Determinants of clutch size and cone in Leucadendron (Proteaceae); Pleiotropy versus trade-offs

Abstract

This study aimed at determining the correlates of clutch size (seed size, seed number and total seed mass per infruotescence) and infructescence (cone) size. A large (hundredfold) variation was found in cone size and seed size amongst the 21 serotinous species of Leucadendron (Proteaceae) investigated. At the interspecific level, total seed mass per infructestence and also infructescence mass was most strongly correlated with mean seed size rather than with the number of seeds per infructescence. This suggests that pleiotropy (correlated effects of a controller gene) is more important than negative trade-offs (size versus number) as an explanation for this pattern. At the intraspecific level, total seed mass and cone mass was more strongly correlated with seed number than seed size. At both the inter- and intraspecific level there was no significant negative correlation between seed number and seed size per cone. Again this suggests no trade-offs occur at the level of the cone.