Respiratory Q10 varies between populations of two species of Myrmica ants according to the latitude of their sites

Metabolic respiration by groups of resting Myrmica ruginodis and M. scabrin odis worker ants from five sites representing a range of latitudes, have be en compared by measuring rates of CO2 production-standardised by fat-free w eight-at 5 and 25 degrees C. M. ruginodis which lives in cooler habitats th an M. scabrinodis consistently produced more CO2. At 5 degrees C ants of bo th species from southern latitudes were metabolically more active than thos e from more northerly latitudes, whereas at 25 degrees C the situation was reversed. Estimates of Q10 were positively correlated with latitude indicat ing that the respiratory metabolism of northern populations increases relat ively more in response to rising temperatures than southern populations. Va lues of Q10 at different latitudes were the same for both species. The resu lts are discussed in terms of seasonal fluctuations of temperature at diffe rent latitudes. (C) 1999 Published by Elsevier Science Ltd. All rights rese rved.