Eutrophication and predation risk interact to affect sexual trait expression and mating success

Area of Science:

• Ecology
• Evolutionary Biology
• Environmental Science

Background:

• Sexual trait expression is sensitive to resource availability and predation.
• The interaction between resource levels and predation on sexual trait investment is poorly understood.
• Cultural eutrophication, driven by increased phosphorus (P) availability, poses a significant environmental challenge.

Purpose of the Study:

• To investigate how increased P availability affects sexual, nonsexual, and viability traits in amphipods.
• To examine the influence of predator cues on these trait developments.
• To understand the interactive effects of P availability and predation on trait trade-offs and sexual selection.

Main Methods:

• Amphipods were exposed to varying P concentrations mimicking eutrophication.
• Predator cues were introduced to assess their impact on trait expression.
• Phenotypic changes in sexual, nonsexual, and viability traits were measured.
• Male mating success was evaluated under different environmental conditions.

Main Results:

• Sexual traits and growth were highly sensitive to low P, more so than nonsexual traits.
• A key sexual trait's response to low P was contingent on the absence of predator cues.
• Investment trade-offs between sexual traits and growth occurred only under low P conditions.
• Predator cues and increased P availability enhanced male mating success.
• Eutrophication masked trait trade-offs related to P demand.

Conclusions:

• Phosphorus availability critically influences sexual trait development and investment trade-offs.
• Predation can modify or mask the effects of resource availability on sexual traits.
• Human-induced eutrophication can alter sexual selection dynamics and evolutionary trajectories.
• Understanding these interactions is crucial for predicting population-level responses to environmental change.