Pollen adaptation to ant pollination: a case study from the Proteaceae

Area of Science:

• Ecology
• Botany
• Pollination Biology

Background:

• Ant-plant interactions are diverse, encompassing antagonistic and mutualistic relationships.
• Ant pollination is a rare mutualistic interaction, with limited scientific documentation.
• Conospermum (Proteaceae) is an insect-pollinated genus native to southwestern Australia.

Purpose of the Study:

• To evaluate the role of ants as pollinators for Conospermum undulatum.
• To assess the pollen viability and carrying capacity of ants for C. undulatum.
• To determine the contribution of ants to the reproductive success of C. undulatum.

Main Methods:

• Pollen germination tests were conducted after exposure to ants and bees for C. undulatum and other plant species.
• Floral visitors of C. undulatum were sampled to quantify pollen loads carried by ants.
• Exclusion experiments (ants, flying insects, control) were performed to measure seed set.

Main Results:

• Conospermum undulatum pollen exhibited an ~80% germination rate after ant contact, similar to bee pollination.
• Other tested plant species showed a significant decrease (~10%) in pollen germination after ant contact.
• Ants carried substantial pollen loads (68-86% viable grains) and significantly contributed to C. undulatum seed set.

Conclusions:

• Generalizations about ants as ineffective pollinators are challenged by these findings.
• Conospermum undulatum pollen possesses resistance to ant secretions, enabling effective pollination.
• Ants provide crucial pollination services to the threatened species Conospermum undulatum.