SHOULD CONGRUENCE BETWEEN INTRASPECIFIC AND INTERSPECIFIC ECOMORPHOLOGICAL RELATIONSHIPS BE EXPECTED - A CASE-STUDY WITH THE GREAT TIT, PARUS-MAJOR

We studied the relationship between leg morphology and posture while f eeding in a population of great tits (Parus major) under controlled co nditions to investigate to what extent morphology and ecology are link ed at the individual level. From predictions generated at the interspe cific level within the genus Parus (Moreno & Carrascal 1993), we teste d whether intra- and interspecific ecomorphological relationships are consistent. Within our population, neither leg bone lengths nor leg mu scle morphology were related to the feeding posture of individuals. Ho wever, differences in body weight were correlated with interindividual differences in time spent hanging. These results demonstrate that the association between intra- and interspecific ecomorphological relatio nships is not uniform. We argue that, at the intraspecific level, body weight overrides the significance of other traits that have a functio nal meaning at the interspecific level (i.e. leg segment lengths, musc ular morphology), due to isometric variation of morphological traits ( muscular and skeletal) with body mass. Thus, the discrepancy between t he ecomorphological associations at intra- and interspecific levels is the result of a problem of scale (morphological changes in evolutiona ry time and isometric variation of morphological traits with body mass in ecological time).