Jumping performance in the highly aquatic frog, Xenopus tropicalis : sex-specific relationships between morphology and performance

Frogs are characterized by a morphology that has been suggested to be related to their unique jumping specialization. Yet, the functional demands associated with jumping and swimming may not be that different as suggested by studies with semi-aquatic frogs. Here, we explore whether features previously identified as indicative of good burst swimming performance also predict jumping performance in a highly aquatic frog, Xenopus tropicalis. Moreover, we test whether the morphological determinants of jumping performance are similar in the two sexes and whether jumping performance differs in the two sexes. Finally we test whether jumping capacity is positively associated with burst swimming and terrestrial endurance capacity in both sexes. Our results show sex-specific differences in jumping performance when correcting for differences in body size. Moreover, the features determining jumping performance are different in the two sexes. Finally, the relationships between different performance traits are sex-dependent as well with females, but not males, showing a trade-off between peak jumping force and the time jumped to exhaustion. This suggests that different selective pressures operate on the two sexes, with females being subjected to constraints on locomotion due to their greater body mass and investment in reproductive capacity. In contrast, males appear to invest more in locomotor capacity giving them higher performance for a given body size compared to females

Multi-level agent-based modeling - A literature survey

During last decade, multi-level agent-based modeling has received significant and dramatically increasing interest. In this article we present a comprehensive and structured review of literature on the subject. We present the main theoretical contributions and application domains of this concept, with an emphasis on social, flow, biological and biomedical models.Comment: v2. Ref 102 added. v3-4 Many refs and text added v5-6 bibliographic statistics updated. v7 Change of the name of the paper to reflect what it became, many refs and text added, bibliographic statistics update

Mounting a specific immune response increases energy expenditure of the subterranean rodent Ctenomys talarum (tuco-tuco): Implications for intraspecific and interspecific variation in immunological traits

It was recently hypothesised that specific induced defences, which require substantial time and resources and are mostly beneficial against repeated infections, are more likely to be favoured in 'slow-living-pace' species. Therefore, understanding how different types of immune defences might vary with life history requires knowledge of the costs and benefits of defence components. Studies that have explored the energetic costs of immunity in vertebrates have done so with a focus primarily on birds and less so on mammals, particularly surface-dwelling rodents. In this study, we evaluated whether an experimental induction of the immune system with a non-pathogenic antigen elevates the energetic expenditure of a subterranean rodent: Ctenomys talarum (tuco-tucos). In both seasons studied, a significant increase in oxygen consumption was verified in immunechallenged tuco-tucos injected with sheep red blood cells (SRBC) compared with control animals. The increase in oxygen consumption 10 days after the exposure to SRBC was lower for female tuco-tucos monitored in the breeding season compared with females in the non-breeding season. Interestingly, antibody titres of female tuco-tucos did not decrease during the breeding season. Our results add new insight into the role of other factors such as basal metabolic rate or degree of parasite exposure besides 'pace of life' in modulating the interspecific immunological variation observed in natural populations of mammals.Fil: Cutrera, Ana Paula. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Ecofisiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Zenuto, Roxana Rita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Ecofisiología; ArgentinaFil: Luna, Facundo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Ecofisiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Antenucci, Carlos Daniel. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Ecofisiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentin

The evolution and protective benefits of immune responses in North American house finches (Haemorhous mexicanus) to Mycoplasma gallisepticum

Pathogen spillover to novel hosts represents a huge selective event, and can result in rapid evolutionary changes in both the pathogen and the host. However, it is seldom possible to identify which specific host characteristics are under selection following emergence, nor understand the evolutionary repercussions of these changes. In the early 1990’s, Mycoplasma gallisepticum emerged in North American house finches (Haemorhous mexicanus) following a jump from poultry. Previous studies monitoring disease spread and response to infection provided details of temporal and geographic patterns of host history of exposure, including evidence of the evolution of resistance in populations with a long history of exposure. In this thesis, I explore the specific host responses that were subject to selection following disease emergence in coevolved, relative to unexposed populations and evaluate how this led to the qualitative disease dynamics previously observed. In chapter one, I show that susceptibility to infection must be equal in both susceptible and resistant host genotypes in order for selection to occur, with mortality avoidance most likely driving the mode and tempo of rapid selection on resistance and virulence evolution observed in this system. In the second chapter, I find limited evidence for a protective benefit of a commonly measured immune component: systemic antibody, and show other important immune processes that are involved in host resistance, including an avoidance of immune manipulation. Findings presented here demonstrate the importance of the specific mechanism of host responses in determining evolutionary trajectories

Frog origins: inferences based on ancestral reconstructions of locomotor performance and anatomy

Frogs are the most species-rich and ecologically diverse group of amphibians and are characterized by a unique body plan including long legs, elongated ilia, and fused caudal vertebrae. Stem anurans such as Triadobatrachus or Czatkobatrachus have been suggested to have used jumping or hopping as part of their locomotor repertoire based on their anatomy. The earliest known true frog, Prosalirus bitis was suggested to have been a proficient jumper. However, data on jumping performance in frogs have never been used to attempt reconstruction of ancestral features at the base of the radiation. Here we provide data on jumping performance (forces and acceleration) in 20 species of extant frogs including representatives of most of the early radiating clades. We next use ancestral character value inferences to assess ancestral features. Our analyses suggest that frog ancestors were of small to medium size, had relatively short limbs, produced rather low jump forces, yet were capable of relatively high acceleration. Given the short limbs and low forces, the unique frog bauplan with a reduced vertebral column and a mobile ilio-sacral joint may not have been an adaptation for powerful jumping

Understanding the Evolution of Emerging Bacterial Pathogens in Response to Host Resistance

Understanding the evolution of parasites and hosts following a host-shit event is increasingly recognised as being of great importance to public health and the clinical/veterinary sciences in predicting the behaviour and evolutionary consequences of emerging infectious diseases. Microbial pathogenesis and virulence are remarkably complex traits, and only by considering them in the context of their hosts can we begin to unravel key questions as to how and why disease emerges and persists. The period immediately following a host-shift event, where a pathogen circulating in one host species successfully jumps into another is critical – whether such outbreak events “burn out” or become endemic, and what the ramifications of this might be are difficult to model and predict. That microbial pathogens and their hosts are in a close coevolutionary relationship has been evident since the early days of our understanding of disease, but it is only relatively recently that the ecological, molecular, genomic and bioinformatic tools all required to understand the subject have become widely available and applicable. In the work presented within this thesis, we utilise an exceptionally well monitored and studied novel host-pathogen interaction – that of the avian bacterial pathogen Mycoplasma gallisepticum and its recently infected novel host the House Finch (Haemorhous mexicanus). Approximately 25 years ago this pathogen jumped from its established host in chickens into the wild passerine finch species, triggering an epidemic which has been well monitored from the outset We aim to address how host-pathogen coevolution drives particularly the evolution of microbial virulence. Our current understanding of such host-pathogen interactions within an evolutionary context centres around the mathematical and ecological framework of the “Trade-off hypothesis”, but many of the assumptions linking pathogen virulence, transmission and replication have been difficult to test or to integrate with our modern understanding of how microbial virulence is manifested on a molecular level. In exploring these issues throughout this text, we consider that this work has progressed our understanding in this field and goes some way towards this integration of evolutionary theory and more descriptive classical microbiology / molecular biology.Natural Environment Research Council (NERC

Accounting for Patterns of Collective Behavior in Crowd Locomotor Dynamics for Realistic Simulations

International audienceDo people in a crowd behave like a set of isolated individuals or like a cohesive group? Studies of crowd modeling usually consider pedestrian behavior either from the point of view of an isolated individual or from that of large swarms. We introduce here a study of small crowds walking towards a common goal and propose to make the link between individual behavior and crowd dynamics. Data show that participants, even though not instructed to behave collectively, do form a cohesive group and do not merely treat one another as obstacles. We present qualitative and quantitative measurements of this collective behavior, and propose a first set of patterns characterizing such behavior. This work is part of a wider effort to test crowd models against observed data

Innate Immunity and the Evolution of Resistance to an Emerging Infectious Disease in a Wild Bird

Innate immunity is expected to play a primary role in conferring resistance to novel infectious diseases, but few studies have attempted to examine its role in the evolution of resistance to emerging pathogens in wild vertebrate populations. Here, we used experimental infections and cDNA microarrays to examine whether changes in the innate and/or acquired immune responses likely accompanied the emergence of resistance in house finches (Carpodacus mexicanus) in the eastern United States subject to a recent outbreak of conjunctivitis-causing bacterium (Mycoplasma gallisepticum—MG). Three days following experimental infection with MG, we observed differences in the splenic transcriptional responses between house finches from eastern U.S. populations, with a 12-year history of MG exposure, versus western U.S. populations, with no history of exposure to MG. In particular, western birds down-regulated gene expression, while eastern finches showed no expression change relative to controls. Studies involving poultry have shown that MG can manipulate host immunity, and our observations suggest that pathogen manipulation occurred only in finches from the western populations, outside the range of MG. Fourteen days after infection, eastern finches, but not western finches, up-regulated genes associated with acquired immunity (cell-mediated immunity) relative to controls. These observations suggest population differences in the temporal course of the response to infection with MG and imply that innate immune processes were targets of selection in response to MG in the eastern U.S. population.Organismic and Evolutionary Biolog

Quantitative host resistance drives the evolution of increased virulence in an emerging pathogen

Emergent infectious diseases can have a devastating impact on host populations. The high selective pressures on both the hosts and the pathogens frequently lead to rapid adaptations not only in pathogen virulence but also host resistance following an initial outbreak. However, it is often unclear whether hosts will evolve to avoid infection‐associated fitness costs by preventing the establishment of infection (here referred to as qualitative resistance ) or by limiting its deleterious effects through immune functioning (here referred to as quantitative resistance ). Equally, the evolutionary repercussions these different resistance mechanisms have for the pathogen are often unknown. Here, we investigate the co‐evolutionary dynamics of pathogen virulence and host resistance following the epizootic outbreak of the highly pathogenic bacterium Mycoplasma gallisepticum in North American house finches (Haemorhous mexicanus ). Using an evolutionary modelling approach and with a specific emphasis on the evolved resistance trait, we demonstrate that the rapid increase in the frequency of resistant birds following the outbreak is indicative of strong selection pressure to reduce infection‐associated mortality. This, in turn, created the ecological conditions that selected for increased bacterial virulence. Our results thus suggest that quantitative host resistance was the key factor underlying the evolutionary interactions in this natural host–pathogen system.Publisher PDFPeer reviewe