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Merrill L.,University of Illinois at Urbana - Champaign | Merrill L.,University of California at Santa Barbara | Stewart T.E.,University of California at Santa Barbara | Stewart T.E.,University of Illinois at Urbana - Champaign | And 6 more authors.
Physiological and Biochemical Zoology | Year: 2015

Some sexually selected signals are thought to convey information about the current condition and genetic/epigenetic quality of the individual signaling, including the ability to resist parasites. However, it is unclear whether semistatic sexual signals that develop periodically and remain stable over protracted periods, such as avian breeding plumage, can relate to measures of current condition and health. We examined a semistatic signal (wing epaulet size) in male redwinged blackbirds (Agelaius phoeniceus) during the breeding season and looked for relationships between this trait and circulating testosterone (T), hematocrit, bacteriakilling ability (BKA) of the blood, and the infection status, richness, and abundance of four functional categories of parasite. We found that epaulet size was positively related to circulating levels of T and ectoparasite infections. We found no relationships between T and parasite infections. In adult males there was a negative relationship between T and BKA, whereas in yearling males there was no relationship. We found no evidence for a general reduction in immunocompetence in males with larger epaulets but rather an increase in susceptibility to specific types of parasites. Our results suggest that semistatic signals can be linked to measures of current condition, and we postulate that these relationships are modulated via activity levels related to breedingseason activities. © 2014 by The University of Chicago. All rights reserved.


Gonzalez-Gomez P.L.,University of California at Davis | Gonzalez-Gomez P.L.,Institute Filosofia Y Ciencias Of La Complejidad Ificc | Merrill L.,Oklahoma State University | Ellis V.A.,University of Missouri-St. Louis | And 4 more authors.
General and Comparative Endocrinology | Year: 2013

Previous studies show that most birds inhabiting temperate regions have well defined life history stages, and they modulate the production of testosterone (T) and corticosterone (CORT) in response to changes in seasonality. In this study we aimed to examine baseline and stress-induced levels of CORT and circulating T in relation with life history stages in the rufous-collared sparrow, Zonotrichia capensis. We carried out this study for a year in a population inhabiting riparian habitats in the Atacama Desert in Chile, one of the most climatically stable and driest places in the world. This environment shows minimal yearly change in average temperature and precipitation is virtually zero. We found individuals breeding, molting and overlapping breeding and molt year round, although most individuals were molting during March and in breeding condition during October. T levels were not related to individual breeding condition, and at population level they were not significantly different across sampling months. Baseline levels of CORT did not vary across the year. Stress-induced levels of CORT were suppressed during March when most of the birds were molting. This phenomenon was also observed in birds not molting during this period suggesting a mechanism other than molt in determining the stress-response suppression. Our results strongly suggest that in this study site, long-term extremely stable conditions could have relaxed the selective pressures over the timing of life history stages which was evidenced by the breeding and molt schedules, its overlap and endocrine profiles. © 2013 Elsevier Inc.


Gonzalez-Gomez P.L.,University of California at Davis | Gonzalez-Gomez P.L.,Institute Filosofia Y Ciencias Of La Complejidad Ificc | Vasquez R.A.,University of Chile | Bozinovic F.,Linc Global
Auk | Year: 2011

We assessed how individual foraging preferences and cognitive performance affect foraging bout interval and the flexibility of foraging behavior in the nectarivorous Green-backed Firecrown (Sephanoides sephaniodes). Our field experiment evaluated the ability of these hummingbirds to recall nectar-renewal rates in two groups of artificial flowers with the same nectar concentration in the absence of visual cues. In a second experiment, we assessed their ability to remember differences in nectar quality combined with different nectar-renewal intervals, given artificial flowers with identical visual cues. Our results indicate that Green-backed Firecrowns adjusted their foraging intervals according to nectar-renewal rates and, furthermore, that birds were able to recall nectar concentration as well as nectar-renewal rate. Individual differences in memory performance resulted in differences in energy intake. These results strongly suggest that individual preferences and individual cognitive performance could play a central role in energy intake and, therefore, in the probability of survival. © The American Ornithologists' Union, 2011.


Gonzalez-Gomez P.L.,University of California at Davis | Gonzalez-Gomez P.L.,Institute Filosofia Y Ciencias Of La Complejidad Ificc | Ricote-Martinez N.,Linc Global | Razeto-Barry P.,Institute Filosofia Y Ciencias Of La Complejidad Ificc | And 3 more authors.
Behavioral Ecology and Sociobiology | Year: 2011

A common assumption in behavioral ecology is that the valuation of a resource by consumers depends on the energetic value of the resource itself. Nevertheless, the value of a resource may be relative to the condition of the organism, which is in turn related to the abiotic conditions such as ambient temperature. We developed a theoretical model-incorporating these untested assumptions-to predict a functional relationship between territorial aggression and ambient temperature for individuals sensitive to daily variations in energy availability. We evaluated our theoretical predictions against a field experiment carried out with the hummingbird Sephanoides sephaniodes. The model predicted a quadratic relation between aggression intensity and ambient temperature. Field data were better explained by a quadratic equation than a linear function, suggesting the existence of lower and upper thresholds of temperature which determine the intensity of territorial defense. Ambient temperature affects energy expenditure for thermoregulation, and therefore, it fixes the benefit level that must be produced by the territory to pay the costs of its defense. Our findings strongly suggest that abiotic conditions can change an animal evaluation of the yield of a resource and in turn influence the behavioral strategy which it adopts. © 2011 Springer-Verlag.


Hornung-Leoni C.T.,Autonomous University of the State of Hidalgo | Gonzalez-Gomez P.L.,University of California at Davis | Gonzalez-Gomez P.L.,Institute Filosofia Y Ciencias Of La Complejidad Ificc | Troncoso A.J.,Institute Filosofia Y Ciencias Of La Complejidad Ificc | Troncoso A.J.,University of La Serena
Acta Oecologica | Year: 2013

Five Andean Puya species (. P uya alpestris, P uya chilensis, P uya coerulea, P uya raimondii and P uya venusta) were studied to determine the relationship between their avian visitors, and plant morphology and nectar characteristics. Our results showed a significant relationship between nectar concentration, presence of sterile apex and avian pollinators's species. In contrast, nectar composition was not related to the frequency of avian visits. We found that Puya species were mainly visited by specialist nectarivorous birds such as hummingbirds (i.e., P.coerulea and P.venusta), lacked a sterile apex and produced highnectar concentration in low volumes. In contrast, species mainly visited by generalist passerines (i.e., P. chilensis and P.alpestris) were characterized by the presence of a sterile apex and production of highly diluted nectar in large volumes. In a mono-specific group we found that P.raimondii produces highly concentrated nectar in large volumes, and its flowers were visited by hummingbirds and passerine birds. We found no effect of nectar composition on bird's visits. Our study highlights the interplay between morphological traits, nectar characteristics and the ecological framework to explain specialized and generalized birds pollination systems. © 2013 Elsevier Masson SAS.


PubMed | University of Colorado at Boulder, University of Missouri-St. Louis, University of Chile, University of Illinois at Urbana - Champaign and 2 more.
Type: | Journal: General and comparative endocrinology | Year: 2015

Rufous-collared sparrows (Zonotrichia capensis peruviensis) from valleys in the Atacama Desert of Chile, live in an extremely stable environment, and exhibit overlap in molt and reproduction, with valley-specific differences in the proportion of birds engaged in both. To better understand the mechanistic pathways underlying the timing of life-history transitions, we examined the relationships among baseline and stress-induced levels of corticosterone (CORT), testosterone, and bacteria-killing ability of the blood plasma (BKA), as well as haemosporidian parasite infections and the genetic structure of two groups of sparrows from separate valleys over the course of a year. Birds neither molting nor breeding had the lowest BKA, but there were no differences among the other three categories of molt-reproductive stage. BKA varied over the year, with birds in May/June exhibiting significantly lower levels of BKA than the rest of the year. We also documented differences in the direction of the relationship between CORT and BKA at different times during the year. The direction of these relationships coincides with some trends in molt and reproductive stage, but differs enough to indicate that these birds exhibit individual-level plasticity, or population-level variability, in coordinating hypothalamo-pituitary-adrenal axis activity with life-history stage. We found weak preliminary evidence for genetic differentiation between the two populations, but not enough to indicate genetic isolation. No birds were infected with haemosporidia, which may be indicative of reduced parasite pressure in deserts. The data suggest that these birds may not trade off among different life-history components, but rather are able to invest in multiple life-history components based on their condition.


Bich L.,University of the Basque Country | Bich L.,Institute Filosofia Y Ciencias Of La Complejidad Ificc | Mossio M.,University of Paris 13 | Ruiz-Mirazo K.,University of the Basque Country | Moreno A.,University of the Basque Country
Biology and Philosophy | Year: 2015

Biological regulation is what allows an organism to handle the effects of a perturbation, modulating its own constitutive dynamics in response to particular changes in internal and external conditions. With the central focus of analysis on the case of minimal living systems, we argue that regulation consists in a specific form of second-order control, exerted over the core (constitutive) regime of production and maintenance of the components that actually put together the organism. The main argument is that regulation requires a distinctive architecture of functional relationships, and specifically the action of a dedicated subsystem whose activity is dynamically decoupled from that of the constitutive regime. We distinguish between two major ways in which control mechanisms contribute to the maintenance of a biological organisation in response to internal and external perturbations: dynamic stability and regulation. Based on this distinction an explicit definition and a set of organisational requirements for regulation are provided, and thoroughly illustrated through the examples of bacterial chemotaxis and the lac-operon. The analysis enables us to mark out the differences between regulation and closely related concepts such as feedback, robustness and homeostasis. © 2015 Springer Science+Business Media Dordrecht


Veloz T.,University of British Columbia | Veloz T.,Institute Filosofia Y Ciencias Of La Complejidad Ificc | Razeto-Barry P.,Institute Filosofia Y Ciencias Of La Complejidad Ificc | Razeto-Barry P.,Diego Portales University | And 2 more authors.
Journal of Mathematical Biology | Year: 2014

The powerful mathematical tools developed for the study of large scale reaction networks have given rise to applications of this framework beyond the scope of biochemistry. Recently, reaction networks have been suggested as an alternative way to model social phenomena. In this "socio-chemical metaphor" molecular species play the role of agents' decisions and their outcomes, and chemical reactions play the role of interactions among these decisions. From here, it is possible to study the dynamical properties of social systems using standard tools of biochemical modelling. In this work we show how to use reaction networks to model systems that are usually studied via evolutionary game theory. We first illustrate our framework by modeling the repeated prisoners' dilemma. The model is built from the payoff matrix together with assumptions of the agents' memory and recognizability capacities. The model provides consistent results concerning the performance of the agents, and allows for the examination of the steady states of the system in a simple manner. We further develop a model considering the interaction among Tit for Tat and Defector agents. We produce analytical results concerning the performance of the strategies in different situations of agents' memory and recognizability. This approach unites two important theories and may produce new insights in classical problems such as the evolution of cooperation in large scale systems. © 2012 Springer-Verlag Berlin Heidelberg.


Kreyssig P.,Friedrich - Schiller University of Jena | Wozar C.,Friedrich - Schiller University of Jena | Peter S.,Friedrich - Schiller University of Jena | Veloz T.,University of British Columbia | And 6 more authors.
Bioinformatics | Year: 2014

Motivation: The functioning of many biological processes depends on the appearance of only a small number of a single molecular species. Additionally, the observation of molecular crowding leads to the insight that even a high number of copies of species do not guarantee their interaction. How single particles contribute to stabilizing biological systems is not well understood yet. Hence, we aim at determining the influence of single molecules on the long-term behaviour of biological systems, i.e. whether they can reach a steady state. Results: We provide theoretical considerations and a tool to analyse Systems Biology Markup Language models for the possibility to stabilize because of the described effects. The theory is an extension of chemical organization theory, which we called discrete chemical organization theory. Furthermore we scanned the BioModels Database for the occurrence of discrete chemical organizations. To exemplify our method, we describe an application to the Template model of the mitotic spindle assembly checkpoint mechanism.. © The Author(s) 2014.


Aerts D.,The Interdisciplinary Center | Sozzo S.,The Interdisciplinary Center | Sozzo S.,University of Leicester | Veloz T.,The Interdisciplinary Center | And 2 more authors.
International Journal of Theoretical Physics | Year: 2015

Increasing experimental evidence shows that humans combine concepts in a way that violates the rules of classical logic and probability theory. On the other hand, mathematical models inspired by the formalism of quantum theory are in accordance with data on concepts and their combinations. In this paper, we investigate a new connection between concepts and quantum entities, namely the way both behave with respect to ‘identity’ and ‘indistinguishability’. We do this by considering conceptual entities of the type Eleven Animals, were a number is combined with a noun. In the combination Eleven Animals, indeed the ‘animals’ are identical and indistinguishable, and our investigation aims at identifying the nature of this conceptual identity and indistinguishability. We perform experiments on human subjects and find significant evidence of deviation from the predictions of classical statistical theories, more specifically deviations with respect to Maxwell-Boltzmann statistics. This deviation is of the ‘same type’ of the deviation of quantum mechanical from classical mechanical statistics, due to indistinguishability of microscopic quantum particles, i.e we find convincing evidence of the presence of Bose-Einstein statistics. We also present preliminary promising evidence of this phenomenon in a web-based study. © 2015, Springer Science+Business Media New York.

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