Sexual display complexity varies non-linearly with age and predicts breeding status in greater flamingos

Wing condition does not negatively impact time budget, enclosure usage, or social bonds in a flock of both full-winged and flight-restrained greater flamingos

Zoo management techniques for captive birds, such as flight restraint and enclosure type, may affect behavioral performance and are consequently worthy of investigation. Flamingos are amongst the most popular of zoo-housed birds and, as such, research into their captive management and associated behavioral responses are widely applicable to many thousands of individuals. As a highly social species, understanding social bonds and behavior of the individual bird and the flock overall can help inform decisions that support husbandry and population management. In this project, 41 greater flamingos at Bristol Zoo Gardens were observed for 49 days across spring and summer 2013 to assess the following: (i) social associations within the flock, (ii) overall activity patterns, and (iii) distribution of time within specific enclosure zones for both full-winged and flight-restrained birds living in the same enclosure. Results showed that pinioning interacted with age in regard to flamingo time-activity patterns, but wing condition did not significantly influence association patterns, performance of social interactions, or performance of breeding behavior. Social network analysis revealed that associations were nonrandom and flamingos, of either wing condition, displayed different roles within the network. Birds of similar age formed the strongest bonds. Enclosure usage was not even, suggesting that the flamingos favored specific areas of the enclosure during the observation period. This study showed that wing condition does not affect flamingo behavior, social bonds, or space use, and that age and sex have more of an overall influence on what flamingos do, and with whom they chose to do it. Further research should extend this study into other, larger captive flocks to further refine behavioral measures of welfare for these popular zoo birds.

Age-Related Change in the Association Choices of Two Species of Juvenile Flamingos

Flamingos are colonial species commonly kept in zoos, well known for their bright plumage and elaborate courtship displays. This project aimed to determine the differences in flock position and association preferences of juvenile Greater Flamingos (Phoenicopterus roseus) and Caribbean Flamingos (P. ruber) housed in the same zoological collection. Little research has been conducted on the association preferences of juvenile flamingos, especially in captive flocks, and therefore this study collected data using photographs taken throughout 2014 and 2015 to further understand association patterns. Data were collected on the age category of each juvenile flamingo observed, the age of their nearest neighbour and their position within the flock, and the location within an enclosure zone at different times of the day. The results showed that Greater Flamingo juveniles mainly associated with individuals of their own age and were most likely positioned at the periphery of their flock significantly more of the time until approximately 24 months of age. Sub-adult Greater Flamingos spent significantly more time associating with adult flamingos at the centre of the flock. In contrast, data collected on Caribbean Flamingos indicated that juveniles did not segregate themselves from the adults as distinctively. Birds aged 13-24 months were observed significantly more at the centre of the flock and had more associations with adult flamingos, in a similar manner to that observed in Greater Flamingos. Due to population management needs, juvenile Caribbean Flamingos were removed from the flock at the start of 2015 and this may have influenced the association and location preferences of the remaining young flamingos. In conclusion, these results indicated that captive juvenile flamingos were often seen away from adult birds and that sub-adult flamingos returned to the heart of their natal flock to associate significantly more with other adult individuals, potentially preparing for mate selection and breeding. Captive enclosure should therefore be spacious enough to enable young flamingos to remove themselves from adult birds so that behavioural development can be unaffected by artificially high rates of aggression.

Notes on resonant and synchronized states in complex networks

Synchronization and resonance on networks are some of the most remarkable collective dynamical phenomena. The network topology, or the nature and distribution of the connections within an ensemble of coupled oscillators, plays a crucial role in shaping the local and global evolution of the two phenomena. This article further explores this relationship within a compact mathematical framework and provides new contributions on certain pivotal issues, including a closed bound for the average synchronization time in arbitrary topologies; new evidences of the effect of the coupling strength on this time; exact closed expressions for the resonance frequencies in terms of the eigenvalues of the Laplacian matrix; a measure of the effectiveness of an influencer node's impact on the network; and, finally, a discussion on the existence of a resonant synchronized state. Some properties of the solution of the linear swing equation are also discussed within the same setting. Numerical experiments conducted on two distinct real networks-a social network and a power grid-illustrate the significance of these results and shed light on intriguing aspects of how these processes can be interpreted within networks of this kind.

Cancer Susceptibility as a Cost of Reproduction and Contributor to Life History Evolution

Reproduction is one of the most energetically demanding life-history stages. As a result, breeding individuals often experience trade-offs, where energy is diverted away from maintenance (cell repair, immune function) toward reproduction. While it is increasingly acknowledged that oncogenic processes are omnipresent, evolving and opportunistic entities in the bodies of metazoans, the associations among reproductive activities, energy expenditure, and the dynamics of malignant cells have rarely been studied. Here, we review the diverse ways in which age-specific reproductive performance (e.g., reproductive aging patterns) and cancer risks throughout the life course may be linked via trade-offs or other mechanisms, as well as discuss situations where trade-offs may not exist. We argue that the interactions between host–oncogenic processes should play a significant role in life-history theory, and suggest some avenues for future research.

Senescence of song revealed by a long-term study of the Seychelles warbler (Acrocephalus sechellensis)

Senescence is widespread in nature, often resulting in diminishing survival or reproduction with age, but its role in age-dependent variation in sexual traits is often poorly understood. One reason is that few studies of sexual traits consider non-linear relationships with age, or only consider a narrow range of years relative to the life span of the species. Birdsong has evolved to allow assessment of conspecific quality in numerous bird species. Whilst theory and empirical work suggests that song may become more elaborate with age, there are a paucity of long-term studies testing whether song is associated with age or longevity. In particular, the occurrence of song senescence has rarely been demonstrated. Using an exceptional long-term dataset for the Seychelles warbler (Acrocephalus sechellensis), we analysed relationships between male song, age, survival, and longevity. This species is a long-lived songbird with early life increases, followed by senescent declines, in survival and reproduction. The study population (Cousin Island, Seychelles) is a closed population, with no depredation of adults, providing an excellent opportunity to study senescence in free-living animals. We tested whether song traits were related to age at recording, future survival, longevity, and territory quality. We found age-dependent changes in five song traits (duration, maximum frequency, peak frequency of songs, and duration and frequency bandwidth of trills). Relationships with age were quadratic, indicating reversal in the expression of song coinciding with the onset of senescence in reproduction and survival in this species. One song trait (trill bandwidth) had a quadratic relationship with future survival, but no song traits were related to longevity, suggesting age-related patterns were not the result of selective disappearance. Our study provides one of the first examples of functional senescence in song, offering new insights into avian senescence. Late-life declines in avian song, and possibly other sexual traits, may be more common than currently known, and may play a fundamental role in age-dependent changes in reproductive success.

Songs versus colours versus horns: what explains the diversity of sexually selected traits?

Papers on sexual selection often highlight the incredible diversity of sexually selected traits across animals. Yet, few studies have tried to explain why this diversity evolved. Animals use many different types of traits to attract mates and outcompete rivals, including colours, songs, and horns, but it remains unclear why, for example, some taxa have songs, others have colours, and others horns. Here, we first conduct a systematic survey of the basic diversity and distribution of different types of sexually selected signals and weapons across the animal Tree of Life. Based on this survey, we describe seven major patterns in trait diversity and distributions. We then discuss 10 unanswered questions raised by these patterns, and how they might be addressed. One major pattern is that most types of sexually selected signals and weapons are apparently absent from most animal phyla (88%), in contrast to the conventional wisdom that a diversity of sexually selected traits is present across animals. Furthermore, most trait diversity is clustered in Arthropoda and Chordata, but only within certain clades. Within these clades, many different types of traits have evolved, and many types appear to have evolved repeatedly. By contrast, other major arthropod and chordate clades appear to lack all or most trait types, and similar patterns are repeated at smaller phylogenetic scales (e.g. within insects). Although most research on sexual selection focuses on female choice, we find similar numbers of traits (among sampled species) are involved in male contests (44%) and female choice (55%). Overall, these patterns are largely unexplained and unexplored, as are many other fundamental questions about the evolution of these traits. We suggest that understanding the diversity of sexually selected traits may require a shift towards macroevolutionary studies at relatively deep timescales (e.g. tens to hundreds of millions of years ago).

Evolution and function of multimodal courtship displays

Courtship displays are behaviours aimed to facilitate attraction and mating with the opposite sex and are very common across the animal kingdom. Most courtship displays are multimodal, meaning that they are composed of concomitant signals occurring in different sensory modalities. Although courtship often strongly influences reproductive success, the question of why and how males use multimodal courtship to increase their fitness has not yet received much attention. Very little is known about the role of different components of male courtship and their relative importance for females. Indeed, most of the work on courtship displays have focused on effects on female choice, often neglecting other possible roles. Additionally, a number of scientists have recently stressed the importance of considering the complexity of a display and the interactions between its different components in order to grasp all the information contained in those multimodal signals. Unfortunately, these methods have not yet been extensively adapted in courtship studies. The aim of this study was to review what is currently known about the functional significance of courtship displays, particularly about the role of multimodality in the courtship communication context. Emphasis is placed on those cases where a complete picture of the communication system can only be assessed by taking complexity and interaction between different modalities into account.

Social and Physiological Context can Affect the Meaning of Physiological Synchrony

Survival of many species, from insects and birds to human and non-human mammals, requires synchronized activity. Among humans, synchrony occurs even at the level of autonomic functioning; people interacting often show mutual, simultaneous changes in activity of the sympathetic or parasympathetic branches of the autonomic nervous system. Critically, autonomic reactivity predicts many mental states and, when synchronized, may reflect higher-order social processes like affiliation. Here, using data from 134 strangers interacting in pairs, we manipulated two features of social context to test their impact on synchrony in sympathetic and parasympathetic reactivity. Participants completed a knot-tying task within a collective reward (“cooperation”) or individual reward (“competition”) framework while conversing or not (“talking” condition). Autonomic reactivity varied by features of social context. Synchrony occurred across social contexts in both autonomic branches. We then examined how synchrony predicted affiliation. Sympathetic synchrony alone predicted affiliation yet social context and parasympathetic reactivity moderated associations between parasympathetic synchrony and affiliation. Thus, social and physiological context of parasympathetic synchrony predicted affiliation better than parasympathetic synchrony alone. We argue that social context and the degree of physiological reactivity underlying physiological synchrony, not the mere existence of physiological synchrony, are key to interpreting physiological synchrony as a social process.

Couples showing off: Audience promotes both male and female multimodal courtship display in a songbird

Social environments can shape animal communication. Although mutual courtship displays are generally thought to function in private communication between a male and a female, we provide experimental evidence that they work in a broader social context than previously thought. We examined the audience effect on mutual courtship in blue-capped cordon-bleus, a socially monogamous songbird. This species is characterized by conspicuous courtship shared between sexes: Both sexes sing songs and sometimes add a unique dance display that looks like human tap dancing. We found that in both sexes, multimodal courtship displays (song accompanied by dance) were promoted in the presence of an audience, especially if it was the opposite sex. In contrast, unimodal displays (song without dance) were suppressed by audiences. Because birds directed the courtship dancing toward their partners (but not the audience), multimodal courtship displays are likely meant to advertise their current mating status to other cordon-bleus.

From flamingo dance to (desirable) drug discovery: a nature-inspired approach

The therapeutic effects of drugs are well known to result from their interaction with multiple intracellular targets. Accordingly, the pharma industry is currently moving from a reductionist approach based on a 'one-target fixation' to a holistic multitarget approach. However, many drug discovery practices are still procedural abstractions resulting from the attempt to understand and address the action of biologically active compounds while preventing adverse effects. Here, we discuss how drug discovery can benefit from the principles of evolutionary biology and report two real-life case studies. We do so by focusing on the desirability principle, and its many features and applications, such as machine learning-based multicriteria virtual screening.

Reproductive senescence: new perspectives in the wild

According to recent empirical studies, reproductive senescence, the decline in reproductive success with increasing age, seems to be nearly ubiquitous in the wild. However, a clear understanding of the evolutionary causes and consequences of reproductive senescence is still lacking and requires new and integrative approaches. After identifying the sequential and complex nature of female reproductive senescence, we show that the relative contributions of physiological decline and alterations in the efficiency of parental care to reproductive senescence remain unknown and need to be assessed in the light of current evolutionary theories of ageing. We demonstrate that, although reproductive senescence is generally studied only from the female viewpoint, age-specific female reproductive success strongly depends on male-female interactions. Thus, a reduction in male fertilization efficiency with increasing age has detrimental consequences for female fitness. Lastly, we call for investigations of the role of environmental conditions on reproductive senescence, which could provide salient insights into the underlying sex-specific mechanisms of reproductive success. We suggest that embracing such directions should allow building new bridges between reproductive senescence and the study of sperm competition, parental care, mate choice and environmental conditions.