Intensity Of Fighting Research Articles

Stalk-eyed flies carrying a driving X chromosome compensate by increasing fight intensity

Exaggerated ornaments provide opportunities to understand how selection can operate at different levels to shape the evolution of a trait. While these features aid their bearer in attracting mates or fending off competitors, they can also be costly and influenced by the environment and genetic variation. The eyestalks of the stalk-eyed fly, Teleopsis dalmanni, are of interest because eyestalk length is the target of both intra- and intersexual selection and is also reduced by loci on a highly-divergent sex ratio X chromosome (XSR), a meiotic driver accounting for up to 30% of wild X chromosomes. Male stalk-eyed flies fight to control access to females and over food using a combination of low-intensity displays and high-intensity physical fights. We staged, filmed, and scored contests between pairs of eyespan-matched males to evaluate whether X chromosome type impacts the behavior and outcome of aggressive interactions. While our results broadly match expectations from previous studies, we found that XSR males used more high-intensity behaviors than males carrying a non-driving, standard X chromosome (XST), particularly when their eyestalks were of similar size or smaller than their opponents. Additionally, we found that when XSR males use high-intensity behaviors, they win more bouts than when they use low-intensity behaviors. Taken together, these results suggest that XSR impacts male aggressive behavior to compensate for the shorter eyestalks of XSR males and may help to explain how this selfish chromosome is maintained.

Public diplomacy during military international conflicts. The Ukraine war case

Nowadays, warfare is characterized by a huge intensity of fight, large investment in military technology that led to new ways of combat and increased its visibility. While the changing strategic, social and cultural features of this environment have forced governments and armies to add new fight strategies including public diplomacy, the public diplomacy itself transformed. Therefore, this article reviews current research in this field and presents a theoretical approach of the actual war. In this regard, the topic discussed is the battle between the Ukrainian and Russian military for image and legitimacy in the international public opinion. In the information age in which we live, the activities and capabilities of public diplomacy can have a significant impact on how people, organizations, and governments perceive this war. The purpose of the article is to examine the management of public diplomacy in the case of both actors involved in this war.

Differences in Agonistic Behavior and Energy Metabolism between Male and Female Swimming Crab Portunus trituberculatus Based on the Analysis of Boldness.

Simple SummaryBoldness is a widely studied personality trait that is positively related to an individual’s willingness to fight. To explore the agonistic behavior between female and male crabs with different degrees of boldness, we quantified the boldness of females and males using a behavior observation system and used the experimentally determined boldness and classification. The results showed that boldness affected the agonistic behavior between female and male swimming crabs, the fighting willingness and capacity of male crabs is higher than that of female individuals and is higher in bold crabs than in shy individuals. Energy reserves and metabolic rates may be one of the factors affecting the agonistic behavior in crabs and that the agonistic behavior resulted in significant changes in key energy metabolites.Individual differences in metabolism and agonistic behavior have been a key research area in evolution and ecology recently. In this study, we investigated the boldness of swimming crabs Portunus trituberculatus and explored the agonistic behavior between female and male crabs, specifically examining competitions between bold females vs. bold males (BF–BM), bold females vs. shy males (BF–SM), shy females vs. shy males (SF–SM), and shy females vs. bold males (SF_BM) and its relationship with energy metabolism. The main results revealed the following: There was no significant difference in boldness between females and males, while there were more bold individuals than shy in both females and males. Bold individuals initiated significantly more fights than shy individuals, and male initiators won significantly more fights than female initiators. The duration and intensity of fight between bold individuals was significantly higher than fights between shy individuals. For males, the concentration of glucose in the hemolymph was significantly higher in shy crabs than bold crabs, while there was no significant difference between shy and bold individuals in females. After fighting, the concentration of glycogen in claws was lower than that before fighting, and the concentrations of glucose and lactate in hemolymph were significantly higher after fighting than before. We found that the fighting willingness and ability were higher in male crabs than females and higher in bold crabs than shy. Fighting ability varied between sexes and was influenced by boldness and energy state.

Comparing the dynamics of agonistic interactions between the native crayfish Faxonius erichsonianus Faxon, 1898 and the invasive F. virilis Hagen, 1870 (Decapoda: Astacidea: Cambaridae)

Abstract Alabama is a hotspot for aquatic biodiversity in North America, but that biodiversity is currently jeopardized by anthropogenic influence and invasive species. Alabama holds nearly a quarter of North America’s crayfish species, but recent introduction of invasive crayfishes poses a threat to crayfish biodiversity in the region. Previous studies suggest higher basal aggression in invasive species allows them to outcompete native species by more efficiently seizing and holding resources. Faxonius virilis (Hagen, 1870) is an invasive crayfish currently spreading throughout Alabama. Our aim was to determine if differences in basal aggression exist between an Alabama native, Faxonius erichsonianus (Faxon, 1898), and the invasive F. virilis. Individuals were used in size-matched dyadic fight trials housed in a specialized arena. Three treatment groups were used to compare basal aggression differences: native versus native, invasive versus invasive, and interspecific. Videos of fight trials were reviewed, and duration and intensity of fights were recorded using a previously established ethogram. Contest duration between individuals was compared using Kruskal-Wallis tests with a Wilcoxon post-hoc. Analyses showed the invasive control treatment was significantly (P = 0.041) shorter than both the native control and interspecific treatments; however, interspecific trials had higher intensity contests than either control treatment. These results did not show that the invasive F. virilis are more aggressive than F. erichsonianus, suggesting that a closer look is necessary to determine the factors affecting the invasion success of F. virilis. The F. virilis invasion may be attributed to other factors like fecundity or growth.

Feeding strategy changes boldness and agonistic behaviour in the swimming crab ( Portunus trituberculatus )

Agonistic behaviours and cannibalism are key factors that restrict increases in the production of crab aquaculture. To explore the effects of feeding strategies on the boldness, agonistic behaviour and physiological response of swimming crab (Portunus trituberculatus), three treatment groups were established (feeding once a day:S0, every 3 days: S3 and every 6 days:S6). The intensity and duration of fighting, and agonistic behaviours were compared. The hepatosomatic index and the concentration of glycogen, glucose and lactate were also measured. The main results were as follows: (1) With an increase in time between feeding, boldness, duration and intensity of fighting increased first, then decreased, reaching a maximum in the S3 group, and this was significantly higher than in the S6 group. (2) Agonistic behaviour increased first and then decreased. The ‘move to’, ‘cheliped display’ and ‘contact behaviours’ of crabs in the S3 group were significantly higher than the S6 group; (3) Before fighting, with the increase in feeding time, the hepatosomatic index, glycogen and glucose concentration of crabs decreased, and these indicators were significantly higher in the S0 group than in the S6 group. (4) After fighting, the glucose and lactate concentrations were significantly greater than those before fighting. These results suggest that both boldness and feeding strategy can affect the agonistic behaviour of crab. Short-term reductions in food resources promoted inter-individual fighting, and bold individuals were more likely to win battles. However, a long-term decrease in food resources reduced fighting among individuals.

The dark-ventral-patch of male red deer, a sexual signal that conveys the degree of involvement in rutting behavior

BackgroundIn polygynous mammals, signalling may play a decisive role in mating behavior, mediating the intensity of male fights and female mate choice. During the rutting season, male red deer may show a visible dark patch in their ventral fur. Recently, this patch has been suggested to act as a flexible sexual signal, due to its relationships with other variables such as age, body size, antler development, volatile compounds, or the competitive environment. The analysis of fur pigmentation at the ventral patch suggests that this might also visually indicate the male intrinsic predisposition to take part in mating competition.ResultsTo assess the possible role of this trait as a communicative signal related to mate competition, we used red deer behavioral observations during the rut in Doñana National Park (Spain) to examine the link between the degree of expression of the dark ventral patch and the rutting activity (assessed from both intra-and-inter-sexual behaviors). Consistent with our predictions, we found in a field study that males with large dark patches showed a higher frequency of rutting behaviors (mainly roaring and flehmen), more interactions with females, and attained larger harem sizes.ConclusionsThe dark ventral patch was a better predictor of male behavior than antler tines or territory holding, thus standing as a short-term indicator of male willingness to invest in mating competition.

Effect of different amount of food and female resource on competitive strategy and agonistic behavior of swimming crab (Portunus trituberculatus)

Obtaining limited resources is an important motivator behind competition in animals. In pond cultures of swimming crabs (Portunus trituberculatus) common resources that cause conflict are food and mates. To explore the effects of different levels of food stimulus (clam extract; CG, control group: 0; LCH, little clam homogenate: 5 mL; ACH, abundant clam homogenate: 25 mL) and mate stimulus (female-conditioned water FCW; SW, seawater: 85 L seawater; LFW, low concentration FCW: 21 L FCW + 64 L seawater; HFW, high concentration FCW: 85 L FCW) on competitive strategies and agonistic behaviors of male crabs, we built an agonistic behavior recording system. We analyzed behavior, changes of oxygen consumption rate (OCR), and the concentrations of glycogen, glucose, and lactate in chelipeds and hemolymph after fighting. The main results revealed the following: (1) With increased perceived availability of food, the frequency of contact and key behaviors was significantly higher in the CG and LCH group than the ACH group. Fight duration in the LCH group was significantly longer than in the ACH group. The fight intensity and OCR of the LCH group were significantly higher than CG and ACH group. The concentration of lactate in hemolymph and glucose in chelipeds of the LCH group were significantly higher than the ACH group. The concentration of glycogen in cheliped muscle of the LCH and ACH group was significantly higher than the CG. (2) The increased concentration of FCW in the HFW group caused the duration of fights and the frequency of contact behaviors to be higher than in the SW group. In the HFW group the key behaviors occurred significantly more than in the SW and LFW groups. Fight intensity was also higher in the HFW group than the other two groups, and the LFW group had higher fight intensity than the SW group. The OCR of LFW and HFW groups were significantly higher than the SW group. The lactate concentrations in hemolymph and chelipeds in the LFW group were significantly higher than those in the SW and LFW groups. The glycogen concentrations in the chelipeds of the LFW and HFW groups were significantly higher than in the SW group. These results showed that the crabs adopt different competitive strategies, either to fight or yield, depending on type and availability of resources. These strategies are associated with costs such as physical risk and energy expenditure. In pond cultures of swimming crabs, increasing the density of food and isolating females from males during the breeding season may help to reduce appendage mutilation or death caused by fighting, thereby increasing aquaculture efficiency.

Analysis of the agonistic behaviour and behaviour pattern of Portunus trituberculatus

To analyse the agonistic behaviour of Portunus trituberculatus, infrared cameras were used to quantitatively analyse the aggressive behaviour in response to different sex pairings and culture densities and mirror-image stimulation. The results show that: P. trituberculatus has nine behaviour patterns which were correlated, and the fighting process followed a specific, rather than random, process. All nine behaviour patterns were stimulated in response to different sex pairings and culture densities, but only five patterns were induced by mirror-image stimulation. The fighting intensity between the males was significantly higher than that between the females and male and female (p < 0.05). The fight intensity in the 8 crabs/m2 density group was significantly higher than the 4 crabs/m2 and 6 crabs/m2 groups (p < 0.05). The fighting experience had a significant impact on the subsequent fight. The probability of the winner winning again was 83.3%, whereas that of the loser winning again was only 25.0%. In the second round of fighting, the fight intensity of the loser was also significantly lower than those of the winner (p < 0.05). Thus, the fighting process of P. trituberculatus follows a certain regularity, and different sex pairings and culture densities have a significant impact on fighting intensity. Fighting experience also has a significant impact on subsequent agonistic behaviour, with a winner–loser effect.

Variation in behavioural responses of sub-tropical marine fishes to experimental longline capture

AbstractFishes are often caught as bycatch on longlines and subsequently discarded. The behavioural response of fishes to longline capture is poorly understood, although it may be linked to the magnitude of the physiological stress response, and, ultimately, contribute to stress-induced mortality. We used accelerometers, video cameras, and hook timers to analyse the behavioural response of 13 subtropical teleost and elasmobranch species to experimental longline capture in The Bahamas. We found that, across all species and species groups, fight intensity during a capture event was best described by a negative linear and positive quadratic response. Nurse sharks and tiger sharks had lower fight intensity values and exhibited less steepness in their quadratic response during the first 10 min of capture than other species, particularly blacktip and Caribbean reef sharks. Nurse sharks also exhibited the most consistent fight intensity during the entire capture event compared to other shark species, particularly the blacknose shark. Generally, obligate ram ventilators and mixed ventilators exhibited higher steepness in fight intensity trajectories than buccal/spiracular pumpers, which had more consistent, lower fight intensity values. Behavioural responses to longline capture are species specific but may be linked to distinct evolutionary traits such as respiratory mode.

Impeding fatal violence through third-party diplomacy: The effect of mediation on conflict intensity

Existing research provides no systematic insights into if and how mediation impedes battle-related deaths. Therefore, this article presents a temporally disaggregated analysis and assesses the effect of mediation on monthly fatal violence. The article predicts that adversaries evaluate opponents’ trustworthiness from both fighting and negotiation behavior. It argues that reducing fighting intensity during negotiations is a sign of cooperation, which can be negotiated by mediators to build trust. Over the course of mediation, the content of negotiations provides information about how genuinely a conflict party is interested in conflict resolution. Only if mediation achieves negotiation of core incompatibilities will conflict parties be willing to reduce fighting intensity. Under these conditions, information revealed in a mediation process can build trust and substantively reduce violence. An empirical analysis of all African conflicts between 1993 and 2007 supports this prediction and shows that on average mediation is followed by substantive and lasting reductions in fatal violence, if mediation discusses the conflict’s main incompatibility. In contrast, mediation on other topics is associated with a small, fleeting reduction in violence. Data of battle-related fatalities in Syria during negotiations as well as qualitative evidence further support the theoretical mechanism and the model prediction. The study concludes that mediation can reduce conflict intensity substantively, if it achieves exchange between conflict parties on the main conflict issues.

The City and War: The Case of Tel Aviv-Jaffa

In wartime cities become prime objects for attack and sustain different levels of destruction. The increase since the 1990s in the number and scale of violent conflicts has resulted in growing awareness of the devastating aspect of war in urban areas, which now enjoys the coinage “urbicide”. It is by far and large the outcome of the shift from research focused on the history and spatiality of armed conflicts, to a moralist-oriented approach based on the political economies and socio-cultural geographies of militarism. Yet, as portrayed in the case of Tel Aviv-Jaffa, it limits the analysis of the variety of effects of war which vary widely due to location, intensity of fighting and prevailing social, cultural and economic realities.

Strategy in Secession Games

Many factors influence the onset and outcome of secessionist movements. We argue that before greed, grievance, opportunity, internal politics, or the international system can matter, potential secessionists must have a credible exit option, and in particular unilaterally exit by force. In this article we create a bargaining model of secession that incorporates this insight and allows us to organize a wide variety of existing explanations for separatist politics into a single theoretical framework where military capabilities, policy preferences and the possibility of a negotiated settlement play central roles. We find that policy polarization increases the intensity of fighting, the decisiveness of military means to suppress the secessionists determines the likelihood of a peaceful solution, and that even with complete information policy differences can drive the secessionists and the central government to war. We consider the role of international actors in secession and explore how they can affect secession outcomes.

Objective and subjective components of resource value in lethal fights between male entomopathogenic nematodes

Males sometimes engage in fights over contested resources such as access to mates; in this case, fighting behaviour may be adjusted based on the value they place on the females. Resource value (RV) can have two components. First, males can assess the quality of females, which constitutes an objective assessment of RV. Second, internal state such as previous mating experience can also influence motivation to fight thus constituting a subjective assessment of RV. If mating opportunities are scarce and available females have a major impact on the lifetime reproductive success of males, then fighting can be fatal; in this situation it is uncertain whether males would adjust fighting behaviour based on RV. We found that both female quality, that is, virginity (objective component of RV) and male mating status (subjective component of RV) influenced fighting intensity between males of the entomopathogenic nematode Steinernema longicaudum which engage in lethal fights. Male nematodes were more likely to engage in fighting and fought longer and more frequently in the presence of virgin (high-quality) females than in the presence of mated (lower-quality) females. Male mating status was also found to influence fighting behaviour: mated males were the winners in staged fights between mated and virgin males. Mated males may have superior fighting ability (greater resource-holding potential), but RV asymmetries between mated and virgin males cannot be excluded. Males were more likely to win when they were resident, but we did not find a significant interaction effect between male mating and residency status.

Effects of female body size and age and male mating status on male combat in Anastatus disparis (Hymenoptera: Eupelmidae)

1. Aggressive behaviour is widely exhibited by animals to acquire important resources and usually shows a dangerous or nondangerous pattern. Dangerous fighting patterns are usually characterized by fights ending with contestants being severely injured or killed. Resource value is an important nonstrategic factor influencing fighting behaviour. Studies of many species addressing nondangerous fighting behaviour have shown that when resource values change, organisms usually adjust their fighting behaviour accordingly. Only a few species show dangerous fighting patterns. Thus, few relevant studies have addressed how variation in resource value affects aggression with a dangerous fighting pattern.2. Here, an egg parasitoid wasp, Anastatus disparis, which exhibits a dangerous fighting pattern to acquire mating opportunities, was used as an experimental model to study the adjustment of fighting behaviour resulting from a change in resource value.3. Our results show that the female properties of body size and age affect their objective resource value and that males increased their fighting intensity for relatively large and young females. However, male mating status in A. disparis may not influence the subjective value of mate resources, and fighting intensity did not significantly differ between mated and virgin males. In addition, the number of times a male had previously mated had no significant effect. These results suggest that mating opportunities are important for both virgin and mated males, resulting in neither of them showing any adjustment in fighting for mating opportunities.4. Generally, A. disparis males with extreme fighting patterns adjust their fighting behaviour according to the variation in resource value, which avoids the meaningless costs of injury and death.

Effect of Winning Experience on Aggression Involving Dangerous Fighting Behavior in Anastatus disparis (Hymenoptera: Eupelmidae).

Aggressive behavior is widely observed in animal species for acquiring important resources and usually includes both dangerous and nondangerous fighting patterns. Only a few species show dangerous fighting patterns that are defined by fights ending with contestants being severely injured or killed. Prior experience, an important factor in many species, has been demonstrated to affect a contestant’s subsequent fighting behavior. Few studies have focused on the effect of experience on aggression involving dangerous fighting patterns. Here, an egg parasitoid wasp, Anastatus disparis, which shows extreme and dangerous fighting behavior to acquire mating opportunities, was used as an experimental model. Our results showed that the fighting intensity of the winning males significantly decreased subsequent fighting behavior, which was inconsistent with general predictions. Transcriptomic analyses showed that many genes related to energy metabolism were downregulated in winners, and winners increased their fighting intensity after dietary supplementation. Our study suggested that fighting in A. disparis is a tremendous drain on energy. Thus, although males won at combat, significant reductions in available energy constrained the intensity of subsequent fights and influenced strategic decisions. In addition, winners might improve their fighting skills and abilities from previous contests, and their fighting intensity after dietary supplementation was significantly higher than that of males without any fighting experience. Generally, in A. disparis, although winners increased their fighting ability with previous experience, the available energy in winners was likely to be a crucial factor affecting the intensity and strategic decisions in subsequent fights.

Fight intensity correlates with stronger and more mechanically efficient weapons in three species of Aegla crabs

In many species, individuals contest resources using specialized morphologies to overpower rivals, hereafter referred to as weapons. Despite their importance in fights, little is known about the selective forces affecting weapon evolution. This may be particularly important to understand why weapons are highly variable among species. Due to their role during fighting, we expect that whenever fighting becomes more important for individual fitness so should the intensity of selection on weapon strength and morphology (which affect the efficiency of a weapon during combat). If true, we expect species that fight more intensely to have stronger and more mechanically efficient weapons. We tested this idea using males of three species of Aegla crabs (A. longirostri, A. abtao, and A. denticulata) that vary in their fight intensity. We compared the muscle size, the mechanical advantage (a proxy for the efficiency of the movable finger of the claw), and the correlation between weapon biomechanics and overall weapon shape (a proxy for the efficiency of the entire claw) among the species. We found that species with more intense fights presented stronger claws, higher mechanical advantage, and less variation in the regression between biomechanics and overall shape. Interestingly, the species with the largest claws were not the most mechanically efficient, suggesting that weapon size is not the sole factor behind weapon evolution. We conclude that fight intensity might be an important factor affecting weapon biomechanics, which ultimately might lead to a better understanding of weapon evolution. Animals fight using specialized morphologies to overpower rivals—termed weapons. Given the importance of fighting on leaving descendants to the next generation, weapon features related to winning fights are probably under selection. If true, then species in which fighting is more important should have stronger and more mechanically efficient weapons. Our results suggest that this might be true: Aegla crabs that fight more intensely have stronger and more efficient weapons (their claws). Interestingly, we also show that size is not the sole predictor of a better claw—muscle mass and mechanical efficiency might be higher in smaller claws when compared to larger claws. Thus, weapon evolution might not be solely tied to weapon size, but also to weapon morphology and mechanical efficiency.

Дослідження інтенсивності змагальних поєдинків юних борців вільного стилю

Анотація. Мета: провести порівняльний аналіз інтенсивності дій борців вільного стилю на чемпіонатах світу і України 2019 року з вільної боротьби, серед кадетів. Матеріал і методи . Для дослідження інтенсивності змагальних сутичок, шляхом експертної оцінки, були визначені критерії оцінки різних зон інтенсивності. Було запропоновано поділити дії борців, під час ведення змагальних поєдинків, на три зони інтенсивності: мала (низька), помірна, висока. До першої зони увійшли дії борців без контакту у стойці, пасивні дії в партері. До другої зони інтенсивності увійшли дії борців у контакті (підготовка до проведення прийому; оманливі атаки; боротьба за захоплення). До третьої зони інтенсивності увійшли спроби виконання технічних дій (вдалі й невдалі) захист від атак супротивника, як в стойці так і в партері; боротьба в небезпечному положенні. Методи дослідження: аналіз і узагальнення науково-методичної літератури; педагогічне спостереження, педагогічний експеримент; аналіз змагальних поєдинків; методи математичної статистики. Результати: Була досліджена інтенсивність дій юних борців на чемпіонатах світу й України 2019 року з вільної боротьби, що дозволило визначити вплив функціональної підготовленості спортсменів на успішність у змагальних поєдинках. Висновки. У фінальних поєдинках чемпіонату світу і чемпіонату України 2019 року з вільної боротьби, серед кадетів найвищу інтенсивність показали борці легких вагових категорій, за ними йдуть середньоваговики, після яких борці важких вагових категорій. Порівняльний аналіз інтенсивності фінальних сутичок досліджуваних змагань показав перевагу борців - учасників чемпіонату світу над учасниками чемпіонату України. На світовій першості спортсмени 38,59 % часу вели активну боротьбу високої інтенсивності, 39,98 % часу боротьби велося з помірною інтенсивністю і 21,43 % - низької інтенсивності. На чемпіонаті України, відповідно – 27,97 %; 45,97 %; 26,06 %. Борці, які перемагали у фінальних сутичках більше балів отримали у другому періоді поєдинків, незалежно від рівня змагань (близько 62,5 %), що є опосередкованим показником їхньої високої функціональної підготовленості. Спортсмени, які програли сутички, на чемпіонаті світу, у першому періоді були більш результативними (57,02 %), а на чемпіонаті України незначно результативнішими були у другому періоді (52,44 %). Переможці обох змагань значно перевершили своїх опонентів за кількістю набраних балів (р&lt;0,001), хоча переможці чемпіонату світу перший період у багатьох сутичках програвали. Ключові слова: юні борці, інтенсивність дій, порівняльний аналіз, переможці, переможені.

Aggressive behavior variation and experience effects in three families of juvenile Chinese mitten crab (Eriocheir sinensis)

To assess how variable is the aggressive behavior among families (A, B, and C) and the experience effect of fighting among juvenile Chinese mitten crab (Eriocheir sinensis), we performed a total of 36 pairs of intrafamily and interfamily contests between three families of Eriocheir sinensis, qualifying and quantifying their aggressive acts and 13 pairs of winners within family and between family A and B. A table of aggression intensity was established, ranging from 1 (chasing) to 4 (intense combat). Crabs of intrafamily association performed more aggressive acts of shorter duration than interfamily, family B was more aggressive than those from families A and C: family C was the least aggressive, which is also the most morphologically distinct strain (a new strain with a red carapace). During the second fighting trail, the intensity and number of fights were significantly different to first fight conditions and also differed among families. Therefore, our results suggest that the aggressive behavior of Eriocheir sinensis is different among different families, and the combat experience has a significant effect on the secondary fight. This is the first report of aggressive behavior in Eriocheir sinensis, a reference for crab aquaculture and provides new ideas for genetic breeding work in crab selected breeding programmes. It will be possible to carry out more profound studies of the behavior of these animals.

Effect of variation in objective resource value on extreme male combat in a quasi-gregarious species, Anastatus disparis

BackgroundAggressive behaviour is widely observed in animal kingdom, which compete for resources such as territory, food and mates. Resource value is the most important non-strategic factor influencing fighting behaviour, and may vary among contests and contestants. Usually, contestants adjust their fighting behaviour when the resource value changes, and as potentially damaging and energetically costly, individuals of most species usually avoid conflict escalation. However, in a quasi-gregarious egg parasitoid, Anastatus disparis (Hymenoptera: Eupelmidae), mates are valuable resources and females mate only once; thus, males engage in frequently extreme combat behaviour to acquire mating opportunities, even in the absence of females. In this study, we attempted to test whether males of this species have the ability to adjust their fighting behaviour in response to changes in the objective value of female.ResultsOur results suggested that objective resource value in A. disparis is likely to be influenced by female mating status rather than by fecundity. Consistent with a number of empirical studies, A. disparis males adjusted their fighting behaviour according to the value of the contested resources: males significantly increased their fighting intensity to acquire mating opportunities with virgin females but decreased their fighting intensity for mated females. We also found that rather than chemical cues, visual cues and physical sexual contact appear to play a role in determining males’ ability to detect variation in female mating status.ConclusionsOur study suggested that although in this species, males have evolved extreme fighting behaviour and females are valuable resources, males do not always escalate fighting behaviour in competition for mating with a female. Valuable resources and variation in resource value were detected and estimated by A. disparis males, which then adjusted their fighting behaviour accordingly and to some extent avoided incoming fighting costs.

The intensity and spectrum of artificial light at night alters crayfish interactions

ABSTRACTEcological light pollution (ELP) is quickly becoming a worldwide concern and can negatively affect aquatic ecosystems. The given intensity and spectrum of a light source can influence how organisms function within their environment. These properties of artificial lighting at night (ALAN) and their impacts on the physiology and behaviour of crayfish were examined in this work. Hemolymph was obtained from crayfish to quantify a physiological response. Behavioural data were measured as the number, duration, and maximum intensity of agonistic fights. Exposure to higher intensities of light and the presence of ultraviolet light induced a behavioural trend, resulting in significantly altered social interactions within both species of crayfish. The number and maximum intensity of lights significantly decreased, whereas the duration of time spent fighting significantly increased. Due to the importance of freshwater environments and the role crayfish play as a keystone species, examining how crayfish are impacted from ALAN is imperative to maintaining the health of aquatic ecosystems.