Disentangling the complex evolutionary history of the Western Palearctic blue tits (Cyanistes spp.) – phylogenomic analyses suggest radiation by multiple colonization events and subsequent isolation

Abstract

Isolated islands and their often unique biota continue to play key roles for understanding the importance of drift, genetic variation and adaptation in the process of population differentiation and speciation. One island system that has inspired and intrigued evolutionary biologists is the blue tit complex (Cyanistes spp.) in Europe and Africa, in particular the complex evolutionary history of the multiple genetically distinct taxa of the Canary Islands. Understanding Afrocanarian colonization events is of particular importance because of recent unconventional suggestions that these island populations acted as source of the widespread population in mainland Africa. We investigated the relationship between mainland and island blue tits using a combination of Sanger sequencing at a population level (20 loci; 12 500 nucleotides) and next-generation sequencing of single population representatives (>3 200 000 nucleotides), analysed in coalescence and phylogenetic frameworks. We found (i) that Afrocanarian blue tits are monophyletic and represent four major clades, (ii) that the blue tit complex has a continental origin and that the Canary Islands were colonized three times, (iii) that all island populations have low genetic variation, indicating low long-term effective population sizes and (iv) that populations on La Palma and in Libya represent relicts of an ancestral North African population. Further, demographic reconstructions revealed (v) that the Canary Islands, conforming to traditional views, hold sink populations, which have not served as source for back colonization of the African mainland. Our study demonstrates the importance of complete taxon sampling and an extensive multimarker study design to obtain robust phylogeographical inferences.

Correlated patterns of genetic diversity and differentiation across an avian family

“…Stervander et al . ), our cytochrome‐ b ‐only tree (not shown) was consistent with previous mitochondrial studies, which achieved near‐complete taxon sampling (e.g. Illera et al .…”

“…Finally, although sparse taxon sampling (5 taxa) and choice of outgroup could potentially introduce biases (e.g. Stervander et al 2015), our cytochrome-b-only tree (not shown) was consistent with previous mitochondrial From top to bottom, the statistics and box details are as follows: F ST among stonechats (peaks shared by three or more comparisons), F ST between flycatchers (peaks that also overlap with shared stonechats peaks), d XY among stonechats (valleys shared by three or more comparisons), d XY among flycatchers (valleys that also overlap with shared stonechats valleys), Tajima's D (valleys shared by two or more taxa), nucleotide diversity (p) (valleys shared by two or more taxa) and Fay & Wu's H (valleys shared by two or more taxa). studies, which achieved near-complete taxon sampling (e.g.…”

Acoustic, genetic, and morphological analyses of the Canarian common chaffinch complexFringilla coelebsssp. reveals cryptic diversification

“…Such divergence events have produced a plethora of forms and colours that taxonomists have frequently described and classified as distinct taxa. Different types of information have been used to understand the origin and variation of biodiversity, for instance, biometry (Grant 1979a, b, Dennison andBaker 1991), acoustic , Päckert et al 2006, Tietze et al 2015, genetic (Alström et al 2015, Stervander et al 2015, or a combination of methods ). However, cryptic differentiation, that is, species evolving similar morphologies, makes the correct identification of unique taxa difficult, which increases the risk of underestimating biodiversity (Padial et al 2010, Fišer et al 2018.…”

Pleistocene extinctions as drivers of biogeographical patterns on the easternmost Canary Islands

“…In this context, placing extinction within a particular spatio‐temporal background (i.e. Pleistocene, easternmost islands) is supported by the fact that ECI populations in these cases are often very recent (<1 Ma) (Bidegaray‐Batista, Taiti, López‐Hernández, Ribera, & Arnedo, ; Husemann, Depperman, & Hochkirch, ; Stervander et al., ). This pattern is in agreement with those revealed by recent plant studies using extensive population sampling of mainland and island regions (García‐Verdugo et al., , ; Valtueña et al., ).…”

“…Incomplete taxon sampling, either due to extinction of closer relatives or limited representation of continental and island species, and incomplete lineage sorting may result in poorly resolved or incorrect phylogenetic relationships, which lead to biased estimates of colonization times (see e.g. Emerson, ; Emerson, Oromi, & Hewitt, ; Stervander et al., ). To account for this source of uncertainty, we adopted the following approach.…”