Graeme D. Ruxton, Walter S. Persons & Philip J. Currie (2017)
A continued role for signalling functions in the early evolution of feathers.
Evolution (advance online publication)
Persons and Currie (2015) argued against either flight, thermoregulation, or signalling as a functional benefit driving the earliest evolution of feathers; rather, they favoured simple feathers having an initial tactile sensory function, which changed to a thermoregulatory function as density increased. Here, we explore the relative merits of early simple feathers that may have originated as tactile sensors progressing instead towards a signalling, rather than (or in addition to), a thermoregulatory function. We suggest that signalling could act in concert with a sensory function more naturally than could thermoregulation. As such, the dismissal of a possible signalling function and the presumption that an initial sensory function led directly to a thermoregulatory function (implicit in the title “bristles before down”) are premature.
Alicia Grealy, Matthew Phillips, Gifford Miller, M. Thomas P. Gilbert, Jean-Marie Rouillard, David Lambert, Michael Bunce, James Haile (2017)
Eggshell palaeogenomics: Palaeognath evolutionary history revealed through ancient nuclear and mitochondrial DNA from Madagascan elephant bird (Aepyornis sp.) eggshell.
Molecular Phylogenetics and Evolution (advance online publication)
Very few elephant bird skeletal specimens have been found with well-preserved aDNA.
Fossil avian eggshell can be an alternative source of aDNA.
We recover a mitochondrial genome and nuclear loci from elephant bird eggshell for the first time.
We independently verify their phylogenetic relationships and refine divergence dates.
The addition of nuclear DNA substantially clarifies many aspects of palaeognath evolution.
Palaeognaths, the sister group of all other living birds (neognaths), were once considered to be vicariant relics from the breakup of the Gondwanan supercontinent. However, recent molecular studies instead argue for dispersal of volant ancestors across marine barriers. Resolving this debate hinges upon accurately reconstructing their evolutionary relationships and dating their divergences, which often relies on phylogenetic information from extinct relatives and nuclear genomes. Mitogenomes from the extinct elephant birds of Madagascar have helped inform the palaeognath phylogeny; however, nuclear information has remained unavailable. Here, we use ancient DNA (aDNA) extracted from fossil eggshell, together with target enrichment and next-generation sequencing techniques, to reconstruct an additional new mitogenome from Aepyornis sp. with 33.5X coverage. We also recover the first elephant bird nuclear aDNA, represented by 12,500 bp of exonic information. While we confirm that elephant birds are sister taxa to the kiwi, our data suggests that, like neognaths, palaeognaths underwent an explosive radiation between 69-52 Ma—well after the break-up of Gondwana, and more rapidly than previously estimated from mitochondrial data alone. These results further support the idea that ratites primarily diversified immediately following the Cretaceous-Palaeogene mass extinction and convergently evolved flightlessness. Our study reinforces the importance of including information from the nuclear genome of extinct taxa for recovering deep evolutionary relationships. Furthermore, with approximately 3% endogenous aDNA retrieved, avian eggshell can be a valuable substrate for recovering high quality aDNA. We suggest that elephant bird whole genome recovery is ultimately achievable, and will provide future insights into the evolution these birds.
Note this similar paper already posted back in December 2016:
Only one extinct species reviewed (the giant Haast's eagle) as *Hieraaetus moorei*
Heather Lerner, Les Christidis, Anita Gamauf, Carole Griffiths, Elisabeth Haring, Christopher J. Huddleston, Sonia Kabra, Annett Kocum, Meade Krosby, Kirsti Kvaløy, David Mindell, Pamela Rasmussen, Nils Røv, Rachel Wadleigh, Michael Wink & Jan Ove Gjershaug (2017)
Phylogeny and new taxonomy of the Booted Eagles (Accipitriformes: Aquilinae).
Zootaxa 4216(4): 301–320
We present a phylogeny of all booted eagles (38 extant and one extinct species) based on analysis of published sequences from seven loci. We find molecular support for five major clades within the booted eagles: Nisaetus (10 species), Spizaetus (4 species), Clanga (3 species), Hieraaetus (6 species) and Aquila (11 species), requiring generic changes for 14 taxa. Additionally, we recommend that the Long-crested Eagle (Lophaetus occipitalis) and the Black Eagle (Ictinaetus malaiensis) remain in their monotypic genera, due to their distinctive morphology. We apply the recently resurrected genus Clanga for the spotted eagles (previously Aquila spp.) to resolve the paraphyly of the genus Aquila such that the clade including the Booted Eagle (H. pennatus), Little Eagle (H. morphnoides), Pygmy Eagle (H. weiskei), Ayres’s Eagle (H. ayresii) and Wahlberg’s Eagle (H. wahlbergi) can remain in the genus Hieraaetus. The Rufous-bellied Eagle should be retained in the genus Lophotriorchis. For consistency in English names, we recommend that the term “hawk-eagles” be used only for the species in the genera Nisaetus and Spizaetus. We suggest following new or modified English names: Cassin’s Eagle (Aquila africana), Bonaparte’s Eagle (A. spilogaster), Ayres’s Eagle (Hieraaetus ayresii), and Black-and-chestnut Hawk-Eagle (Spizaetus isidori).