The keel colour polymorphism in Lotus corniculatus L.: differences in internal flower temperatures

Area of Science:

• Ecology
• Plant Biology
• Evolutionary Biology

Background:

• Flower color variation in Lotus corniculatus is widespread.
• Previous research suggested environmental factors influence this polymorphism.
• The specific role of temperature in keel color adaptation remained unclear.

Purpose of the Study:

• To investigate the relationship between keel color in Lotus corniculatus and flower temperature.
• To determine how temperature differences influence reproductive success based on keel color.
• To understand the role of temperature in maintaining keel color polymorphism.

Main Methods:

• Temperature measurements were taken within the flower keels of dark-keeled and light-keeled Lotus corniculatus individuals under varying ambient conditions.
• Microhabitat temperatures were recorded for both dark- and light-keeled plants.
• Reproductive success was inferred based on temperature-related advantages for pollen germination and growth.

Main Results:

• Dark-keeled flowers were consistently warmer than light-keeled flowers in bright sunshine, with temperature differences increasing at higher ambient temperatures.
• No significant temperature differences were observed in overcast conditions; light-keeled flowers were sometimes warmer.
• Dark-keeled plants tended to inhabit colder microhabitats than light-keeled plants.

Conclusions:

• Keel color in Lotus corniculatus is strongly influenced by temperature.
• Dark keels provide a thermal advantage in cold microhabitats, potentially increasing fecundity.
• Light keels may offer advantages in warmer microhabitats, promoting seed set and maintaining the observed polymorphism.