| The original paper may be accessed for free through August 11 2016, using the following link: Stervander et al. 2016 MPE |
A couple of years ago, Alström et al. (2013) revealed that larks (Alaudidae) comprised unusually many examples of both cryptic taxa (whose evolutionary and taxonomic distinctness have gone overlooked, owing to phenotypic similarity to other taxa) and convergent evolution among unrelated species. One striking example of the latter was the species pair White-winged Lark Alauda leucoptera and Mongolian Lark Melanocorypha mongolica (Figure 1, upper panel), which display very similar plumage, and have been assumed to be closely related. Instead, they turned out to be of two different genera, separated since 11 million years ago. Likewise, the two clades which have traditionally formed the genus Calandrella, have been separated for 12 million years, and are not at all each other’s closest relatives, despite superficial similarities (Figure 1 middle panel). Urban Olsson, Per Alström, and others are currently looking closely into the clade which, following their recommendation, is now known as the genus Alaudala. Together with Per and Urban, Ulf Ottosson, Bengt Hansson, and Staffan Bensch, I dived into trying to sort out the phylogenetic relationships of the remaining Calandrella clade.
Figure 1 (from Stervander 2015). Larks (family Alaudidae) display strong adaptations in bill morphology and plumage, and recent studies have revealed both convergent evolution and cryptic taxa. Alström et al. (2013) demonstrated an extreme case of convergent evolution in the White-winged Lark Alauda leucoptera (top left) and the Mongolian Lark Melanocorypha mongolica (top right), previously thought to be congeneric. We confirmed that Calandrella [brachydactyla] dukhunensis (middle left) is a separate species from the Greater Short-toed Lark C. brachydactyla (middle right), more closely related to Hume’s Short-toed Lark C. acutirostris, though it morphologically resembles the Greater Short-toed lark. We also show that C. blanfordi daaroodensis and C. b. eremica form a clade that split over four million years ago from C. b. blanfordi and C. erlangeri, which are recently split sister taxa (bottom). Photos, with permission for use in Stervander (2015): Kari Eischer (top left), David Thorns (top right), Matt Poll (middle left), Juan Lacruz (middle right), Martin Stervander with permission from the British Museum of Natural History (bottom).
My curiosity dates back to the early 2000’s, when a small and isolated population of Red-capped Larks C. cinerea
was rediscovered close to the Nigerian research institute APLORI
, where I have been teaching. The Jos plateau, in central Nigeria, is a curious distribution outlier for this species, which is common in Southern Africa, but has its otherwise most northerly distribution in Congo – over 1,000 km away. Continue reading