A General Explanation for the Persistence of Reproductive Interference

Area of Science:

• Evolutionary biology
• Behavioral ecology
• Speciation research

Background:

• Reproductive interference is common, contradicting evolutionary theory predicting its elimination via reproductive character displacement (RCD).
• A persistent evolutionary dilemma may arise when females of sympatric species are phenotypically similar, impeding male mate recognition (MR) evolution.
• This creates a cycle where MR cannot evolve without further female phenotype divergence, and vice versa.

Purpose of the Study:

• To test the "evolutionary catch-22" hypothesis explaining persistent reproductive interference.
• To investigate the role of female phenotype similarity and male mate recognition in reproductive isolation.
• To examine evidence for reproductive character displacement in rubyspot damselflies (Hetaerina spp.).

Main Methods:

• Analyzing data from rubyspot damselflies (Hetaerina spp.).
• Assessing the breakdown of reproductive isolation with increasing interspecific female phenotype similarity.
• Comparing allopatric and sympatric populations to detect RCD.

Main Results:

• Reproductive isolation decreased significantly as female phenotypes became more similar between species.
• No evidence of RCD was found when comparing allopatric and sympatric populations.
• Divergence in female coloration and male MR in allopatry appears to dictate reproductive isolation upon secondary contact.

Conclusions:

• The "evolutionary catch-22" hypothesis provides a robust explanation for persistent reproductive interference.
• When reproductive isolation relies on male mate recognition and sympatric females are phenotypically similar, interference endures.
• This highlights the complex interplay between sexual selection and speciation in natural populations.