Linking Ecological Specialization to Its Macroevolutionary Consequences: An Example with Passerine Nest Type

Area of Science:

• Evolutionary Biology
• Zoology

Background:

• The evolutionary dead end hypothesis posits that resource specialization limits diversification and adaptability.
• Recent advances in comparative methods allow for more robust testing of this hypothesis.

Purpose of the Study:

• To test the evolutionary dead end hypothesis in passerine birds.
• To investigate if hole-nesting specialization affects net diversification rates.
• To determine the frequency of transitions into and out of hole-nesting.

Main Methods:

• Analysis of diversification rates across 3224 passerine species.
• Estimation of net diversification rate differences associated with nest-type specialization.
• Application of diversification models accounting for rate heterogeneity and extinction scenarios.

Main Results:

• Hole-nesting specialization was not associated with significant differences in net diversification rates.
• Transitions out of hole-nesting were found to be more frequent than transitions into hole-nesting.
• Interspecific competition may influence hole-nesting adoption but not diversification.

Conclusions:

• Resource specialization, specifically hole-nesting in passerines, does not typically lead to evolutionary dead ends.
• Specialists can transition back to more generalist strategies, challenging the evolutionary dead end hypothesis.
• Findings contribute to a growing body of evidence against specialization as a common evolutionary bottleneck.