Presence Of Rivals Research Articles

Personality affects mate choice: bolder males show stronger audience effects under high competition

Males in various species adjust their mate choice to sperm competition risk and intensity arising when females potentially mate with several competing males. If males use social information and copy other males’ choices, this leads to an increased likelihood of sperm competition for both, the copying and the copied male. In livebearing fishes (Poeciliidae), males appear to avoid the risk of being copied by temporarily moving away from preferred females and approaching nonpreferred ones (audience effect), thereby exploiting the rival’s propensity to copy. Responding to rival presence with an audience effect bears the risk of losing the initially preferred female, which may swim away, but may help to reduce sperm competition intensity. Males may rate this risk–benefit ratio differentially depending on their personality, for example, more risk-taking (bolder) males might be more likely to respond to an audience. Using Atlantic mollies (Poecilia mexicana) as our study organism, we characterized focal and audience males along the boldness–activity behavioral axis. As overall competition levels are known to affect male mate choice, we subjected half of the males to a low competition (single-male housing) and the other half to a high-competition treatment (group housing) before they were tested in binary mate choice tests. Only males from the high competition treatment responded to rival presence with an audience effect. In congruence with our prediction, bolder males within this cohort showed a stronger audience effect. Our study exemplifies that (depending on the social context) bolder, not shyer, individuals can be more responsive to their social environment.

Sociosexual environment influences patterns of ejaculate transfer and female kicking in Callosobruchus maculatus

There is growing evidence that many organisms adjust their physiology and behaviour during sexual encounters according to changes in their sociosexual situation. Selection tends to favour plasticity in males that can strategically ejaculate and females that can alter their resistance or remating behaviour adaptively. We investigated plasticity both in the ejaculate transfer patterns of males and in the pericopulatory kicking behaviour of female seed beetles, Callosobruchus maculatus . We altered the sociosexual environment of the beetles by (1) manipulating male mating history, (2) preventing females from kicking and (3) altering the risk of sperm competition. Males mating for the second time transferred half the weight of ejaculate of virgin males, but at the same rate. Males mating in the presence of rivals did not alter the weight of ejaculate, as might have been expected; however, the transfer of ejaculate began sooner. By looking at the effect of female kicking on male ejaculate transfer, we found that when females have their hindlegs ablated to prevent kicking, the rate of ejaculate transfer slows, but the weight remains the same. From the female perspective we found that the probability of females kicking was positively related to both copula duration and ejaculate weight, but also to male mating history; females were less likely to kick males that had mated more times previously even after controlling for copula duration and ejaculate weight. Finally, we found that removing a female's hindlegs increased the probability that females (attempted to) kick. Our results show that males are, to some extent, plastic in their ejaculatory responses to the sociosexual environment. More striking, however, and not previously documented, is that female kicking is affected by environmental variables, including male mating history. • Males can adjust ejaculate transfer dynamics to the sociosexual environment. • The presence of rival males did not affect the volume of ejaculate transferred. • Probability of female kicking increases with mating duration and ejaculate weight. • Probability of female kicking varies with male mating history.

Sperm production responds to perceived sperm competition risk in male Drosophila melanogaster

Postcopulatory sexual selection arising from female multiple mating leads to the evolution of ejaculates that maximize a male's reproductive success under sperm competition. Where the risk of sperm competition is variable, optimal fitness may be achieved by plastically altering ejaculate characteristics in response to the prevailing sperm competition environment. In the model species Drosophila melanogaster, males expecting to encounter sperm competition mate for longer and transfer more accessory proteins and sperm. Here we show that after being housed with a single rival for one week, the seminal vesicles of male D. melanogaster contain a significantly greater proportion of live sperm than those of males maintained alone, indicating adaptive adjustment of sperm quality in response to the perceived risk of sperm competition. This effect is due to an increase in the number of live sperm produced, indicating that males upregulate sperm production in response to the presence of rivals. Our data suggest that males show plasticity in the rate of spermatogenesis that is adaptive in the context of a fluctuating sperm competition environment.

Stickleback Males Increase Red Coloration and Courtship Behaviours in the Presence of a Competitive Rival

AbstractIn species where females preferentially select the most colourful males, males may strategically invest in courtship and nuptial colour according to the presence of rivals. In this experimental study, we tested this in the three‐spined stickleback (Gasterosteus aculeatus) in which mature males exhibit carotenoid‐based red coloration to attract mates and defend their territories against male competitors. We challenged experimental males with either a red‐ornamented dummy male or a non‐ornamented dummy for five min per day in six‐d experimental trial, which was repeated twice during the breeding season. We found that the males presented with a coloured rival exhibited more frequent courtship behaviours (i.e. fanning and gluing) to females than those presented with a non‐coloured intruder during the second experimental trial. At the end of each trial, the experimental males also showed a significantly larger area of red coloration in the presence of a coloured intruder. Our findings suggest that male sticklebacks regulate mating effort according to the presence of competitive rivals by increasing their investment in costly signals when successful mating and territory defence is at risk.

McDonald's and KFC in China: Competitors or Companions?

In this paper, we study the entry and expansion decisions of McDonald's and KFC in China using an originally assembled data set on the two chains' expansion in the China market from their initial entry up to year 2007. We analyze how the presence of a rival affects each firm's strategies. The results indicate that a rival's presence has a net positive effect on a chain's expansion decision. We focus on testing two possible explanations for a positive rival impact: market learning and demand expansion. First, we derive a set of theoretical predictions on how a chain's optimal expansion decision would react to its rival's expansion patterns when market learning versus demand expansion is the driving force of the rival's positive influence. The empirical analysis based on these predictions consistently suggests that market learning is more likely to explain the positive effect of KFC on McDonald's and that demand expansion is more plausible with McDonald's positive spillover on KFC. In other words, the results are consistent with the presence of KFC signaling market demand potential and growth to McDonald's and the presence of McDonald's helping to cultivate consumer taste and generate demand for Western fast food, which benefits KFC.

Ejaculate economics: an experimental test in a moth

Increasing evidence shows that spermatogenesis is costly. As a consequence, males should optimize the use of their sperm to maximize their reproductive outputs in their lifetime. However, experimental evidence on this prediction is largely lacking. Here, we examine how a male moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) responds to the presence of rivals or additional mates and how such response influences his lifetime reproductive fitness. We show that when rival males are present around a copulating pair, the male ejaculates more sperm to win a sperm competition battle but in such an environment he inseminates fewer females, sires fewer offspring and lives shorter. The opposite is the case when additional females are present during copulation. These findings reveal that elevated reproductive expenditure owing to sperm competition intensity is made at the expense of longevity and future reproduction.

How Does Rivals' Presence Affect Firms' Decision to Enter New Markets? Economic and Sociological Explanations

Four distinct theoretical programs have examined market entry decisions of multiunit firms, advancing different explanations for the relationship between a firm's likelihood of entry into a geographical market and the number of rivals that are already present in the target market. Within the strategy literature, theory of strategic interactions explains that firms will want to establish a foothold in markets where their multimarket competitors are scarce, but avoid markets where there are many multimarket competitors. Within economic geography, positive externalities such as increase in demand explain firms' desire to locate close to their rivals whereas negative externalities such as competition explain their desire to avoid them. Within the ecological tradition, density dependence theory explains this relationship in terms of legitimation of an organizational form in a particular market and subsequently increased competition for resources there. Within new institutional theory, the presence of rivals is seen as a signal that a particular market is suitable for entry. Although generally quoted and mentioned in the literature, these four explanations have not been sufficiently separated to indicate whether these four mechanisms all operate simultaneously or whether one of them might account for the often found inverse-U-shaped relationship. Distinguishing firms with different strategies and using various moderators, we test the four explanations jointly and demonstrate their scope of operation. Data, as supplemental material, are available at http://dx.doi.org/10.1287/mnsc.2013.1723 . This paper was accepted by Jesper Sørensen, organizations.

Management Insights

Management Insights

Casanovas are liars: behavioral syndromes, sperm competition risk, and the evolution of deceptive male mating behavior in live-bearing fishes

Male reproductive biology can by characterized through competition over mates as well as mate choice. Multiple mating and male mate choice copying, especially in internally fertilizing species, set the stage for increased sperm competition, i.e., sperm of two or more males can compete for fertilization of the female’s ova. In the internally fertilizing fish Poecilia mexicana, males respond to the presence of rivals with reduced expression of mating preferences (audience effect), thereby lowering the risk of by-standing rivals copying their mate choice. Also, males interact initially more with a non-preferred female when observed by a rival, which has been interpreted in previous studies as a strategy to mislead rivals, again reducing sperm competition risk (SCR). Nevertheless, species might differ consistently in their expression of aggressive and reproductive behaviors, possibly due to varying levels of SCR. In the current study, we present a unique data set comprising ten poeciliid species (in two cases including multiple populations) and ask whether species can be characterized through consistent differences in the expression of aggression, sexual activity and changes in mate choice under increased SCR. We found consistent species-specific differences in aggressive behavior, sexual activity as well as in the level of misleading behavior, while decreased preference expression under increased SCR was a general feature of all but one species examined. Furthermore, mean sexual activity correlated positively with the occurrence of potentially misleading behavior. An alternative explanation for audience effects would be that males attempt to avoid aggressive encounters, which would predict stronger audience effects in more aggressive species. We demonstrate a positive correlation between mean aggressiveness and sexual activity (suggesting a hormonal link as a mechanistic explanation), but did not detect a correlation between aggressiveness and audience effects. Suites of correlated behavioral tendencies are termed behavioral syndromes, and our present study provides correlational evidence for the evolutionary significance of SCR in shaping a behavioral syndrome at the species level across poeciliid taxa.

Casanovas are liars: behavioral syndromes, sperm competition risk, and the evolution of deceptive male mating behavior in live-bearing fishes

Male reproductive biology can by characterized through competition over mates as well as mate choice. Multiple mating and male mate choice copying, especially in internally fertilizing species, set the stage for increased sperm competition, i.e., sperm of two or more males can compete for fertilization of the female’s ova. In the internally fertilizing fish Poecilia mexicana, males respond to the presence of rivals with reduced expression of mating preferences (audience effect), thereby lowering the risk of by-standing rivals copying their mate choice. Also, males interact initially more with a non-preferred female when observed by a rival, which has been interpreted in previous studies as a strategy to mislead rivals, again reducing sperm competition risk (SCR). Nevertheless, species might differ consistently in their expression of aggressive and reproductive behaviors, possibly due to varying levels of SCR. In the current study, we present a unique data set comprising ten poeciliid species (in two cases including multiple populations) and ask whether species can be characterized through consistent differences in the expression of aggression, sexual activity and changes in mate choice under increased SCR. We found consistent species-specific differences in aggressive behavior, sexual activity as well as in the level of misleading behavior, while decreased preference expression under increased SCR was a general feature of all but one species examined. Furthermore, mean sexual activity correlated positively with the occurrence of potentially misleading behavior. An alternative explanation for audience effects would be that males attempt to avoid aggressive encounters, which would predict stronger audience effects in more aggressive species. We demonstrate a positive correlation between mean aggressiveness and sexual activity (suggesting a hormonal link as a mechanistic explanation), but did not detect a correlation between aggressiveness and audience effects. Suites of correlated behavioral tendencies are termed behavioral syndromes, and our present study provides correlational evidence for the evolutionary significance of SCR in shaping a behavioral syndrome at the species level across poeciliid taxa.

The effect of competitors on calling effort and life span in male field crickets

Temporal variation in the strength of selection on male sexual traits is often attributable to changes in the social environment that alter the number of competitors. Selection could favor phenotypic plasticity in male investment into sexual traits if there are cues indicative of current and, possibly, future levels of mating competition. In many taxa, males court more intensely when rivals are present, but the extent to which phenotypically plastic responses differ predictably among males is less well studied. For example, will larger males show a greater or smaller change in courtship in response to the presence of rivals? In addition, the effects of any changes in courtship on key life-history traits have been understudied. In this study, we experimentally tested male crickets (Teleogryllus commodus) from 3 populations to determine how the presence or absence of a affects: 1) calling effort, 2) life span, and 3) whether male body size (correlated with dominance) influences any changes in life span or calling effort. Calling effort increased significantly with body size, mainly due to daily calling effort increasing with age and larger males living longer. Considering all males, there was no effect of presence on lifetime calling effort. However, within the rival present treatment, after correcting for age, the longer lived of 2 paired males called significantly more before his died than afterwards. This implies that there is a plastic shift in courtship effort. Finally, larger males lived significantly longer and, crucially, males housed with a had, on average, a significantly shorter life span.

Casanovas are liars: behavioral syndromes, sperm competition risk, and the evolution of deceptive male mating behavior in live-bearing fishes

Mate choice in many species is sensitive to social cues from neighboring individuals; for example, animals can copy mate choice decisions. If males copy other males' choices, sperm of two or more males can compete for fertilization of the female's ova. In the internally fertilizing fish Poecilia mexicana, males respond to the presence of rivals with reduced expression of mating preferences (audience effect), thereby lowering the risk of by-standing rivals copying their mate choice. Also, males interact initially more with a non-preferred female when observed by a rival, which has been interpreted in previous studies as a strategy to mislead rivals, again reducing sperm competition risk (SCR). Using a comparative approach, we tested the hypothesis that SCR is indeed a driving force explaining the occurrence of audience-induced changes in poeciliid male mate choice behavior. If this were true, then males of species with higher overall sexual activity - and, thus, higher potential for multiple mating - should show stronger audience effects. We investigated ten poeciliid species (in two cases including multiple populations) and found support for our hypothesis as mean sexual activity correlated positively with the occurrence of potentially deceptive behavior. An alternative explanation for audience effects would be that males attempt to avoid aggressive encounters, which would predict stronger audience effects in more aggressive species, and so we also characterized the examined species for aggressiveness using staged contests of size-matched males. We demonstrate a positive correlation between mean aggressiveness and sexual activity (suggesting a hormonal link as a mechanistic explanation), but we detected no correlation between aggressiveness and audience effects. Suites of correlated behavioral tendencies are termed behavioral syndromes, and our present study provides correlational evidence for the evolutionary significance of SCR in shaping a behavioral syndrome at the species level across poeciliid taxa.

Second Sourcing with Capacity Constrained Firms and Locked-In Buyers

I begin by surveying the motivations for second-sourcing agreements in the absence of licensing fees. I then focus on a particular motivation – that of an incumbent wanting to relax a capacity constraint. I develop a general model with buyers locked into a product, and find necessary and sufficient conditions for an incumbent to benefit from the presence of rivals without any need to sign contracts with them, in contrast with Dick (1992) and with the literature on subcontracting. I show that multiple equilibria due to the self-fulfilling expectations of rivals are possible. With regards to policy, I find that, with homogeneous buyers, a monopolist incumbent will produce where price and marginal cost coincide. I illustrate the model’s results with observations from the semiconductor industry.

Coalition building dynamics in video format wars

This paper analyses standard-setting coalition dynamics in video formats wars. We study the behavior of actors from several industries joining or leaving format standard-setting coalitions. Our research is based on a cross-analysis of standards literature and secondary data from Internet sites. Our analysis shows that the presence of major actors from various industries connected to the format business ecosystem, the presence of rivals, and the number of actors (size) deeply influence coalition success and can lead actors to leave one coalition for another.

Rival presence leads to reversible changes in male mate choice of a desert dwelling ungulate

Gregarious animals often face the problem of unintended interception of information by group members, as almost all communicatory interactions occur in a public domain. For example, individuals may observe and copy the choices of others. Male mate choice copying in species with internal fertilization remains a conundrum, as both the copying and the copied male incur increased sperm competition risk (SCR), and males are predicted to evolve strategies to reduce SCR. Specifically, males that are at imminent risk of being copied should cease expressing mating preferences. In this study, we gave male sand gazelles (Gazella marica) an opportunity to choose between 2 stimulus females in a 24-h association preference test, then repeated testing for another 24 h either while an audience male was presented close to the focal male’s compartment or without an audience (control treatment). Overall, focal males were highly consistent in their choices between day 1 and day 2. However, after the audience was presented, they showed a distinct short-term response that lasted for approximately 1 h: focal males altered their preferences, that is, interacted more equally with the 2 females and even tended to spend more time near the initially nonpreferred female. We discuss this effect as a counterstrategy of resident males to reduce SCR arising when new males join the group. In our experiment, habituation to the continued presence of a rival that was experimentally prevented from approaching females may be responsible for why focal males returned to express mating preferences some time after the audience was presented.

An Empirical Model of Industry Dynamics with Common Uncertainty and Learning from the Actions of Competitors

Retailers may face uncertainty about the profitability of local markets, which provide opportunities for learning when making entry decisions. To study these informational aspects, I develop an empirical framework for studying industry dynamics with uncertainty and learning (from others). Using data about fast food chains, I estimate the model with a two-step estimation approach augmented with particle filtering as a way to flexibly account for unobserved posterior beliefs about market profitability, as well as persistent unobserved states that evolve exogenously. The estimates confirm the presence of uncertainty and learning. Furthermore, simulations using the estimated model demonstrate that learning from others partially offsets the negative business-stealing effects of rival presence.

Males Use Multiple, Redundant Cues to Detect Mating Rivals

Across many species, males exhibit plastic responses when they encounter mating rivals. The ability to tailor responses to the presence of rivals allows males to increase investment in reproduction only when necessary. This is important given that reproduction imposes costs that limit male reproductive capacity, particularly when sperm competition occurs. Fruitfly (Drosophila melanogaster) males exposed to rivals subsequently mate for longer and thus accrue fitness benefits under increased competition, in line with theory. Here, we show that male D. melanogaster detect rivals by using a suite of cues and that the resulting responses lead directly to significant fitness benefits. We used multiple techniques to systematically remove auditory, olfactory, tactile, and visual cues, first singly and then in all possible combinations. No single cue alone was sufficient to allow males to detect rivals. However, the perception of any two cues from sound, smell, or touch permitted males to detect and respond adaptively to rivals through increased offspring production. Vision was only of marginal importance in this context. The findings indicate adaptive redundancy through the use of multiple, but interchangeable, cues. We reveal the robust mechanisms by which males assess their socio-sexual environment to precisely attune responses via the expression of plastic behavior.

Adaptations to sexual selection and sexual conflict: insights from experimental evolution and artificial selection.

Artificial selection and experimental evolution document natural selection under controlled conditions. Collectively, these techniques are continuing to provide fresh and important insights into the genetic basis of evolutionary change, and are now being employed to investigate mating behaviour. Here, we focus on how selection techniques can reveal the genetic basis of post-mating adaptations to sexual selection and sexual conflict. Alteration of the operational sex ratio of adult Drosophila over just a few tens of generations can lead to altered ejaculate allocation patterns and the evolution of resistance in females to the costly effects of elevated mating rates. We provide new data to show how male responses to the presence of rivals can evolve. For several traits, the way in which males responded to rivals was opposite in lines selected for male-biased, as opposed to female-biased, adult sex ratio. This shows that the manipulation of the relative intensity of intra- and inter-sexual selection can lead to replicable and repeatable effects on mating systems, and reveals the potential for significant contemporary evolutionary change. Such studies, with important safeguards, have potential utility for understanding sexual selection and sexual conflict across many taxa. We discuss how artificial selection studies combined with genomics will continue to deepen our knowledge of the evolutionary principles first laid down by Darwin 150 years ago.

Notes

China's relations with African nations have changed dramatically over the past decade. African oil now accounts for more than 30% of China's oil imports, and China is Africa's second-largest single-country trading partner, as well as a leading lender and infrastructure investor on the continent. Yet these developments are bringing challenges, not only for Africa and the West, but for China as well. This book examines these challenges, considering Africa as a testing ground, both for Chinese companies ‘going global’ and for a Chinese government that is increasingly having to deal with issues beyond its shores and immediate control. What does China need to do to protect and develop its African engagements, against a backdrop of mounting African expectations, concerns from Western actors in Africa, and the rival presence of other emerging actors? How sustainable is the momentum that China has established in its African ventures? China's adaptations to the challenges it is facing in Africa are examined and assessed, as are the implications of these changes for China, Africa and the West. China's African engagements are certainly changing Africa, but could they also be changing China?

Chapter Two: Managing China's African Relations

China's relations with African nations have changed dramatically over the past decade. African oil now accounts for more than 30% of China's oil imports, and China is Africa's second-largest single-country trading partner, as well as a leading lender and infrastructure investor on the continent. Yet these developments are bringing challenges, not only for Africa and the West, but for China as well. This book examines these challenges, considering Africa as a testing ground, both for Chinese companies ‘going global’ and for a Chinese government that is increasingly having to deal with issues beyond its shores and immediate control. What does China need to do to protect and develop its African engagements, against a backdrop of mounting African expectations, concerns from Western actors in Africa, and the rival presence of other emerging actors? How sustainable is the momentum that China has established in its African ventures? China's adaptations to the challenges it is facing in Africa are examined and assessed, as are the implications of these changes for China, Africa and the West. China's African engagements are certainly changing Africa, but could they also be changing China?