Evolutionary dynamics and population biology of a polymorphic insect

Area of Science:

• Evolutionary Biology
• Ecological Genetics
• Animal Behavior

Background:

• Heritable polymorphisms provide insights into the stability of morph frequencies across generations.
• Long-term studies on the genetic dynamics of color polymorphisms are scarce.
• The blue-tailed damselfly (Ischnura elegans) exhibits trimorphism, including a male-colored (androchrome) female morph potentially maintained by sexual conflict.

Purpose of the Study:

• To investigate morph-frequency dynamics and female fecundity in the trimorphic blue-tailed damselfly (Ischnura elegans).
• To examine multi-generational genetic dynamics and evolutionary trajectories of morph frequencies.
• To understand the role of sexual conflict in maintaining female color polymorphisms.

Main Methods:

• Long-term monitoring of morph frequencies across multiple populations of Ischnura elegans over a 4-year period.
• Analysis of female fecundity in relation to morph type.
• Assessment of population age as a factor influencing morph-frequency dynamics.

Main Results:

• Significant year-to-year fluctuations in morph frequencies were observed across all studied populations.
• A directional frequency change was evident, with androchrome females increasing in 9 out of 10 populations over the study duration.
• Population age influenced evolutionary trajectories; young populations initially showed high androchrome frequencies that decreased over time.

Conclusions:

• Morph frequencies in Ischnura elegans are dynamic and not stable across generations.
• Frequency-dependent sexual conflict likely plays a role in maintaining the androchrome morph.
• Factors such as morph-specific fecundity, dispersal, and population age contribute to the observed evolutionary dynamics.