Temperature can reverse sexual conflict, facilitating population growth

Area of Science:

• Evolutionary Biology
• Ecology
• Animal Behavior

Background:

• Sexual conflict often results in male adaptations that harm females, reducing population growth.
• Understanding the ecological factors influencing male harm is crucial for assessing sexual conflict's impact on population viability.

Purpose of the Study:

• To investigate how temperature modulates male harm in seed beetles (Callosobruchus maculatus).
• To examine the effects of temperature on pre- and postcopulatory male harm mechanisms under varying sexual conflict levels.

Main Methods:

• Seed beetles were exposed to different temperatures (24, 28, 32 °C) and sexual conflict levels (no males, 1 male, 2 males).
• Male harm was assessed through harassment and traumatic insemination, with some males ablated to isolate harassment effects.
• Female fitness and population growth rates were measured under these conditions.

Main Results:

• Constant male exposure decreased female fitness at warmer temperatures (28 °C), especially under high sexual conflict.
• At 24 °C, male harassment and mating increased female fitness, particularly under low sexual conflict.
• Population growth was higher without constant male exposure at 28 and 32 °C, but optimal with constant exposure at 24 °C.

Conclusions:

• Temperature significantly modulates sexual conflict, influencing female fitness and population dynamics.
• Environmental variation, like temperature, can decrease sexual conflict levels and potentially benefit populations.
• The study highlights temperature's role in reversing the negative impacts of male harm and promoting population growth.