A comparative analysis of experimental selection on the stickleback pelvis

Area of Science:

• Evolutionary Biology
• Ecology
• Behavioral Ecology

Background:

• Natural selection mechanisms are studied experimentally, but often lack statistical power.
• Stickleback pelvic armor variation is linked to predation, yet experimental evidence is inconsistent.
• Meta-analysis can aggregate data to reveal aggregate selection effects.

Purpose of the Study:

• To test if prickly sculpin favor longer stickleback pelvic spines.
• To meta-analyze experimental data on pelvic armor selection in sticklebacks.
• To investigate drivers of pelvic armor evolution.

Main Methods:

• Mesocosm experiment manipulating threespine stickleback spine length.
• Experimental predation by prickly sculpin.
• Meta-analysis combining current and previous experimental selection studies.

Main Results:

• A mesocosm experiment showed a non-significant trend for fish predation favoring longer spines.
• Meta-analysis revealed moderate evidence for fish predation favoring increased pelvic armor.
• Meta-analysis found little evidence for insect predation favoring reduced pelvic armor.

Conclusions:

• Fish predation is a likely driver of increased pelvic armor in sticklebacks.
• The causes of reduced pelvic armor in some stickleback populations remain unclear.
• Meta-analysis is a powerful tool for detecting selection in ecological experiments.