Jan I. Ohlson

Diversification of Neoaves: integration of molecular sequence data and fossils

Patterns of diversification and timing of evolution within Neoaves, which includes almost 95% of all bird species, are virtually unknown. On the other hand, molecular data consistently indicate a Cretaceous origin of many neoavian lineages and the fossil record seems to support an Early Tertiary diversification. Here, we present the first well-resolved molecular phylogeny for Neoaves, together with divergence time estimates calibrated with a large number of stratigraphically and phylogenetically well-documented fossils. Our study defines several well-supported clades within Neoaves. The calibration results suggest that Neoaves, after an initial split from Galloanseres in Mid-Cretaceous, diversified around or soon after the K/T boundary. Our results thus do not contradict palaeontological data and show that there is no solid molecular evidence for an extensive pre-Tertiary radiation of Neoaves.

Nuclear DNA from old collections of avian study skins reveals the evolutionary history of the Old World suboscines (Aves, Passeriformes)

Museum study skins represent an invaluable source of DNA for phylogenetics, phylogeography and population genetics. This becomes evident by comparing the number of study skins of birds housed in museums worldwide (c. 10 million) with the corresponding number of tissue samples (probably fewer than 500 000). While the laboratory techniques used hitherto have primarily allowed PCR‐based studies of mitochondrial genes from museum skins, we present here the first avian phylogeny based on a large number of nuclear sequences. The targeted fragment sizes and the properties of the primers used are important contributory factors to obtain good amplification results. In this study we routinely amplified fragments of c. 350 bp nuclear DNA. This advance in methodology opens up a new avenue for the use of avian museum skins, as nuclear DNA is especially useful when studying ancient patterns of diversification. The phylogenetic hypothesis of the Old World suboscines (Eurylaimides) presented herein strongly supports a monophyletic origin of the pittas (Pittidae). The phylogeny further suggests that pittas could be divided into three major groups, in agreement with the external morphological variation found in this group. The broadbills (Eurylaimidae) as currently defined are, on the other hand, found to be a paraphyletic family, as both Sapayoa aenigma and the asities (Philepittidae) are nested among them. Based on the phylogenetic results we suggest a revised classification of the Old World suboscines (Eurylaimides).

Tyrant flycatchers coming out in the open : phylogeny and ecological radiation of Tyrannidae (Aves, Passeriformes)

Tyrant flycatchers constitute a substantial component of the land bird fauna in all South American habitats. Past interpretations of the morphological and ecological evolution in the group have been hampered by the lack of a well‐resolved hypothesis of their phylogenetic interrelationships. Here, we present a well‐resolved phylogeny based on DNA sequences from three nuclear introns for 128 taxa. Our results confirm much of the overall picture of Tyrannidae relationships, and also identify several novel relationships. The genera Onychorhynchus, Myiobius and Terenotriccus are placed outside Tyrannidae and may be more closely related to Tityridae. Tyrannidae consists of two main lineages. An expanded pipromorphine clade includes flatbills, tody‐tyrants and antpipits, and also Phylloscartes and Pogonotriccus. The spadebills, Neopipo and Tachuris are their closest relatives. The remainder of the tyrant flycatchers forms a well‐supported clade, subdivided in two large subclades, which differ consistently in foraging behaviour, the perch‐gleaning elaeniines and the sallying myiarchines, tyrannines and fluvicolines. A third clade is formed by the genera Myiotriccus, Pyrrhomyias, Hirundinea and three species currently placed in Myiophobus. Ancestral habitat reconstruction and divergence date estimation suggest that early divergence events in Tyrannida took place in a humid forest environment during the Oligocene. Large‐scale diversification in open habitats is confined to the clade consisting of the elaeniines, myiarchines, tyrannines and fluvicolines. This radiation correlates in time to the expansion of semi‐open and open habitats from the mid‐Miocene (c. 15 Mya) onwards. The pipromorphine, elaeniine and myiarchine–tyrannine–fluvicoline clades each employ distinct foraging strategies (upward striking, perch‐gleaning and sallying, respectively), but the degree of diversity in morphology and microhabitat exploitation is markedly different between these clades. While the pipromorphines and elaeniines each are remarkably homogenous in morphology and exploit a restricted range of microhabitats, the myiarchine–tyrannine–fluvicoline clade is more diverse in these respects. This greater ecological diversity, especially as manifested in their success in colonizing a wider spectrum of open habitats, appears to be connected to a greater adaptive flexibility of the search‐and‐sally foraging behaviour.

Synchronous intercontinental splits between assemblages of woodpeckers suggested by molecular data

The woodpeckers (Piciformes: Picinae) comprise a widely distributed and species‐rich clade of birds that is strongly associated with trees for feeding, nesting, or both. Because of this association, woodpeckers provide a useful model for evaluating the impact of climatic and tectonic events on the diversification of forest birds during the Tertiary. In order to resolve the biogeographical history of the woodpeckers, we have analysed sequences from two nuclear introns and one mitochondrial gene using likelihood and Bayesian approaches. Our analyses favour a tropical Eurasian origin; divergences between African, Indo‐Malayan and New World clades with subsequent colonizations of Africa and the New World occurred synchronously during the Middle Miocene, a period corresponding to the expansion of the C4 grasses and the uplift of the Himalayan‐Tibetan plateau. The taxonomic diversification of woodpeckers at this time may be attributed to the fragmentation of forests in response to the drier climate, which in turn prevented gene flow between tropical stocks in Africa, Indo‐Malaya and the New World. Our estimates of colonization times of South America predate the closure of the Panama Isthmus and support the hypothesis of a short‐lived, terrestrial corridor at the end of the Miocene, 5.7 Myr BP.

Evolution of complex symbiotic relationships in a morphologically derived family of lichen-forming fungi.

We studied the evolutionary history of the Parmeliaceae (Lecanoromycetes, Ascomycota), one of the largest families of lichen-forming fungi with complex and variable morphologies, also including several lichenicolous fungi. We assembled a six-locus data set including nuclear, mitochondrial and low-copy protein-coding genes from 293 operational taxonomic units (OTUs). The lichenicolous lifestyle originated independently three times in lichenized ancestors within Parmeliaceae, and a new generic name is introduced for one of these fungi. In all cases, the independent origins occurred c. 24 million yr ago. Further, we show that the Paleocene, Eocene and Oligocene were key periods when diversification of major lineages within Parmeliaceae occurred, with subsequent radiations occurring primarily during the Oligocene and Miocene. Our phylogenetic hypothesis supports the independent origin of lichenicolous fungi associated with climatic shifts at the Oligocene-Miocene boundary. Moreover, diversification bursts at different times may be crucial factors driving the diversification of Parmeliaceae. Additionally, our study provides novel insight into evolutionary relationships in this large and diverse family of lichen-forming ascomycetes.

The division of the major songbird radiation into Passerida and ‘core Corvoidea’ (Aves: Passeriformes) — the species tree vs. gene trees

The knowledge of evolutionary relationships among oscine songbirds has been largely improved in recent years by molecular phylogenetic studies. However, current knowledge is still largely based on sequence data from a limited number of loci. In this study, we re‐evaluate relationships among basal lineages within the ‘core Corvoidea’ and Passerida radiations, by adding additional loci to previously published data. The trees obtained from the individual genes suggest incongruent topologies. Especially the positions of Callaeatidae (wattlebirds), Cnemophilidae (satinbirds) and Melanocharitidae (longbills and berrypeckers) vary among the trees, but RAG‐1 is the only gene that unambiguously suggested a ‘core Corvoidea’ affinity for these taxa. Analyses of various combined data sets show that the phylogenetic positions for Callaeatidae, Cnemophilidae and Melanocharitidae largely depend on which genes that have been combined. As the RAG‐1 gene has contributed to a majority of the phylogenetic information in previous studies, it has deeply influenced previous molecular affinities of these taxa. Based on the current data, we found a reasonable support for a Passerida affinity of Callaeatidae and Cnemophilidae, contrary to previous molecular studies. The position of Melanocharitidae is more unstable but a basal position among Passerida is congruent with a deletion observed in the glyceraldehyde‐3‐phosphodehydrogenase (GAPDH) loci. Molecular clock estimations conducted on the combined data sets were generally found to be similar, but for some divergences significant differences were found. These results illustrate the potential problem of phylogenies predominantly based on characters from one or a few loci, and exemplify the importance of well‐supported phylogenies before reasonable time estimates of passerine divergences could be achieved.

A complete multilocus species phylogeny of the tits and chickadees (Aves: Paridae).

The avian family Paridae (tits and chickadees) contains c. 55 species distributed in the Palearctic, Nearctic, Afrotropics and Indomalaya. The group includes some of the most well-known and extensively studied avian species, and the evolutionary history, in particular the post-glacial colonization of the northern latitudes, has been comparably well-studied for several species. Yet a comprehensive phylogeny of the whole clade is lacking. Here, we present the first complete species phylogeny for the group based on sequence data from two nuclear introns and one mitochondrial gene for 67 taxa of parids. Our results strongly support the inclusion of the Fire-capped Tit (Cephalopyrus flammiceps), currently placed in the Remizidae, as the most basal member of the Paridae. The Yellow-browed Tit (Sylviparus modestus) and the Sultan Tit (Melanochlora sultanea) constitute the next two sequential branches whereas the remaining tits fall into two large clades, one of which contains the seed hoarding and nest excavating species. The indicated clades within these two groups are largely congruent with recent classifications, but with several unforeseen relationships, such as non-monophyly of the Sombre Tit (Poecile lugubris) and the Marsh Tit (Poecile palustris), as well as non-monophyly of both the African gray and the African black tits. Further, our results support a close relationship between the White-fronted Tit (Parus semilarvatus) and the varied Tit (Poecile varius) as well as a close relationship between the White-naped Tit (Parus nuchalis) and the Yellow-cheeked and Black-lored tits (Parus spilonotus and P. xanthogenys). Finally, Humes Ground-tit (Pseudopodoces humilis) is found to be closely related to the Green-backed Tit (Parus monticolus) and the Great Tit (Parus major). We propose a new classification that is in accordance with this phylogeny.

The systematic affinity of the enigmatic Lamprolia victoriae (Aves: Passeriformes)—An example of avian dispersal between New Guinea and Fiji over Miocene intermittent land bridges?

The systematic affinity of the enigmatic Lamprolia victoriae (Aves: Passeriformes) - an example of avian dispersal between New Guinea and Fiji over Miocene intermittent land bridges?

Phylogeny and classification of the New World suboscines (Aves, Passeriformes)

Here we present a phylogenetic hypothesis for the New World suboscine radiation, based on a dataset comprising of 219 terminal taxa and five nuclear molecular markers (ca. 6300 bp). We also estimate ages of the main clades in this radiation. This study corroborates many of the recent insights into the phylogenetic relationships of New World suboscines. It further clarifies a number of cases for which previous studies have been inconclusive, such as the relationships of Conopophagidae, Melanopareiidae and Tityridae. We find a remarkable difference in age of the initial divergence events in Furnariida and Tyrannida. The deepest branches in Furnariida are of Eocene age, whereas the extant lineages of Tyrannida have their origin in the Oligocene. Approximately half of the New World suboscine species are harboured in 5 large clades that started to diversify around the Mid Miocene Climatic Optimum (16-12 Mya). Based on our phylogenetic results we propose a revised classification of the New World suboscines. We also erect new family or subfamily level taxa for four small and isolated clades: Berlepschiinae, Pipritidae, Tachurididae and Muscigrallinae.

Molecular phylogeny of the manakins (Aves: Passeriformes: Pipridae), with a new classification and the description of a new genus.

The phylogenetic relationships within the manakin family (Pipridae) were investigated with sequence data from three nuclear introns and one mitochondrial protein-coding gene. This study confirms a sister group relationship between Neopelminae and Piprinae. We also find support for dividing the Piprinae into two principal clades: Ilicurini and Piprini. The genera Pipra and Chloropipo are found to be polyphyletic. Chloropipo species are placed in three different clades, including two species in an unresolved position alongside Ilicurini and Piprini. We propose a new classification of the family, where the most important modifications include recognizing the genus Ceratopipra for five species formerly placed in Pipra and the erection of a new genus for Chloropipo holochlora.