Introduced and Native Congeners Use Different Resource Allocation Strategies to Maintain Performance during Infection

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Online enhancements: appendix, tables. The University of Chicago Press ABSTRACTHosts can manage parasitic infections using an array of tactics, which are likely to vary contingent on coevolutionary history between the host and the parasite. Here we asked whether coping ability of congeners that differ in host-parasite coevolutionary history differed in response to experimental infections with a coccidian parasite. House sparrows (Passer domesticus) and gray-headed sparrows (Passer griseus) are sympatric and ecologically similar, but house sparrows are recent colonizers of Kenya, the site of our comparison, whereas gray-headed sparrows are native. We evaluated three variables as barometers of infection coping ability: vertical flight, pectoral muscle size, and fat score. We also measured routing of a dose of 13 C-labeled leucine, an essential amino acid, among tissues to compare resource allocation strategies in response to infection. We found that burden effects on performance were minimal in both species, but house sparrows maintained considerably higher burdens than gray-headed sparrows regardless of exposure. House sparrows also had more exogeneous leucine tracer in all tissues after 24 h, demonstrating a difference in the way the two species allocate or distribute resources. We argue that house sparrows may be maintaining larger resource reserves to mitigate costs associated with exposure and infection. Additionally, in response to increased parasite exposure, gray-headed sparrows had less leucine tracer in their spleens and more in their gonads, whereas house sparrows did not change allocation, perhaps indicating a trade-off that is not experienced by the introduced species.

Highway to the danger zone: exposure‐dependent costs of immunity in a vertebrate ectotherm

“…(); Coon et al . (). After treatments, all individuals were returned to their respective housing and climate control containers.…”

“…; Coon et al . ). All procedures met guidelines for the use and care of animals in research and were approved by USF IACUC (W0059).…”

“…The 13 C‐leucine values measured in the liver and gonads were recorded as δ 13 C VPDB , which is the difference between the sample and an industry 13 C standard (Slater, Preston & Weaver ; Coon et al . ). The naturally occurring background δ 13 C was calculated from the average tissue values from the six individuals not dosed with leucine.…”

Stress and immunity at the invasion front: a comparison across cane toad (Rhinella marina) populations

“…Previous investigations into the effects of invasion on physiology, immunology and pathogens have used interspecific comparisons between invasive species and related non‐invasive taxa (Lee, Martin & Wikelski, ; Martin et al ., ; Coon et al ., ) or compared invasive taxa in their native vs. introduced ranges (Torchin et al ., ; Roche et al ., ). To understand the dynamics playing out on invasion fronts, however, a more robust approach is to make intraspecific comparisons along gradients from the invasion front through successively older populations towards the range core (Coon et al ., ; Martin & Liebl, ; Martin et al ., ; Martin, Liebl & Kilvitis, ). In the present study, we use the latter approach to identify in situ spatial patterns and interactions among immune measures, energy stores, stress response, and pathogen exposure in cane toads ( Rhinella marina ) across their invasive range in tropical Australia.…”

Plasma carotenoid levels in passerines are related to infection by (some) parasites

“…However, it is possible that the effects of the other groups of parasites on carotenoids is larger than for coccidians and had masked the results. It is also possible that the impact of coccidians (and any other of the groups of parasites studied) differs between species (see i.e., Coon et al, 2014) making difficult to detect significant correlations in comparative studies. Additionally, most of the samples in our study (69%) were collected during the morning, while studies in passerines showed a strong time of day-effect for passage of oocystsm with the peak in late afternoon/evening (Brawner and Hill, 1999;López et al, 2007).…”