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Nest predation rates critically influence avian biodiversity and evolution. In the north temperate zone, increased nest failure along edges of forest fragments is hypothesized to play a major role in the disappearance of bird species from disturbed landscapes. However, we lack comprehensive syntheses from tropical latitudes, where biodiversity is highest and increasingly threatened by habitat fragmentation and disturbance. We assembled data from five decades of field studies across the global tropics (1,112 populations of 661 species) and used phylogenetic models to evaluate proposed predictors of nest success. We found significant effects of several traits, including adult body mass and nest architecture. Contrary to results from many temperate locations, anthropogenic habitat disruption did not consistently reduce nest success; in fact, raw nest success rates were lower in large tracts of primary forest than in disturbed or fragmented landscapes. Follow-up analyses within species, using a subset of 76 species for which we had estimates of nest survival in habitats with different levels of disruption, confirmed that neither disturbance nor fragmentation significantly influenced nest success. These results suggest that nest predation alone cannot explain observed declines in avian biodiversity in tropical forest fragments, raising new questions about the demographic processes that drive extinction in the tropics., Competing Interests: Competing interests statement:The authors declare no competing interest.

Principal component analysis (PCA) and partial least squares regression (PLS) were combined in this study to identify key material descriptors determining tabletability in direct compression and roller compaction. An extensive material library including 119 material descriptors and tablet tensile strengths of 44 powders and roller compacted materials with varying drug loads was generated to systematically elucidate the impact of different material descriptors, raw API and filler properties as well as process route on tabletability. A PCA model was created which highlighted correlations between different powder descriptors and respective characterization methods and, thus, can enable reduction of analyses to save resources to a certain extent. Subsequently, PLS models were established to identify key material attributes for tabletability such as density and particle size but also surface energy, work of cohesion and wall friction, which were for the first time demonstrated by PLS as highly relevant for tabletability in roller compaction and direct compression. Further, PLS based on extensive material characterization enabled the prediction of tabletability of materials unknown to the model. Thus, this study highlighted how PCA and PLS are useful tools to elucidate the correlations between powder and tabletability, which will enable more robust prediction of manufacturability in formulation development., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Film-coated tablets as solid oral dosage forms are a well-accepted way of administering drugs but are not without specific challenges during manufacturing. One relevant criterion of the final product is the visual integrity and therewith, the absence of cosmetic optical defects such as edge chipping. The aim of the present study was to examine the origin of those edge chipping defects, which were observed during commercial manufacturing of film-coated tablets, and to provide recommendations for process optimization to reduce the defect occurrence. The unraveling of the herein described phenomenon necessitated an interplay of in-depth material characterization, discrete element modeling (DEM) as well as an in-house developed optical measurement system for the automated quantification of tablet defects. As a result of this investigation, the automatic unloading step after the tablet coating process was identified as the most critical step for the occurrence of chipping defects and a replacement by manual unloading was proposed to reduce the defect propensity. The recommended optimization was subsequently confirmed in several manufacturing runs and a reduction of defect propensity by a factor of 5 was observed, highlighting the relevance and the impact of the performed thorough investigation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Purpose: Although the mechanical properties of paracetamol and MCC are extensively described in literature, there still is a need for a better understanding of the material properties impacting them. Thus, this study systematically analyzed material properties of paracetamol-MCC blends to elucidate their influence on the mechanical tablet properties in roller compaction and direct compression with special focus on surface properties., Methods: Multiple material characteristics of binary mixtures of paracetamol and MCC with varying drug loads were analyzed, with particular emphasis on specific surface area and surface energy. Subsequently, mechanical tablet properties of the materials in direct compression and after roller compaction were examined., Results: It was demonstrated that the impact of the initial material properties on mechanical tablet properties prevailed over the impact of processing route for paracetamol-MCC blends, underlining the importance of material characterization for tabletability of oral solid dosage forms. By applying bivariate as well as multivariate analysis, key material properties influencing the tabletability of paracetamol, MCC and its mixtures such as surface area, surface energy, effective angle of internal friction and density descriptors were identified., Conclusions: This study highlighted the importance of comprehensive assessment of different material characteristics leading to a deeper understanding of underlying factors impacting mechanical tablet properties in direct compression and after roller compaction by the example of paracetamol-MCC mixtures with varying drug loads. Furthermore, it was shown that multivariate analysis could be a valuable extension to common bivariate analysis to reveal underlying correlations of material properties., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Referential signaling, a complex form of communication in which specific signals are associated with external referents, was once thought to be limited to primates. Recent research has documented referential signaling in several other cooperative taxa, predominantly in kin-based societies. Here, we show that greater anis, communally nesting birds that breed in nonkin groups, give one type of alarm call in response to aerial threats (flying raptors) and another to more general threats (nonaerial predators). Observational data show that anis give these calls in response to different classes of threats, and playback experiments in the field confirmed that the alarm calls alone are sufficient to elicit appropriate behavioral responses even in the absence of an actual threat. Genetic data on a subset of groups confirmed that breeding groups are composed of nonkin, suggesting that referential alarm calls are often given in situations when no genetic relatives are present. These results suggest that complex referential communication can occur in social groups composed of nonrelatives, despite the absence of kin-selected fitness benefits.

Variation in group size is ubiquitous in social animals, but explaining the range of group sizes seen in nature remains challenging. 1-3 Group-living species occur most frequently in climatically unpredictable environments, such that the costs and benefits of sociality may change from year to year. 4-6 It is, therefore, possible that variation in climate may help to maintain a range of group sizes, but this hypothesis is rarely tested empirically. 7 , 8 Here, we examine selection on breeding group size in the greater ani (Crotophaga major), a tropical bird that nests in cooperative groups containing multiple co-breeders and non-breeding helpers. 9 We found that larger groups experience lower nest predation (due to cooperative nest defense) but suffer higher nestling starvation (due to intra-clutch competition). Long-term data revealed that the relative magnitude of these costs and benefits depends on climate, with frequent changes across years in the strength and direction of selection on group size. In wet years, individual reproductive success was higher in large groups than in small groups, whereas the opposite was true in dry years. This was partly a consequence of competition among nestlings in large clutches, which suffered significantly higher mortality in dry years than in wet years. Averaged over the 13-year study period, annual reproductive success was approximately equal for females in small and large groups. These results suggest that temporal changes in the direction of selection may help explain the persistence of a range of group sizes and that a full understanding of the selective pressures shaping sociality requires long-term fitness data., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The relevance of the polymorphic form, particle size, and processing of mannitol for the mechanical properties of solid oral dosage forms was examined. Thus, particle and powder properties of spray granulated β D-mannitol, β D-mannitol, and δ D-mannitol were assessed in this study with regards to their manufacturability. D-mannitol is a commonly used excipient in pharmaceutical formulations, especially in oral solid dosage forms, and can be crystallized as three polymorphic forms, of which β is the thermodynamically most stable form and δ is a kinetically stabilized polymorph. A systematic analysis of the powders as starting materials and their respective roller compacted granules is presented to elucidate the multidimensional effects of powder and granules characteristics such as polymorphic form, particle size, and preprocessing on the resulting tablets' mechanical properties. In direct compression and after roller compaction, δ polymorph displayed superior tableting properties over β mannitol, but was outperformed by spray granulated β mannitol. This could be primarily correlated to the higher specific surface area, leading to higher bonding area and more interparticle bonds within the tablet. Hence, it was shown that surface characteristics and preprocessing can prevail over the impact of polymorphism on manufacturability for oral solid dosage forms.

Cooperative breeding strategies lead to short-term direct fitness losses when individuals forfeit or share reproduction. The direct fitness benefits of cooperative strategies are often delayed and difficult to quantify, requiring data on lifetime reproduction. Here, we use a longitudinal dataset to examine the lifetime reproductive success of cooperative polygamy in acorn woodpeckers ( Melanerpes formicivorus ), which nest as lone pairs or share reproduction with same-sex cobreeders. We found that males and females produced fewer young per successful nesting attempt when sharing reproduction. However, males nesting in duos and trios had longer reproductive lifespans, more lifetime nesting attempts and higher lifetime reproductive success than those breeding alone. For females, cobreeding in duos increased reproductive lifespan so the lifetime reproductive success of females nesting in duos was comparable to those nesting alone and higher than those nesting in trios. These results suggest that for male duos and trios, reproductive success alone may provide sufficient fitness benefits to explain the presence of cooperative polygamy, and the benefits of cobreeding as a duo in females are higher than previously assumed. Lifetime individual fitness data are crucial to reveal the full costs and benefits of cooperative polygamy.

Intermittent breeding, in which an adult skips a breeding opportunity, can represent a non-adaptive constraint or an adaptive response to the tradeoff between current and future reproduction. In group-living animals, the social group may also affect the frequency of reproduction, but this possibility has received little attention. Here we use an 11-year data set to investigate intermittent breeding in the greater ani (Crotophaga major), a tropical bird that nests in stable breeding groups containing several unrelated co-breeding females. Population-wide, an average of 62% of females laid eggs in a given year (range 35-84%), and the average female failed to lay eggs once every 3.2 years. We found little support for the hypothesis that intermittent breeding reflects a tradeoff between current and future reproduction: breeding in year t did not affect a female's likelihood of breeding in year t + 1, and clutch size in year t did not affect clutch size in year t + 1. Increases in clutch size were associated with decreases in egg mass for eggs laid at the end of that clutch, but this did not affect subsequent nesting attempts. However, reproductive skipping was associated with changes in group membership. Females whose groups changed in composition after year t were significantly less likely to breed in year t + 1 than females whose groups remained stable. These results indicate that breeding group stability influences the frequency of reproduction, suggesting that transitions between groups may be costly to females and their mates.

Classic evolutionary theory predicts that monogamy should be intimately linked with parental care. It has long been assumed, therefore, that avian brood parasites-which lay their eggs in the nests of 'host' species and provide little, if any, parental care-should be overwhelmingly promiscuous. However, recent studies have revealed that the social mating systems of brood parasites are surprisingly diverse, encompassing lek polygyny, monogamy, polygamy and promiscuity. What ecological or phylogenetic factors explain this variation, and why are some brood parasites apparently monogamous? Here we review the social and genetic mating systems of all 75 brood parasitic species for which data are available and evaluate several hypotheses that may help explain these patterns. We find that social monogamy is widespread, often co-occurring with territoriality and cooperative behaviour by the mated pair. Comparative studies, though preliminary, suggest that in some species, monogamy is associated with low host density and polygamy with higher host density. Interestingly, molecular data show that genetic and social mating systems can be entirely decoupled: genetic monogamy can occur in parasitic species that lack behavioural pair-bonds, possibly as a by-product of territoriality; conversely, social monogamy has been reported in parasites that are genetically polygamous. This synthesis suggests that social and genetic monogamy may result from very different selective pressures, and that male-female cooperative behaviours, population density and territoriality may all interact to favour the evolution of monogamous mating in brood parasites. Given that detailed descriptive data of social, and especially genetic, mating systems are still lacking for the majority of brood parasitic species, definitive tests of these hypotheses await future work. This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.

Cooperatively nesting birds are vulnerable to social parasites that lay their eggs in host nests but provide no parental care 1-4 . Most previous research has focused on the co-evolutionary arms race between host defences and the parasites that attempt to circumvent them 5-9 , but it remains unclear why females sometimes cooperate and sometimes parasitize, and how parasitic tactics arise in cooperative systems 10-12 . Here we show that cooperative and parasitic reproductive strategies result in approximately equal fitness pay-offs in the greater ani (Crotophaga major), a long-lived tropical cuckoo, using an 11-year dataset and comprehensive genetic data that enable comparisons of the life-histories of individual females. We found that most females in the population nested cooperatively at the beginning of the breeding season; however, of those birds that had their first nests destroyed, a minority subsequently acted as reproductive parasites. The tendency to parasitize was highly repeatable, which indicates individual specialization. Across years, the fitness pay-offs of the two strategies were approximately equal: females who never parasitized (a 'pure cooperative' strategy) laid larger clutches and fledged more young from their own nests than did birds that both nested and parasitized (a 'mixed' strategy). Our results suggest that the success of parasites is constrained by reproductive trade-offs as well as by host defences, and illustrate how cooperative and parasitic tactics can coexist stably in the same population.

Hosts of avian brood parasites often use visual cues to reject foreign eggs, and several lineages of brood parasites have evolved mimetic eggshell coloration and patterning to circumvent host recognition. What is the mechanism of parasitic egg color mimicry at the chemical level? Mimetic egg coloration by Common Cuckoos Cuculus canorus is achieved by depositing similar concentrations of colorful pigments into their shells as their hosts. The mechanism of parasitic egg color mimicry at the chemical level in other lineages of brood parasites remains unexplored. Here we report on the chemical basis of egg color mimicry in an evolutionarily independent, and poorly studied, host-parasite system: the Neotropical Striped Cuckoo Tapera naevia and one of its hosts, the Rufous-and-white Wren Thryophilus rufalbus. In most of South America, Striped Cuckoos lay white eggs that are identical to those of local host species. In Central America, however, Striped Cuckoos lay blue eggs that match those of the Rufous-and-white Wren, suggesting that blue egg color in these cuckoo populations is an adaptation to mimic host egg appearance. Here we confirm that Striped Cuckoo eggs are spectrally similar to those of their hosts and consistently contain the same major eggshell pigment, biliverdin. However, wren eggshells lacked protoporphyrin, which was present in the parasitic cuckoo eggshells. Furthermore, biliverdin concentrations were significantly lower in cuckoo eggshells than in host eggshells. Similarity of host-parasite eggshell appearance, therefore, need not always be paralleled by a quantitative chemical match to generate effective visual mimicry in birds.

Animal social groups are complex systems that are likely to exhibit tipping points-which are defined as drastic shifts in the dynamics of systems that arise from small changes in environmental conditions-yet this concept has not been carefully applied to these systems. Here, we summarize the concepts behind tipping points and describe instances in which they are likely to occur in animal societies. We also offer ways in which the study of social tipping points can open up new lines of inquiry in behavioural ecology and generate novel questions, methods, and approaches in animal behaviour and other fields, including community and ecosystem ecology. While some behaviours of living systems are hard to predict, we argue that probing tipping points across animal societies and across tiers of biological organization-populations, communities, ecosystems-may help to reveal principles that transcend traditional disciplinary boundaries., (© 2018 The Authors.)

Social animals often form long-lasting relationships with fellow group members, usually with close kin. In primates, strong social bonds have been associated with increased longevity, offspring survival and reproductive success. However, little is known about the fitness effects of social bonds between non-kin, especially outside of mammals. In this study, we use long-term field research on a cooperatively breeding bird, the greater ani ( Crotophaga major ), to ask whether adult females benefit by remaining in long-term associations with unrelated, co-breeding females. We find that females that have previously nested together synchronize their reproduction more rapidly than those nesting with unfamiliar partners, which leads to lower competition and higher fledging success. Importantly, although previous experience with a co-breeding female influenced reproductive synchrony, the degree of reproductive synchrony did not influence whether co-breeding females remained together in subsequent years, ruling out the alternate hypothesis that highly synchronized females are simply more likely to remain together. These results indicate that switching groups is costly to females, and that social familiarity improves reproductive coordination. Stable social relationships therefore have significant fitness consequences for cooperatively nesting female birds, suggesting that direct benefits alone may favour the evolution of associations between non-relatives and contribute to long-term group stability., (© 2018 The Author(s).)

Social animals vary in how reproduction is divided among group members, ranging from monopolization by a dominant pair (high skew) to equal sharing by cobreeders (low skew). Despite many theoretical models, the ecological and life-history factors that generate this variation are still debated. Here I analyze data from 83 species of cooperatively breeding birds, finding that kinship within the breeding group is a powerful predictor of reproductive sharing across species. Societies composed of nuclear families have significantly higher skew than those that contain unrelated members, a pattern that holds for both multimale and multifemale groups. Within-species studies confirm this, showing that unrelated subordinates of both sexes are more likely to breed than related subordinates are. Crucially, subordinates in cooperative groups are more likely to breed if they are unrelated to the opposite-sex dominant, whereas relatedness to the same-sex dominant has no effect. This suggests that incest avoidance, rather than suppression by dominant breeders, may be an important proximate mechanism limiting reproduction by subordinates. Overall, these results support the ultimate evolutionary logic behind concessions models of skew-namely, that related subordinates gain indirect fitness benefits from helping at the nests of kin, so a lower direct reproductive share is required for selection to favor helping over dispersal-but not the proximate mechanism of dominant control assumed by these models.

Reproduction among members of social animal groups is often highly synchronized, but neither the selective advantages nor the proximate causes of synchrony are fully understood. Here I investigate the evolution of hatching synchrony in the Greater Ani (Crotophaga major), a communally nesting bird in which several unrelated females contribute eggs to a large, shared clutch. Hatching synchrony is variable, ranging from complete synchrony to moderate asynchrony, and is determined by the onset of incubation of the communal clutch. Data from a 10-year field study indicate that individual reproductive success is highest in synchronous groups, and that nestlings that hatch in the middle of the hatching sequence are most likely to survive. Nestling mortality is high in asynchronous clutches because early-hatching nestlings are more likely to be killed by adult group members, whereas late-hatching nestlings are more likely to starve due competition with their older nest-mates. Therefore, the timing of hatching appears to be under stabilizing selection from infanticide and resource competition acting in concert. These results provide empirical support for models predicting that synchrony may evolve as an adaptive counter-strategy to infanticide, and they highlight the importance of competition in shaping the timing of reproduction in social groups., (© 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.)

The general belief that cooperation and altruism in social groups result primarily from kin selection has recently been challenged, not least because results from cooperatively breeding insects and vertebrates have shown that groups may be composed mainly of non-relatives. This allows testing predictions of reciprocity theory without the confounding effect of relatedness. Here, we review complementary and alternative evolutionary mechanisms to kin selection theory and provide empirical examples of cooperative behaviour among unrelated individuals in a wide range of taxa. In particular, we focus on the different forms of reciprocity and on their underlying decision rules, asking about evolutionary stability, the conditions selecting for reciprocity and the factors constraining reciprocal cooperation. We find that neither the cognitive requirements of reciprocal cooperation nor the often sequential nature of interactions are insuperable stumbling blocks for the evolution of reciprocity. We argue that simple decision rules such as 'help anyone if helped by someone' should get more attention in future research, because empirical studies show that animals apply such rules, and theoretical models find that they can create stable levels of cooperation under a wide range of conditions. Owing to its simplicity, behaviour based on such a heuristic may in fact be ubiquitous. Finally, we argue that the evolution of exchange and trading of service and commodities among social partners needs greater scientific focus., (© 2016 The Author(s).)

Cheaters-genotypes that gain a selective advantage by taking the benefits of the social contributions of others while avoiding the costs of cooperating-are thought to pose a major threat to the evolutionary stability of cooperative societies. In order for cheaters to undermine cooperation, cheating must be an adaptive strategy: cheaters must have higher fitness than cooperators, and their behaviour must reduce the fitness of their cooperative partners. It is frequently suggested that cheating is not adaptive because cooperators have evolved mechanisms to punish these behaviours, thereby reducing the fitness of selfish individuals. However, a simpler hypothesis is that such societies arise precisely because cooperative strategies have been favoured over selfish ones-hence, behaviours that have been interpreted as 'cheating' may not actually result in increased fitness, even when they go unpunished. Here, we review the empirical evidence for cheating behaviours in animal societies, including cooperatively breeding vertebrates and social insects, and we ask whether such behaviours are primarily limited by punishment. Our review suggests that both cheating and punishment are probably rarer than often supposed. Uncooperative individuals typically have lower, not higher, fitness than cooperators; and when evidence suggests that cheating may be adaptive, it is often limited by frequency-dependent selection rather than by punishment. When apparently punitive behaviours do occur, it remains an open question whether they evolved in order to limit cheating, or whether they arose before the evolution of cooperation., (© 2016 The Author(s).)

Cooperative breeding in birds typically occurs when offspring - usually males - delay dispersal from their natal group, remaining with the family to help rear younger kin. Sex-biased dispersal is thought to have evolved in order to reduce the risk of inbreeding, resulting in low relatedness between mates and the loss of indirect fitness benefits for the dispersing sex. In this review, we discuss several recent studies showing that dispersal patterns are more variable than previously thought, often leading to complex genetic structure within cooperative avian societies. These empirical findings accord with recent theoretical models suggesting that sex- biased dispersal is neither necessary, nor always sufficient, to prevent inbreeding. The ability to recognize relatives, primarily by learning individual or group-specific vocalizations, may play a more important role in incest avoidance than currently appreciated., (© 2015 WILEY Periodicals, Inc.)

Inferential reasoning-associating a visible consequence with an imagined event-has been demonstrated in several bird species in captivity, but few studies have tested wild birds in ecologically relevant contexts. Here, we investigate inferential reasoning by the greater ani, a cooperatively breeding cuckoo in which several females lay eggs in one nest. Prior to laying her first egg, each female removes any eggs that have already been laid by other females in the shared nest. After laying her first egg, however, each female stops removing eggs, presumably in order to avoid accidentally rejecting her own. But are anis using inferential reasoning to track the fate of their eggs in the communal nest, or is egg ejection governed by non-cognitive determinants? We experimentally removed eggs from two-female nests after both females had laid at least one egg and used video recording to verify that both females viewed the empty nest. We waited until one female (A) laid an egg in the nest, and video recorded the behavior of the female that had not yet re-laid (B). We predicted that if capable of inferential reasoning, female B should infer that the new egg could not be her own and she should remove it. Five out of five females tested failed to make this inference, suggesting that egg removal is either determined by the female's reproductive status or by the amount of time elapsed between egg removal and re-laying. This apparent cognitive constraint may have implications for the evolutionary stability of the anis' unusual breeding system.