Mate choice decision rules: Trait synergisms and preference shifts

Area of Science:

• Behavioral Ecology
• Sexual Selection
• Animal Behavior

Background:

• Females often assess multiple secondary sexual traits (SSTs) during mate choice.
• Understanding how females integrate information from uncorrelated traits is crucial for sexual selection theory.
• The interplay between multiple SSTs and female preference remains understudied.

Purpose of the Study:

• To investigate how female zebra finches evaluate multiple, phenotypically uncorrelated SSTs.
• To test the hypotheses of preference shifts versus trait synergisms in mate choice.
• To determine the combined effect of beak color and cheek patch size on male mating success.

Main Methods:

• Mate choice experiments were conducted using zebra finches (Taeniopygia guttata castanotis).
• Males were raised on diets influencing SST expression, and traits were manipulated in a follow-up experiment.
• Male pairing success was analyzed in relation to combinations of beak color and cheek patch size.

Main Results:

• Female mate choice was best predicted by synergisms between beak color and cheek patch size, supporting the trait synergism hypothesis.
• Evidence did not support the preference shift hypothesis, where reliance on other traits increases with obstacles.
• Results were consistent across experiments with varied dietary and trait manipulation conditions.

Conclusions:

• Female mate choice in zebra finches integrates information from multiple SSTs through synergistic interactions.
• Synergistic evaluation of traits may explain the persistence of multiple secondary sexual traits in populations.
• Findings impact the understanding of mate preference repeatability and heritability in sexual selection.