Phylogénie des touracos (Aves, Musophagidae). Analyse des caractères morphologiques

Phylogeny of turacos (Aves, Musophagidae). Analysis of morphological characters
A cladistic analysis of the 23 species of turacos (Musophagidae) using 34 morphological characters produces, after successive weighting, 4 shortest-length trees (consistency index = 0.76) that present two major clades: the first one with 'grey' turacos (genus Crinifer, Corythaixoides ), the other one with the great blue turaco (genus Corythaeola ) and the turacine bearers turacos (genus Tauraco , Musophaga , Ruwenzorornis , Gallirex ). This result also suggests that the species ' persa ' is not valid; T. schalowi , T. livingstonii , T. corythaix which were included in this species are more closely related to T. fisheri and T. schuettii than they are to T. persa . The polymorphism of these green turacos is also discussed. Ruwenzorornis johnstoni and Gallirex porphyreolophus do not belong to the Tauraco clade nor to the Musophaga clade, but they are closer to the first than to the second. The species Corythaixoides leucogaster is closer to the Crinifer species than to the other Corythaixoides species.     

Phylogenetic relationships within the turacos (Musophagidae)

Cytochrome b sequences were used to investigate both the systematic position of the Musophagidae and the species relationships within the family. Phylogenetic analyses (neighbour-joining, maximum likelihood and maximum parsimony) supported the hypothesis that the Musophagidae are more closely related to the cuckoos, parrots and the Hoatzin than the gamebirds. Within the family, three major clades are evident that correspond to the three subfamilies generally recognized. The 'grey turacos' and the turacin-bearing turacos form two separate monophyletic groups. Corythaixoides leucogaster appears to be basal within the subfamily Criniferinae (the 'grey turacos'). This analysis yields a hypothesis for the controversy surrounding the position of Gallirex porphyreolophus and Tauraco johnstoni, which appear to be closely related and basal to the other turacin-bearing turacos. The Musophaga species are placed within the Tauraco clade and appear to be specialized forms of typical turacos. The superspecies persa forms a monophyletic group, within which T. hartlaubi falls. This is an association that has not been suggested previously.     

Biomechanical features of the bill and and jaw apparatus of cuckoos,turacos and the hoatzin in relation to food acquisition and processing

A morphofunctional analysis of the feeding apparatus was conducted from an evolutionary perspective on the hoatzin (Opisthocomidae), some cuckoos (Cuculidae) and some turacos (Musophagidae). These goups share a common ancestral adaptation of the bill apparatus linked to starting food processing at base of the bill. The morphofunctional analyses give results different from what is known for the Galliformes and allow the construction of the hypothesis of two trophic adaptive pathways. One followed by the Cuculidae would have led to the consumption of a large range of arthropods, including toxic species; the other, followed by the Musophagidae and Opisthocomidae, would have led to the consumption of plant parts.     

A phylogenetic study of the malagasy couas with insights into cuckoo relationships

The avian family Cuculidae (cuckoos) is a diverse group of birds that vary considerably in behaviors of interest to behavioral ecologists, e.g., obligate brood parasitism and cooperative breeding. The taxonomy of this group has historically been relatively stable but has not been extensively evaluated using molecular methods. The goal of this study was to evaluate phylogenetic relationships within the ecologically diverse genus Coua and the placement of Coua among major cuckoo lineages. We sequenced 429 bp of cytochrome b (cyt b) and 522 bp of ND2, both mitochondrial genes, for 26 species of cuckoos spanning 13 genera. We also included the enigmatic hoatzin (Opisthocomus hoazin) and used two Tauraco species as outgroups. ND2 exhibited higher rates of DNA sequence and amino acid substitution than cyt b; however, this did not greatly affect the overall levels of phylogenetic resolution and support provided by these two genes. Combined analyses produced two alternative phylogenies, depending on weighting scheme, both of which were fully resolved and were characterized by high bootstrap support. These phylogenies recovered monophyly for all of the traditional cuckoo subfamilies and indicated, with strong support, that the hoatzin is outside of Cuculidae. Within Coua, an arboreal and a terrestrial clade were identified. In contrast, habitat choice of Coua species did not greatly reflect the phylogeny.     

Monophyly and phylogeny of cuckoos (Aves, Cuculidae) inferred from osteological characters

A reanalysis of 32 characters from the literature previously deemed diagnostic of the Cuculidae revealed only five to be synapomorphic. I subsequently examined skeletons from 54 avian families and identified nine additional synapomorphies that supported cuckoo monophyly. My cladistic analysis of 33 cuculid genera using 135 skeletal characters differs markedly from currently accepted taxonomies. The most striking deviation is the placement of both New and Old World parasitic cuckoos in the Cuculinae, supporting the evolution of brood parasitism in a single event rather than three times as previously proposed. Unlike earlier classifications, the Cuculinae also includes the facultative parasites Coccyzus. This, suggests that the ancestral Coccyzus was an obligate parasite, and is consistent with the many behavioral adaptations to parasitism exhibited by this genus. Other changes include the placement of three subfamilies, comprising non-parasitic, terrestrial cuckoos of Old World (Centropodinae and Carpococcystinae) and New World (Neomorphinae) distribution, in basal positions on the tree. Nineteen characters support a sister relationship between the Hoatzin ( Opisthocamus hoatzin Müller) and turacos (Musophagidae), and not cuckoos. Three synapomorphies of the os carpi ulnare were found to unite the Cuculidae, turacos, and the Hoatzin, suggesting that these three diverse taxa may constitute a monophyletic group.     

Application of molecular cytogenetics for chromosomal evolution of the Lemuriformes (Prosimians)

R-banding chromosomal studies of 21 species of Lemuriformes allowed us to reconstruct the presumed ancestral karyotype of all the Lemuriformes except for Daubentoniidae and permitted the construction of their phylogenetic tree. Chromosome painting with fluorescently labeled heterologous DNA probes permitted comparative chromosome maps to be established. The Zoo-FISH method was used to reassess the karyotypes of 22 species or subspecies. While our results largely confirm the previous reconstruction of the ancestral karyotype, they resulted in a modification of the previously established phylogenetic tree. The Daubentoniidae emerged first followed by the divergence of the families Cheirogaleidae, Indriidae, Lepilemuridae and Lemuridae. Eight chromosome rearrangements occurred in all Lemuriformes except for Daubentoniidae in the common trunk. The present findings do not allow us to propose the occurrence of any rearrangement common to Daubentoniidae and other Lemuriformes, and probably other Prosimii. Conserved syntenies previously described in various mammalian orders were also conserved, while others were specific to the Lemuriformes.     

Developments in avian cytotaxonomy: implications for Afro-avian Species

Ejere. VC. 2000. Developments in avian cytotaxonomy: implications for Afro-avian Species. Ostrich 71 (1 & 2): 40.

Karyological studies of the extant species of birds have progressed slower than those of other animal groups. To date, a paltry proportion of less than 20% of about an estimated 9 000 avian species have been karyotyped, such that for most orders, karyological information remains largely scanty. Data accumulated so far, has revealed a lot of interesting features of the typical avian karyotype. Essentially, the karyotype is dichotomous, containing several pairs of fairly big chromosomes (= macrochomosomes) and very small to minute chromosome elements (= microchromosmes). The diploid chromosome number is also variable, ranging from 2n = 40 to 2n = 92 with a mode of 2n = 80 chromosomes observed in a majority of species. Studies have further revealed that chromosomal evolution in birds is highly conservative especially with reference to the first 3 pairs of macrochromosomes. (Group A), while considerable variability in number and morphology occurs in the remaining groups of chromosome elements. These variabilities, as well as the homologies revealed by chromosome banding techniques, have aided the cytotaxonomy of various individual avian groups. In this review, the karyological as well as the phylogenetic relationships of the various avian species so far karyotyped, vis-a-vis the cytotaxonomic implications for the abundant Afro-avian fauna are highlighted. Similarly, the significance of the observed peculiarities in the avian karyotype is briefly discussed. Suggestions are proffered in respect of the application of karyotype analysis technique to bird conservation in Africa. This will focus mainly on the identification of the gender of birds for the singular purpose of breeding rare and endangered species for zoological gardens and related institutions.     

Phylogenetic Relationships of the Order Insectivora Based on Complete 12S rRNA Sequences from Mitochondria

Despite numerous studies, there is no single accepted hypothesis of eutherian ordinal relationships. Among the least understood mammalian orders is the group Insectivora. Currently, molecular and morphological data are in conflict over the possible monophyly of the living members of Insectivora (lipotyphlans), and the relationships within the group remain largely unresolved. One of the primary criticisms concerning molecular analyses is the noticeable lack of data from a well-sampled group of lipotyphlan insectivores. The mitochondrial 12S rRNA gene has been widely used to resolve interordinal and intraordinal relationships across a variety of mammalian taxa. This study compares 118 complete mammalian 12S rRNA sequences, representing all of the 18 eutherian orders and 3 metatherian orders, and includes as well taxa from each of the six families of lipotyphlan insectivores. Insectivoran lineages are thought to have diverged concurrently with the general radiation of mammalian orders. This study suggests that the 12S rRNA sequences lack the ability to resolve relationships extending into this period. This would explain the polyphyly, unusual affinities, and low support derived in this and other studies employing 12S rRNA sequences to diagnose relationships among eutherian orders. The results of these analyses suggest that even extensive taxon sampling is insufficient to provide well supported groups among eutherian orders. Additional genes and species sampling will be necessary to elucidate whether the Insectivora form a monophyletic group.     

Mitochondrial genomic rearrangements in songbirds

The organization of the mitochondrial genome is generally very conserved among vertebrates. Because of this, examination of the rare rearrangements which do occur has been suggested as offering a powerful alternative to phylogenetic analyses of mitochondrial DNA sequences. Here, we report on an avian mitochondrial rearrangement in a group of oscine passerines (warblers of the genus Phylloscopus). This rearrangement is identical to the mitochondrial organization recently identified in representatives of four orders of birds, including subsoscine Passeriformes. The rearrangement involves the movement of three genes (tRNA(Pro), NADH6, and tRNA(Glu)) from their normal position in birds between tRNA(Thr) and the control region (CR), to a new location between the CR and a novel, supposedly noncoding (NC), region. Our results suggest that this derived arrangement cannot be used to distinguish between suboscine and oscine passerines, as it has multiple origins both within Passeriformes and within birds as a whole. We found short stretches of DNA with high degrees of similarity between the CR and each NC region, respectively, all of which could be located in the same area of the CR. This suggests that the CR and the NC region are homologous and that the mechanism behind this mitochondrial rearrangement is a tandem duplication followed by multiple deletions. However, the similarities between the control and NC regions of each species were less pronounced than those between the control or NC regions from the different species, supporting the hypothesis of a single basal rearrangement in the Phylloscopus warblers.     

Genetic mapping in a natural population of collared flycatchers (Ficedula albicollis): conserved synteny but gene order rearrangements on the avian Z chromosome

Data from completely sequenced genomes are likely to open the way for novel studies of the genetics of nonmodel organisms, in particular when it comes to the identification and analysis of genes responsible for traits that are under selection in natural populations. Here we use the draft sequence of the chicken genome as a starting point for linkage mapping in a wild bird species, the collared flycatcher - one of the most well-studied avian species in ecological and evolutionary research. A pedigree of 365 flycatchers was established and genotyped for single nucleotide polymorphisms in 23 genes selected from (and spread over most of) the chicken Z chromosome. All genes were also found to be located on the Z chromosome in the collared flycatcher, confirming conserved synteny at the level of gene content across distantly related avian lineages. This high degree of conservation mimics the situation seen for the mammalian X chromosome and may thus be a general feature in sex chromosome evolution, irrespective of whether there is male or female heterogamety. Alternatively, such unprecedented chromosomal conservation may be characteristic of most chromosomes in avian genome evolution. However, several internal rearrangements were observed, meaning that the transfer of map information from chicken to nonmodel bird species cannot always assume conserved gene orders. Interestingly, the rate of recombination on the Z chromosome of collared flycatchers was only approximately 50% that of chicken, challenging the widely held view that birds generally have high recombination rates.     

Evolution of the Spindlin Gene in Birds: Independent Cessation of the Recombination of Sex Chromosomes at the Spindlin Locus in Neognathous Birds and Tinamous, a Palaeognathous Avian Family

Tinamous (Aves, Palaeognathae, Tinamiformes) are primitive birds, generally considered to be the sister group to the ratites. Tinamous possess a W sex-chromosome, intermediate in heterochromatization between the largely euchromatic W chromosome of the ratites and the highly condensed W chromosome of the neognathous birds. Of the four genes which are known to have diverged copies on the neognathous avian W and Z chromosome (ATP5A1, CHD1, PKC and SPIN) only the spindlin gene has W- and Z-chromosomal forms in the tinamiformes. This paper describes experiments which show that the sequences of these forms are more similar to each other and to the homologous undifferentiated spindlin gene sequences in the ratite genome than to the W or Z forms of the spindlin gene in other, neognathous species. This suggests that cessation of recombination at the spindlin locus of the ancestral W and Z chromosomes of the paleognathous tinamiformes and the neognathous avian species were independent events.     

The impact of researcher disturbance on nest predation rates: a meta‐analysis

The effects of visits to nests by researchers interested in quantifying avian nesting success have received considerable attention, as researchers have long been concerned about the possible negative effects of their own activities on the resulting estimates. There is a widely held view that investigator disturbance has an overall negative effect on breeding success by increasing nest predation rates in the nests studied. However, to date no one has statistically assessed the empirical evidence for such a relationship. We undertook a meta‐analysis of published results to assess whether researcher activities increase nest predation in birds. We also assessed the variability in this effect in relation to the traits of the study species and the methodology used. These analyses used data from 18 experimental studies involving 25 species from six avian orders. Our results suggest that, contrary to the traditional view, researcher activities do not generally affect the incidence of nest predation. Moreover, this relationship appears inconsistent among avian orders and, surprisingly, nest survival of passerines increased weakly with researcher activities. We also found significant positive effects of researcher activity on nest survival for species breeding on coastal areas and for species nesting on the ground. The possible explanation for these differences among orders and guilds could be due to different nest predator communities. This new perspective on the effect of investigators could have important implications for bird management and conservation, as well as for other fields of study such as ecology and evolution, in which nest survival rates measured in the field are widely used to test and support a range of hypotheses.     

上海城市绿地冬季鸟类群落特征与生境的关系

2005年11月至2006年2月对上海市区绿地鸟类进行了调查,共记录到鸟类34种,隶属5目16科。研究发现冬季鸟类群落结构相对稳定,优势种为麻雀(Passer montanus)和白头鹎(Pycnonotus sinensis)。冬季鸟类群落多样性受多种因素的影响,其中绿地面积、乔木盖度和栖息地类型多样性是影响鸟类多样性的关键因子。聚类结果表明,面积大、生境类型丰富及人为干扰相对较少的绿地,鸟类多样性高。因此提出如下建议:(1)增加城市中植物种类,特别是乡土物种,适当提高冬季常绿乔木以及乔、灌、草的比例;(2)在绿地中尽可能多地保留自然生境;(3)在城市绿地中适当开辟湿地生境,以吸引水鸟栖息。     

Fourfold polyphyly of the genus formerly known as Upucerthia, with notes on the systematics and evolution of the avian subfamily Furnariinae

The traditional avian subfamily Furnariinae, a group of terrestrial ovenbirds typical of the Andean and Patagonian arid zones, consists of the genera Furnarius, Cinclodes, Geositta, Upucerthia, Chilia, and Eremobius. We investigated phylogenetic relationships within the Furnariinae, with particular attention to the nine species of the genus Upucerthia, using nuclear and mitochondrial DNA sequences from all genera in the subfamily. Upucerthia was found to be highly polyphyletic, its constituent species forming four non-sister clades: (1) a basal lineage consisting of two Upucerthia species, U. ruficaudus and U. andaecola, as well as the monotypic genera Eremobius and Chilia; (2) a lineage consisting of U. harterti and U. certhioides, two species behaviorally divergent from other Upucerthia species; (3) a lineage consisting of U. serrana, which is not closely related to any other Upucerthia species; and (4) a lineage, sister to Cinclodes, consisting of the four Upucerthia species U. dumetaria, U. albigula, U. validirostris, and U. jelskii. The larger Furnariinae was also found to be highly polyphyletic; the terrestrial open country ecotype characteristic of this subfamily occurs in four unrelated clades in the family Furnariidae, including a basal lineage as well as derived lineages. Although the large degree of divergence among Upucerthia clades was not previously recognized, owing to ecological, behavioral, and morphological similarities, the groupings correspond closely to relationships suggested by plumage. This is in contrast to studies of other avian genera in which plumage patterns have been shown to be extensively convergent. The generic names Upucerthia and Ochetorhynchus are available for two of the former Upucerthia clades; new generic names may be warranted for the other two.     

Congruent Avian Phylogenies Inferred from Mitochondrial and Nuclear DNA Sequences

Recent molecular studies addressing the phylogenetic relationships of avian orders have had conflicting results. While studies using nuclear DNA sequences tend to support traditional taxonomic views, also supported by morphological data [(paleognaths (galloanseres (all other birds)))], with songbirds forming a clade within Neoaves (all other birds), analyses with complete mtDNA genomes have resulted in topologies that place songbirds as one of the earliest-diverging avian lineages. Considering that over half of the extant bird species are songbirds, these different results have very different implications for our understanding of avian evolution. We analyzed data sets comprising nearly 4 kb of mitochondrial DNA (mtDNA) (complete 12S, ND1, ND2, and cytochrome b) plus 600 bp of the nuclear gene c-mos for 15 birds that were chosen to represent all major avian clades and to minimize potential long-branch attraction problems; we used a partition-specific maximum likelihood approach. Our results show congruence with respect to the ingroup among phylogenies obtained with mtDNA and the nuclear gene c-mos, separately or combined. The data sets support a traditional avian taxonomy, with paleognaths (ratites and tinamous) occupying a basal position and with songbirds more derived and forming a monophyletic group. We also show that, for mtDNA studies, turtles may be a better outgroup for birds than crocodilians because of their slower rate of sequence evolution.     

Comparative mapping of Z-orthologous genes in vertebrates: implications for the evolution of avian sex chromosomes

Sex chromosomes of birds and mammals are highly differentiated and share several cytological features. However, comparative gene mapping reveals extensive conserved synteny between the chicken Z sex chromosome and human chromosome 9 but not the human X sex chromosome, implying an independent origin of avian and mammalian sex chromosomes. To better understand the evolution of the avian Z chromosome we analysed the synteny of chicken Z-linked genes in zebrafish, which is the best-mapped teleost genome so far. Existing zebrafish maps do not support the existence of an ancestral Z linkage group in the zebrafish genome, whereas mammalian X-linked genes show at least some degree of synteny conservation. This is consistent with in situ hybridisation mapping data in the freshwater pufferfish, Tetraodon nigroviridis where mammalian X-linked genes show a much higher degree of conserved synteny than human chromosome 9 or the avian Z chromosome. Collectively, these data argue in favour of a more recent evolution of the avian Z chromosome, compared with the mammalian X.     

Synteny conservation of chicken macrochromosomes 1-10 in different avian lineages revealed by cross-species chromosome painting

Cross-species chromosome painting can directly visualize syntenies between diverged karyotypes and, thus, increase our knowledge on avian genome evolution. DNA libraries of chicken (Gallus gallus, GGA) macrochromosomes 1 to 10 were hybridized to metaphase spreads of 9 different species from 3 different orders (Anseriformes, Gruiformes and Passeriformes). Depending on the analyzed species, GGA1-10 delineated 11 to 13 syntenic chromosome regions, indicating a high degree of synteny conservation. No exchange between the GGA macrochromosome complement and microchromosomes of the analyzed species was observed. GGA1 and GGA4 were distributed on 2 or 3 chromosomes each in some of the analyzed species, indicating rare evolutionary rearrangements between macrochromosomes. In all 6 analyzed species of Passeriformes, GGA1 was diverged on 2 macrochromosomes, representing a synapomorphic marker for this order. GGA4 was split on 2 chromosomes in most karyotypes, but syntenic to a single chromosome in blackcap (Passeriformes). GGA5/10 and also GGA8/9 associations on chromosomes were found to be important cytogenetic features of the Eurasian nuthatch (Passeriformes) karyotype. Fusion of GGA4 and GGA5 segments and of entire GGA6 and GGA7, respectively, was seen in the 2 analyzed species of Gruiformes. Consistent with the literature, our inter-species chromosome painting demonstrates remarkable conservation of macrochromosomal synteny over 100 million years of avian evolution. The low rate of rearrangements between macrochromosomes and the absence of detectable macrochromosome-microchromosome exchanges suggests a predominant role for rearrangements within the gene-dense microchromosome complement in karyotypic diversification.     

Introns outperform exons in analyses of basal avian phylogeny using clathrin heavy chain genes

Neoaves is the most diverse major avian clade, containing ~95% of avian species, and it underwent an ancient but rapid diversification that has made resolution of relationships at the base of the clade difficult. In fact, Neoaves has been suggested to be a "hard" polytomy that cannot be resolved with any amount of data. However, this conclusion was based on slowly evolving coding sequences and ribosomal RNAs and some recent studies using more rapidly evolving intron sequences have suggested some resolution at the base of Neoaves. To further examine the utility of introns and exons for phylogenetics, we sequenced parts of two unlinked clathrin heavy chain genes (CLTC and CLTCL1). Comparisons of phylogenetic trees based upon individual partitions (i.e. introns and exons), the combined dataset, and published phylogenies using Robinson-Foulds distances (a metric of topological differences) revealed more similarity than expected by chance, suggesting there is structure at the base of Neoaves. We found that introns provided more informative sites, were subject to less homoplasy, and provided better support for well-accepted clades, suggesting that intron evolution is better suited to determining closely-spaced branching events like the base of Neoaves. Furthermore, phylogenetic power analyses indicated that existing molecular datasets for birds are unlikely to provide sufficient phylogenetic information to resolve relationships at the base of Neoaves, especially when comprised of exon or other slowly evolving regions. Although relationships among the orders in Neoaves cannot be definitively established using available data, the base of Neoaves does not appear to represent a hard polytomy. Our analyses suggest that large intron datasets have the best potential to resolve relationships among avian orders and indicate that the utility of intron data for other phylogenetic questions should be examined.     

Comparative chromosome painting of chicken autosomal paints 1-9 in nine different bird species

In a Zoo-FISH study chicken autosomal chromosome paints 1 to 9 (GGA1-GGA9) were hybridized to metaphase spreads of nine diverse birds belonging to primitive and modern orders. This comparative approach allows tracing of chromosomal rearrangements that occurred during bird evolution. Striking homologies in the chromosomes of the different species were noted, indicating a high degree of evolutionary conservation in avian karyotypes. In two species, the quail and the goose, all chicken paints specifically labeled their corresponding chromosomes. In three pheasant species as well as in the American rhea and blackbird, GGA4 hybridized to chromosome 4 and additionally to a single pair of microchromosomes. Furthermore, in the pheasants fission of the ancestral galliform chromosome 2 could be documented. Hybridization of various chicken probes to two different chromosomes or to only the short or long chromosome arm of one chromosome pair in the species representing the orders Passeriformes, Strigiformes, and Columbiformes revealed translocations and chromosome fissions during species radiation. Thus comparative analysis with chicken chromosome-specific painting probes proves to be a rapid and comprehensive approach to elucidate the chromosomal relationships of the extant birds.