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Daniel T. Blumstein - One of the best experts on this subject based on the ideXlab platform.

  • Sociality in New World hystricognath rodents is linked to predators and burrow digging
    Behavioral Ecology, 2006
    Co-Authors: Luis A Ebensperger, Daniel T. Blumstein
    Abstract:

    The importance of predation and burrow digging in explaining the evolution of sociality is generally unclear. We focused on New World hystricognath rodents to evaluate three key predictions of the predation hypothesis. First, large-bodied surface-dwelling species will be more vulnerable because they are more detectable; thus sociality should be associated with body size. Second, surface-dwelling, diurnal species would be more vulnerable to predators than nocturnal species; thus sociality should be associated with the evolution of Diurnality. Third, species living in open habitats will be more vulnerable; thus sociality should evolve in species living in open habitats. Regarding the importance of burrows, we tested if species that dig burrows can benefit from communal labor; thus, sociality should be associated with burrow digging. All traits had significant phylogenetic signal, thus comparative analyses should explicitly address this. In a comparative analysis on independent contrasts we found that sociality was correlated with body size (larger species were more social), Diurnality (diurnal species were more social), and burrowing (burrowing species were more social), but we found no effect of overhead plant cover of habitat on sociality in hystricognath rodents. Somewhat different results were found when we analyzed the raw data. Taken together, our results provide support for a link between predation risk, burrow digging, and sociality in this group. Copyright 2006.

  • the evolution of vocal alarm communication in rodents
    Behavioral Ecology, 2005
    Co-Authors: Erin L Shelley, Daniel T. Blumstein
    Abstract:

    On encountering a predator, many species emit potentially risky vocalizations known as alarm calls. We evaluated the relative importance of two adaptive hypotheses on the evolution of calling: (1) communicating to predators, which may function by deterring pursuit and hence increasing individual survival, and (2) an alternative nepotistic hypothesis for alarm calling whereby callers obtain direct and indirect fitness by warning relatives. Focusing on 209 species of rodents, we found significant associations between Diurnality and alarm calling, living socially and alarm calling, and Diurnality and sociality. Diurnality, however, accounted for nearly three times as much variation in whether or not a species alarm called than did sociality. Phylogenetic tests revealed that the evolution of Diurnality preceded the evolution of alarm calling, and that the evolutions of Diurnality and sociality were unrelated. Our results are consistent with the hypothesis that alarm communication evolved to communicate to predators. If so, then nepotistic benefits, although important for the maintenance of alarm calling in some rodents, may be relatively less important in its evolution. Copyright 2005.

  • The evolution of vocal alarm communication in rodents
    2005
    Co-Authors: Erin L Shelley, Daniel T. Blumstein
    Abstract:

    On encountering a predator, many species emit potentially risky vocalizations known as alarm calls. We evaluated the relative importance of two adaptive hypotheses on the evolution of calling: (1) communicating to predators, which may function by deterring pursuit and hence increasing individual survival, and (2) an alternative nepotistic hypothesis for alarm calling whereby callers obtain direct and indirect fitness by warning relatives. Focusing on 209 species of rodents, we found significant associations between Diurnality and alarm calling, living socially and alarm calling, and Diurnality and sociality. Diurnality, however, accounted for nearly three times as much variation in whether or not a species alarm called than did sociality. Phylogenetic tests revealed that the evolution of Diurnality preceded the evolution of alarm calling, and that the evolutions of Diurnality and sociality were unrelated. Our results are consistent with the hypothesis that alarm communication evolved to communicate to predators. If so, then nepotistic benefits, although important for the maintenance of alarm calling in some rodents, may be relatively less important in its evolution. Key words: alarm calling, evolution, rodent behavior. [Behav Ecol] Why animals emit potentially risky alarm calls has puzzledevolutionary biologists for decades (Klump and Shalter, 1984; Maynard Smith, 1965), and understanding the adaptive utility of alarm communication has been influential in explaining the evolution of social behavior through kin selection (Keller and Reeve, 2002). Since Sherman’s (1977

Toon A B Van Veen - One of the best experts on this subject based on the ideXlab platform.

  • analysis of 24 h rhythm in ventricular repolarization identifies qt Diurnality as a novel clinical parameter associated with previous ventricular arrhythmias in heart failure patients
    Frontiers in Physiology, 2017
    Co-Authors: Bastiaan C Du Pre, Linda W Van Laake, M Meine, Jeroen F Van Der Heijden, Pieter A Doevendans, Marc A Vos, Toon A B Van Veen
    Abstract:

    Introduction: Cardiac repolarization abnormalities are among the major causes of ventricular arrhythmias and sudden cardiac death. In humans, cardiac repolarization duration has a 24-hour rhythm. Animal studies show that this rhythm is regulated by 24-hour rhythms in ion channel function and that disruption of this rhythm leads to ventricular arrhythmias. We hypothesized that 24-hour rhythms in QT duration can be used as a predictor for sudden cardiac death and are associated with ventricular arrhythmias. Secondly, we assessed a possible mechanistic explanation by studying the putative role of hERG channel dysfunction. Materials and Methods: In 2 retrospective studies, measures of the 24-hour variation in the QT and QTc intervals (QT and QTc Diurnality, QTd and QTcd respectively) have been derived from Holter analyses and compared between groups: 1) 39 post-infarct patients with systolic heart failure (CHF: EF<35 %), of which 14 with, and 25 without a history of ventricular arrhythmias and 2) 5 patients with proven (LQTS2) and 16 with potential (Sotalol-induced) hERG channel dysfunction vs 22 controls. Results: QTd was 2-fold higher in CHF patients with a history of ventricular arrhythmias (38±15ms) compared to CHF patients without VT (16±9ms, p=0.001). QTd was significantly increased in LQT2 patients (43±24ms) or those treated with Sotalol (30±10ms) compared to controls (21±8ms, p<0.05 for both). Discussion: QT Diurnality presents a novel clinical parameter of repolarization that can be derived from Holter registrations and may be useful for identification of patients at risk for ventricular arrhythmias.

Horacio O De La Iglesia - One of the best experts on this subject based on the ideXlab platform.

  • light intensity determines temporal niche switching of behavioral activity in deep water nephrops norvegicus crustacea decapoda
    Journal of Biological Rhythms, 2010
    Co-Authors: Juan Jose Chiesa, Jacopo Aguzzi, Jose A Garcia, Francesc Sarda, Horacio O De La Iglesia
    Abstract:

    The temporal distribution of behavioral programs throughout the 24-h day, known as temporal niche of a species, is determined by ecological factors that directly affect the adaptive value of the timing of specific behaviors. Temporal niche switching has been described in several species and is likely adaptive in habitats where the daily timing of those factors changes. Benthic species whose habitats span a wide range of water depths are exposed to considerable depth-dependent environmental changes. Temporally scheduled trawl surveys of the Norway lobster, Nephrops norvegicus, reveal that animals emerge from burrows at night on the shallow shelf (10-50 m deep), at crepuscular hours on the lower shelf (50-200 m), and at daytime on the slope (200-400 m). The mechanisms underlying nocturnality/Diurnality switches are chiefly unknown, and Nephrops offers a unique model for their study. The depth-dependent decrease in luminance is a likely candidate determining the temporal distribution of behavior. The authors explored this possibility in the laboratory by exposing Nephrops to light:dark (LD) cycles of 470-nm monochromatic lighting that mimic conditions at the 100-m-deep shelf (10 lux) or the 300-m slope (0.1 lux). Two groups of animals were respectively exposed to each light intensity according to the following protocol: an initial 12:12 LD stage followed by constant darkness (DD), followed in turn by a second 12:12 LD stage. Activity at the burrow opening (door-keeping = DK), as well as full emergence (E), was continuously monitored. Under 10-lux LD cycles, most animals showed nocturnal DK activity-with some being crepuscular or diurnal-and all animals showed nocturnal E activity. In contrast, both behaviors were clearly diurnal in animals under 0.1-lux LD cycles. The phase of the nocturnal and diurnal DK rhythms detected respectively at 10 and 0.1 lux upon release into DD revealed that these rhythms are entrained circadian rhythms. The present data indicate that nocturnality/Diurnality switches in Nephrops in its natural habitat, evidenced by captures at different depths, are likely determined by light intensity. This temporal niche switching involves different patterns of photic entrainment, leading to bona fide circadian diurnal or nocturnal phenotypes, as well as exogenous masking of behavioral outputs.

Roelof A Hut - One of the best experts on this subject based on the ideXlab platform.

  • Diurnality as an energy saving strategy energetic consequences of temporal niche switching in small mammals
    The Journal of Experimental Biology, 2015
    Co-Authors: Vincent Van Der Vinne, Jenke A Gorter, Sjaak J Riede, Roelof A Hut
    Abstract:

    Endogenous daily (circadian) rhythms allow organisms to anticipate daily changes in the environment. Most mammals are specialized to be active during the night (nocturnal) or day (diurnal). However, typically nocturnal mammals become diurnal when energetically challenged by cold or hunger. The circadian thermo-energetics (CTE) hypothesis predicts that diurnal activity patterns reduce daily energy expenditure (DEE) compared with nocturnal activity patterns. Here, we tested the CTE hypothesis by quantifying the energetic consequences of relevant environmental factors in mice. Under natural conditions, Diurnality reduces DEE by 6-10% in energetically challenged mice. Combined with night-time torpor, as observed in mice under prolonged food scarcity, DEE can be reduced by ∼20%. The dominant factor determining the energetic benefit of Diurnality is thermal buffering provided by a sheltered resting location. Compared with nocturnal animals, diurnal animals encounter higher ambient temperatures during both day and night, leading to reduced thermogenesis costs in temperate climates. Analysis of weather station data shows that Diurnality is energetically beneficial on almost all days of the year in a temperate climate region. Furthermore, Diurnality provides energetic benefits at all investigated geographical locations on European longitudinal and latitudinal transects. The reduction of DEE by Diurnality provides an ultimate explanation for temporal niche switching observed in typically nocturnal small mammals under energetically challenging conditions. Diurnality allows mammals to compensate for reductions in food availability and temperature as it reduces energetic needs. The optimal circadian organization of an animal ultimately depends on the balance between energetic consequences and other fitness consequences of the selected temporal niche.

  • Preference for twilight activity or diurnal activity.
    2014
    Co-Authors: Erik P. Ensing, Simone Ciuti, Freek A. L. M. De Wijs, Dennis H. Lentferink, André Ten Hoedt, Mark S. Boyce, Roelof A Hut
    Abstract:

    Crepuscularity (A–D) and Diurnality (E–F) indices for male (A,C,E,G) and female (B,D,F,H) red deer in the Veluwezoom (A,B,E,F) and Alberta (C,D,G,H). The black line represents the average index value, the grey areas represent the 95% confidence interval, which can be interpreted as a one-sided T-test: when the 95% confidence interval (grey area) does not encompass the 0 line, the activity pattern significantly deviates from an equal distribution (p

Gisele A Oda - One of the best experts on this subject based on the ideXlab platform.

  • nocturnal to diurnal switches with spontaneous suppression of wheel running behavior in a subterranean rodent
    PLOS ONE, 2015
    Co-Authors: Patricia Tachinardi, Oivind Toien, Veronica S Valentinuzzi, Loren C Buck, Gisele A Oda
    Abstract:

    Several rodent species that are diurnal in the field become nocturnal in the lab. It has been suggested that the use of running-wheels in the lab might contribute to this timing switch. This proposition is based on studies that indicate feed-back of vigorous wheel-running on the period and phase of circadian clocks that time daily activity rhythms. Tuco-tucos (Ctenomys aff. knighti) are subterranean rodents that are diurnal in the field but are robustly nocturnal in laboratory, with or without access to running wheels. We assessed their energy metabolism by continuously and simultaneously monitoring rates of oxygen consumption, body temperature, general motor and wheel running activity for several days in the presence and absence of wheels. Surprisingly, some individuals spontaneously suppressed running-wheel activity and switched to Diurnality in the respirometry chamber, whereas the remaining animals continued to be nocturnal even after wheel removal. This is the first report of timing switches that occur with spontaneous wheel-running suppression and which are not replicated by removal of the wheel.

  • diurnos ou noturnos discutindo padroes temporais de atividade Diurnality and nocturnality discussing activity patterns
    2012
    Co-Authors: Barbara M Tomotani, Gisele A Oda
    Abstract:

    Resumo. A classificacao de um animal como diurno ou noturno parece, a primeira vista, extremamente simples quando se caracteriza o comportamento geral. Entretanto, tal distincao nao e tao evidente nem na natureza e nem nas condicoes artificiais de laboratorio. Atualmente, os mecanismos fisiologicos que definem mamiferos diurnos e noturnos estao sendo investigados em diversos niveis biologicos. Relatos de animais com fases diferentes de atividade em laboratorio e em campo estao aumentando, podendo revelar um aspecto fundamental da organizacao temporal, especialmente em mamiferos. Palavras-chave. Arrastamento, mascaramento, ritmo diario, roedores.