the presence of additive genetic benefits but again found only inconclusive evidence for adaptive differences in offspring quality between monandrous and polyandrous females. All results combined, we here speculate that the stereotypic female attack might be a ghost of a past antagonistic co-evolution.

Universal and variable leadership dimensions across human societies

Many researchers have turned to evolutionary theory to better understand diversity in leadership. Evolutionary theories of leadership, in turn, draw on ethnographic cases of societies thought to more closely resemble the smaller-scale, face-to-face communities in which humans evolved. Currently, though, there is limited systematic data on the nature of leadership in such societies. We coded 109 dimensions of leadership, including costs and benefits relevant to evolutionary models, in 1212 ethnographic texts from 59 mostly nonindustrial populations in Human Relations Area Files (HRAF). We discovered evidence for both cultural universals in leadership, as well as important variation by continental region, subsistence strategy, group context, and leader sex. Candidate universals included that leaders were intelligent and knowledgeable, resolved conflicts, and received material and social benefits. Evidence for other leader dimensions varied by group context (e.g., there was more evidence that leaders of kin groups were older and tended to provide counsel and direction), subsistence (e.g., hunter-gatherers tended to lack leaders with coercive authority), and sex (e.g., female leaders tended to be associated with family contexts). There was generally more evidence of benefits than costs for both leaders and followers, with material, social, and mating benefits being particularly important for leaders, and material and other benefits important for followers. Shamans emerged as an important category of leaders who did not clearly conform to influential models that emphasize two leader strategies: using knowledge and expertise to provide benefits to followers vs. using physical formidability to impose costs. Instead, shamans and other leaders with supernatural abilities used their knowledge to both provide benefits and impose costs on others. We therefore propose a modified scheme in which leaders deploy their cognitive, social, material, and somatic capital to provide benefits and/or impose costs on others. • Comprehensive cross-cultural assessment of leadership traits • Universals include that leaders are knowledgeable, intelligent, and resolve conflicts. • Leaders receive important material, social, and reproductive benefits. • Shaman leaders use knowledge to provide benefits and impose costs. • The importance of shaman leaders highlights value of evidence from non-WEIRD cultures.