Resource availability as a proxy for terminal investment in a beetle

Area of Science:

• Evolutionary Biology
• Animal Behavior
• Reproductive Strategies

Background:

• The terminal investment hypothesis posits that organisms increase reproductive effort as survival and reproduction prospects diminish.
• Previous empirical tests of this hypothesis have produced inconsistent results, highlighting the need for further investigation.
• Understanding the factors influencing reproductive strategies is crucial for evolutionary biology.

Purpose of the Study:

• To experimentally confirm the terminal investment hypothesis in yellow mealworm beetles (Tenebrio molitor).
• To investigate the role of food resource availability in modulating the decision to adopt a terminal investment strategy.
• To examine the trade-offs between immune response, survival, and sexual attractiveness under varying food conditions.

Main Methods:

• Immune challenge was applied to yellow mealworm beetles.
• Beetles were subjected to two conditions: limited food resources and food ad libitum (unlimited).
• Investment in sexual attractiveness, immune response, lifespan, and survival were measured.

Main Results:

• Male yellow mealworm beetles invested in sexual attractiveness at the expense of immune response and survival when food was limited.
• Under conditions of food ad libitum, beetles did not decrease their lifespan or invest in sexual attractiveness.
• Food availability critically influences the decision to adopt a terminal investment strategy.

Conclusions:

• This study provides experimental confirmation of the terminal investment hypothesis.
• Food availability and quality are key determinants in the evolution of reproductive strategies.
• The findings underscore the complex interplay between resource availability and life-history trade-offs.