Ryan L. Earley

Bio: Ryan L. Earley is an academic researcher from University of Alabama. The author has contributed to research in topics: Mangrove rivulus & Population. The author has an hindex of 33, co-authored 127 publications receiving 3806 citations. Previous affiliations of Ryan L. Earley include Georgia State University & California State University, Fresno.

Modulation of aggressive behaviour by fighting experience: mechanisms and contest outcomes.

Abstract: Experience in aggressive contests often affects behaviour during, and the outcome of, later contests. This review discusses evidence for, variations in, and consequences of such effects. Generally, prior winning experiences increase, and prior losing experiences decrease, the probability of winning in later contests, reflecting modifications of expected fighting ability. We examine differences in the methodologies used to study experience effects, and the relative importance and persistence of winning and losing experiences within and across taxa. We review the voluminous, but somewhat disconnected, literature on the neuroendocrine mechanisms that mediate experience effects. Most studies focus on only one of a number of possible mechanisms without providing a comprehensive view of how these mechanisms are integrated into overt behaviour. More carefully controlled work on the mechanisms underlying experience effects is needed before firm conclusions can be drawn. Behavioural changes during contests that relate to prior experience fall into two general categories. Losing experiences decrease willingness to engage in a contest while winning experiences increase willingness to escalate a contest. As expected from the sequential assessment model of contest behaviour, experiences become less important to outcomes of contests that escalate to physical fighting. A limited number of studies indicate that integration of multiple experiences can influence current contest behaviour. Details of multiple experience integration for any species are virtually unknown. We propose a simple additive model for this integration of multiple experiences into an individual's expected fighting ability. The model accounts for different magnitudes of experience effects and the possible decline in experience effects over time. Predicting contest outcomes based on prior experiences requires an algorithm that translates experience differences into contest outcomes. We propose two general types of model, one based solely on individual differences in integrated multiple experiences and the other based on the probability contests reach the escalated phase. The difference models include four algorithms reflecting possible decision rules that convert the perceived fighting abilities of two rivals into their probabilities of winning. The second type of algorithm focuses on how experience influences the probability that a subsequent contest will escalate and the fact that escalated contests may not be influenced by prior experience. Neither type of algorithm has been systematically investigated. Finally, we review models for the formation of dominance hierarchies that assume that prior experience influences contest outcome. Numerous models have reached varied conclusions depending on which factors examined in this review are included. We know relatively little about the importance of and variation in experience effects in nature and how they influence the dynamics of aggressive interactions in social groups and random assemblages of individuals. Researchers should be very active in this area in the next decade. The role of experience must be integrated with other influences on contest outcome, such as prior residency, to arrive at a more complete picture of variations in contest outcomes. We expect that this integrated view will be important in understanding other types of interactions between individuals, such as mating and predator-prey interactions, that also are affected significantly by prior experiences.

Eavesdropping on visual cues in green swordtail (Xiphophorus helleri) fights: a case for networking

Abstract: Aggressive contests probably occur in networking environments where information about fighting ability is conveyed both to an opponent and to individuals peripheral to the fight itself, the bystanders. Our primary aim was to investigate the relative influences of eavesdropping and prior social experience on the dynamics of aggressive contests in Xiphophorus helleri . A bystander's ability to witness an encounter was manipulated using clear, one–way mirror, and opaque partitions. After watching (or not watching) the initial contest, the bystander encountered either the winner or loser of the bout. Treatment comparisons of bystander–winner or bystander–loser contest dynamics indicated the presence or absence of winner, loser, or eavesdropping effects. Winner and loser effects had negligible influences on bystander contest dynamics. Eavesdropping significantly reduced the bystander's propensity to initiate aggression, escalate, and win against seen winners regardless of whether the watched bout had escalated or not. Though eavesdropping had relatively little effect on bystander–loser contest dynamics, bystanders were less prone to initiate aggression and win against losers that had escalated in the witnessed bout. Thus, bystanders appear to preferentially retain and utilize information gained about potentially dangerous opponents (winners or persistent losers). Our data lend clear support for the importance of eavesdropping in visually based aggressive signalling systems.

An evolutionary framework for studying mechanisms of social behavior

Abstract: Social interactions are central to most animals and have a fundamental impact upon the phenotype of an individual. Social behavior (social interactions among conspecifics) represents a central challenge to the integration of the functional and mechanistic bases of complex behavior. Traditionally, studies of proximate and ultimate elements of social behavior have been conducted by distinct groups of researchers, with little communication across perceived disciplinary boundaries. However, recent technological advances, coupled with increased recognition of the substantial variation in mechanisms underlying social interactions, should compel investigators from divergent disciplines to pursue more integrative analyses of social behavior. We propose an integrative conceptual framework intended to guide researchers towards a comprehensive understanding of the evolution and maintenance of mechanisms governing variation in sociality.

An evolutionary framework for studying mechanisms of social behavior Working Group on Integrative Models of Vertebrate Sociality: Evolution, Mechanisms, and Emergent Properties

Abstract: 1 The University of Texas at Austin, Department of Integrative Biology and Institute for Cellular and Molecular Biology, 2415 Speedway, Austin, TX 78712, USA 2 Smith College, Department of Psychology and Program in Neuroscience, Northampton, MA 01063, USA 3 University of California, Department of Ecology and Evolutionary Biology, 621 Young Drive South, Los Angeles, CA 90095-1606, USA 4 Princeton University, Department of Ecology and Evolutionary Biology, Princeton, NJ 08644, USA 5 University of Alabama, Department of Biological Sciences, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA 6 University of Tennessee at Chattanooga, Department of Biological and Environmental Sciences, Chattanooga, TN 37403, USA 7 University of Alberta, Department of Psychology and Centre for Neuroscience, Edmonton, Alberta, T6G 2E9, Canada 8 University of California at Berkeley, Museum of Vertebrate Zoology and Department of Integrative Biology, 3101 Valley Life Sciences Building, Berkeley, CA 94720-3160, USA 9 Miami University, Department of Biology, Oxford, OH 45056, USA 10 University of Bern, Institute of Ecology and Evolution, Division of Behavioural Ecology, Wohlenstrasse 50a, 3032 Hinterkappelen, Switzerland 11 Emory University, Center for Translational Social Neuroscience, Yerkes National Primate Research Center, 954 Gatewood Road, Atlanta, GA 30329, USA 12 Columbia University, Department of Ecology, Evolution and Environmental Biology, 1200 Amsterdam Avenue, New York, NY 10027, USA Review

Human biochemical genetics

Abstract: So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Biochemistry of oxidative stress

Abstract: The terms 'antioxidant', 'oxidative stress' and 'oxidative damage' are widely used but rarely defined. This brief review attempts to define them and to examine the ways in which oxidative stress and oxidative damage can affect cell behaviour both in vivo and in cell culture, using cancer as an example.

Consilience: The Unity of Knowledge.

Abstract: When the red harvester ant is threatened, nestmates rush to its assistance. The message is a chemical one. Distress is communicated and help summoned by the potential victim ejecting a tiny cocktail of alkanes and terpenoids. Professor E 0 Wilson, who made this discovery, is a distinguished zoologist whose writings have twice been awarded Pulitzer Prizes. His interests extend far beyond entomology, however. Why should human communication be qualitatively different from that of the ant, in being achieved by definable, physicochemical processes? And, if this is the case, surely the same must be true of other social phenomena? Having conceded so much, on what grounds can we exclude other products of human activity such as the social sciences, arts, humanities and ethics? In a mechanistic universe, the whole of human civilization is the ultimate product of the interaction between genes and environment, incredibly complex, as Wilson admits, but susceptible to fundamentally the same analytic techniques as communication in the harvester ant. Consilience (literally, a 'jumping together') is the notion that a common groundwork of explanation applies not only to the sciences but also to the arts, ethics and religion. In his book Consiliencel Wilson applies a combination of broad learning and a style of baroque exuberance to put the case for such a unity of knowledge. Wilson is thus, as he makes clear, a child of the Enlightenment, paying homage to Bacon and Newton but most of all to Condorcet, who trod the same intellectual path (and who came to grief in the Revolution for reasons probably not unrelated to his philosophy). He mourns the triumph at the end of the eighteenth century of revelatory religion fearful of the outcomes of science, and most of all of Romanticism although regrettably overlooking the

Neural mechanisms of aggression

Abstract: Unchecked aggression and violence exact a significant toll on human societies. Aggression is an umbrella term for behaviours that are intended to inflict harm. These behaviours evolved as adaptations to deal with competition, but when expressed out of context, they can have destructive consequences. Uncontrolled aggression has several components, such as impaired recognition of social cues and enhanced impulsivity. Molecular approaches to the study of aggression have revealed biological signals that mediate the components of aggressive behaviour. These signals may provide targets for therapeutic intervention for individuals with extreme aggressive outbursts. This Review summarizes the complex interactions between genes, biological signals, neural circuits and the environment that influence the development and expression of aggressive behaviour.