Population variation in the metabolic response of deer mice to infection with &lt;i&gt;Capillaria&lt;/i&gt; &lt;i&gt;hepatica&lt;/i&gt; (Nematoda)

Meagher, Shawn; O’Connor, Timothy P.

doi:10.1139/cjz-79-4-554

Cited by 6 publications

(5 citation statements)

References 38 publications

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“…However, we did not detect an interactive effect of thermoregulation and pathogen infection on metabolic rate, indicating that the energetic costs of infection with M. gallisepticum are comparable at thermoneutral and subthermoneutral temperatures. Our results are consistent with previous work in endothermic rodents, which detected additive but not interactive effects of cold exposure and nematode parasitism on RMR (Kristan & Hammond 2000, 2003), but in contrast to work by Meagher & O’Connor (2001), which found that nematode infection resulted in increased metabolic rates in deer mice only under short‐term but severe cold stress (2 °C plus Heliox gas flow).…”

Section: Discussionsupporting

confidence: 92%

Additive metabolic costs of thermoregulation and pathogen infection

et al. 2012

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Summary1. Thermoregulation and pathogen resistance are two energetically demanding processes that co-occur during seasonal epidemics for many endothermic vertebrates. The ability of hosts to cope with these processes simultaneously may influence population-level disease dynamics. 2. In North American house finches (Carpodacus mexicanus), outbreaks of the bacterium Mycoplasma gallisepticum occur during fall and winter, when ambient temperatures across the host's range are often below thermoneutrality. Here, we examined how ambient temperature influences host energetics and susceptibility to this naturally occurring seasonal pathogen by experimentally infecting wild-caught house finches with M. gallisepticum at either thermoneutral or subthermoneutral temperatures in the laboratory. We quantified the metabolic costs of infection, measures of body condition, two components of the acute-phase response, disease expression and pathogen loads under both temperature regimes. 3. The metabolic costs of simultaneous infection with M. gallisepticum and thermoregulation were additive and significant (combined costs of 4AE71 kJ per night; within the range of the daily energy requirements of passerine moult). Contrary to our predictions, house finches at subthermoneutral temperatures had lower disease expression and higher circulating levels of the cytokine interleukin-6 in response to experimental infection with M. gallisepticum than finches at thermoneutral. However, pathogen loads did not differ between the two temperature treatments. Finches from both treatments expressed fever in response to infection, but the magnitude of fever did not vary with ambient temperature. 4. Despite the significant energy costs of infection and thermoregulation, house finches from both temperature treatments maintained body mass and pectoral muscle condition, suggesting that birds housed at subthermoneutral consumed more food to maintain energy balance. In the field, competition for finite resources would be expected to exacerbate the effects found here and force infected birds to spend more time at feeders where M. gallisepticum is transmitted. 5. Overall, our results indicate that moderate cold stress alters house finch immunity, energetics and disease pathology, but does not alter infectiousness as measured by pathogen load. The effects of ambient temperature on host response and energy demands could directly or indirectly contribute to seasonal and geographical variation in disease dynamics in free-living house finches. More broadly, our results suggest that even subtle changes in abiotic factors such as temperature can alter host disease expression, with broad implications for disease dynamics.

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Section: Discussionsupporting

confidence: 92%

Additive metabolic costs of thermoregulation and pathogen infection

et al. 2012

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“…How else can we explain the fact that a difference as small as 10% (often less!) between the mean resting MR of two populations, groups, or treatments can be the subject of pages of discussion while variation as large as 200% in resting MR among individuals does not even merit mention (Meagher and O'Connor 2001, Thomas et al 2001, Mathias et al 2006, Scantlebury et al 2007)? Many comparative eco‐physiologists may implicitly assume that among‐individual variation in resting MR is simply noise that has the undesirable effect of obscuring an underlying ecological or evolutionary signal.…”

Section: Energy Metabolism: the Mystery Of Intra‐specific Variationmentioning

confidence: 99%

Energy metabolism and animal personality

Careau

Thomas²,

Humphries³

et al. 2008

Oikos

741

833

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In this paper we show how animal personality could explain some of the large inter-individual variation in resting metabolic rate (MR) and explore methodological and functional linkages between personality and energetics. Personality will introduce variability in resting MR measures because individuals consistently differ in their stress response, exploration or activity levels, all of which influence MR measurements made with respirometry and the doubly-labelled water technique. Physiologists try to exclude these behavioural influences from resting MR measurements, but animal personality research indicates that these attempts are unlikely to be successful. For example, because reactive animals ''freeze'' when submitted to a stress, their MR could be classified as ''resting'' because of immobility when in fact they are highly stressed with an elevated MR. More importantly, recent research demonstrating that behavioural responses to novel and highly artificial stimuli are correlated with both behaviour and fitness under more natural circumstances calls into question the wisdom of excluding these behavioural influences on MR measurements. The reason that intra-specific variation in resting MR are so weakly correlated with daily energy expenditure (DEE) and fitness, may be that the latter two measures fully incorporate personality while the former partially excludes its influence. Because activity, exploration, boldness and aggressiveness are energetically costly, personality and metabolism should be correlated and physiological constraints may underlie behavioural syndromes. We show how physiological ecologists can better examine behavioural linkages between personality and metabolism, as required to better understand the physiological correlates of personality and the evolutionary consequences of metabolic variability.Although inter-individual variation in phenotypic traits is omnipresent, it has historically been considered to be noise superimposed on the evolutionarily important signal, the population mean. Recently, however, researchers from a broad array of ecological sub-disciplines Á population biology (Bolnick et al. 2003), epidemiology (Lloyd-Smith et al. 2005), endocrinology (Williams 2008), behavioural ecology (Wilson et al. 1994, Sih et al. 2004a, Réale et al. 2007, and physiology (Bennett 1987, this paper) Á have begun to consider inter-individual variation as an important ecological and evolutionary characteristic of wild populations. The burgeoning field of animal personality seeks to explain the maintenance of variation in numerous behavioural traits, including exploration, boldness, activity and stress response among others, by examining their fitness in a variety of ecological, developmental, and demographic contexts. In this forum, we argue that personality may explain some of the large observed variation in rates of energy metabolism in animals and we explore potential synergies between personality and metabolism research. Energy metabolism: the mystery of intra-specific variationEnergy is the c...

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“…The intensity of parasite-mediated selection, the degree of genetic isolation between populations, and the historical duration of the host-parasite contact are all likely to play important roles in determining the precise evolutionary response of a given population to parasites, leading to the possible development of local adaptations. Thus, for example, Meagher and O'Connor (2001) found that populations of deer mice (Peromyscus maniculatus (Wagner, 1845)) exhibited different degrees of resistance to nematodes (Capillaria hepatica) depending on their geographic location and the length of their historical association with the parasite.…”

Section: Introductionmentioning

confidence: 98%

Between-population differences in nestling size and hematocrit level in blue tits (Parus caeruleus): a cross-fostering test for genetic and environmental effects

Simon¹,

Thomas²,

Bourgault³

et al. 2005

Can. J. Zool.

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Geographically separated populations may diverge genetically in response to differing environmental conditions. Two populations of blue tits (Parus caeruleus L., 1758) that inhabit distinct valleys in northern Corsica are exposed to extreme differences in food abundance and parasite loads and show differences in nestling mass and hematocrit levels at fledging. We used partial cross-fostering coupled with experimental manipulation of parasite loads to test the hypothesis that between-population differences in nestling mass and hematocrit reflect adaptive genetic responses to differing parasite prevalence. Although asymptotic mass and hematocrit were strongly affected by variation in parasite loads and caterpillar abundance, we did not detect any significant genetic (population of origin) effect or genotype-environment interaction. We conclude that in these populations of blue tits, asymptotic mass and hematocrit are phenotypically plastic traits that are primarily set by environmental conditions during the sensitive growth phase. Résumé :Des populations séparées géographiquement peuvent réagir différemment à des conditions de milieu dissemblables pour des raisons génétiques. Deux populations de la mésange bleue (Parus caeruleus L., 1758) qui habitent des vallées distinctes du nord de la Corse sont exposées à des différences extrêmes d'abondance de nourriture et de charges parasitaires; elles montrent des différences dans les masses des oisillons au nid et dans les valeurs de l'hématocrite à l'envol. Nous avons procédé à des transferts partiels d'oisillons entre les nichées et nous avons manipulé expérimenta-lement les charges parasitaires afin d'éprouver l'hypothèse selon laquelle les différences entre les populations dans la masse des petits au nid et dans l'hématocrite à l'envol sont des réponses génétiques adaptatives à des prévalences diffé-rentes de parasites. Bien que la masse asymptotique et l'hématocrite soient fortement affectés par les variations de charges parasitaires et d'abondance de chenilles, nous n'avons pas décelé d'effet génétique significatif (d'après la population d'origine), ni d'interaction génotype-environnement. En conclusion, chez ces populations de mésanges bleues, la masse asymptotique et l'hématocrite sont des caractéristiques phénotypiques variables qui sont fixées principalement par les conditions du milieu durant la phase sensible de la croissance.[Traduit par la Rédaction] Simon et al. 701

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Population variation in the metabolic response of deer mice to infection with <i>Capillaria</i> <i>hepatica</i> (Nematoda)

Cited by 6 publications

References 38 publications

Additive metabolic costs of thermoregulation and pathogen infection

Additive metabolic costs of thermoregulation and pathogen infection

Energy metabolism and animal personality

Between-population differences in nestling size and hematocrit level in blue tits (Parus caeruleus): a cross-fostering test for genetic and environmental effects

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