Male interference with pollination efficiency in a hermaphroditic orchid

Area of Science:

• Plant reproductive biology
• Evolutionary ecology
• Sexual conflict in hermaphrodites

Background:

• Hermaphroditism presents potential for intra- and intersexual conflict between male and female reproductive functions.
• The impact of these sexual conflicts on pollination efficiency in hermaphroditic species remains under-investigated.

Purpose of the Study:

• To investigate whether male interference affects pollination efficiency in the self-compatible, moth-pollinated orchid Satyrium longicauda.
• To quantify the consequences of male function on pollination success and fecundity.

Main Methods:

• Partial emasculation of S. longicauda inflorescences to reduce male gamete availability.
• Comparison of pollination success and fecundity between partially emasculated and intact control plants.
• Color-labeling of pollen to track dispersal by hawkmoth pollinators.

Main Results:

• Partially emasculated flowers exported more pollen and received more cross-pollen but less self-pollen compared to intact flowers.
• Fruit set proportion per plant was similar across treatments.
• Fruits from partially emasculated plants exhibited a higher proportion of viable seeds.

Conclusions:

• Empirical evidence supports the occurrence of male interference with pollination efficiency in hermaphroditic plants.
• Male interference can negatively impact plant fecundity, likely due to competition for pollinator services (hawkmoth proboscis).
• Male competition for siring success may drive the evolution of sexual systems in hermaphroditic, pollinator-dependent plants.