Evidence for selection on a CONSTANS-like gene between two red oak species

Area of Science:

• Evolutionary biology
• Genetics
• Speciation research

Background:

• Hybridizing oak species provide a model for studying selection during speciation.
• Closely related oak species maintain distinct identities and adaptations despite gene flow, likely due to selection on specific genes.
• Identifying outlier loci with signatures of divergent selection can reveal candidate genes for speciation.

Purpose of the Study:

• To investigate the role of selection in maintaining species integrity in oaks with gene flow.
• To identify candidate genes under divergent selection in interfertile oak species.
• To explore the genetic basis of adaptation and reproductive isolation in Quercus.

Main Methods:

• Screened 36 genic and 8 non-genic microsatellite markers in two pairs of Quercus rubra and Quercus ellipsoidalis populations.
• Investigated markers with putative roles in flowering time and drought tolerance.
• Tested putative outlier loci in additional populations from different geographic regions to confirm their role in adaptive divergence.

Main Results:

• A microsatellite marker within a CONSTANS-like (COL) gene showed strong divergent selection across all studied oak populations.
• COL genes are known to regulate flowering time and are involved in photoperiodic control.
• This finding suggests a specific gene's role in the adaptive divergence of oak species.

Conclusions:

• The Quercus COL gene is a promising candidate for a speciation gene due to its role in adaptive divergence and reproductive isolation.
• Further research on phenological traits and flowering time genes is recommended to understand species integrity maintenance.
• Next-generation sequencing and genetic maps can reveal genome-wide outlier distribution and their role in reproductive isolation.