The maintenance of genetic variation in traits under natural selection is a long-standing paradox in evolutionary biology [1][2][3] . Of the processes capable of maintaining variation, negative frequency-dependent selection (where rare types are favoured by selection) is the most powerful, at least in theory 1 ; however, few experimental studies have confirmed that this process operates in nature. One of the most extreme, unexplained genetic polymorphisms is seen in the colour patterns of male guppies (Poecilia reticulata) 4,5 . Here we manipulated the frequencies of males with different colour patterns in three natural populations to estimate survival rates, and found that rare phenotypes had a highly significant survival advantage compared to common phenotypes. Evidence from humans 6,7 and other species 8,9 implicates frequency-dependent survival in the maintenance of molecular, morphological and health-related polymorphisms. As a controlled manipulation in nature, this study provides unequivocal support for frequency-dependent survival-an evolutionary process capable of maintaining extreme polymorphism.Colour-pattern polymorphism in guppies is limited to males and consists of irregular spots of several different structural (blue, green and purple) and pigment-based (yellow, orange, red and black) colours that occur on the body, caudal fin and dorsal fin (Fig. 1). The position, number, size and hue of the spots are highly heritable 5,10 , although the colour saturation (chroma) of orange spots can be influenced by diet 11,12 . Male colouration is highly polymorphic despite being subject to sexual and ecological selection. Female mating preferences usually favour males with the greatest area of orange, although the strength of that preference varies among populations 10,12,13 . Predators also exert selection on colour patterns; they preferentially prey upon males with brighter or more conspicuous colours 14,15 . Despite the apparently strong and directional selection within populations, colour patterns are so variable that any two males are easily distinguishable based on colour pattern alone, unless they are closely related 10 .Several mechanisms have been proposed to explain the maintenance of this extreme polymorphism 10,14 . Mate-choice experiments indicate that females preferentially mate with males bearing rare or novel colour patterns 16,17 . A trade-off (antagonistic pleiotropy) between male sexual attractiveness and offspring viability has also been reported 18 . Both processes could contribute to the maintenance of genetic variation in nature. However, experiments demonstrating these processes were conducted in laboratory environments, and it is not clear whether either process occurs in nature. Another process capable of maintaining polymorphism is a rare-morph survival advantage. This process has been implicated in the maintenance of colour polymorphism in some invertebrates 19,20 and vertebrates 21 , but it has not been tested in the highly polymorphic guppy system. We tested the hypothesis that ma...

Background With data becoming a centerpiece of modern scientific discovery, data sharing by scientists is now a crucial element of scientific progress. This article aims to provide an in-depth examination of the practices and perceptions of data management, including data storage, data sharing, and data use and reuse by scientists around the world. Methods The Usability and Assessment Working Group of DataONE, an NSF-funded environmental cyberinfrastructure project, distributed a survey to a multinational and multidisciplinary sample of scientific researchers in a two-waves approach in 2017-2018. We focused our analysis on examining the differences across age groups, sub-disciplines of science, and sectors of employment. Findings Most respondents displayed what we describe as high and mediocre risk data practices by storing their data on their personal computer, departmental servers or USB drives. Respondents appeared to be satisfied with short-term storage solutions; however, only half of them are satisfied with available mechanisms for storing data beyond the life of the process. Data sharing and data reuse were viewed positively: over 85% of respondents admitted they would be willing to share their data with others and said they would use data collected by others if it could be easily accessed. A vast majority of respondents felt that the lack of access to data generated by other researchers or institutions was a major impediment to progress in science at large, yet only about a half thought that it restricted their own ability to

Male red-winged blackbirds (Agelaius phoeniceus) often cooperate with their neighbours in defending nests against predators. Some studies have suggested that this is an example of by-product mutualism, whereas others have suggested the possibility of reciprocal altruism. No study has addressed the possibility of kinselected cooperation in nest defence in this species. Reciprocal altruism, kin selection and by-product mutualism are not mutually exclusive alternatives, but few studies of territorial neighbours have tested for multiple mechanisms simultaneously. We test for these three possibilities in a population of red-winged blackbirds. We used simulated defections to test for reciprocal altruism. We used analysis of microsatellite loci to test for kin selection between adult male neighbours. We also used microsatellite loci to test for by-product mutualism resulting from nest defence of offspring sired on neighbouring territories. We found that male red-winged blackbirds cooperate in nest defence primarily as a form of reciprocal altruism. Experimental males reduced their level of nest defence relative to controls following simulated defection by a neighbour. In contrast to some earlier studies, we found no evidence for by-product mutualism: males did not defend nests where they had sired extra-pair offspring. We also found no evidence for kin selection: males were no more cooperative with more closely related neighbours. Considered alongside the results from other studies, our study suggests that mechanisms stabilizing cooperation in red-winged blackbirds may vary among populations.

Maintenance of genetic variation in the face of strong natural selection is a long‐standing problem in evolutionary biology. One of the most extreme examples of within‐population variation is the polymorphic, genetically determined color pattern of male Trinidad guppies (Poecilia reticulata). Female mating preference for rare or novel patterns has been implicated as a factor in maintaining this variation. The origin of this preference is not understood, although inbreeding avoidance has been proposed as a mechanism. Inbreeding avoidance is advantageous when populations exhibit inbreeding depression and the opportunity for mating between relatives exists. To determine whether these conditions are met in a natural guppy population, we assessed mating and reproductive patterns using polymorphic molecular markers. Females produced more offspring with less‐related males than with more‐related ones. In addition, females were more likely to have mated with less‐related males, but this trend was only marginally significant. Male heterozygosity was positively correlated with mating success and with the number of offspring sired, consistent with strong inbreeding depression for adult male fitness. These results provide substantial insight into mating patterns of a wild guppy population: strong inbreeding depression occurs, and individuals tend to avoid mating with relatives.

This article underwent semi-anonymous peer review in accordance with JLSC's peer review policy.

In many species, territorial neighbours fight to establish their mutual border and then develop a truce, known as the dear-enemy phenomenon, characterized by reduced vigilance and aggression along the border. We present evidence that among male red-winged blackbirds (Agelaius phoeniceus) the dear-enemy relationship is a form of reciprocal conditional cooperation that is stabilized, at least in part, by retaliation against cheaters. Simulated intrusions by randomly chosen neighbours were punished by a targeted increase in vigilance and aggression that persists for days. We interpret this increase in vigilance towards trespassers as a manifestation of distrust. The conditional decrease in vigilance and aggression is tempered by each neighbour's probability of cuckolding the focal male. Male red-winged blackbirds maintained greater vigilance and aggression towards sexually attractive neighbours that were more successful at extrapair fertilizations (EPFs). It is unlikely that males directly observed neighbours copulating with their mates. They were more likely to assess a neighbour's ability to achieve extra-pair copulations using surrogate cues that correlate with success at EPFs, including body size. Our results suggest that red-winged blackbirds use rules that incorporate their neighbour's behaviour and quality in their territorial interactions with one another. Our results expand our understanding of cooperation for animals and for humans as well.

We used presentations of models to determine the effectiveness of nest defence in the Acadian Flycatcher Empidonax virescens against a nest predator (Blue Jay Cyanocitta mistata) and a brood parasite (Brown-headed Cowbird Molothrus ater) . Principal components analysis (PCA) of four component variables of nest defence (call rate, swoop rate, closest approach and number of adults) generated a measure of overall nest defence (aggression). We determined effectiveness of defence by looking for correlations between measures of defence and measures of nest success (nest predation and brood parasitism).We also determined whether nest defence increased with clutch size, nestling age and time in the breeding season. Defence against model Brown-headed Cowbirds did not correlate with levels of parasitism, clutch size, age of young or time of breeding. There was, however, a strong, but insignificant, trend for nests with high levels of all measures of defence to suffer less from brood parasitism. Aggression, vocalization rate, closest approach and number of adults defending against models of predatory Blue Jays correlated positively with nesting success during the egg stage but not the nestling stage of the nesting cycle. Aggression, vocalization rate, closest approach correlated with clutch 0 2000 British Ornithologists' Union

Objective: Many academic and research institutions are exploring opportunities to better support researchers in sharing their data. As partners in the Data Curation Network project, our six institutions developed a comparison of the current levels of support provided for researchers to meet their data sharing goals through library-based data repository and curation services. Methods:Each institutional lead provided a written summary of their services based on a previously developed structure, followed by group discussion and refinement of descriptions. Service areas assessed include the repository services for data, technologies used, policies, and staffing in place.Conclusions: Through this process we aim to better define the current levels of support offered by our institutions as a first step toward meeting our project's overarching goal to develop a shared staffing model for data curation across multiple institutions.