Hybrid Mimulus flowers attract a new pollinator.

Area of Science:

• Plant reproductive biology
• Evolutionary ecology
• Pollination biology

Background:

• Hybridization is a significant evolutionary process in flowering plants.
• Hybrid offspring can display novel trait combinations.
• These new traits may alter plant-pollinator interactions, potentially driving speciation.

Purpose of the Study:

• To investigate pollinator attraction in hybrids of Mimulus cardinalis and Mimulus parishii.
• To identify the floral traits responsible for novel pollinator attraction in these hybrids.
• To explore the role of petal color genetics in mediating bumblebee interactions.

Main Methods:

• Cross-pollination experiments between Mimulus cardinalis and Mimulus parishii.
• Observation and identification of pollinators attracted to hybrid flowers.
• Analysis of floral traits: nectar concentration, corolla size, and petal color.
• Reflectance spectroscopy and multispectral imaging to model flower appearance in bee vision.
• Genetic analysis focusing on the YUP locus.

Main Results:

• Hybrids attracted bumblebees (Bombus impatiens), a pollinator not visiting either parent species.
• Novel pollinator attraction was linked to a combination of petal color, nectar concentration, and corolla size.
• Flower color variation in hybrids significantly impacts detectability by bumblebees.
• The YUP genetic locus was confirmed to be crucial for this novel bumblebee attraction.

Conclusions:

• Hybridization can lead to the attraction of novel pollinators, facilitating pollinator shifts.
• Floral trait variation, particularly petal color influenced by the YUP locus, is key to new pollinator interactions.
• The attraction of new pollinators to hybrid plants represents an understudied mechanism for plant speciation.