Early Duplication of a Single MHC IIB Locus Prior to the Passerine Radiations.

A key characteristic of MHC genes is the persistence of allelic lineages over macroevolutionary periods, often through multiple speciation events. This phenomenon, known as trans-species polymorphism (TSP), is well documented in several major taxonomic groups, but has less frequently been observed in birds. The order Passeriformes is arguably the most successful terrestrial vertebrate order in terms of diversity of species and ecological range, but the reasons for this success remain unclear. Passerines exhibit the most highly duplicated MHC genes of any major vertebrate taxonomic group, which may generate increased immune response relative to other avian orders with fewer MHC loci. Here, we describe phylogenetic patterns of the MHC IIB in the passerine family Corvidae. Our results indicate wide-spread TSP within this family, with at least four supported MHC IIB allelic lineages that predate speciation by many millions of years. Markov chain Monte Carlo simulations indicate that divergence of these lineages occurred near the time of the divergence of the Passeriformes and other avian orders. We suggest that the current MHC diversity observed in passerines is due in part to the multiple duplication of a single MHC locus, DAB1, early in passerine evolution and that subsequent duplications of these paralogues have contributed to the enormous success of this order by increasing their ability to recognize and mount immune responses to novel pathogens

Old divergences in a boreal bird supports long-term survival through the Ice Ages

<p>Abstract</p> <p>Background</p> <p>Unlike northern Europe and most of northern North America, the Eastern Palearctic and the northwesternmost tip of North America are believed to have been almost unglaciated during the Quarternary glacial periods. This could have facilitated long-term survival of many organisms in that area. To evaluate this, we studied the phylogeography in east Asia and Alaska of a boreal migratory passerine bird, the Arctic Warbler <it>Phylloscopus borealis</it>, and compared our results with published data on especially North American species.</p> <p>Results</p> <p>In a sample of 113 individuals from 18 populations we identified 42 haplotypes of the mitochondrial cytochrome <it>b </it>gene, which separated into three clades: A - Alaska and mainland Eurasia (except Kamchatka); B - Kamchatka, Sakhalin and Hokkaido; and C - Honshu, Shikoku and Kyushu (i.e. Japan except Hokkaido). The oldest split among these clades, between A/B and C, is estimated to have taken place sometime between the mid Pliocene and early Pleistocene, and the second divergence, between clades A and B, in the early to mid Pleistocene. Within all of the three main clades, there are signs of population expansion.</p> <p>Conclusions</p> <p>The Arctic Warbler separated into three main clades in close succession around the Pliocene/Pleistocene border, with the two northern clades diverging last. All three clades probably experienced population bottlenecks during the Pleistocene as a result of range shifts and contractions, but nevertheless survived and maintained their integrities. Several other clades of Northeastern Palearctic birds are noted to have diversified during the Pliocene. In contrast, avian species or phylogroups presently occupying formerly glaciated North American ground are generally younger. The differences between these regions could be due to slower speciation rates in the Eastern Palearctic due to less fragmentation of forest habitats during glacial periods, or to longer survival of Eastern Palearctic clades as a result of less severe conditions in that region compared to northern North America. Several other Palearctic organisms show concordant biogeographical patterns to that of the Arctic Warbler, indicating common causes of their diversifications.</p

オオヨシキリにおける性配分

要旨pdfファイル:タイトル「オオヨシキリにおける性分配」京都大学0048新制・論文博士博士(理学)乙第10195号論理博第1366号新制||理||1132(附属図書館)UT51-99-S312(主査)教授 山岸 哲, 教授 米井 脩治, 助教授 今福 道夫学位規則第4条第2項該当Doctor of ScienceKyoto UniversityDA

Tandem duplications in the C-terminal domain of the mesotocin receptor exclusively identified among East Eurasian thrushes.

Mesotocin is a neurohypophyseal hormone found in some non-mammalian vertebrates, including birds, reptiles, and amphibians. In this study, we identified and characterized 18-amino acid duplications in the C-terminal domain of the mesotocin receptor (MTR), specifically found in Turdus thrushes (Aves: Passeriforms: Turdidae). These duplicated elements are located in the distal part of the C-terminal tails of MTR and consist of amino acids that are highly conserved among major vertebrates. Intraspecific polymorphisms in a variable number of tandem duplications are commonly found in East Eurasian Turdus, but not in any other genus of Turdidae. Moreover, the genus Turdus can be further classified into 2 groups according to the presence or absence of a 3-amino acid deletion just adjacent to the putative palmitoylation site in the cytoplasmic C-terminal tail. The phylogeny presented here strongly supports the conspecific group of 4 East Eurasian thrushes (Turdus pallidus, T. chrysolaus, T. obscurus, and T. celaenops). Our findings, therefore, provide a new synapomorphy that can be used for phylogenetic assumptions and shed a light on the history of diversification within Eurasian Turdus clades

Patterns of evolution of MHC class II genes of crows (Corvus) suggest trans-species polymorphism

A distinguishing characteristic of genes that code for the major histocompatibility complex (MHC) is that alleles often share more similarity between, rather than within species. There are two likely mechanisms that can explain this pattern: convergent evolution and trans-species polymorphism (TSP), in which ancient allelic lineages are maintained by balancing selection and retained by descendant species. Distinguishing between these two mechanisms has major implications in how we view adaptation of immune genes. In this study we analyzed exon 2 of the MHC class IIB in three passerine bird species in the genus Corvus: jungle crows (Corvus macrorhynchos japonensis) American crows (C. brachyrhynchos) and carrion crows (C. corone orientalis). Carrion crows and American crows are recently diverged, but allopatric, sister species, whereas carrion crows and jungle crows are more distantly related but sympatric species, and possibly share pathogens linked to MHC IIB polymorphisms. These patterns of evolutionary divergence and current geographic ranges enabled us to test for trans-species polymorphism and convergent evolution of the MHC IIB in crows. Phylogenetic reconstructions of MHC IIB sequences revealed several well supported interspecific clusters containing all three species, and there was no biased clustering of variants among the sympatric carrion crows and jungle crows. The topologies of phylogenetic trees constructed from putatively selected sites were remarkably different than those constructed from putatively neutral sites. In addition, trees constructed using non-synonymous substitutions from a continuous fragment of exon 2 had more, and generally more inclusive, supported interspecific MHC IIB variant clusters than those constructed from the same fragment using synonymous substitutions. These phylogenetic patterns suggest that recombination, especially gene conversion, has partially erased the signal of allelic ancestry in these species. While clustering of positively selected amino acids by supertyping revealed a single supertype shared by only jungle and carrion crows, a pattern consistent with convergence, the overall phylogenetic patterns we observed suggest that TSP, rather than convergence, explains the interspecific allelic similarity of MHC IIB genes in these species of crows

Table S2. Molecular sample list

Museum voucher information for all genetic samples of the varied tit (Sittiparus varius) complex used in this study. Stars indicate individuals selected for multilocus nuclear sequencing. Acronyms: National Museum of Nature and Science, Tokyo (NSMT); Taiwan Endemic Species Research Institute (TESRI); Liaoning University, China (LU); Cincinnati Museum Center (CMC); American Museum of Natural History (AMNH); University of Kansas University Natural History Museum (KUNMH)

Table S6. Loci table

Descriptive statistics for the seven molecular loci used to construct phylogenetic relationships among S. varius, S. castaneoventris, S. owstoni, and S. olivaceus. The summary includes the length of the sequences (in base pairs), the number of alleles, the number of segregating sites (s), the number of parsimony-informative sites (PI sites), nucleotide diversity (π), and the nucleotide substitution model. Statistics are drawn from ingroup sequences only. Note that ND2 statistics are drawn from a reduced ND2 alignment, which comprised the 16 samples sequenced for nuclear loci

Quaternary-related genetic differentiation and parallel population dynamics of the Eurasian Jay (Garrulus glandarius) in the circum-Japan Sea region

The circum-Japan Sea region (CJSR) greatly impacted animal diversity in the Eastern Palearctic during the Quaternary. However, its role in avian diversification has been underestimated because of the high dispersal capabilities of birds over the sea. We investigated the phylogeographic and demographic history of the Eurasian Jay (Garrulus glandarius), focusing on CJSR populations. We sequenced a total of 1744 bp of mitochondrial DNA (cytochrome b and control region) from 73 samples. Together with the database sequences, we reconstructed a phylogenetic tree for the Eurasian Jay over the Palearctic. The earliest phylogenetic divergence was inferred to be related to geological vicariance between the Japanese archipelago and Eurasian mainland around the Pliocene–Pleistocene boundary. Several demographic analyses have suggested that there are two divergent subspecies across the CJSR, G. g. brandtii on the mainland, Sakhalin, and Hokkaido and G. g. japonicus in the archipelago. These simultaneously experienced population contractions to independent refugia and subsequent expansions around the last glacial period, i.e., parallel population dynamics. We suggest that the two landmasses of the CJSR were important for generating and preserving the phylogenetic structure of the Eurasian Jay. © Dt. Ornithologen-Gesellschaft e.V. 2018.1

Demonstration of the potential of environmental DNA as a tool for the detection of avian species

Birds play unique functional roles in the maintenance of ecosystems, such as pollination and seed dispersal, and thus monitoring bird species diversity is a first step towards avoiding undesirable consequences of anthropogenic impacts on bird communities. In the present study, we hypothesized that birds, regardless of their main habitats, must have frequent contact with water and that tissues that contain their DNA that persists in the environment (environmental DNA; eDNA) could be used to detect the presence of avian species. To this end, we applied a set of universal PCR primers (MiBird, a modified version of fish/mammal universal primers) for metabarcoding avian eDNA. We confirmed the versatility of MiBird primers by performing in silico analyses and by amplifying DNAs extracted from bird tissues. Analyses of water samples from zoo cages of birds with known species composition suggested that the use of MiBird primers combined with Illumina MiSeq could successfully detect avian species from water samples. Additionally, analysis of water samples collected from a natural pond detected five avian species common to the sampling areas. The present findings suggest that avian eDNA metabarcoding would be a complementary detection/identification tool in cases where visual census of bird species is difficult