TL;DR: Parsimony reconstruction of the evolution of plumage pattern within Aquilini suggests that transverse barring of parts of the body plumage was lost in the Palearctic Aquila-Hieraaetus clade, pale underparts in adult plumages evolved three times independently, and dimorphic adult plumage is a derived character of the small-bodied HieraaetusClade.
TL;DR: A molecular phylogeny of the Spizaetus cirrhatus complex is presented, based on two sections of the mitochondrial genome: partial sequences of the cytochrome b gene and of the control region (CR), suggesting a more recent radiation of this group of hawk-eagles in the course of the last ice ages.
Abstract: Summary A molecular phylogeny of the Spizaetus cirrhatus complex is presented in this study, based on two sections of the mitochondrial genome: partial sequences of the cytochrome b gene and of the control region (CR). The topologies derived from the two sequences are in agreement. Within S. cirrhatus distances are rather low (0–1.5% in cytochrome b). Among the cirrhatus subspecies the island taxa floris, vanheurni and andamanensis form distinct haplogroups in the CR trees, conforming to the earlier subspecific divisions which were based on morphological characters. On the other hand, the most widespread subspecies, limnaeetus, does not represent a monophyletic group in the gene trees and its haplogroups do not cluster according to geographic affinities. An unambiguous resolution of relationships among haplotypes and haplogroups, respectively, was not achieved, suggesting a more recent radiation of this group of hawk-eagles in the course of the last ice ages. Concerning the outgroup taxa Spizaetus philippensis and Spizaetus lanceolatus, our data indicate a clear genetic distinction between the two subspecies S. p. philippensis and S. p. pinskeri, suggesting that they should be treated as distinct species. Yet the phylogenetic relationships of the three outgroup taxa with respect to S. cirrhatus are ambiguous in our trees. The taxonomic consequences of applying different species concepts (BSC, PSC) are discussed. The species concept chosen would result in different conservation strategies.
TL;DR: Investigations indicate that hawk-eagles represent a paraphyletic assemblage and thus their external similarities have to be ascribed to convergent evolution, and suggest assigning the species of the genus Spizaetus to three different genera.
Abstract: The phylogenetic relationships within the New and Old World hawk-eagle assemblage (genus Spizaetus; Aves: Accipitridae) were studied using mitochondrial DNA sequences (cytochrome b, control region). Eighty-four specimens representing all Spizaetus species and almost all currently distinguished subspecies as well as 11 other booted and non-booted eagle genera from the Neotropics, Africa, Eurasia, South Asia and Australasia (Oroaetus, Harpia, Morphnus, Lophaetus, Stephanoaetus, Hieraaetus, Aquila, Ictinaetus, Spilornis, Pithecophaga, Harpyopsis) were investigated. Although the basal branching could not be resolved, our investigations clearly indicate that hawk-eagles represent a paraphyletic assemblage and thus their external similarities have to be ascribed to convergent evolution. The New World taxa of Spizaetus cluster together, but the South American species Oroaetus isidori appears embedded within this clade. The taxa from Southeast to East Asia form a clearly separated monophyletic group. It is further divided into two subgroups, which are also characterized by distinct juvenile plumage patterns. Spizaetus africanus, the only African representative of the genus, is found in a mixed cluster consisting of members of the genera Aquila and Hieraaetus. These findings are in accordance with previous studies of other authors based on various molecular markers and different sets of taxa, but disagree with current taxonomy. Therefore, we suggest assigning the species of the genus Spizaetus to three different genera: (1) Spizaetus (including Oroaetus isidori) in Central and South America and (2) Nisaetus for the Southeast to East Asian group. (3) The African taxon (Spizaetus africanus) is discussed to be included into the genus Aquila. Furthermore, we propose to use the former genus name Lophotriorchis Sharpe, 1874, for the monotypic species Hieraaetus kienerii, which has an isolated phylogenetic position.
TL;DR: It is proposed that Nisaetus floris (Flores Hawk-eagle) should be treated as a distinct species, whereas the taxonomic status of NISAetus c.
Abstract: Morphological, vocal and molecular data have been used to reevaluate the taxonomy of some Asian Nisaetus taxa. This name is used instead of Spizaetus because the latter genus is polyphyletic with clades in Asia, South America and Africa. The Changeable Hawk-eagle complex (N. cirrhatus cirrhatus, N. c. limnaeetus, N. c. floris, N. lanceolatus and N. philippensis) has been studied. We propose that Nisaetus floris (Flores Hawk-eagle) should be treated as a distinct species, whereas the taxonomic status of Nisaetus c. cirrhatus and N. c. limnaeetus is still uncertain. We also propose that the Philippine Hawk-eagle should be split into two species Nisaetus philippensis and N. pinskeri. In the Mountain Hawk-eagle Nisaetus nipalensis complex, we propose that Nisaetus kelaarti (Legge’s Hawk-eagle) should be treated as a distinct species. The conservation status of Nisaetus floris, Nisaetus kelaarti and Nisaetus bartelsi has been evaluated from population density estimates, which are based on territory size. N. floris and N. bartelsi qualify for the category “Endangered” on the IUCN Red List, whereas N. kelaarti qualifies as “Near Threatened”. The changes in taxonomy of Nisaetus floris and N. kelaarti meet the qualification for being included in the Red List.