A new species of Late Pleistocene rail (Aves: Rallidae) from Abaco, the Bahamas

We describe a new species of rail from the Sawmill Sink blue hole on Abaco Island in the northern Bahamas. Known from abundant, beautifully preserved Late Pleistocene fossils, Rallus cyanocavi sp. nov. was a medium-sized, flightless species that probably was endemic to the Little Bahama Bank, which is a carbonate platform surrounded by deeper water. We are uncertain whether R. cyanocavi survived into the Holocene, when higher sea levels transformed the Little Bahama Bank from a single large, Late Pleistocene island (ca. 12000 km²) to the scattering of smaller islands seen today, the largest of which is Abaco (1681 km²). Fossils of additional extinct, flightless species of Rallus probably await discovery on some of the 21 other carbonate banks that span the Bahamian Archipelago.     

Behaviour, natural history, and annual cycle of the Henderson Island rail Porzana atra (Aves: Rallidae)

The little known endemic Henderson Island rail (or Henderson rail) Porzflna atra , inhabits forest on the coastal plain and upraised plateau of Henderson Island. Rails were studied for 15 months from January 1991 to March 1992. The population was estimated at c. 6200 individuals living in pairs or cooperative groups of 3–4 adults on territories averaging about 1 ha. Two or three eggs were laid in covered or open nests near the ground from mid-July to mid-February. Up to five consecutive nesting attempts were made in cases where eggs or young chicks were lost. Adults laid a second clutch when chicks were fully feathered at about one month of age. Both sexes incubated and helped rear the young. Older chicks sometimes helped feed younger siblings. Dispersal of juveniles from the natal territory took place in April. Adult birds underwent a rapid, simultaneous post-nuptial moult of the remiges in February-April; the post-juvenile moult involved body feathers only. Data on morphometries, breeding ecology, courtship behaviour and voice are compared with available information for the spotless crake P. tabuensis , the Henderson rail's closest relative and probable ancestor. These comparisons provide some information on how these two taxa have differentiated since rails arrived on Henderson Island some time in the last 380000 years.     

A new species of rail (Aves: Rallidae) from the Upper Pleistocene and Holocene of Eivissa (Pityusic Islands, western Mediterranean)

A new species of rail is described from a Pleistocene and Holocene cave deposit on the island of Eivissa, Pityusic Islands (western Mediterranean Sea). Rallus eivissensis sp. nov. was an insular relative of the European Water Rail Rallus aquaticus . Compared with the extant Water Rail, the new species was smaller and stouter, had shorter and more robust hind limbs and shorter wings, with probably reduced flight ability. The Pityusics were the only Mediterranean islands with a vertebrate Quaternary fauna lacking terrestrial mammals, and this absence is no doubt related to the Eivissan rail evolution. The chronology of the Rallus eivissensis sp. nov. extinction overlaps broadly with a period of uncertainty for the arrival of humans at Eivissa, suggesting a relationship between the two events.     

Vocalizations of chicks and juveniles and the development of adult calls in the Aldabra White-throated rail Dryolimnas cuvieri aldabranus (Aves: Rallidae)

Calls were recorded from eggs, chicks and juveniles of the Aldabra White-throated rail Dryolimnas cuvieri aldabranus. A sonagraphic analysis was made of these calls, their behavioural contexts described and probable functions suggested. Three calls, the twitter, tiuu and contented peep were produced by chicks in the egg. All three calls may be derived from the basic peep first recorded some 36 hours before hatching. Shortly after hatching two more calls, the distress call and the alarm call, can be elicited from the rail chicks. Contented peeps and twitters are restricted to the repertoire of young rails. Song was first heard from wild rail chicks at the age of ten days and may develop from the contented peep. Three adult calls, the 'mp yeah, 'mptiuu and 'mpclick appear at the age of three months and six months later the adult vocal repertoire is completed by the appearance of 'mps, toks, purrs and nest-defence squeals. With the exception of the 'mp, all adult calls can be derived from the vocalizations of chicks and juveniles.     

Genome-wide distribution of linkage disequilibrium in the population of Palau and its implications for gene flow in Remote Oceania

Linkage disequilibrium (LD) between alleles on the same human chromosome results from various evolutionary processes and is thus telling about the history of populations. Recently, LD has garnered substantial interest for its value to map and fine-map disease genes. We examine the distribution of LD between short tandem repeat alleles on autosomes and sex chromosomes in the Remote Oceanic population of Palau to evaluate whether the data are consistent with a recent hypothesis about the origins of genetic variation in Palau, specifically that the population experienced extensive male-biased gene flow following initial settlement. Consistent with evolutionary theory based on effective population size, LD between X-linked alleles is stochastically greater than LD between autosomal alleles, however, small but detectable LD occurs for autosomal markers separated by substantial distances. By contrast, while Y-linked alleles experience only one-third the effective population size of X-linked alleles, their mean value for pairwise LD is only slightly larger than X-linked alleles. For a small population known to experience at least two extreme bottlenecks, 56 six-locus Y haplotypes exhibit remarkable diversity (0.96), comparable to Y diversity of Europeans, however, autosomal and X-linked markers display significantly less diversity, as measured by heterozygosity (4.1% less). Palauan Y haplotypes also fall into distinct clusters, again unlike that of Europe. We argue these data are consistent with waves of male-biased gene flow.     

Convergent morphological responses to loss of flight in rails (Aves: Rallidae)

The physiological demands of flight exert strong selection pressure on avian morphology and so it is to be expected that the evolutionary loss of flight capacity would involve profound changes in traits. Here, we investigate morphological consequences of flightlessness in a bird family where the condition has evolved repeatedly. The Rallidae include more than 130 recognized species of which over 30 are flightless. Morphological and molecular phylogenetic data were used here to compare species with and without the ability to fly in order to determine major phenotypic effects of the transition from flighted to flightless. We find statistical support for similar morphological response among unrelated flightless lineages, characterized by a shift in energy allocation from the forelimbs to the hindlimbs. Indeed, flightless birds exhibit smaller sterna and wings than flighted taxa in the same family along with wider pelves and more robust femora. Phylogenetic signal tests demonstrate that those differences are independent of phylogeny and instead demonstrate convergent morphological adaptation associated with a walking ecology. We found too that morphological variation was greater among flightless rails than flighted ones, suggesting that relaxation of physiological demands during the transition to flightlessness frees morphological traits to evolve in response to more varied ecological opportunities.     

Gene flow and rapid differentiation characterize a rapid insular radiation in the southwest Pacific (Aves: Zosterops)

As a dispersive lineage expands its distribution across a heterogeneous landscape, it leaves behind allopatric populations with varying degrees of geographic isolation that often differentiate rapidly. In the case of oceanic islands, even narrowly separated populations often differentiate, which seems contrary to the highly dispersive nature of the founding lineage. This pattern of highly dispersive lineages differentiating across narrow sea barriers has perplexed biologists for more than a century. We used two reduced-representation genomic datasets to examine the diversification of a recent, rapid geographic radiation, the white-eyes (Aves: Zosterops) of the Solomon Islands. We incorporated methods that targeted phylogenetic structure, population structure, and explicit tests for gene flow. Both datasets showed evidence of gene flow among species, but not involving the closely spaced islands in the New Georgia Group. Instead, gene flow has occurred among the larger islands in the archipelago, including those recently connected by land bridges as well as those isolated by large expanses of deep ocean. Populations separated by shallow seas, and connected by land bridges during glacial cycles, ranged from no differentiation to both phenotypic and genomic differentiation. These complex patterns of gene flow and divergence support a model of rapid geographic radiation in which lineages differentially evolve dispersal disparity and phenotypic differences.     

Trans‐equatorial range of a land bird lineage (Aves: Rallidae) from tropical forests to subantarctic grasslands

Despite the capacity for dispersal, range size varies considerably among birds species. Many species have restricted geographic spread, whilst others routinely travel long distances to reach preferred habitat. These alternatives are well expressed amongst the rails (Rallidae) and a varying tendency for movement results in overlapping distribution patterns. Here, we examine the situation of a particular lineage, the Lewinia rails (L. mirifica, L. pectoralis and L. muelleri) that inhabit a very wide spatial and ecological range. Lewinia occurs from the Philippines, north of the equator in Oceania, to Australia and the subantarctic Auckland Islands far to the south. Allopatric distribution and differences in plumage colour result in their treatment as distinct species but our mitochondrial molecular analysis (cyt b and CR) reveals genetic distances of less than < 1%. The genetic and phylogeographical structure in the Lewinia lineage includes shared nuclear sequence alleles and this is consistent with a callibrated multigene phylogeny suggesting trans‐hemispheric dispersal since the middle Pleistocene. Despite this recent history, available morphometric data indicates that the subantarctic population has relatively small wings for its mass, and this implies adaptation away from flight. Lewinia provides a nice example of the way dispersal and adaptation intersect over short time frames to generate diversity.     

Flightlessness and phylogeny amongst endemic rails (Aves:Rallidae) of the New Zealand region.

The phylogenetic relationships of a number of flightless and volant rails have been investigated using mtDNA sequence data. The third domain of the small ribosomal subunit (12S) has been sequenced for 22 taxa, and part of the 5'' end of the cytochrome-b gene has been sequenced for 12 taxa. Additional sequences were obtained from outgroup taxa, two species of jacana, sarus crane, spur-winged plover and kagu. Extinct rails were investigated using DNA extracted from subfossil bones, and in cases where fresh material could not be obtained from other extant taxa, feathers and museum skins were used as sources of DNA. Phylogenetic trees produced from these data have topologies that are, in general, consistent with data from DNA-DNA hybridization studies and recent interpretations based on morphology. Gallinula chloropus moorhen) groups basally with Fulica (coots), Amaurornis (= Megacrex) ineptus falls within the Gallirallus/Rallus group, and Gallinula (= Porphyrula) martinica is basal to Porphyrio (swamphens) and should probably be placed in that genus. Subspecies of Porphyrio porphyrio are paraphyletic with respect to Porphyrio mantelli (takahe). The Northern Hemisphere Rallus aquaticus is basal to the south-western Pacific Rallus (or Gallirallus) group. The flightless Rallus philippensis dieffenbachii is close to Rallus modestus and distinct from the volant Rallus philippensis, and is evidently a separate species. Porzana (crakes) appears to be more closely associated with Porphyrio than Rallus. Deep relationships among the rails remain poorly resolved. Rhynochetus jubatus (kagu) is closer to the cranes than the rails in this analysis. Genetic distances between flightless rails and their volant counterparts varied considerably with observed 12S sequence distances, ranging from 0.3% (Porphyrio porphyrio melanotus and P. mantelli mantelli) to 7.6% (Rallus modestus and Rallus philippensis). This may be taken as an indication of the rapidity with which flightlessness can evolve, and of the persistence of flightless taxa. Genetic data supported the notion that flightless taxa were independently derived, sometimes from similar colonizing ancestors. The morphology of flightless rails is apparently frequently dominated by evolutionary parallelism although similarity of external appearance is not an indication of the extent of genetic divergence. In some cases taxa that are genetically close are morphologically distinct from one another (e.g. Rallus (philippensis) dieffenbachii and R. modestus), whilst some morphologically similar taxa are evidently independently derived (e.g. Porphyio mantelli hochstetteri and P.m. mantelli).     

Rapid morpho‐functional changes among insular populations of the greater white‐toothed shrew

Islands are often considered to be natural laboratories where repeated ‘evolutionary experiments’ have taken place. Consequently, islands have been key model systems in our understanding of evolutionary theory. The greater white‐toothed shrew (Crocidura russula) is of interest as it has invaded French Atlantic islands within the last few thousand years and is considered to be morphologically and genetically stable in this area. In this article, we study the shape of the mandible of the greater white‐toothed shrew on four islands and compare it with that of individuals from populations on the mainland to quantify the effects of insularity. The degree of insularity (i.e. island size and distance to the continent) is thought to be linked to differences in ecological characteristics of islands compared with the mainland. We used geometric morphometric analyses to quantify differences in size and shape between populations and employed a simple biomechanical model to evaluate the potential effects of shape differences on bite force. Specimens from island populations are different from continental populations in shape and mechanical potential of the mandible. Among islands, the mandible shows various shapes that are correlated with both the distance from the coast and island area. The shape differences are located on different parts of the mandible, suggesting different ecological constraints on each island. Moreover, these shapes are linked to the ‘mechanical potential’, which is markedly different between islands. Mechanical potential has been suggested to evolve in response to prey size and or mechanical properties. In conclusion, our results show that, in spite of the relatively recent colonization of the Atlantic Islands, the mandible of C. russula possesses a distinct shape. Moreover, the shape differs among islands and is probably linked to the consumption of different prey. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

Extraordinary MHC class II B diversity in a non‐passerine,wild bird: the Eurasian Coot Fulica atra (Aves: Rallidae)

The major histocompatibility complex (MHC) hosts the most polymorphic genes ever described in vertebrates. The MHC triggers the adaptive branch of the immune response, and its extraordinary variability is considered an evolutionary consequence of pathogen pressure. The last few years have witnessed the characterization of the MHC multigene family in a large diversity of bird species, unraveling important differences in its polymorphism, complexity, and evolution. Here, we characterize the first MHC class II B sequences isolated from a Rallidae species, the Eurasian Coot Fulica atra. A next‐generation sequencing approach revealed up to 265 alleles that translated into 251 different amino acid sequences (β chain, exon 2) in 902 individuals. Bayesian inference identified up to 19 codons within the presumptive peptide‐binding region showing pervasive evidence of positive, diversifying selection. Our analyses also detected a significant excess of high‐frequency segregating sites (average Tajima's D = 2.36, P < 0.05), indicative of balancing selection. We found one to six different alleles per individual, consistent with the occurrence of at least three MHC class II B gene duplicates. However, the genotypes comprised of three alleles were by far the most abundant in the population investigated (49.4%), followed by those with two (29.6%) and four (17.5%) alleles. We suggest that these proportions are in agreement with the segregation of MHC haplotypes differing in gene copy number. The most widespread segregating haplotypes, according to our findings, would contain one single gene or two genes. The MHC class II of the Eurasian Coot is a valuable system to investigate the evolutionary implications of gene copy variation and extensive variability, the greatest ever found, to the best of our knowledge, in a wild population of a non‐passerine bird.     

A multi‐gene phylogeny disentangles the chat‐flycatcher complex (Aves: Muscicapidae)

Zuccon, D. & Ericson, P. G. P. (2010). A multi‐gene phylogeny disentangles the chat‐flycatcher complex (Aves: Muscicapidae).—Zoologica Scripta, 39, 213–224. We reconstructed the first well‐sampled phylogenetic hypothesis in the chat‐flycatcher complex combining nuclear and mitochondrial sequences. The dichotomy between chats‐terrestrial feeders and flycatchers‐aerial feeders does not reflect monophyletic groups. The flycatching behaviour and morphological adaptations to aerial feeding (short tarsi, broad bill, rictal bristles) evolved independently from chat ancestors in three different lineages. The genera Alethe, Brachypteryx, and Myiophonus are nested within the Muscicapidae radiation and their morphological and behavioural similarities with the true thrushes Turdidae are presumably the result of convergence. The postulated close relationships among Erithacus, Luscinia and Tarsiger cannot be confirmed. Erithacus is part of the African forest robin assemblage (Cichladusa, Cossypha, Pogonocichla, Pseudalethe, Sheppardia, Stiphrornis), while Luscinia and Tarsiger belong to a large, mainly Asian radiation. Enicurus belongs to the same Asian clade and it does not deserve the recognition as a distinct subfamily or tribe. We found good support also for an assemblage of chats adapted to arid habitats (Monticola, Oenanthe, Thamnolaea, Myrmecocichla, Pentholaea, Cercomela, Saxicola, Campicoloides, Pinarochroa) and a redstart clade (Phoenicurus, Chaimarrornis and Rhyacornis). Five genera (Muscicapa, Copsychus, Thamnolaea, Luscinia and Ficedula) are polyphyletic and in need of taxonomic revision.     

Floral differentiation among insular and mainland populations of Weigela coraeensis (Caprifoliaceae)

We compared the floral morphologies, floral scents, and flower visitor compositions of Weigela coraeensis var. coraeensis on the Japanese mainland and its variety fragrans endemic to the Izu Islands to examine the differentiation process of W. coraeensis var. fragrans. The corolla lengths of W. coraeensis were smaller on the Izu Islands than those on the mainland and decreased gradually with the distance from the mainland, probably resulting from changes in pollinator fauna. A total of 13 volatile compounds were identified in the floral scent analyses, and limonene was produced at the highest level, although the floral scents were not different between var. coraeensis and var. fragrans. In this study, it was suggested that the pollinator fauna peculiar to the Izu Islands influenced the morphological differentiation of W. coraeensis var. fragrans.     

Assortative mating and the role of phenotypic plasticity in male competition: implications for gene flow among host-associated parasitoid populations

Local adaptation is promoted when habitat or mating preferences reduce gene flow between populations. However, gene flow is not only a function of dispersal but also of the success of migrants in their new habitat. In this study I investigated mating preference in conjunction with phenotypic plasticity using Aphidius parasitoids adapted to different host species. Males actively attempted to assortatively mate, but actual mating outcomes were strongly influenced by the relative size of the adult males. Results are discussed in the context of assortative mating in combination with the success of migrant males in mitigating gene flow between host-associated parasitoid populations.     

Reappraisal of early Miocene rails (Aves,Rallidae) from central France: diversity and character evolution

In Europe, Miocene rails (Aves, Rallidae) are quite abundant, but their phylogenetic placement in the context of recent forms has remained elusive. Rails from the early Miocene of the Saint‐Gérand‐le‐Puy area in central France were first described in the 19th century, and currently, only two species are recognized, namely Palaeoaramides christyi and Paraortygometra porzanoides. Our examination of the material however suggests the presence of four, likely coeval, species of rail from these deposits. Palaeoaramides eximius, previously synonymized with Palaeoaramides christyi, is here shown to probably be a distinct species, and a previously unrecognized rail, Baselrallus intermedius gen. et sp. nov., is described. To find out how these fossil rails are related to modern Rallidae, we compared them with an extensive sample of extant rails and identified plesiomorphic and derived features for crown group Rallidae. Our assessment does not support a particularly close relationship of either Palaeoaramides to Aramides or Paraortygometra to Crex (Ortygometra), and overall, these fossil rails are more primitive than previously assumed. Based on our observations of the morphology of the previously undescribed humerus of Palaeoaramides, we show this taxon to be outside crown group Rallidae, and perhaps closely related to the early Oligocene taxon Belgirallus. On the other hand, Paraortygometra porzanoides bears a resemblance to recent flufftails (Sarothrura spp.) in some elements, but whether it can be included in a clade together with flufftails is uncertain.     

Oligoryzomys flavescens (Rodentia, Muridae): gene flow among populations from central-eastern Argentina

In species acting as hosts of infectious agents, the extent of gene flow between populations is of particular interest because the expansion of different infectious diseases is usually related to the dispersal of the host. We have estimated levels of gene flow among populations of the sigmodontine rodent Oligoryzomys flavescens, in which high titers of antibodies have been detected for a Hantavirus in Argentina that produces a severe pulmonary syndrome. Enzyme polymorphism was studied by means of starch gel electrophoresis in 10 populations from the area where human cases of Hantavirus have occurred. Genetic differentiation between populations was calculated from F_ST values with the equation Nm = [(1/F_ST−1]/4. To assess the relative importance of current gene flow and historical associations between populations, the relationship of population pairwise log Nm and log geographic distance was examined. Low F_ST (mean = 0.038) and high Nm (15.27) values suggest high levels of gene flow among populations. The lack of an isolation by distance pattern would indicate that this species has recently colonized the area. The northernmost population, located on the margin of a great river, shows very high levels of gene flow with the downstream populations despite the large geographic distances. Passive transport of animals down the river by floating plants would promote unidirectional gene flow. This fact and the highest mean heterozygosity of that northernmost population suggest it is a center of dispersal within the species' range. This revised version was published online in July 2006 with corrections to the Cover Date.     

中国甜菜夜蛾地理种群的遗传分化与基因流

【目的】为了明确我国甜菜夜蛾Spodoptera exigua地理种群间的遗传分化及基因流,阐明该种害虫在我国的种群历史动态。【方法】本研究对采自我国20个地理种群的529头甜菜夜蛾样品进行线粒体COI基因序列测定与分析,利用DnaSP 5.0和Arlequin 3.11软件分析种群间遗传多样性、遗传分化、基因流水平及分子变异,构建了单倍型系统发育树与单倍型网络图。【结果】在所分析的所有529个序列样本中,共检测出10个单倍型,其中Hap_1为所有种群所共享。总群体遗传多样性较低（Hd=0.257±0.025,Pi=0.0007±0.0001,Kxy=0.323）,群体间遗传分化较小（F_ST=0.211）,基因流水平较高（N_m=1.870）。AMOVA分析表明,甜菜夜蛾遗传变异主要来自种群内,种群间变异水平较低。各种群间遗传分化程度与地理距离无显著相关性（R²=0.005,P>0.05）。各单倍型相互散布在不同种群中,未形成明显系统地理结构。中性检验（Tajima’s D=-2.177, P<0.05; Fu’s F_S=-8.629, P<0.05)与错配分布分析表明,我国甜菜夜蛾种群曾经历种群近期扩张。【结论】研究结果揭示,甜菜夜蛾各种群间的基因交流并未受到地理距离的影响,验证了甜菜夜蛾具有高度的迁飞能力。