Patterns of contact call differentiation in the panmictic East African Abyssinian White-eye Zosterops abyssinicus (Aves: Passeriformes).

Jan Christian Habel,Martin Husemann,Werner Ulrich

doi:10.1002/ece3.1828

Abstract

Species distribution patterns range from highly disjunct to continuous, depending on their ecological demands and the availability of respective habitats. East African savannahs are mostly interconnected and ecologically comparatively homogenous and thus provide a prerequisite for a rather panmictic distribution pattern for species occurring in this habitat. The Abyssinian white-eye Zosterops abyssinicus is a savannah inhabiting bird species, representing such a continuous distribution. This species occurs in high abundances and is very mobile, and past population genetic studies have suggested that gene flow is high and genetic differentiation is low even across relatively large geographic distances. Further, only little morphological differences were found. In order to test for potential divergence in acoustic traits despite its interconnected geographic distribution, we analyzed 2795 contact calls of Z.abyssinicus, which were recorded at 19 sites across Kenya. Our data indicate weak, but significant differentiation in call characteristics across latitudinal gradients. We found strong changes in call characteristics in populations where Z.abyssinicus occurs in sympatry with its highland congener, Zosterops poliogaster. However, the changes in call characteristics in sympatry were in different directions and lead to strong differentiation of the sympatric populations to other conspecific populations potentially representing a case of cascade reinforcement. The detected spatial gradients likely result from ecological differences and balancing effects of natural and sexual selection.

Highlights

The extent of a species0 distribution depends on habitat demands, the dispersal behavior of species, the availability of the respective habitat type and local competition (Lomolino et al 2006)
Ecology and Evolution published by John Wiley & Sons Ltd
We found high local variability of contact calls across all sites, in accordance with a Poisson random distribution

Summary

Introduction

The extent of a species0 distribution depends on habitat demands, the dispersal behavior of species, the availability of the respective habitat type and local competition (Lomolino et al 2006). While species with specific habitat demands and limited dispersal behavior often occur in small and isolated habitat patches, species with a broad ecological tolerance and high mobility are often found in interconnected population networks (Devictor et al 2008). These contrasting distribution settings are often reflected by the intraspecific population structure: studies showed that habitat specialists with disjunct distributions are characterized by strong within-taxon differentiation and a comparatively low intraspecific variability, while taxa with panmictic distributions often do not show signals of intraspecific divergence, and generally have larger intraspecific variability (Hampe and Petit 2005).

Results

Discussion

Conclusion