Time filter

Source Type

Maldonado K.,Institute Filosofia Y Ciencias Of La Complejidad | Bozinovic F.,University of La Serena | Rojas J.,University of Santiago de Chile | Sabat P.,University of Chile
Physiological and Biochemical Zoology | Year: 2011

The climatic variability hypothesis (CVH) states that species are geographically more widespread at higher latitudes because individuals have a broader range of physiological tolerance or phenotypic flexibility as latitude and climatic variability increase. However, it remains unclear to what extent climatic variability or latitude, acting on the phenotype, account for any observed geographical gradient in mean range size. In this study, we analyzed the physiological flexibility within the CVH framework by using an intraspecific population experimental approach. We tested for a positive relationship between digestive- tract flexibility (i.e., morphology and enzyme activities) and latitude and climatic and natural diet variability in populations of rufous-collared sparrows (Zonotrichia capensis) captured in desert (27°S), Mediterranean (33°S), and coldtemperate (41°S) sites in Chile. In accordance with the CVH, we observed a positive relationship between the magnitude of digestive-tract flexibility and environmental variability but not latitude. The greatest digestive flexibility was observed in birds at middle latitudes, which experience the most environmental variability (a Mediterranean climate), whereas individuals from the most stable climates (desert and cold-temperate) exhibited little or no digestive-tract flexibility in response to experimental diets. Our findings support the idea that latitudinal gradients in geographical ranges may be strongly affected by the action of regional features, which makes it difficult to find general patterns in the distribution of species.© 2011 by The University of Chicago. All rights reserved.


Gonzalez-Gomez P.L.,Institute Filosofia Y Ciencias Of La Complejidad | Razeto-Barry P.,Institute Filosofia Y Ciencias Of La Complejidad | Razeto-Barry P.,Diego Portales University | Araya-Salas M.,New Mexico State University | Estades C.F.,University of Chile
Integrative and Comparative Biology | Year: 2015

In the context of global change the possible loss of biodiversity has been identified as a major concern. Biodiversity could be seriously threatened as a direct consequence of changes in availability of food, changing thermal conditions, and loss and fragmentation of habitat. Considering the magnitude of global change, an understanding of the mechanisms involved in coping with a changing environment is urgent. We explore the hypothesis that species and individuals experiencing highly variable environments are more likely to develop a wider range of responses to handle the different and unpredictable conditions imposed by global change. In the case of vertebrates, the responses to the challenges imposed by unpredictable perturbations ultimately are linked to cognitive abilities allowing the solving of problems, and the maximization of energy intake. Our models were hummingbirds, which offer a particularly compelling group in which to examine the functional and mechanistic links between behavioral and energetic strategies in individuals experiencing different degrees of social and environmental heterogeneity. © 2015 The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.


Van Dongen W.F.D.,University of Chile | Maldonado K.,University of Chile | Maldonado K.,Institute Filosofia Y Ciencias Of La Complejidad | Sabat P.,University of Chile | And 2 more authors.
Behavioral Ecology | Year: 2010

Animal personalities are interindividual behavioral differences that are consistent across time or contexts. Increasing research is revealing the adaptive significance of personalities, although the mechanisms driving this variation remain largely unknown. A possible source of variation in personality traits is interpopulational differences in the strength of selection acting upon them. The response to selection can be measured indirectly via the behavior's repeatability, as repeatability generally sets an upper limit to trait heritability. However, no information currently exists on geographic variation in personality repeatability. We therefore quantified repeatability in exploratory behavior, a common personality trait, over multiple trials for 3 populations of rufous-collared sparrow (Zonotrichia capensis), focusing on 3 specific measures (exploration speed, diversity of perches visited, and number of hops). We also asked how differences in repeatability of these 3 measures affect other aspects of exploration, such as the temporal consistency of intercorrelations between the measures. Exploration speed was highly repeatable across all populations, whereas diversity was only repeatable in 2 of 3 populations and hopping behavior not at all. These differences in repeatability lead to temporal variation in the correlation matrices of the 3 exploration measures. Finally, only trial number influenced interindividual variability in exploration, whereas population identity, experimental conditions (i.e., conducting the novel environment assay under laboratory or field conditions), and time since capture all had no effect. Our findings highlight the complexity of using measures of behavioral consistency as a definition of personalities and emphasize the value of quantifying interpopulational patterns of trait repeatability. © The Author 2010. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved.


Razeto-Barry P.,Institute Filosofia Y Ciencias Of La Complejidad | Razeto-Barry P.,University of Chile | Razeto-Barry P.,Diego Portales University | Diaz J.,Institute Filosofia Y Ciencias Of La Complejidad | And 2 more authors.
Genetics | Year: 2012

The general theories of molecular evolution depend on relatively arbitrary assumptions about the relative distribution and rate of advantageous, deleterious, neutral, and nearly neutral mutations. The Fisher geometrical model (FGM) has been used to make distributions of mutations biologically interpretable. We explored an FGM-based molecular model to represent molecular evolutionary processes typically studied by nearly neutral and selection models, but in which distributions and relative rates of mutations with different selection coefficients are a consequence of biologically interpretable parameters, such as the average size of the phenotypic effect of mutations and the number of traits (complexity) of organisms. A variant of the FGM-based model that we called the static regime (SR) represents evolution as a nearly neutral process in which substitution rates are determ ined by a dynamic substitutionprocess in which the population's phenotype remains around a suboptimum equilibrium fitness produced by a balance between slightly deleterious and slightly advantageous compensatory substitutions. As in previous nearly neutral models, the SR predicts a negative relationship between molecular evolutionary rate and population size; however, SR does not have the unrealistic properties of previous nearly neutral models such as the narrow window of selection strengths in which they work. In addition, the SR suggests that compensatory mutations cannot explain the high rate of fixations driven by positive selection currently found in DNA sequences, contrary to what has been previously suggested. We also developed a generalization of SR in which the optimum phenotype can change stochastically due to environmental or physiological shifts, which we called the variable regime (VR). VR models evolution as an interplay between adaptive processes and nearly neutral steady-state processes. When strong environmental fluctuations are incorporated, the process becomes a selection model in which evolutionary rate does not depend on population size, but is critically dependent on the complexity of organisms and mutation size. For SR as well as VR we found that key parameters of molecular evolution are linked by biological factors, and we showed that they cannot be fixed independently by arbitrary criteria, as has usually been assumed in previous molecular evolutionary models. © 2012 by the Genetics Society of America.


Gonzalez-Gomez P.L.,University of Chile | Gonzalez-Gomez P.L.,Institute Filosofia Y Ciencias Of La Complejidad | Bozinovic F.,University of Chile | Vasquez R.A.,University of Chile
Animal Behaviour | Year: 2011

Episodic memory has been described as the ability to recall personal past events, involving what, where and when an event has been experienced. Cognitive abilities like learning and memory are pivotal to the performance of many behavioural traits such as food procurement. Nectar, the primary food of hummingbirds, is dispersed in hundreds of flowers and varies in concentration and renewal rate. Therefore, a hummingbird that can remember elements of episodic-like memory such as what, where and when the nectar becomes available will have a higher energy rate of intake when compared to random foraging. We conducted a field experiment with green-backed firecrown hummingbirds, Sephanoides sephaniodes. We assessed the ability to recall the location, nectar quality and renewal rate of the most rewarding flowers among several less rewarding flowers with identical visual cues. Hummingbirds were able to remember the most profitable nectar sources and flower position and adjust their visits to nectar renewal interval. Cognitive performance varied among individuals, implying up to 6.3-fold differences in energy gain. Our results strongly suggest that hummingbirds use cognitive abilities to exploit nectar sources efficiently and, therefore, that cognitive abilities are potentially tied to survival probability. © 2011 The Association for the Study of Animal Behaviour.


Romero-Maltrana D.,Pontifical Catholic University of Valparaíso | Romero-Maltrana D.,Institute Filosofia Y Ciencias Of La Complejidad
Studies in History and Philosophy of Science Part B - Studies in History and Philosophy of Modern Physics | Year: 2015

There is general consensus among physicists in considering symmetries as a source of conserved quantities, a conclusion allegedly supported by Emmy Noether's theorems. Recently it has been pointed out that no arrow of explanation can be extracted from Noether's work, and there are also criticisms against the priority of particular symmetries over specific conserved quantities under Noether's ideas, but there are no general arguments against the aforementioned consensus, nor proposals promoting an explanation that leads from conserved quantities to symmetries. In this paper a general argument is built which favours conserved quantities over symmetries inasmuch as the presence of the former seems to allow (i.e. it seems to be a sufficient condition leading to) symmetrical descriptions. © 2015 Elsevier Ltd.


Ossa G.,Programa Para la Conservacion de Los Murcielagos de Chile PCMCh | Pedro A.R.-S.,Institute Filosofia Y Ciencias Of La Complejidad
Mammalian Species | Year: 2015

Myotis chiloensis (Waterhouse, 1838), the Chilean myotis, is found only in Argentina and Chile, where it is the most common bat species in the southern part of Chile. It is a small insectivorous bat and differs from other members of the genus because of its darker pelage. It uses human buildings and caves to establish colonies, and forages in dense forests of Nothofagus to capture insects, thereby providing ecosystem services to agriculture and forestry. M. chiloensis is considered of "Least Concern" by the International Union for Conservation of Nature and Natural Resources. © 2015 by American Society of Mammalogists.


Razeto-Barry P.,Institute Filosofia Y Ciencias Of La Complejidad | Frick R.,Institute Filosofia Y Ciencias Of La Complejidad | Frick R.,Andrés Bello University | Frick R.,Diego Portales University
Studies in History and Philosophy of Science Part C :Studies in History and Philosophy of Biological and Biomedical Sciences | Year: 2011

The explanatory role of natural selection is one of the long-term debates in evolutionary biology. Nevertheless, the consensus has been slippery because conceptual confusions and the absence of a unified, formal causal model that integrates different explanatory scopes of natural selection. In this study we attempt to examine two questions: (i) What can the theory of natural selection explain? and (ii) Is there a causal or explanatory model that integrates all natural selection explananda? For the first question, we argue that five explananda have been assigned to the theory of natural selection and that four of them may be actually considered explananda of natural selection. For the second question, we claim that a probabilistic conception of causality and the statistical relevance concept of explanation are both good models for understanding the explanatory role of natural selection. We review the biological and philosophical disputes about the explanatory role of natural selection and formalize some explananda in probabilistic terms using classical results from population genetics. Most of these explananda have been discussed in philosophical terms but some of them have been mixed up and confused. We analyze and set the limits of these problems. © 2011 Elsevier Ltd.


Razeto-Barry P.,Institute Filosofia Y Ciencias Of La Complejidad | Razeto-Barry P.,Diego Portales University
Origins of Life and Evolution of Biospheres | Year: 2012

The concept of autopoiesis was proposed 40 years ago as a definition of a living being, with the aim of providing a unifying concept for biology. The concept has also been extended to the theory of knowledge and to different areas of the social and behavioral sciences. Given some ambiguities of the original definitions of autopoiesis, the concept has been criticized and has been interpreted in diverse and even contradictory ways, which has prevented its integration into the biological sciences where it originated. Here I present a critical review and conceptual analysis of the definition of autopoiesis, and propose a new definition that is more precise, clear, and concise than the original ones. I argue that the difficulty in understanding the term lies in its refined conceptual subtlety and not, as has been claimed by some authors, because it is a vacuous, trivial or very complex concept. I also relate the concept of autopoiesis to the concepts of closed systems, boundaries, homeostasis, self-reproduction, causal circularity, organization and multicellularity. I show that under my proposed definition the concept of a molecular autopoietic system is a good demarcation criterion of a living being, allowing its general integration into the biological sciences and enhancing its interdisciplinary use. © 2012 Springer Science+Business Media Dordrecht.


Razeto-Barry P.,Institute Filosofia Y Ciencias Of La Complejidad | Razeto-Barry P.,Institute Ecologia y Biodiversidad | Diaz J.,Institute Filosofia Y Ciencias Of La Complejidad | Cotoras D.,Institute Filosofia Y Ciencias Of La Complejidad | And 2 more authors.
Genetics | Year: 2011

The influence of phenotypic effects of genetic mutations on molecular evolution is not well understood. Neutral and nearly neutral theories of molecular evolution predict a negative relationship between the evolutionary rate of proteins and their functional importance; nevertheless empirical studies seeking relationships between evolutionary rate and the phenotypic role of proteins have not produced conclusive results. In particular, previous studies have not found the expected negative correlation between evolutionary rate and gene pleiotropy. Here, we studied the effect of gene pleiotropy and the phenotypic size of mutations on the evolutionary rate of genes in a geometrical model, in which gene pleiotropy was characterized by n molecular phenotypes that affect organismal fitness. For a nearly neutral process, we found a negative relationship between evolutionary rate and mutation size but pleiotropy did not affect the evolutionary rate. Further, for a selection model, where most of the substitutions were fixed by natural selection in a randomly fluctuating environment, we also found a negative relationship between evolutionary rate and mutation size, but interestingly, gene pleiotropy increased the evolutionary rate as √n. These findings may explain part of the disagreement between empirical data and traditional expectations. Copyright © 2011 by the Genetics Society of America.

Loading Institute Filosofia Y Ciencias Of La Complejidad collaborators
Loading Institute Filosofia Y Ciencias Of La Complejidad collaborators