Male-male aggression is unlikely to stabilize a poison frog polymorphism

Area of Science:

• Evolutionary Biology
• Animal Behavior
• Ecology

Background:

• Phenotypic polymorphism requires mechanisms to counteract homogenizing forces like drift and selection.
• Male-male competition can stabilize polymorphism if males direct aggression towards same-phenotype rivals.

Purpose of the Study:

• Investigate whether male aggression biases contribute to the maintenance of color polymorphism in poison frogs (Oophaga pumilio).
• Test if males direct aggression towards same-phenotype or most common phenotype rivals.

Main Methods:

• Simulated territorial intrusions were used in contact zones of red and blue poison frog lineages.
• Aggression levels were recorded towards simulated intruders of different color phenotypes.

Main Results:

• Males in monomorphic populations showed aggression towards matching local color intruders.
• Males in polymorphic populations did not bias aggression based on phenotype or local frequency.
• Rarer color morphs gain no advantage from reduced aggression in sympatry.

Conclusions:

• Male aggression alone appears unlikely to stabilize color polymorphism in these O. pumilio populations.
• Divergent male aggression's role in maintaining phenotypic diversity depends on the bias generation and persistence mechanisms in sympatry.