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Visually Sexing Loggerhead Shrike Lanius Ludovicianus Using Plumage Coloration and Pattern

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Characterizing selection in black-throated blue warblers using a sexual network approach.

E R A Cramer^1,2, S A Kaiser³, M S Webster²

¹Migratory Bird Center, Smithsonian Conservation Biology Institute, Washington, DC, USA.

Journal of Evolutionary Biology

|October 8, 2017

Summary

Social environments impact trait evolution. This study found male body size did not influence competitive interactions or fitness in black-throated blue warblers, suggesting other traits are more important for social selection.

Keywords:

body size competition selection gradient sexual selection social network social selection

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Area of Science:

Evolutionary Biology
Behavioral Ecology
Quantitative Genetics

Background:

Trait evolution studies often assume uniform selective environments.
Understanding how social environments influence trait selection and fitness is crucial for evolutionary insights.

Purpose of the Study:

To investigate the effect of social environment variation on individual phenotype selection.
To test for direct and social selection on male body size in black-throated blue warblers (Setophaga caerulescens).

Main Methods:

Applied a novel sexual network framework to quantify male social environments based on competitor body size.
Utilized a 10-year dataset to analyze direct and social selection on male body size.
Assessed the role of body size in male-male competition and its impact on fitness.

Main Results:

Direct selection on male body size was weak and not statistically significant.
Social selection, mediated by competitors' body size, was also nonsignificant.
Simultaneous analysis rejected a significant role for body size in male competition and fitness.

Conclusions:

Body size is not a key factor in male-male competition or fitness for this population of black-throated blue warblers.
The study highlights the utility of the sexual network approach for empirical data analysis.
Other phenotypic traits, such as song and plumage, may be more relevant for male competition in this species.