ИСТИНА

Basal metabolic rate (BMR) is a most examined energetic trait, which often considered to be an indicator of competitive ability of an animal. Several studies showed that BMR is a very flexible physiological trait and vary under the influence of many endogenous and environmental factors. To test whether BMR could be a characteristic feature of an individual, we estimated the repeatability of mass-specific BMR in natural populations of Pied Flycatcher (Ficedula hypoleuca) in Moscow region (55º44´N, 36º51´E) using our long-term (1992-2008) data-set and in Tomsk (56º20´N, 84º56´E; 2008-2009). In some years BMR of the same Pied Flycatcher males was measured two times within reproductive season: 1) shortly after arrival to breeding area in late April or early May, when males perform advertising behaviour; 2) in the middle of chick-rearing period in June. Males showed highly significant BMR increase from advertising period till chick-rearing period. As a consequence, BMR repeatability (R) within the same year was not significantly differ from zero (n=81). In Moscow the BMR repeatability measured in the same period of a season was R=0.40±0.09 between consecutive years (n=81), R=0.61±0.14 for 2 year interval (n=20) and R=0.85±0.13 for 3 year interval (n=6). In Tomsk the BMR repeatability between consecutive years was R=0.49±0.11 (n=50). This is a first report of BMR repeatability in free-living animals over period more than one year. The repeatability value sets the upper limit for heritability. Therefore, intra-individual consistency of BMR over considerable time intervals implies the potential for direct selection on this energetic trait.