The generic nomenclature of the Trochilini: a correction.

Because the generic name Elliotia proposed by us (Stiles et al. 2017a) was found to be preoccupied, we herein rename this genus, including a detailed diagnosis; the generic circumscription and type species remain unchanged. This change does not affect the generic reorganization of the Trochilini presented by Stiles et al. (2017a).

The generic classification of the Trochilini (Aves: Trochilidae): Reconciling taxonomy with phylogeny.

The generic nomenclature of the hummingbirds is unusually complicated. McGuire et al.'s (2014) recent phylogeny of the Trochilidae based on DNA sequence data has greatly clarified relationships within the family but conflicts strongly with the traditional classification of the family at the genus level, especially that of the largest and most recently derived clade, the Trochilini or "emeralds". We recently presented a historical review of this classification and the generic modifications required by the Code of the International Commission on Zoological Nomenclature. Herein we present a revised generic classification of the Trochilini based upon McGuire et al.'s genetic data, while producing diagnosable generic groupings and preserving nomenclatural stability insofar as possible. However, this generic rearrangement has necessitated the resurrection of nine generic names currently considered synonyms, the synonymization of seven currently recognized genera and the creation of one new genus. The generic changes we recommend to the classification are drastic, and we summarize these in tabular form in comparison with the three most recent classifications of the Trochilini. Where appropriate, we outline alternatives to our proposed arrangement. The classification treats 110 species in 35 genera, including two species that remain unplaced for lack of genetic samples.

A brief history of the generic classification of the Trochilini (Aves: Trochilidae): the chaos of the past and problems to be resolved.

The generic classification of the Trochilidae is unusually complicated because early authors, faced with a deluge of specimens with little or no data, often based species and genus names on superficial plumage characters derived from figured plates of varying artistic quality and reproduction. Working independently and with little knowledge of species distributions and with the fixation of type species for genera inconsistent or ignored, these authors produced a bewildering array of generic synonyms. The generic nomenclature of the largest and most recently derived clade of hummingbirds, the tribe Trochilini or "emeralds", presents an unusually tangled web. Here we review the history of hummingbird generic nomenclature from Linnaeus to the present, giving detailed attention to two generic names that epitomize this confusion: Amazilia (the variety of spellings, supposed type species and circumscriptions makes for an especially complicated tangle) and Leucippus (for which nearly every successive author has advocated a different circumscription). Through application of the International Code for Zoological Nomenclature, this review lays the foundation for a revision of the generic nomenclature of the emeralds to bring it into conformity with recent genetic studies elucidating the phylogeny of this clade.

Correction of Cassicinae Bonaparte, 1853 (Aves, Icteridae) to Cacicinae Bonaparte, 1853.

In our recently published revised classification of the Icteridae (Remsen et al. 2016), we used the family group name Cassicinae Bonaparte, 1853 on the assumption that its type genus was Cassicus Illiger, 1811. We have since confirmed, after kind advice from Thomas Donegan (pers. comm. 2016), that Cassicus Illiger (1811: 214) is simply an unjustified emendation of Cacicus Lacépède, 1799, made clear by Illiger (l.c.) in a footnote to his description of Cassicus. Under Articles 32.5.3.2 and 35.4.2 of the International Code of Zoological Nomenclature (ICZN 1999), a family-group name formed from an unjustified emendation of the name of its type genus is to be corrected, unless the emendation has come into use as a substitute name or through prevailing use. This is not the case here, and accordingly we correct the spelling of Cassicinae to Cacicinae. Bonaparte (1853) retains authorship; and, although not expressly mentioned before, his originally ligatured suffix -eoe for the name was automatically corrected by us (Remsen et al. l.c.) under Articles 11.7.1.3 and 32.5.3 of the Code (ICZN l.c.).

A revised classification of the Icteridae (Aves) based on DNA sequence data.

The higher-level classification of the New World blackbirds (Icteridae; Aves) has remained relatively stable for nearly a half-century, with most currently used classifications (e.g. Sibley & Monroe 1990; Jaramillo & Burke 1999; Fraga 2011; Remsen et al. 2015) following Blake's (1968) delimitation and sequence of genera in the Peters Check-list of Birds of the World series. Early molecular studies (e.g., Lanyon 1992, 1994; Johnson & Lanyon 1999; Price & Lanyon 2002; Cadena et al. 2004) produced only minor modifications.

Adaptive processes drive ecomorphological convergent evolution in antwrens (Thamnophilidae).

Phylogenetic niche conservatism (PNC) and convergence are contrasting evolutionary patterns that describe phenotypic similarity across independent lineages. Assessing whether and how adaptive processes give origin to these patterns represent a fundamental step toward understanding phenotypic evolution. Phylogenetic model-based approaches offer the opportunity not only to distinguish between PNC and convergence, but also to determine the extent that adaptive processes explain phenotypic similarity. The Myrmotherula complex in the Neotropical family Thamnophilidae is a polyphyletic group of sexually dimorphic small insectivorous forest birds that are relatively homogeneous in size and shape. Here, we integrate a comprehensive species-level molecular phylogeny of the Myrmotherula complex with morphometric and ecological data within a comparative framework to test whether phenotypic similarity is described by a pattern of PNC or convergence, and to identify evolutionary mechanisms underlying body size and shape evolution. We show that antwrens in the Myrmotherula complex represent distantly related clades that exhibit adaptive convergent evolution in body size and divergent evolution in body shape. Phenotypic similarity in the group is primarily driven by their tendency to converge toward smaller body sizes. Differences in body size and shape across lineages are associated to ecological and behavioral factors.

Molecular phylogenetics and the diversification of hummingbirds.

The tempo of species diversification in large clades can reveal fundamental evolutionary mechanisms that operate on large temporal and spatial scales. Hummingbirds have radiated into a diverse assemblage of specialized nectarivores comprising 338 species, but their evolutionary history has not, until now, been comprehensively explored. We studied hummingbird diversification by estimating a time-calibrated phylogeny for 284 hummingbird species, demonstrating that hummingbirds invaded South America by ∼22 million years ago, and subsequently diversified into nine principal clades (see [5-7]). Using ancestral state reconstruction and diversification analyses, we (1) estimate the age of the crown-group hummingbird assemblage, (2) investigate the timing and patterns of lineage accumulation for hummingbirds overall and regionally, and (3) evaluate the role of Andean uplift in hummingbird speciation. Detailed analyses reveal disparate clade-specific processes that allowed for ongoing species diversification. One factor was significant variation among clades in diversification rates. For example, the nine principal clades of hummingbirds exhibit ∼15-fold variation in net diversification rates, with evidence for accelerated speciation of a clade that includes the Bee, Emerald, and Mountain Gem groups of hummingbirds. A second factor was colonization of key geographic regions, which opened up new ecological niches. For example, some clades diversified in the context of the uplift of the Andes Mountains, whereas others were affected by the formation of the Panamanian land bridge. Finally, although species accumulation is slowing in all groups of hummingbirds, several major clades maintain rapid rates of diversification on par with classical examples of rapid adaptive radiation.

DNA sequence data reveal a subfamily-level divergence within Thamnophilidae (Aves: Passeriformes).

The Thamnophilidae is a diverse radiation of insectivorous passerine birds that comprises nearly 220 species and is mostly restricted to the lowlands and lower montane forests of the Neotropics. Current classification within Thamnophilidae relies primarily on morphological variation, but recent incorporation of molecular and vocal data has promoted changes at various taxonomic levels. Here we demonstrate that the genus Terenura is polyphyletic because Terenura callinota, T. humeralis, T. spodioptila, and T. sharpei are phylogenetically distant from the type species of the genus, Terenura maculata. More importantly, the former four species are not particularly closely related to any other thamnophilids and represent a clade that is sister to all other members of the family. Because no genus name is available for this previously undetected lineage in the Thamnophilidae, we describe the genus Euchrepomis for callinota, humeralis, spodioptila, and sharpei, and erect the subfamily Euchrepomidinae. We discuss the taxonomic and evolutionary significance of this divergent lineage. This study highlights the importance of taxonomic coverage and the inclusion of type taxa to redefine classifications to reflect accurately evolutionary relationships.

Ecological opportunity and diversification in a continental radiation of birds: climbing adaptations and cladogenesis in the Furnariidae.

Ecological theories of adaptive radiation predict that ecological opportunity stimulates cladogenesis through its effects on competitive release and niche expansion. Given that key innovations may confer ecological opportunity, we investigated the effect of the acquisition of climbing adaptations on rates of cladogenesis in a major avian radiation, the Neotropical bird family Furnariidae, using a species-level phylogeny. Morphological specializations for vertical climbing originated in the woodcreepers ∼23 million years ago, well before that adaptation occurred in woodpeckers (Picidae) or in other potential competitors in South America. This suggests that the acquisition of climbing adaptations conferred ample ecological opportunity to early woodcreepers. Nonetheless, we found that increases in speciation rates in Furnariidae did not coincide with the acquisition of climbing adaptations and that the relationship between the accumulation of climbing adaptations and rates of speciation was negative. In addition, we did not detect a diversity-dependent decline in woodcreeper diversification rates consistent with saturation of the trunk-climbing niche. These findings do not support the hypothesis that ecological opportunity related to trunk foraging stimulated cladogenesis in this radiation. The negative effect of climbing on diversification may be mediated by an indirect positive effect of climbing on dispersal ability, which may reduce speciation rates over evolutionary timescales.

High dispersal ability inhibits speciation in a continental radiation of passerine birds.

Dispersal can stimulate speciation by facilitating geographical expansion across barriers or inhibit speciation by maintaining gene flow among populations. Therefore, the relationship between dispersal ability and speciation rates can be positive or negative. Furthermore, an 'intermediate dispersal' model that combines positive and negative effects predicts a unimodal relationship between dispersal and diversification. Because both dispersal ability and speciation rates are difficult to quantify, empirical evidence for the relationship between dispersal and diversification remains scarce. Using a surrogate for flight performance and a species-level DNA-based phylogeny of a large South American bird radiation (the Furnariidae), we found that lineages with higher dispersal ability experienced lower speciation rates. We propose that the degree of fragmentation or permeability of the geographical setting together with the intermediate dispersal model are crucial in reconciling previous, often contradictory findings regarding the relationship between dispersal and diversification.

Lineage diversification and morphological evolution in a large-scale continental radiation: the neotropical ovenbirds and woodcreepers (aves: Furnariidae).

Patterns of diversification in species-rich clades provide insight into the processes that generate biological diversity. We tested different models of lineage and phenotypic diversification in an exceptional continental radiation, the ovenbird family Furnariidae, using the most complete species-level phylogenetic hypothesis produced to date for a major avian clade (97% of 293 species). We found that the Furnariidae exhibit nearly constant rates of lineage accumulation but show evidence of constrained morphological evolution. This pattern of sustained high rates of speciation despite limitations on phenotypic evolution contrasts with the results of most previous studies of evolutionary radiations, which have found a pattern of decelerating diversity-dependent lineage accumulation coupled with decelerating or constrained phenotypic evolution. Our results suggest that lineage accumulation in tropical continental radiations may not be as limited by ecological opportunities as in temperate or island radiations. More studies examining patterns of both lineage and phenotypic diversification are needed to understand the often complex tempo and mode of evolutionary radiations on continents.

Molecular phylogenetics of the hummingbird genus Coeligena.

Advances in the understanding of biological radiations along tropical mountains depend on the knowledge of phylogenetic relationships among species. Here we present a species-level molecular phylogeny based on a multilocus dataset for the Andean hummingbird genus Coeligena. We compare this phylogeny to previous hypotheses of evolutionary relationships and use it as a framework to understand patterns in the evolution of sexual dichromatism and in the biogeography of speciation within the Andes. Previous phylogenetic hypotheses based mostly on similarities in coloration conflicted with our molecular phylogeny, emphasizing the unreliability of color characters for phylogenetic inference. Two major clades, one monochromatic and the other dichromatic, were found in Coeligena. Closely related species were either allopatric or parapatric on opposite mountain slopes. No sister lineages replaced each other along an elevational gradient. Our results indicate the importance of geographic isolation for speciation in this group and the potential interaction between isolation and sexual selection to promote diversification.

Phylogenetic systematics and biogeography of hummingbirds: Bayesian and maximum likelihood analyses of partitioned data and selection of an appropriate partitioning strategy.

Hummingbirds are an important model system in avian biology, but to date the group has been the subject of remarkably few phylogenetic investigations. Here we present partitioned Bayesian and maximum likelihood phylogenetic analyses for 151 of approximately 330 species of hummingbirds and 12 outgroup taxa based on two protein-coding mitochondrial genes (ND2 and ND4), flanking tRNAs, and two nuclear introns (AK1 and BFib). We analyzed these data under several partitioning strategies ranging between unpartitioned and a maximum of nine partitions. In order to select a statistically justified partitioning strategy following partitioned Bayesian analysis, we considered four alternative criteria including Bayes factors, modified versions of the Akaike information criterion for small sample sizes (AIC(c)), Bayesian information criterion (BIC), and a decision-theoretic methodology (DT). Following partitioned maximum likelihood analyses, we selected a best-fitting strategy using hierarchical likelihood ratio tests (hLRTS), the conventional AICc, BIC, and DT, concluding that the most stringent criterion, the performance-based DT, was the most appropriate methodology for selecting amongst partitioning strategies. In the context of our well-resolved and well-supported phylogenetic estimate, we consider the historical biogeography of hummingbirds using ancestral state reconstructions of (1) primary geographic region of occurrence (i.e., South America, Central America, North America, Greater Antilles, Lesser Antilles), (2) Andean or non-Andean geographic distribution, and (3) minimum elevational occurrence. These analyses indicate that the basal hummingbird assemblages originated in the lowlands of South America, that most of the principle clades of hummingbirds (all but Mountain Gems and possibly Bees) originated on this continent, and that there have been many (at least 30) independent invasions of other primary landmasses, especially Central America.

Ivory-billed woodpecker (Campephilus principalis) persists in continental North America.

The ivory-billed woodpecker (Campephilus principalis), long suspected to be extinct, has been rediscovered in the Big Woods region of eastern Arkansas. Visual encounters during 2004 and 2005, and analysis of a video clip from April 2004, confirm the existence of at least one male. Acoustic signatures consistent with Campephilus display drums also have been heard from the region. Extensive efforts to find birds away from the primary encounter site remain unsuccessful, but potential habitat for a thinly distributed source population is vast (over 220,000 hectares).