PHYLOGENETIC AUTOCORRELATION AND EVOLUTIONARY CONSTRAINTS IN WORKER BODY-SIZE OF SOME NEOTROPICAL STINGLESS BEES (HYMENOPTERA, APIDAE)

Developments in the analysis of comparative data in evolutionary biolo gy suggest that it is possible to partition the total variance of some quantitative trait into a phylogenetic component, which contains that part of the variation attributed to common ancestry with other specie s, and a specific component, which results from independent evolution after cladogenesis. In this paper, we analysed the variation in worker body size across 16 neotropical species of stingless bees (Meliponina e), using phylogenetic autocorrelation models to evaluate evolutionary constraints in this complex trait. Body size was defined in a multiva riate sense as the first principal component extracted from the covari ance matrix of 10 log-transformed morphometric characters. The estimat ed phylogenetic autoregressive coefficient (p) was equal to 0.495 +/- 0.192, indicating that only 24.5 per cent of variability in worker bod y size can be attributed to inertial phylogenetic effects. This relati vely low value of p in bees is to be expected, considering that this c omplex trait has traditionally been recognized as an expression of wor ker adaptation related to foraging activity and resource exploitation.