Molecular and phenotypic divergence in the bluethroat (Luscinia svecica) subspecies complex

Abstract

Subspecies complexes may provide valuable insights into the early stages of the speciation process. The bluethroat (Luscinia svecica) consists of many morphologically distinct subspecies that differ most strikingly in the ornamental colour pattern of the male throat. We investigated the genetic and phenotypic differentiation in this subspecies complex, using (i) microsatellite genotyping (11 loci) of a sample of 364 individuals from bluethroat populations in Europe and Asia, and (ii) spectrometric and morphological measurements of a sample of 131 museum skin specimens. Population genetic analyses, based on microsatellite allele frequency variation, revealed a slight but significant overall population differentiation (F(ST) = 0.042). There was a well-differentiated southern group of subspecies with white or no throat spots and a less-differentiated northern group of chestnut-spotted populations. Phylogenetic analyses indicated that the southern all-blue and white-spotted forms are ancestral to the chestnut-spotted subspecies. In addition to the qualitative variation in throat plumage pattern already described in the literature, we found significant quantitative variation among subspecies in hue, chroma and brightness of the ultraviolet (UV)/blue throat coloration, and this variation seemed to be unrelated to the phylogenetic distance between subspecies.

Usefulness of Biometrics to Analyse Some Ecological Features of Birds

“…Currently, a greater accuracy when defining different population taxonomic categories has been achieved through the analysis of genes present in mitochondrial and/or nuclear DNA. To continue with the example of the Bluethroat, molecular genetics have confirmed the validity of the subspecies namnetum and also of other subspecies which are biometrically similar between them (Johnsen et al, 2006). Similarly, in the Southern grey shrike, the biometric study suggested marked differences between the subspecies meridionalis from the Iberian Peninsula and the subspecies koenigi from the Canary islands (Gutiérrez-Corchero et al, 2007a,b).…”

Differential response of males of a subarctic population of Bluethroat Luscinina svecica svecica to playbacks of their own and foreign subspecies

“…In our experiments, we used recordings of two subspecies that differ in phenotype, habitat selection, and song structure (Turčoková et al 2010). The nominate subspecies Luscinia svecica svecica has a red-chestnut spot, and breeds in arctic and boreal latitudes and mountainous regions of Scandinavia and northern Russia (Cramp 1988), though isolated populations are also known from Central European mountains (Johnsen et al 2006;Chutný and Pavel 2009). Such populations may occasionally come into contact and hybridize with the local subspecies Luscinia svecica cyanecula (Chutný and Pavel 2009).…”

“…This Palaearctic taxon, which probably diverged over the last 15,000 years (Zink et al 2003), is a complex of several distinct morphs that are usually given subspecies status; 10-11 subspecies are recognized that differ to various extents morphologically (Glutz von Blotzheim and Bauer 1988;Eybert et al 1999;Arizaga et al 2006), in throat ornamentation (Johnsen et al 2006) and in breeding habitat preferences (Cramp 1988). Microsatellite genotyping (Johnsen et al 2006) has supported the genetic divergence of some but not all tested putative subspecies. However, it has also confirmed that subspecies with more southern distribution, carrying either a white or plain blue throat spot, are well differentiated from each other as well as from northern populations with a red throat spot.…”

“…However, it has also confirmed that subspecies with more southern distribution, carrying either a white or plain blue throat spot, are well differentiated from each other as well as from northern populations with a red throat spot. Splitting of these red-spotted populations into several taxa seems to be more problematic (Johnsen et al 2006).…”

The Utility of Plumage Coloration for Taxonomic and Ecological Studies

“…They used the contrasting results to infer recent colonization of the islands and rapid morphological change. In the Bluethroat (Luscinia svecica), a widespread, polytypic species distributed across Europe, Johnsen et al [68] used molecular markers to assess phylogenetic relationships among multiple subspecies, augmenting these data with spectrometer measurements of plumage coloration. They found concordance between genetic structuring and color differences in most subspecies, but not all, yet a poor relationship between overall genetic distance among subspecies and absolute differences in coloration values.…”