Difference in flowering time as an isolating barrier

Area of Science:

• Ecology
• Evolutionary Biology
• Genetics

Background:

• Reproductive isolation is crucial for speciation.
• Existing models often overlook daily flowering time differences in diurnal and nocturnal species.
• Daily flowering patterns present unique challenges due to simultaneous flower opening/closing and pollen carry-over.

Purpose of the Study:

• To develop a new model analyzing the impact of daily flowering time differences on reproductive isolation in diurnal and nocturnal plant species.
• To investigate pollinator-mediated effects on reproductive isolation.

Main Methods:

• Developed a genetic model with two loci, each having two alleles, controlling flower opening and closing times.
• Numerically calculated changes in gamete frequencies.
• Incorporated factors like reduced hybrid viability, flowering costs, recombination rate, and degree of dominance.

Main Results:

• Early-opening flowers exhibited significantly higher fitness compared to late-opening flowers.
• Species maintenance proved challenging even without overlapping flowering times.
• The model highlights the difficulty in maintaining distinct diurnal and nocturnal species based solely on flowering time.

Conclusions:

• Flowering time differences within a day can impede reproductive isolation between diurnal and nocturnal species.
• Additional mechanisms, such as pollinator preference, are likely essential for the coexistence of closely related diurnal and nocturnal flowers.
• Further research is needed to understand the complex interplay of factors maintaining species boundaries.