scholarly journals Juvenile Experience with Male Cues Triggers Cryptic Choice Mechanisms in Adult Female Redback Spiders

Insects ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 825
Author(s):  
Maydianne C. B. Andrade ◽  
Aiswarya Baskaran ◽  
Maria Daniela Biaggio ◽  
Maria Modanu

Female choice may be linked to population density if the expected encounter rates with potential mates affects choosiness (the energy and risk engaged to express mate preferences). Choosiness should covary with male availability, which could be assessed using the social cues available during development. We tested whether the exposure of juvenile females to cues of male density affected the mechanisms of choosiness of adult Latrodectus hasselti spiders in two experiments simulating natural contexts. The juvenile females were exposed to (1) volatile chemicals from two densities of adult males (airborne cues), and (2) tactile, vibrational and chemical cues from adult males or other females (cohabitation cues). As adults, the females mated readily, regardless of the treatment, but there was strong evidence for post-copulatory mechanisms of choosiness in females exposed to cues of high male availability. These included abbreviated matings (in both experiments), cannibalism of the males before the mating was complete (cohabitation), and, remarkably, a reduction in the successful placement of internal sperm plugs (cohabitation). These shifts decrease the likelihood that the first mate would monopolize paternity if the female chose to mate again. We conclude that female choosiness may impose a strong selection on males despite the high mating rates, and these effects can hinge on the cues of male availability detected by juveniles.

1997 ◽  
Vol 75 (6) ◽  
pp. 971-977 ◽  
Author(s):  
Christophe Pélabon ◽  
Petr E. Komers

We investigated time-budget variations among female and yearling (socially immature 1.5-year-old) male fallow deer (Dama dama) during the rutting season in six captive populations in central Sweden. The effects of population density, male density, and operational sex ratio on time budgets were analyzed. Although no differences were apparent before the rut, populations differed in the time budgets of females and yearling males during the rut. During this period, the time spent by females in feeding and resting activities of yearling males decreased with increasing population density, whereas feeding and resting activities of yearling males decreased with increasing male density. Behaviour of adult males during the rut and interactions of adult males with other animals appeared to be the principal factors affecting the time budgets of both females and yearling males. Our results show that density-dependent effects may occur through social interactions alone, regardless of the effects on resource depletion. The decrease in the proportion of time spent in restoring (lying and grazing) behaviours represents an energy cost for both females and young males. Given the timing of the rut just before the winter, this cost may negatively effect the condition of individuals.


Behaviour ◽  
1992 ◽  
Vol 120 (3-4) ◽  
pp. 177-191 ◽  
Author(s):  
Andrew Balmford

AbstractLek-breeding in Uganda kob was associated with extremely high population density (c. 140 animals/km2). Kob were typically found in unstable aggregations of more than one hundred animals, including several adult males. Females occupied unusually large, overlapping home ranges, but reasons for such widespread movements were unclear. The social dispersion of Uganda kob was therefore similar to that of other lekking ungulates, and confirms predictions of several recent hypotheses of lek evolution. However, resolution of alternative models is nevertheless difficult, since in practice these make very few exclusive predictions.


2010 ◽  
Vol 7 (2) ◽  
pp. 217-220 ◽  
Author(s):  
Nathan W. Bailey ◽  
Brian Gray ◽  
Marlene Zuk

Increased investment in immunity is expected to be beneficial under crowded conditions because of the greater risk of pathogen and parasite transmission, but the evolution of this facultative response relies on the ability to accurately assess social cues in the environment and adjust immune defences accordingly. Because of their highly conspicuous nature, long-range sexual signals are prime candidates to be used in evaluating the social conditions likely to be experienced upon adulthood in continuously breeding species; however, their role in mediating immune responses is unknown. We tested whether exposure to acoustic sexual signals in the field cricket Teleogryllus oceanicus affects immunity by manipulating male juvenile experience of acoustic signals, and measuring the effect on adult immunity. Adult males exposed to song during rearing showed stronger immune responses than males reared in silence: they were better able to encapsulate artificial nylon implants and showed higher levels of antimicrobial lysozyme-like activity in their haemolymph. Experience of sexual signals thus translates into increased immunity, which suggests that such signals may play a role in conveying information about population demography and shaping density-dependent responses in unintended receivers.


2019 ◽  
Vol 286 (1900) ◽  
pp. 20190191
Author(s):  
Lan Zhao ◽  
Li-Ming Fang ◽  
Qiu-Hong Wan ◽  
Sheng-Guo Fang

The regulation of population density is suggested to be indirect and occurs with a time-lag effect, as well as being female centred. Herein, we present a quantitative analysis on the precise, timely and male-dominated self-regulation of Chinese alligator ( Alligator sinensis ) populations. Analysis of 31 years of data revealed gender differences in regulation patterns. Population dynamics were restricted by male density rather than population density, and population growth was halted (birth rate = 0) when male density exceeded 83.14 individuals per hectare, until some males were removed, especially adult males. This rapid and accurate response supports the notions of intrinsic mechanisms and population-wide regulation response. Furthermore, density stress affected mating success rather than parental care to juveniles, i.e. females avoided unnecessary reproduction costs, which may represent an evolutionary advantage. Our findings highlighted the importance of further studies on related physiological mechanisms that focus on four characteristics: quantity breeds quality, gender differences, male density thresholds and nonlinearity.


2020 ◽  
Author(s):  
Abdulaziz Abubshait ◽  
Patrick P. Weis ◽  
Eva Wiese

Social signals, such as changes in gaze direction, are essential cues to predict others’ mental states and behaviors (i.e., mentalizing). Studies show that humans can mentalize with non-human agents when they perceive a mind in them (i.e., mind perception). Robots that physically and/or behaviorally resemble humans likely trigger mind perception, which enhances the relevance of social cues and improves social-cognitive performance. The current ex-periments examine whether the effect of physical and behavioral influencers of mind perception on social-cognitive processing is modulated by the lifelikeness of a social interaction. Participants interacted with robots of varying degrees of physical (humanlike vs. robot-like) and behavioral (reliable vs. random) human-likeness while the lifelikeness of a social attention task was manipulated across five experiments. The first four experiments manipulated lifelikeness via the physical realism of the robot images (Study 1 and 2), the biological plausibility of the social signals (Study 3), and the plausibility of the social con-text (Study 4). They showed that humanlike behavior affected social attention whereas appearance affected mind perception ratings. However, when the lifelikeness of the interaction was increased by using videos of a human and a robot sending the social cues in a realistic environment (Study 5), social attention mechanisms were affected both by physical appearance and behavioral features, while mind perception ratings were mainly affected by physical appearance. This indicates that in order to understand the effect of physical and behavioral features on social cognition, paradigms should be used that adequately simulate the lifelikeness of social interactions.


Author(s):  
Kara Walker ◽  
Brian Hare

The dominance style of bonobos presents an evolutionary puzzle. Bonobos are not male dominant but female bonobos do not show traits typical of female-dominant species. This chapter proposes the offspring dominance hypothesis (ODH) as a potential solution. ODH suggests the social system of bonobos evolved as a defence against infanticide and is not due to pressure to monopolize resources. Females that prevented aggression towards offspring and preferred mating with less aggressive males were most successful. Supporting ODH, during observations at Lola ya Bonobo Sanctuary it was found that: 1) adult male bonobos are rarely aggressive towards offspring with mothers, 2) some mother-reared juvenile bonobos attain rank higher than adult males and 3) mother-reared offspring often socially interact with adult males without their mothers nearby. These preliminary findings provide initial support that the bonobo social system evolved due to fitness advantages of effectively protecting offspring against consequences of male aggression. Le style de dominance des bonobos présente un puzzle évolutionnaire. Les bonobos ne sont pas dominés par les mâles mais les bonobos femelles ne montrent pas les traits caractéristiques d’une espèce dominée par femelles. On propose l’hypothèse de dominance de progéniture (ODH) comme une solution potentielle. La ODH suggère que le système social des bonobos a évolué en défense contre l’infanticide et pas sous pression pour la monopolisation des ressources. Les femelles qui préviennent l’agression vers leur progéniture et leur préférence d’accouplement avec des mâles moins agressives étaient très efficaces. À l’appui de la ODH on a trouvé pendant nos observations à Lola ya Bonobo Sanctuary que: 1) les mâles adultes bonobos agressent rarement vers les bébés avec mères, 2) quelques adolescents bonobos qui furent élevés par leurs mères atteignent un rang plus haut que les mâles adultes et 3) la progéniture élevée par la mère interagissent avec avec d’adultes mâles sans la présence de leur mère. Ces trouvailles préliminaires donnent appuie à l’hypothèse que le système social des bonobos a évolué par les avantages corporelles de la protection de la progéniture contre les conséquences de l’agression mâle.


Author(s):  
Darrell R J Mullowney ◽  
Krista D Baker

Abstract A sex-asymmetric downward shift in size-at-terminal-molt has recently occurred in males in some portions of the Newfoundland and Labrador (NL) snow crab stock range, a first known occurrence for such processes in snow crab (Chionoecetes opilio) stocks. This study examines plausible factors promoting the shift in size-at-terminal-molt [synonymous with size-at-maturity (SaM)] including individual size, temperature, population density, and sex ratio. Analyses highlight expanse of cold water and large male density as being significant predictors of molt-type outcomes. A confluence of cold conditions and low density of large males promoted the SaM shift. In turn, the low male density was associated with recently elevated fishery exploitation rates under quota-controlled management. It remains unknown the extent to which the reduction in terminal size reflects a phenotypic vs. genotypic process. Factors affecting skip-molting in male snow crab are investigated, and we find that skip-molting occurs most frequently under extreme cold and high population density conditions. Potential complications arising from altered growth dynamics are discussed. Overall, the results advance knowledge on intraspecific competition processes within snow crab populations and inform fisheries management systems that male-only harvest strategies do not provide full protection from biological harm to aquatic resources through fishing.


2003 ◽  
Vol 30 (3) ◽  
pp. 281 ◽  
Author(s):  
David S. Dique ◽  
Jim Thompson ◽  
Harriet J. Preece ◽  
Deidré L. de Villiers ◽  
Frank N. Carrick

Koala dispersal was investigated as part of a detailed ecological study of a nationally significant koala population located 20 km south-east of Brisbane, Queensland. From 1996 to 2000, 195 koalas from three sites were captured and fitted with radio-collars. A total of 40 koalas (23 males and 17 females) dispersed from these sites. Most (93%) dispersing individuals were 20–36 months of age. Three adult females (more than 36 months old) dispersed and no adult males dispersed during the study. A significantly higher proportion of young males dispersed than females. Dispersal occurred between June and December, with most dispersal of males commencing in July and August and that of females commencing between September and November prior to, and early in, the annual breeding season. The mean straight-line distance between the natal and breeding home ranges for males and females was similar and was measured at 3.5 km (range 1.1–9.7 km) and 3.4 km (range 0.3–10.6 km) respectively. Dispersing males and females tended to successfully disperse south and west of their natal home ranges and were generally unable to successfully disperse to urban areas within the study area, as a high proportion of the mortality of dispersing koalas was associated with attacks by domestic dogs and with collisions with vehicles on roads. Information from other studies indicates that most young koalas disperse from their natal areas. It is likely that the social behaviour and mating systems of koala populations provide mechanisms for young koalas to disperse. The potential role of dispersal in the dynamics of regional koala populations is discussed.


2022 ◽  
Author(s):  
Kendra Leigh Seaman ◽  
Alexander P. Christensen ◽  
Katherine Senn ◽  
Jessica Cooper ◽  
Brittany Shane Cassidy

Trust is a key component of social interaction. Older adults, however, often exhibit excessive trust relative to younger adults. One explanation is that older adults may learn to trust differently than younger adults. Here, we examine how younger (N=33) and older adults (N=30) learn to trust over time. Participants completed a classic iterative trust game with three partners. Younger and older adults shared similar amounts but differed in how they shared money. Compared to younger adults, older adults invested more with untrustworthy partners and less with trustworthy partners. As a group, older adults displayed less learning than younger adults. However, computational modeling shows that this is because older adults are more likely to forget what they have learned over time. Model-based fMRI analyses revealed several age-related differences in neural processing. Younger adults showed prediction error signals in social processing areas while older adults showed over-recruitment of several cortical areas. Collectively, these findings suggest that older adults attend to and learn from social cues differently from younger adults.


2019 ◽  
Vol 14 (2) ◽  
pp. 174-190 ◽  
Author(s):  
April Rose Panganiban ◽  
Gerald Matthews ◽  
Michael D. Long

Human–Machine teaming is a very near term standard for many occupational settings and still requires considerations for the design of autonomous teammates (ATs). Transparency of system processes is important for human–machine interaction and reliance but standards for its implementation are still being explored. Embedding social cues is a potential design approach, which may capture the social benefits of a team environment, yet vary with task setting. The current study examined the manipulation of transparency of benevolent intent from an AT within a piloting task requiring suppression of enemy defenses. Specifically, the benevolent AT maintained task communication as in a neutral condition, but included messages of support and awareness of errors. Benevolent communication reduced reported workload and increased reported team collaboration, indicating that this team intent was beneficial. In addition, trust and acceptance of the AT were rated higher by individuals tasked with depending on the system to protect them from missile threats. The need for information from ATs is beneficial, however may vary depending on team type.


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