The phylogeny of 18 taxa in the Lanius excubitor complex, and the related species
L. sphenocercus, L. ludovicianus and L. somalicus, was estimated based on the mitochondrial
cytochrome b gene and the non-coding D-loop (in total approximately 1.3 kb). According
to the mitochondrial gene tree, Lanius excubitor s.l. is non-monophyletic, with some
of its subspecies being more closely related to L. sphenocercus, L. ludovicianus,
and L. somalicus. Also the division of the L. excubitor complex into a northern (L.
excubitor) and a southern (L. meridionalis) species, as has been proposed based on
morphological and ecological similarity and geographical distributions, is not compatible
with the mitochondrial tree. Overall, genetic divergences among the ingroup taxa are
small, indicating a recent radiation. A tree based on the nuclear ornithine decarboxylase
(ODC) introns 6-7 is unresolved with respect to the ingroup, but provides strong support
for a clade containing the Lanius excubitor complex, L. sphenocercus, L. ludovicianus
and L. somalicus. We discuss the incongruence between the current taxonomy and the
mitochondrial gene tree, and conclude that based on the latter the Lanius excubitor
complex may be treated as at least six species, L. borealis, L. elegans, L. excubitor,
L. lahtora, L. meridionalis, and L. uncinatus, but that other taxonomic treatments
are also possible. However, uncertainty regarding to which extent the mitochondrial
gene tree reflects the species phylogeny prevents us from recommending taxonomic change
without further investigation. This study highlights the possible danger of relying
on a single molecular marker, such as mitochondrial DNA, in taxonomic revisions and
phylogenetic inference.
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