Immunocompetence and high metabolic rates enhance overwinter survival in the root vole, Microtus oeconomus

Abstract

Despite its presumed significance, the association between immune defence, energy expenditures and overwinter survival is rarely studied. We analysed individual variation in immunocompetence quantified as neutrophil-tolymphocyte ratio (N/L), total white blood cells (WBC) and natural antibody levels, along with resting (RMR) and peak metabolic rates (PMR) and mortality during three consecutive winter seasons in a natural population of the root vole, Microtus oeconomus. In early winter, WBC count was negatively correlated with RMR, whereas N/L ratio was negatively correlated with swim-elicited PMR. We suggest that while the first correlation reflected the trade-off between energy allocation in immunocompetence and other metabolically demanding processes, the latter correlation stemmed from stress-induced immunosuppression elicited by the necessity to cope with swimming in frequently flooded habitat. In addition, the analysis carried out during the first year of study characterized by a high population density and prevalence of infestation with a blood parasite-Babesia spp., showed that its intensity was inversely correlated with the N/L ratio. In summary, our results suggest that elevated N/L ratio increases the winter survival of free-ranging rodents by increasing their ability to cope with parasitic infections.

Capacity of blood plasma is higher in birds breeding in radioactively contaminated areas

“…Different immune components are not necessarily positively related to each other [41]. Although negative associations are consistent with a trade-off between different components of immunity [42], other studies detected positive or no associations among different lines of immunity [43].…”

“…Although selection acting on the immune system of birds at Chernobyl during the last 30 years may explain inconsistency of results and the absence of a relationship between different levels of radioactivity and innate immune response of individuals affected by the Chernobyl catastrophe, this could also be due to different aspects of immune responses being investigated in different studies. Different immune components are not necessarily positively related to each other [ 41 ]. Although negative associations are consistent with a trade-off between different components of immunity [ 42 ], other studies detected positive or no associations among different lines of immunity [ 43 ].…”

Effect of seasonal changes on the innate immunity of wild Pseudois nayaur: potential reason for its endangerment

“…In this study, WBC was found the highest in winter and the upward trend was also obvious for the recovery of immunity in many other immunology findings, which are complied with similar phenomenon found previously in root voles. The rising number of WBC and other indexes would make them survive better in winter Zub, 2014；Książek andZub, 2017). For the reason of the primier rising of MCV in autumn might suggest the mechanism of resistance to the reduction of MCH and MCHC.…”