The co-evolution of multiply-informed dispersal: information transfer across landscapes from neighbors and immigrants

Dispersal plays a key role in natural systems by shaping spatial population and evolutionary dynamics. Dispersal has been largely treated as a population process with little attention to individual decisions and the influence of information use on the fitness benefits of dispersal despite clear empirical evidence that dispersal behavior varies among individuals. While information on local density is common, more controversial is the notion that indirect information use can easily evolve. We used an individual-based model to ask under what conditions indirect information use in dispersal will evolve. We modeled indirect information provided by immigrant arrival into a population which should be linked to overall metapopulation density. We also modeled direct information use of density which directly impacts fitness. We show that immigrant-dependent dispersal evolves and does so even when density dependent information is available. Use of two sources of information also provides benefits at the metapopulation level by reducing extinction risk and prolonging the persistence of populations. Our results suggest that use of indirect information in dispersal can evolve under conservative conditions and thus could be widespread

Loss of flockmates weakens winter site fidelity in golden-crowned sparrows (\u3ci\u3eZonotrichia atricapilla\u3c/i\u3e)

Animal social interactions have an intrinsic spatial basis as many of these interactions occur in spatial proximity. This presents a dilemma when determining causality: Do individuals interact socially because they happen to share space, or do they share space because they are socially linked? We present a method that uses demographic turnover events as a natural experiment to investigate the links between social associations and space use in the context of interannual winter site fidelity in a migratory bird. We previously found that golden-crowned sparrows (Zonotrichia atricapilla) show consistent flocking relationships across years, and that familiarity between individuals influences the dynamics of social competition over resources. Using long-term data on winter social and spatial behavior across 10 y, we show that i) sparrows exhibit interannual fidelity to winter home ranges on the scale of tens of meters and ii) the precision of interannual site fidelity increases with the number of winters spent, but iii) this fidelity is weakened when sparrows lose close flockmates from the previous year. Furthermore, the effect of flockmate loss on site fidelity was higher for birds that had returned in more than 2 winters, suggesting that social fidelity may play an increasingly important role on spatial behavior across the lifetime of this migratory bird. Our study provides evidence that social relationships can influence site fidelity, and shows the potential of long-term studies for disentangling the relationship between social and spatial behavior

Winter GPS tagging reveals home ranges during the breeding season for a borealnesting migrant songbird, the Goldencrowned Sparrow

Determining space use for species is fundamental to understanding their ecology, and tracking animals can reveal insights into their spatial ecology on home ranges and territories. Recent technological advances have led to GPS-tracking devices light enough for birds as small as ~30 g, creating novel opportunities to remotely monitor fine-scale movements and space use for these smaller species. We tested whether miniaturized GPS tags can allow us to understand space use of migratory birds away from their capture sites and sought to understand both pre-breeding space use as well as territory and habitat use on the breeding grounds. We used GPS tags to characterize home ranges on the breeding grounds for a migratory songbird with limited available breeding information, the Golden-crowned Sparrow (Zonotrichia atricapilla). Using GPS points from 23 individuals across 26 tags (three birds tagged twice), we found home ranges in Alaska and British Columbia were on average 44.1 ha (95% kernel density estimate). In addition, estimates of territory sizes based on field observations (mean 2.1 ha, 95% minimum convex polygon [MCP]) were three times smaller than 95% MCPs created using GPS tags (mean 6.5 ha). Home ranges included a variety of land cover classes, with shrubland particularly dominant (64–100% of home range cover for all but one bird). Three birds tracked twice returned to the same breeding area each year, supporting high breeding site fidelity for this species. We found reverse spring migration for five birds that flew up to 154 km past breeding destinations before returning. GPS-tracking technology allowed for critical ecological insights into this migratory species that breeds in very remote locations

Dispersal syndromes in challenging environments: A cross‐species experiment

Dispersal is a central biological process tightly integrated into life-histories, morphology, physiology and behaviour. Such associations, or syndromes, are anticipated to impact the eco-evolutionary dynamics of spatially structured populations, and cascade into ecosystem processes. As for dispersal on its own, these syndromes are likely neither fixed nor random, but conditional on the experienced environment. We experimentally studied how dispersal propensity varies with individuals' phenotype and local environmental harshness using 15 species ranging from protists to vertebrates. We reveal a general phenotypic dispersal syndrome across studied species, with dispersers being larger, more active and having a marked locomotion-oriented morphology and a strengthening of the link between dispersal and some phenotypic traits with environmental harshness. Our proof-of-concept metacommunity model further reveals cascading effects of context-dependent syndromes on the local and regional organisation of functional diversity. Our study opens new avenues to advance our understanding of the functioning of spatially structured populations, communities and ecosystems. Keywords: context-dependent dispersal; dispersal strategy; distributed experiment; predation risk; resource limitatio

Data from: Signal architecture: temporal variability and individual consistency of multiple sexually selected signals

1. Multiple signals should be favoured when the benefit of additional signals outweigh their costs. Despite increased attention on multiple-signalling systems, few studies have focused on signal architecture to understand the potential information content of multiple signals. 2. To understand the patterns of signal plasticity and consistency over the lifetime of individuals we conducted a longitudinal study of multiple signals known to be under sexual selection in male lark buntings, Calamospiza melanocorys. 3. Within years, we found extensive among-individual variation in all four plumage ornaments we measured. Surprisingly, there were few correlations among these signals, suggesting that individuals contain a mosaic of signals. Signals were only moderately repeatable across years, which indicates some signal plasticity or age related change. In some years, the direction of change in particular signals relative to the previous year was consistent for most individuals in the population, suggesting that broad scale ecological factors affected the ornament phenotype. Different ornaments were affected by different ecological or social factors because the population-wide shift in a given signal was independent of change in other signals. 4. Our combined results suggest that different signals—including different components of the same color patch in some cases—provide diverse and independent information about the individual to signal receivers in the context of sexual selection

Experimental confirmation that avian plumage traits function as multiple status signals in winter contests

Status signals are thought to reduce costs of overt conflict over resources by advertising social status or an individual’s ability to win contests. While most studies have focused on single badges of status, recent empirical work has shown that multiple status signals may exist. To provide robust evidence for multiple badges of status, an experimental manipulation is required to decouple signals from one another and from other traits linked to fighting ability. Such experimental evidence is lacking for most studies of multiple status signals to date. We previously found that two plumage traits in golden-crowned sparrows, Zonotrichia atricapilla, were correlated with social dominance in encounters between unfamiliar individuals. To confirm that each plumage patch functions as an independent status signal, we experimentally augmented the sizes of the gold crown patch and the black crown patch during encounters between unfamiliar individuals with similar premanipulation crown sizes. In nearly all cases, the individual with the artificially augmented gold or black crown was dominant during the trial and manipulations of each color were equally successful in conferring dominance. The relative differences in crown sizes between manipulated and unmanipulated individuals in a dyad and mismatches in crown sizes of the manipulated bird led to escalation in gold trials, but these same factors were not significant for black trials. This study provides unequivocal evidence for multiple status signals: both black and gold crown patches influence social status per se and they do so independently of the other crown patch

Sparrows Use Multiple Status Signals in Winter Social Flocks

Status signals are thought to reduce the potential costs of social conflict over resources by advertising social status to other group members and reducing unnecessary contests between individuals of differing abilities. Nearly all studies of status signals to date have focused on single signaling traits, and most studies that have investigated multiple traits did not examine whether different traits are used in different contexts, as is required for them to function as multiple signals. We examined the role of gold and black crown patches of wintering golden-crowned sparrows, Zonotrichia atricapilla, in determining social dominance during experimentally staged encounters between unfamiliar individuals. Specifically, we determined whether variation in weakly correlated or uncorrelated traits (crown patch size and color, body size) differentially affected the outcome of interactions involving avoidance versus aggression. Overall, crown patch size and color were better predictors of dominance than were body size or sex. Several traits, including both crown features and morphological traits, predicted which individual avoided the other in dyadic interactions that did not escalate beyond avoidance. However, when dyads had similar gold crown patch sizes, the interaction was more likely to escalate, leading to aggression. In contrast to avoidance interactions, the outcomes of aggressive contests were largely predicted by variation in the color of black crown patches. Taken together, our results show that gold and black crown features operate as multiple status signals that accommodate an escalated gradient of interactions and suggest that social status involves more complexity than can be accommodated by a single signal

Altitudinal differences in foraging decisions under predation risk in great tits

International audienceForaging decisions under risk of predation are crucial for survival as predation risk can contribute to a reduction of food intake over time leading to a trade-off between starvation and predation. Environmental variation can provoke changes in food accessibility or predation risk that will in turn affect foraging decisions. Specifically, less predictable or harsher environments, such as those found at high elevation, should lead to more risk-prone foraging in order to prevent risk of starvation, but empirical confirmation of this hypothesis is lacking. In the current study, we used video playbacks combined with an automatic feeder to measure continuous foraging choices between control and predator videos by wild great tits originating from high and low elevations and tested under controlled conditions. Great tits discriminated between two conditions representing differences in predation risk and visited the feeder less frequently when a predator was shown. Moreover, we found that birds from low elevation populations were more risk-averse and visited the feeder significantly less when a predator video playback was broadcasted compared with high elevation individuals. This elevation-related contrast was also dependent on the season, body mass, and fat reserves of individuals, and was more marked in females. Furthermore, adults visited the feeder less in the presence of a predator compared with yearlings. These results are consistent with predictions from life-history theory and starvation–predation trade-off hypotheses and could have implications for individual movements and population dynamics in changing environments

Sexual conflict arising from extrapair matings in birds.

The discovery that extrapair copulation (EPC) and extrapair paternity (EPP) are common in birds led to a paradigm shift in our understanding of the evolution of mating systems. The prevalence of extrapair matings in pair-bonded species sets the stage for sexual conflict, and a recent focus has been to consider how this conflict can shape variation in extrapair mating rates. Here, we invert the causal arrow and consider the consequences of extrapair matings for sexual conflict. Extrapair matings shift sexual conflict from a simple two-player (male vs. female) game to a game with three or more players, the nature of which we illustrate with simple diagrams that highlight the net costs and benefits of extrapair matings to each player. This approach helps identify the sorts of traits that might be under selection because of sexual conflict. Whether EPP is driven primarily by the extrapair male or the within-pair female profoundly influences which players are in conflict, but the overall pattern of conflict varies little among different mating systems. Different aspects of conflict are manifest at different stages of the breeding cycle and can be profitably considered as distinct episodes of selection caused by conflict. This perspective is illuminating both because conflict between specific players can change across episodes and because the traits that evolve to mediate conflict likely differ between episodes. Although EPP clearly leads to sexual conflict, we suggest that the link between sexual conflict and multiple paternity might be usefully understood by examining how deviations from lifetime sexual monogamy influence sexual conflict