The White-eyes are small passerine birds native to tropical, subtropical and temperate Sub-Saharan Africa, Southeast Asia and Australasia. Hybridization has been recorded in one genus, Zosterops.
Hybrids between Silvereye (Z. lateralis) and Slender-billed White-eye (Z. tenuirostris) have been described morphologically (Gill, 1970).
Genetic analyses of Canary White-eye (Z. luteus) and Slender-billed White-eye (Z. tenuirostris) revealed a discordance between nuclear and mitochondrial DNA (Degnan, 1993). In addition, the mtDNA structure of Canary White-eye is paraphyletic (Degnan & Moritz, 1992). These patterns can be attributed to historical hybridization.
A multi-locus phylogeny of the Zosteropidae indicated hybridization in areas of sympatry between Orange River White-eye (Z. pallidus) and Cape White-eye (Z. capensis). Morphological analyses suggested hybridization between Orange River White-eye and Green White-eye (Z. virens), but this was not confirmed by this phylogenetic analysis (Oatley et al., 2012).
Montane White-eye (Z. poliogaster) and Abyssinian White-eye (Z. abyssinicus) inhabit different habitats, where their distributions overlap they show reproductive character displacement which leads to strong divergence in call patterns (Husemann, Ulrich & Habel, 2014).
On the French island Reunion, three colour morphs of the endemic Reunion Grey White-eye (Z. borbonicus) meet in three narrow contact zones (Delahaie et al., 2017). Genomic analyses suggest that a few genes underlie genetic differentiation (Bourgeois et al., 2020).
Despite recent divergence (about 2 million years), the Solomons White-eye (Z. kulambangrae) and the Kolombangara White-eye (Z. murphyi) don’t hybridize. What reproductive isolation mechanisms are at work remains to be investigated (Cowles & Uy, 2019; Ottenburghs, 2019).
Bourgeois, Y. X., Bertrand, J. A., Delahaie, B., Holota, H., Thébaud, C., & Milá, B. (2020). Differential divergence in autosomes and sex chromosomes is associated with intra‐island diversification at a very small spatial scale in a songbird lineage. Molecular Ecology, 29(6), 1137-1153.
Cowles, S. A., & Uy, J. A. C. (2019). Rapid, complete reproductive isolation in two closely‐related Zosterops White‐eye bird species despite broadly overlapping ranges. Evolution.
Degnan, S. M. (1993). The Perils of Single-Gene Trees – Mitochondrial Versus Single-Copy Nuclear-DNA Variation in White-Eyes (Aves, Zosteropidae). Molecular Ecology 2, 219-225.
Degnan, S. M. & Moritz, C. (1992). Phylogeography of Mitochondrial-DNA in 2 Species of White-Eyes in Australia. Auk 109, 800-811.
Delahaie, B., Cornuault, J., Masson, C., Bertrand, J.A., Bourgeois, Y.X., Milá, B., Thébaud, C., (2017). Narrow hybrid zones in spite of very low population differentiation in neutral markers in an island bird species complex. Journal of Evolutionary Biology.
Gill, F. B. (1970). Hybridization in Norfolk-Island White-Eyes (Zosterops). Condor 72, 481-&.
Husemann, M., Ulrich, W. & Habel, J. C. (2014). The evolution of contact calls in isolated and overlapping populations of two white-eye congeners in East Africa (Aves, Zosterops). Bmc Evolutionary Biology 14.
Oatley, G., Voelker, G., Crowe, T. M. & Bowie, R. C. K. (2012). A multi-locus phylogeny reveals a complex pattern of diversification related to climate and habitat heterogeneity in southern African white-eyes. Molecular Phylogenetics and Evolution 64, 633-644.
Ottenburghs, J. (2019) Digest: White‐eye birds provide possible answer to the paradox of the great speciator. Evolution