Shell bone histology indicates terrestrial palaeoecology of basal turtles

The palaeoecology of basal turtles from the Late Triassic was classically viewed as being semi-aquatic, similar to the lifestyle of modern snapping turtles. Lately, this view was questioned based on limb bone proportions, and a terrestrial palaeoecology was suggested for the turtle stem. Here, we present independent shell bone microstructural evidence for a terrestrial habitat of the oldest and basal most well-known turtles, i.e. the Upper Triassic Proterochersis robusta and Proganochelys quenstedti. Comparison of their shell bone histology with that of extant turtles preferring either aquatic habitats or terrestrial habitats clearly reveals congruence with terrestrial turtle taxa. Similarities in the shell bones of these turtles are a diploe structure with well-developed external and internal cortices, weak vascularization of the compact bone layers and a dense nature of the interior cancellous bone with overall short trabeculae. On the other hand, 'aquatic' turtles tend to reduce cortical bone layers, while increasing overall vascularization of the bone tissue. In contrast to the study of limb bone proportions, the present study is independent from the uncommon preservation of appendicular skeletal elements in fossil turtles, enabling the palaeoecological study of a much broader range of incompletely known turtle taxa in the fossil record.     

Embryos of therizinosauroid theropods from the Upper Cretaceous of China: diagnosis and analysis of ossification patterns

Exceptionally complete, in ovo dinosaur embryos from the Upper Cretaceous of China are analysed. Ossification patterns of these embryos suggest that they died during the final third of their development. The therizinosauroid identity of the embryos follows from: (1) an edentulous premaxilla with a sharp downturned edge; (2) dentary with a lateral shelf; (3) teeth with fan-shaped crowns, with a few marginal cusps; (4) humerus with a massive deltopectoral crest extending proximally, with a pointed proximomedial tuberosity; (5) ilium with an expanded and hooked preacetabular process; (6) strongly curved hypertrophied manual unguals tapering to sharp points. These embryos are closest to two Chinese therizinosauroids, Neimongosaurus yangi Zhang et al . 2001 and Erliansaurus bellamanus Xu et al . 2002 . An elongated narial opening, reduced basipterygoid process, low cervical neural spines, a transversely narrow pubic apron, and a pubic foot expanded anteriorly are found in these embryos and are synapomorphies uniting the Therizinosauroidea and the Oviraptorosauria. Fusion of cervical and caudal neural arches and centra, complete ossification of thoracic ribs and ilium, possible co-ossification of tibia and fibula, fused pubes, complete meta- and acropodial elements, together with small portions of unossified epiphyses of long bones suggest an advanced precociality of these embryos.     

Identification of the French Upper Cretaceous bothremydid turtle Foxemys mechinorum in the Spanish record

Bothremydidae is the most abundant and diverse group of turtles in the upper Cretaceous fossil sites of southwestern Europe. Several species a priori recognized as exclusive of the Portuguese, Spanish and French records were defined. The most abundant and best-preserved Spanish collection of pleurodiran turtles from the last Stages of the Upper Cretaceous comes from the fossil site of Lo Hueco (Cuenca Province, Central Spain). The bothremydid Iberoccitanemys convenarum, defined by a single specimen from the Maastrichtian of Haute-Garonne (Southern France), was subsequently recognized as a very abundant form in this Spanish site, corresponding to the only bothremydid so far identified as being part of the diversity of Bothremydidae of both countries. The presence of a second member of Bothremydidae was recognized in Lo Hueco, representing the only evidence of the synchronic and sympatric coexistence of two members of this lineage in a European site. However, very scarce information about this second form from Lo Hueco was available. Thus, its attribution to a new taxon or to a member of Foxemydina previously identified in the Spanish record, or in that of other European regions, could not be evaluated until now. New material from Lo Hueco, not attributable to I. convenarum but to this second larger form, allows its generic and specific identification. Close paleobiogeographical relationships considering the fauna of pleurodiran turtles from Spain and France are recognized thanks to the findings performed in Lo Hueco: not only I. convenarum is known in both countries, but also the French Foxemys mechinorum is identified in Central Spain.     

Proposal of Carbonactinosporaceae fam. nov. within the class Actinomycetia. Reclassification of Streptomyces thermoautotrophicus as Carbonactinospora thermoautotrophica gen. nov., comb. nov

Streptomyces thermoautotrophicus UBT1^T has been suggested to merit generic status due to its phylogenetic placement and distinctive phenotypes among Actinomycetia. To evaluate whether ‘S. thermoautotrophicus’ represents a higher taxonomic rank, ‘S. thermoautotrophicus’ strains UBT1^T and H1 were compared to Actinomycetia using 16S rRNA gene sequences and comparative genome analyses. The UBT1^T and H1 genomes each contain at least two different 16S rRNA sequences, which are closely related to those of Acidothermus cellulolyticus (order Acidothermales). In multigene-based phylogenomic trees, UBT1^T and H1 typically formed a sister group to the Streptosporangiales-Acidothermales clade. The Average Amino Acid Identity, Percentage of Conserved Proteins, and whole-genome Average Nucleotide Identity (Alignment Fraction) values were ≤58.5%, ≤48%, ≤75.5% (0.3) between ‘S. thermoautotrophicus’ and Streptosporangiales members, all below the respective thresholds for delineating genera. The values for genomics comparisons between strains UBT1^T and H1 with Acidothermales, as well as members of the genus Streptomyces, were even lower. A review of the ‘S. thermoautotrophicus’ proteomic profiles and KEGG orthology demonstrated that UBT1^T and H1 present pronounced differences, both tested and predicted, in phenotypic and chemotaxonomic characteristics compared to its sister clades and Streptomyces. The distinct phylogenetic position and the combination of genotypic and phenotypic characteristics justify the proposal of Carbonactinospora gen. nov., with the type species Carbonactinospora thermoautotrophica comb. nov. (type strain UBT1^T, = DSM 100163^T = KCTC 49540^T) belonging to Carbonactinosporaceae fam. nov. within Actinomycetia.     

Electrophoretic delineation of species boundaries within the short-necked freshwater turtles of Australia (Testudines: Ghelidae)

A total of 222 specimens from 55 populations of short-necked chelid turtle was collected from drainages in Australia and Papua New Guinea. Two populations were initially considered to belong to different diagnosable taxa if all individuals in one population could be distinguished from all individuals in the other by fixed allozyme differences. When two populations or diagnosable taxa shared allozymes at all presumptive loci, their profiles were combined into a single diagnosable taxon. Comparisons between populations and emerging diagnosable taxa were repeated until no further changes were possible. The species Elseya dentata comprised five clearly diagnosable taxa, differing by between 4 and 19 fixed allozyme differences. The currently recognized El. latisternum and El. novaeguineae were each a single diagnosable taxon, and there were three diagnosable taxa, including a sibling pair, that could not be assigned to a currendy described Elseya species. In contrast, all forms of Emydura were very closely related, with no two taxa differing by more than three fixed allozyme differences. There were three diagnosable taxa in the north (Em. victoriae, Em. subglobosa and one new form), though support for them was marginal. In the south, Em. macquarii, Em. krefflii and Em. signata formed only a single diagnosable taxon, even sharing rare alleles. If the phylogenetic species concept is adopted, there is support for recognition of 16 species of short-necked turtle in Australia, including Pseudemydura umbrina. Currendy only 10 are described. Our data also provide evidence of reproductive isolation in some cases (sympatric or parapatric), and comparative evidence (sensu Mayr) in others, than the traditional biological species concept applies also to these diagnosable taxa.     

A shoot regeneration protocol effective on diverse genotypes of sunflower (Helianthus annuus L.)

Summary We describe a protocol, and several experiments that helped lead to its development, for sunflower regeneration. Important factors for sunflower regeneration were explant age, cytokinin type and concentration, basal medium, and explant source. We could not induce shoot regeneration from the explants derived from mature tissues including leaf, petiole, and stem. However, use of juvenile explants such as embryo meristem and primordial leaf tissues allowed routine regeneration of 17 different sunflower genotypes. High frequency of shoot regeneration was achieved with these explants taken from seedlings up to 5 d after germination. Explant age was less critical for embryo meristem explants than for primordial leaf tissues. Of the four basal media tested, MS and B5 media produced higher shoot-regeneration frequencies than did Anderson and woody plant media. The highest shoot-regeneration frequency was obtained with MS medium supplemented with 2 μM BA and without auxin. Addition of 1 μM naphthalene-acetic acid to the medium significantly reduced both the percentage of explants producing shoots and average number of shoots per explant. Regenerated shoots were grown to maturity in a greenhouse.     

Logic in systematics

Systematic biologists attempt to infer the taxonomic relationship of one species to another based on the available evidence. Phylogenetic systematists demand that these species relationships reflect evolutionary history (they expect their taxa to be monophyletic). Just exactly how this is to be achieved remains a subject of debate. There are many different kinds of evidence, and many different ways of inferring taxonomic relationships (plus evolutionary history) from them. In this paper, we argue that one such way of inferring species relationships, the hypothetico‐deductive method, proves a bad fit with phylogenetic systematics because it requires an excessively strong assumption of the relationship that obtains between hypotheses of descent and the available evidence.     

Phylogeny and evolution of the Australo-Papuan honeyeaters (Passeriformes, Meliphagidae)

We analyzed nucleotide variation at four loci for 75 species to produce a phylogenetic hypothesis for the Meliphagidae, and to examine the evolution and biogeographic history of the Meliphagidae. Both maximum parsimony and Bayesian methods of phylogenetic analysis were employed. The family was found to be monophyletic, though the genera Certhionyx, Anthochaera, and Phylidonyris were not. Four major clades were recovered and the spinebills (Acanthorhynchus) formed the sister clade to the remainder of the family in most analyses. The Australian endemic arid-adapted chats (Epthianura, Ashbyia) were found to be nested deeply within the family Meliphagidae. No evidence was found to support the hypothesis of separate New Guinean and Australian endemic radiations, nor of a close phylogenetic relationship between taxa from the New Guinea highlands and those from Australian northern rainforests.