Is resource overlap disadvantageous to three sympatric legumes?

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Abstract
The sympatric legumes Dillwynia hispida, Dillwynia uncinata and Pultenaea densifolia overlap in flowering phenology, floral characters and native bee pollinators. Tests for pollen‐limitation were conducted to determine whether or not the overlap in pollinator use was detrimental to individuals of these species. Pollen limitation was only detected in D. hispida. Pollen loads on bees were examined and it was found that pollen loads from Dillwynia and P. densifolia were spatially segregated on the pollinator's body reducing the likelihood of pollen transfer between these species. The pollen of D. hispida and D. uncinata overlapped on the heads of bees suggesting that interspecific pollinations may be responsible for lowered fruit‐set in D. hispida. However, hand pollinations involving heterospecific pollen and controlled floral visits by bees to the two Dillwynia species revealed that heterospecific pollen loads did not significantly depress fruit‐set in either D. hispida or D. uncinata. Pollinator preferences were examined in detail and it was found that D. uncinata flowers received twice as many bees in a day compared with D. hispida and P. densifolia. Competition through pollinator preference is implicated here as a mechanism of competition. Intraspecific competition is also implicated as D. hispida was pollen limited in the absence of D. uncinata and P. densifolia.