Phylogeny of babblers (Aves, Passeriformes): major lineages, family limits and classification

Geography and elevation as drivers of cloacal microbiome assemblages of a passerine bird distributed across Sulawesi, Indonesia

BACKGROUND

Empirical field studies allow us to view how ecological and environmental processes shape the biodiversity of our planet, but collecting samples in situ creates inherent challenges. The majority of empirical vertebrate gut microbiome research compares multiple host species against abiotic and biotic factors, increasing the potential for confounding environmental variables. To minimize these confounding factors, we focus on a single species of passerine bird found throughout the geologically complex island of Sulawesi, Indonesia. We assessed the effects of two environmental factors, geographic Areas of Endemism (AOEs) and elevation, as well as host sex on the gut microbiota assemblages of the Sulawesi Babbler, Pellorneum celebense, from three different mountains across the island. Using cloacal swabs, high-throughput-amplicon sequencing, and multiple statistical models, we identified the core microbiome and determined the signal of these three factors on microbial composition.

RESULTS

The five most prevalent bacterial phyla within the gut microbiome of P. celebense were Proteobacteria (32.6%), Actinobacteria (25.2%), Firmicutes (22.1%), Bacteroidetes (8.7%), and Plantomycetes (2.6%). These results are similar to those identified in prior studies of passeriform microbiomes. Overall, microbiota diversity decreased as elevation increased, irrespective of sex or AOE. A single ASV of Clostridium was enriched in higher elevation samples, while lower elevation samples were enriched with the genera Perlucidibaca (Family Moraxellaceae), Lachnoclostridium (Family Lachnospiraceae), and an unidentified species in the Family Pseudonocardiaceae.

CONCLUSIONS

While the core microbiota families recovered here are consistent with other passerine studies, the decreases in diversity as elevation increases has only been seen in non-avian hosts. Additionally, the increased abundance of Clostridium at high elevations suggests a potential microbial response to lower oxygen levels. This study emphasizes the importance of incorporating multiple statistical models and abiotic factors such as elevation in empirical microbiome research, and is the first to describe an avian gut microbiome from the island of Sulawesi.

Genome survey sequencing and mining of genome-wide microsatellite markers in yellow-billed babbler (Turdoides affinis)

Turdoides affinis is a species of group dwelling old world passerine of family Leiothrichidae. Unavailability of genome-wide sequence and species-specific molecular markers have hindered comprehensive understanding of cooperative breeding behaviour in T. affinis. Therefore, we generated genome-wide microsatellite markers through whole genome short read sequencing of T. affinis. A total of 68.8 gigabytes of paired-end raw data were sequenced containing 195,067,054 reads. Total sequenced reads spanned a coverage of 17X with genome size of 1.18 Gb. A large number of microsatellite markers (265,297) were mined in the T. affinis genome using Krait, and 50 most informative markers were identified and validated further. In-silico PCR results validated 47 markers. Of these 47 markers, five were randomly selected and validated in-vitro in twelve individuals of T. affinis. Genotyping data on these five loci estimated observed heterozygosity (H₀) and expected heterozygosity (H_e) ratios between 0.333 - 0.833 and 0.851-0.906, respectively. Effective allele size ranged from 6.698 to 10.667, inbreeding coefficient of the population ranged from 0.080 to 0.631 and null allele frequency was calculated at 0.055 to 0.303. Polymorphic information content of all the five loci varied between 0.850 and 0.906. Probabilities of exclusion and identity across 5 loci was estimated to be 0.95 and 0.0036, respectively. All the loci showed significant adherence to Hardy-Weinberg equilibrium. The microsatellite markers reported in this study will facilitate future population genetics studies on T. affinis and other congeneric species.

PHYLOGENETIC RELATIONSHIPS OF GUIMARAESIELLA AND PRICEIELLA (PHTHIRAPTERA: ISCHNOCERA) FROM BABBLERS AND NON-BABBLERS (PASSERIFORMES)

Babblers (Passeriformes: Leiothrichidae, Pellorneidae, Timaliidae) are parasitized by more genera of lice of the Brueelia complex than any other group of songbirds. However, the relationships of these louse groups are poorly known. We here try to resolve the relationships between Guimaraesiella (Guimaraesiella), Guimaraesiella (Cicchinella), and their putative sister group Priceiella by using mitochondrial cytochrome c subunit 1 (COI), 12S, and 16S sequences. Our data indicate that G. (Cicchinella) forms a monophyletic group of lice from babblers, but the relationship between G. (Guimaraesiella), G. (Cicchinella), and Priceiella could not be resolved. Moreover, the position of the third lineage of babbler-specific lice, containing only the aberrant species Guimaraesiella montisodalis, is unresolved. Morphologically, this species is different from all other Guimaraesiella in several characters and may represent a distinct lineage. We present some data indicating that (1) the Nanling Mountain range may be a biogeographical barrier to chewing lice and (2) host participation in mixed-species feeding flocks may influence host associations in Brueelia-complex chewing lice.

A phylogeny of white-eyes based on ultraconserved elements

White-eyes are an iconic radiation of passerine birds that have been the subject of studies in evolutionary biology, biogeography, and speciation theory. Zosterops white-eyes in particular are thought to have radiated rapidly across continental and insular regions of the Afro- and Indo-Pacific tropics, yet their phylogenetic history remains equivocal. Here, we sampled 77% of the genera and 47% of known white-eye species and sequenced thousands of ultraconserved elements to infer the phylogeny of the avian family Zosteropidae. We used concatenated maximum likelihood and species tree methods and found strong support for seven clades of white-eyes and three clades within the species-rich Zosterops radiation.

Complete mitochondrial genome of fire-tailed myzornis (Myzornis pyrrhoura) and white-browed fulvetta (Fulvetta vinipectus)

In this study, the complete mitochondrial genomes of Myzornis pyrrhoura and Fulvetta vinipectus were sequenced and described for the first time. The whole mitochondrial genomes of M. pyrrhoura and F. vinipectus are 17,397 bp and 16,961 bp in length, with the G + C percentage 46.34% and 47.36%, respectively. Both genomes contain 13 protein-coding genes, 22 transfer RNA genes, 2 ribosome RNA genes, and 1 non-coding control region. The arrangement of genes is identical to mitochondrial genomes of Sylviidae species reported previously. A phylogenetic reconstruction supported that M. pyrrhoura and F. vinipectus are members of family Sylviidae. The mitochondrial genomes of these two species reported here would be helpful in better understanding the phylogeny and evolution of Sylviidae.

Chewing lice from high-altitude and migrating birds in Yunnan, China, with descriptions of two new species of Guimaraesiella

In total, 366 birds representing 55 species in 24 families and eight orders, were examined for chewing lice (Phthiraptera: Amblycera, Ischnocera) in two high-altitude localities in Yunnan Province, China. In Ailaoshan, almost all of the birds examined were resident passeriforms, of which 36% were parasitized by chewing lice. In Jinshanyakou, most birds were on migration, and included both passerine and non-passerine birds. Of the passerine birds caught in Jinshanyakou, only one bird (0.7%) was parasitized by chewing lice. The prevalence of Myrsidea and Brueelia-complex lice on birds caught in Ailaoshan was higher than in previous reports. Of the chewing lice identifiable to species level, three represent new records for China: Actornithophilus hoplopteri (Mjöberg, 1910), Maculinirmus ljosalfar Gustafsson & Bush, 2017 and Quadraceps sinensis Timmermann, 1954. In total, 17 new host records are included, of which we describe two as new species in the Brueelia-complex: Guimaraesiella (Cicchinella) ailaoshanensis sp. nov. ex Schoeniparus dubius dubius (Hume, 1874) and G. (C.) montisodalis sp. nov. ex Fulvetta manipurensis tonkinensis Delacour & Jabouille, 1930. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:9FC3D8EE-2CED-4DBE-A1DB-471B71260D27.

Novel genome and genome-wide SNPs reveal early fragmentation effects in an edge-tolerant songbird population across an urbanized tropical metropolis

Although edge-tolerant species are known to benefit from habitat fragmentation, less is known about the population genetic impacts fragmentation may exert on edge-tolerant species. We examined the landscape genomic structure of an edge-tolerant forest-dependent bird species, the Striped Tit-Babbler Mixornis gularis, in the heavily urbanized island of Singapore to determine if two centuries of fragmentation have led to signs of isolation and loss of population-genetic diversity in different parts of the island. We obtained a high-quality complete reference genome with 78x coverage. Using almost 4000 SNPs from double-digest RAD-Sequencing across 46 individuals, we found that the population has likely experienced a recent contraction in effective population size and presently exhibits low population genetic diversity. Using empirical and simulation-based landscape genomic analyses, we also found that the subtle population genetic structure observed in the Striped Tit-Babbler population in Singapore is likely driven by isolation by distance resulting from limited dispersal. Our results demonstrate that population genetic impoverishment and subdivision can accumulate at relatively rapid rates in edge-tolerant bird species such as the Striped Tit-Babbler as a result of fragmentation, and that subtle spatial genetic structure can be detected over fine spatial and temporal scales using relatively few multilocus genomic SNPs.

Complete species-level phylogeny of the leaf warbler (Aves: Phylloscopidae) radiation

The leaf warbler radiation (Aves: Phylloscopidae) has undergone a c. 50% increase in the number of recognised species over the last three decades, mainly as a result of analyses of vocalisations and DNA. Using a multilocus dataset for all of the species in this family, and multispecies coalescent-based as well as concatenation methods, we provide the first complete species-level phylogeny for this important group, as well as an estimate of the timing of diversification. The most recent common ancestor for the family was dated at 11.7 million years ago (mya) (95% highest posterior density 9.8-13.7 mya), and divergence times between sister species ranged from 0.5 mya (0.3-0.8 mya) to 6.1 mya (4.8-7.5 mya). Based on our results, we support synonymising Seicercus with Phylloscopus, which results in a monogeneric Phylloscopidae. We discuss the pros and cons of this treatment,and we argue againstproliferation of taxonomic names,and conclude that a large monogeneric Phylloscopidae leads to the fewest taxonomic changes compared to traditional classifications. We briefly discuss morphological evolution in the light of the phylogeny. The time calibrated phylogeny is a major improvement compared to previous studies based on a smaller number of species and loci and can provide a basis for future studies of other aspects of phylloscopid evolution.

Two new mitogenomes of Pellorneidae (Aves : Passeriformes) and a phylogeny of the superfamily Sylvioidea

The superfamily Sylvioidea contains the most diversified species within the Passerida. The grey-cheeked fulvetta (Alcippe morrisonia) and the eyebrowed wren-babbler (Napothera epilepidota) are birds with a weak flight that live in lightly wooded or scrubland environments. In the present study, two new mitogenomes of A. morrisonia (KX376475) and N. epilepidota (KX831093) within the superfamily Sylvioidea were sequenced and their total lengths were 17788bp and 17913bp, respectively. Both mitogenomes comprised 13 protein-coding genes, 22 tRNAs, 2 rRNAs and two control regions (CR and CCR). Similar to most metazoans, both mitogenomes and their protein-coding genes encoded on the H-strand displayed typical positive AT skews and negative GC skews. Bayesian inference and maximum-likelihood phylogenetic analyses were conducted on the basis of partitioned data of mitogenomes and two identical topologies were observed. The family-level phylogenetic relationships ((((Pellorneidae, Leiothrichidae) Timaliidae) Zosteropidae) Sylviidae) among the superfamily Sylvioidea were strongly supported. Within the family Pellorneidae, A. morrisonia clustered with N. epilepidota. Within Leiothrichidae, we further demonstrated that Babax lanceolatus is sister to Garrulax perspicillatus, and Spizixos semitorques was nested within the genus Pycnonotus according to the mitogenomic data and we propose that the generic placement of Spizixos should be reconsidered.

A quadratic correlation between long-term mean group size and group density in a cooperatively breeding passerine

Both mean group size (MGS) and mean group density (MGD) are critical indices to characterize a population of cooperatively breeding birds. When a population reaches its carrying capacity, both long‐term MGS and long‐term MGD will remain relatively stable. However, there has been little study of how these two variables relate. The Masked laughingthrush Garrulax perspicillatus is a cooperatively breeding bird living in fragmented habitats. During 2010 and 2012‐2016, we used song playback to observe and confirm the group sizes and territory ranges of the birds and the data of bird presence to determine habitat suitability. By grouping the nearest territories according to their geographical coordinates, we divided the whole study area into 12 subareas and the whole population into 12 subpopulations. Then, we calculated both MGS and MGD for different time durations for each subpopulation. Finally, using MGD as independent variable and MGS as the dependent variable, we explored the correlations between MGS and MGD by fitting quadratic functions and modeling quadratic regression. Both MGS and MGD were averaged for different time durations and were cross‐related. Our results show that the MGS for more than 2 years significantly correlated with MGD for more than 3 years in a reverse parabolic shape, differing from that of short‐term effects. Our findings suggest that long‐term MGD is a better predictor of long‐term habitat quality and that long‐term MGS is determined by long‐term habitat quality in Masked Laughingthrushes. Based on above findings, we can infer that: (1) Long‐term habitat quality determines the long‐term MGS, but it sets no prerequisite for the status and source of group members; (2) Long‐term MGS in certain populations is adapted to the corresponding level of long‐term habitat quality, it facilitates us to predict the helper effects on current or future survival or reproduction in different situations. These findings and inferences are both helpful for us to understand the evolution of cooperative breeding.

Two new genera of songbirds represent endemic radiations from the Shola Sky Islands of the Western Ghats, India

Background

A long-standing view of Indian biodiversity is that while rich in species, there are few endemics or in-situ radiations within the subcontinent. One exception is the Western Ghats biodiversity hotspot, an isolated mountain range with many endemic species. Understanding the origins of the montane-restricted species is crucial to illuminate both taxonomic and environmental history.

Results

With evidence from genetic, morphometric, song, and plumage data, we show that two songbird lineages endemic to the Western Ghats montane forest each have diversified into multiple distinct species. Historically labeled as single species of widespread Asian genera, these two lineages are highly divergent and do not group with the taxa in which they were previously classified but rather are distinct early divergences in larger Asian clades of flycatchers and babblers. Here we designated two new genera, the Western Ghats shortwings as Sholicola and the laughingthrushes as Montecincla, and evaluated species-limits to reflect distinct units by revising six previously named taxa and describing one novel species. Divergence dating showed that both these montane groups split from their Himalayan relatives during the Miocene, which is coincident with a shift towards arid conditions that fragmented the previously contiguous humid forest across peninsular India and isolated these lineages in the Western Ghats. Furthermore, these two genera showed congruent patterns of diversification across the Western Ghats Sky Islands, coincident with other climatic changes.

Conclusion

Our study reveals the existence of two independent endemic radiations in the high montane Western Ghats or Shola Sky Islands with coincident divergence times, highlighting the role of climate in the diversification of these ancient lineages. The endemic and highly divergent nature of these previously unrecognized species underscores the dearth of knowledge about the biogeography of the Asian tropics, even for comparatively well-known groups such as birds. The substantial increase in the diversity of this region underscores the need for more rigorous systematic analysis to inform biodiversity studies and conservation efforts.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-017-0882-6) contains supplementary material, which is available to authorized users.

Complete mitochondrial genome of Minla ignotincta (Passeriformes: Timaliidae)

We sequenced the complete mitochondrial genome from Minla ignotincta. The genome sequence was 17 868 bp in length, and the gene arrangement and contents were identical to those of previously reported Timaliidae mitochondrial genomes. The overall base composition of the mitogenome is biased toward A + T content at 54.04%. All protein-coding genes (PCGs) began with ATG. Nine of the 13 PCGs used complete (TAA) or incomplete (TA or T) stop codon, while ND1 and ND5 ended with AGA, COI ended with AGG and ND6 with TAG. All the genes in M. ignotincta were distributed on the H-strand, except for the ND6 subunit gene and eight tRNA genes which were encoded on the L-strand.

The complete mitochondrial genome sequence of White-collared Yuhina (Yuhina diademata)

We sequenced the complete mitochondrial DNA genome of Yuhina diademata by means of polymerase chain reaction. The circle genome (17 834 bp in length) contained 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and 2 control regions (Dloop1 and Dloop2), which was similar to the other published mitogenome of Timaliidae species. Most PCGs began with ATG, while COI and ND2 genes started with GTG. Nine of the PCGs used complete (TAA) or incomplete (TA- or T--) stop codon, while ND1 and ND6 genes ended with AGA, COI gene ended with AGG, and ND6 gene with TAG. Overall base composition of the complete mtDNA was 30.30% A, 23.81% T, 31.72% C, and 14.17% G. All the PCGs in Y. diademata were distributed on the H-strand, except for the ND6 gene and eight tRNA genes which were encoded on the L-strand.

Untangling taxonomic confusion and diversification patterns of the Streak-breasted Scimitar Babblers (Timaliidae: Pomatorhinus ruficollis complex) in southern Asia

Biodiversity patterns in Asia are poorly understood due to inferences drawn from incorrect taxonomy and limited survey effort. The Streak-breasted Scimitar Babblers (Pomatorhinus ruficollis complex) have a wide distribution across southern Asia and exhibit a high degree of plumage variability within and among populations. Continued use of traditional subspecies designations over revised species-limits based on plumage and DNA sequence data furthers confusion in this group and obscures complex biogeographic patterns. In this study, we combined previously published DNA sequences with newly sampled populations to produce a comprehensive dataset for the ruficollis complex. Phylogenetic analysis of these data confirms that traditional subspecies based on plumage alone are paraphyletic and therefore not good descriptors of evolutionary history. With increased sampling, our study supported previous delimitations of phylogenetic species as distinct units, refined the range limits of two taxa - P. reconditus (throughout central China) and P. nigrostellatus (Hainan, Guangxi, N Vietnam), showed two additional clades that may be distinct species, and uncovered a 'suture' zone where populations of multiple species occur in the same localities. Diversification within the ruficollis complex indicates a clade of Sino-Himalayan and SE Asian species sister to a clade distributed in central and southern China species. The 'suture' zone where different ruficollis species are in contact coincides with the meeting of these four major geographic areas in a highly geomorphologically complex region.

Dating the diversification of the major lineages of Passeriformes (Aves)

BACKGROUND

The avian Order Passeriformes is an enormously species-rich group, which comprises almost 60% of all living bird species. This diverse order is believed to have originated before the break-up of Gondwana in the late Cretaceous. However, previous molecular dating studies have relied heavily on the geological split between New Zealand and Antarctica, assumed to have occurred 85-82 Mya, for calibrating the molecular clock and might thus be circular in their argument.

RESULTS

This study provides a time-scale for the evolution of the major clades of passerines using seven nuclear markers, five taxonomically well-determined passerine fossils, and an updated interpretation of the New Zealand split from Antarctica 85-52 Mya in a Bayesian relaxed-clock approach. We also assess how different interpretations of the New Zealand-Antarctica vicariance event influence our age estimates. Our results suggest that the diversification of Passeriformes began in the late Cretaceous or early Cenozoic. Removing the root calibration for the New Zealand-Antarctica vicariance event (85-52 Mya) dramatically increases the 95% credibility intervals and leads to unrealistically old age estimates. We assess the individual characteristics of the seven nuclear genes analyzed in our study. Our analyses provide estimates of divergence times for the major groups of passerines, which can be used as secondary calibration points in future molecular studies.

CONCLUSIONS

Our analysis takes recent paleontological and geological findings into account and provides the best estimate of the passerine evolutionary time-scale currently available. This time-scale provides a temporal framework for further biogeographical, ecological, and co-evolutionary studies of the largest bird radiation, and adds to the growing support for a Cretaceous origin of Passeriformes.

Comparative phyloclimatic analysis and evolution of ecological niches in the scimitar babblers (Aves: Timaliidae: Pomatorhinus)

We present the first extensive and integrative analysis of niche evolution based on climatic variables and a dated molecular phylogeny of a heterogeneous avian group of Southeast Asian scimitar babblers of the genus Pomatorhinus. The four main clades of scimitar babblers have species that co-occur in similar areas across southern Asia but some have diverged at different timeframes, with the most recently evolved clade harboring the highest number of species. Ecological niche models and analysis of contributing variables within a phylogenetic framework indicate instances of convergent evolution of members of different clades onto similar ecological parameter space, as well as divergent evolution of members from within clades. Pomatorhinus species from different clades occupying Himalayan foothills show convergence towards similar climatic tolerances, whereas within a clade, allopatric sister-species occurring in the Himalayas have diverged to occupy different climatic parameter spaces. Comparisons of climatic tolerances of Himalayan foothills taxa with species distributed further south in Assam/Burma and Burma/Thailand indicate convergence towards similar parameter spaces in several climatic variables. Niche overlap was observed to be lower among species of the youngest clade (ruficollis) and higher among species of older clades (ferruginosus). Analysis of accumulation of ecological disparity through time indicates rapid divergence within recent time frames. As a result, Himalayan taxa originating at different temporal scales within the four main scimitar babbler clades have differentiated ecologically only in recently diverged taxa. Our study suggests that the repeated orogenic and climatic fluctuations of the Pliocene and Pleistocene within mainland Southeast Asia served as an important ecological speciation driver within scimitar babblers, by providing opportunities for rapid geographic expansion and filling of novel environmental niches.

An Update of Wallace’s Zoogeographic Regions of the World

Modern attempts to produce biogeographic maps focus on the distribution of species, and the maps are typically drawn without phylogenetic considerations. Here, we generate a global map of zoogeographic regions by combining data on the distributions and phylogenetic relationships of 21,037 species of amphibians, birds, and mammals. We identify 20 distinct zoogeographic regions, which are grouped into 11 larger realms. We document the lack of support for several regions previously defined based on distributional data and show that spatial turnover in the phylogenetic composition of vertebrate assemblages is higher in the Southern than in the Northern Hemisphere. We further show that the integration of phylogenetic information provides valuable insight on historical relationships among regions, permitting the identification of evolutionarily unique regions of the world.

Faithful females receive more help: the extent of male parental care during incubation in relation to extra-pair paternity in songbirds

Parental care provided by males occurs in a diverse array of animals and there are large differences among species in its extent compared with female care. However, social and ecological factors responsible for interspecific differences in male's share of parental duties remain unclear. Genetic fidelity of females has been long considered important. Theory predicts that females should receive more help from their mates in raising the offspring in species with high genetic fidelity. Using avian incubation behaviour as a model system, we confirmed this prediction. The extent of male's help during incubation increased with decreasing rate of extra-pair paternity across species (22 species of socially monogamous songbirds from 13 families; male's share of incubation ranged from 6% to 58%), even after accounting for covariates, biases in species selection and intraspecific variability. Moreover, this result was not sensitive to two different phylogenies and branch length estimates. We suggest that our findings support the notion, backed by theory, that genetic fidelity is an important factor in the evolution of male parental care. We offer several behavioural scenarios for the coevolution between male's share of parental duties and the genetic mating system.

New insights into family relationships within the avian superfamily Sylvioidea (Passeriformes) based on seven molecular markers

Background

The circumscription of the avian superfamily Sylvioidea is a matter of long ongoing debate. While the overall inclusiveness has now been mostly agreed on and 20 families recognised, the phylogenetic relationships among the families are largely unknown. We here present a phylogenetic hypothesis for Sylvioidea based on one mitochondrial and six nuclear markers, in total ~6.3 kbp, for 79 ingroup species representing all currently recognised families and some species with uncertain affinities, making this the most comprehensive analysis of this taxon.

Results

The resolution, especially of the deeper nodes, is much improved compared to previous studies. However, many relationships among families remain uncertain and are in need of verification. Most families themselves are very well supported based on the total data set and also by indels. Our data do not support the inclusion of Hylia in Cettiidae, but do not strongly reject a close relationship with Cettiidae either. The genera Scotocerca and Erythrocercus are closely related to Cettiidae, but separated by relatively long internodes. The families Paridae, Remizidae and Stenostiridae clustered among the outgroup taxa and not within Sylvioidea.

Conclusions

Although the phylogenetic position of Hylia is uncertain, we tentatively support the recognition of the family Hyliidae Bannerman, 1923 for this genus and Pholidornis. We propose new family names for the genera Scotocerca and Erythrocercus, Scotocercidae and Erythrocercidae, respectively, rather than including these in Cettiidae, and we formally propose the name Macrosphenidae, which has been in informal use for some time. We recommend that Paridae, Remizidae and Stenostiridae are not included in Sylvioidea. We also briefly discuss the problems of providing a morphological diagnosis when proposing a new family-group name (or genus-group name) based on a clade.

Palaeoclimatic events, dispersal and migratory losses along the Afro-European axis as drivers of biogeographic distribution in Sylvia warblers

BACKGROUND

The Old World warbler genus Sylvia has been used extensively as a model system in a variety of ecological, genetic, and morphological studies. The genus is comprised of about 25 species, and 70% of these species have distributions at or near the Mediterranean Sea. This distribution pattern suggests a possible role for the Messinian Salinity Crisis (from 5.96-5.33 Ma) as a driving force in lineage diversification. Other species distributions suggest that Late Miocene to Pliocene Afro-tropical forest dynamics have also been important in the evolution of Sylvia lineages. Using a molecular phylogenetic hypothesis and other methods, we seek to develop a biogeographic hypothesis for Sylvia and to explicitly assess the roles of these climate-driven events.

RESULTS

We present the first strongly supported molecular phylogeny for Sylvia. With one exception, species fall into one of three strongly supported clades: one small clade of species distributed mainly in Africa and Europe, one large clade of species distributed mainly in Africa and Asia, and another large clade with primarily a circum-Mediterranean distribution. Asia is reconstructed as the ancestral area for Sylvia. Long-distance migration is reconstructed as the ancestral character state for the genus, and sedentary behavior subsequently evolved seven times.

CONCLUSION

Molecular clock calibration suggests that Sylvia arose in the early Miocene and diverged into three main clades by 12.6 Ma. Divergence estimates indicate that the Messinian Salinity Crisis had a minor impact on Sylvia. Instead, over-water dispersals, repeated loss of long-distance migration, and palaeo-climatic events in Africa played primary roles in Sylvia divergence and distribution.