A comprehensive molecular phylogeny of Afrotropical white-eyes (Aves: Zosteropidae) highlights prior underestimation of mainland diversity and complex colonisation history

Abstract

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Contrasting trajectories of morphological diversification on continents and islands in the Afrotropical white‐eye radiation

“…A few Zosterops species have colonized the temperate zone as far as South Africa, Japan and New Zealand. Within the Afrotropics, the division between island and continental forms is roughly equal (Martins et al., 2020), whereas outside the Afrotropics the majority of species are insular forms with another centre of diversification in continental South and East Asia. Despite exhibiting a signal of density dependence (Moyle et al, 2009), Zosterops are remarkably homogeneous in morphology and plumage (Mayr 1963; Mees, 1953; Moreau, 1957), apart from some aberrant island forms (Melo et al., 2011).…”

“…We used the dated comprehensive phylogenetic tree from Martins et al. (2020) based on three mitochondrial markers (Cytb, ATP6 and ND3), five nuclear introns (TGFß2, G3PDH, Fib 7, CHD1 and MUSK) and comprehensive sampling of all known Afrotropical species and subspecies (with the exception of Z. maderaspatanus menaiensis ). Overall, this timetree is based on results from phylogenetic inference and quantitative species delimitation methods for 46 Afrotropical taxa (described species, and possible candidate species [represented by trinomial nomenclature]), comprising 25 mainland and 21 island taxa, respectively (for locality data, see Martins et al., 2020, Appendix S1).…”

“…The songbird genus Zosterops (white‐eyes) provides a useful model to examine trends of phenotypic and lineage diversification across different geographical contexts having radiated within various archipelagos (Warren, Bermingham, Prŷs‐Jones, & Thébauds, 2006) and continents (Martins, Cox, Irestedt, Prŷs‐Jones, & Day, 2020). Lauded by biologists as a ‘great speciator’ (Diamond, Gilpin, & Mayr, 1976; Moyle, Filardi, Smith, & Diamond, 2009), this genus contains ca .…”

“…100 species (van Balen, 2019), including many exceptional colonizers (Melo, Warren, & Jones, 2011; Phillimore et al., 2008; Slikas, Jones, Derrickson, & Fleischer, 2000; Warren et al., 2006). Although a disproportionate number of species occur on islands (Moreau, 1957), recent studies have highlighted increased continental species diversity (Lim et al., 2019; Martins et al., 2020). Overall, the Zosterops clade has the highest net diversification rate of any bird lineage, and one of the highest among vertebrates (Jetz, Thomas, Joy, Hartmann, & Mooers, 2012; Moyle et al, 2009).…”

“…To address whether mainland and island lineages followed the same pattern of morphological and lineage evolution, we focus on the Afrotropics, which we define as continental Africa‐Arabia, and associated island archipelagos including the western Indian Ocean, Madagascar and Gulf of Guinea. The advantage of this study region is the availability of a comprehensive species‐level taxonomy of Zosterops (Martins et al., 2020) spanning a similar number of taxa distributed on the continent versus surrounding islands. Based on new measurements of nine morphological traits, we used evolutionary models to test if morphological diversity of Afrotropical Zosterops ( n = 46 species and candidate species), and its constituent mainland and island radiations, is best explained by adaptive or non‐adaptive processes.…”