Table 4. Contribution of assessed pre-pollination (A) and post-pollination (B) barriers to reproductive isolation (RI) between P. calyculatus (CO) and P. auriculatus (AO) in sympatry for the studied reproductive barriers. Isolation components generally vary from zero (no barrier) to one (complete isolation).

Contributions to total RI were calculated for sequential reproductive barriers, with the sum of contributions equaling total isolation. Sobel & Chen’s (2014) methodology was used for RI (see Supplemental Information for detailed explanations of RI calculations).

Isolating barrier	Raw values		Sobel & Chen (2014) RI value	Absolute cumulative strength	Relative cumulative strength
(A) Pre-pollination barriers affecting co-occurrence	Heterospecific	Conspecific
Host species isolation	0.200	0.800	0.800	0.800	0.808
Seed dispersers isolation	0.400	0.600	0.600	0.120	0.121
Pollinator isolation	0.800	0.200	0.200	0.016	0.016
(B) Post-pollination barriers not affecting co-occurrence	Shared	Unshared
CO Fruit set	0.185	0.814	0.629	0.049	0.049
AO Fruit set	0.400	0.600	0.200	0.005	0.005
Total isolation	0.990