Flower shape and visitor specialization in the Colletieae (Rhamnaceae)

MEDAN, DIEGO; AAGESEN, LONE; HILGER, HARTMUT

St. Louis, USA

Congreso; XVI International Botanical Congress; 1999

Intermediate floral tubes are basic and both long- and short tubes are derived in the Colletieae. To understand (a) trait distribution across the tribe, and (b) how generalist relationships are maintained or lost, we correlated tube depth and composition of visiting assemblages. Both flower depth and visitor specialization grow in the generic sequence Discaria - Trevoa - Retanilla - Colletia. Intermediate specialization seems ancestral (as conserved in the Trevoa - Retanilla clade), in the sister clade specialization either increases (Colletia subclade) or decreases Discaria subclade). Generalist pollination is associated with variable Diptera-dominated assemblages, the opposite trend approaches eutropic floral syndromes in Colletia.