Multiple origins of parasitism in lice

A major fraction of the diversity of insects is parasitic, as herbivores, parasitoids or vertebrate ectopara sites. Understanding this diversity requires information on the origin of parasitism in various insect groups. Parasitic lice (Phthiraptera) are the only major group of insects in which all members are permanent parasites of birds or mammals. Lice are classified into a single order but are thought to be closely related to, or derived from, book lice and bark lice (Psocoptera). Here, we use sequences of the nuclear 18S rDNA gene to investigate the relationships among Phthiraptera and Psocoptera and to identify the origins of parasitism in this group (termed Psocodea). Maximum-likelihood (ML), Bayesian ML and parsimony analyses of these data indicate that lice are embedded within the psocopteran infraorder Nanopsocetae, making the order Psocoptera paraphyletic (i.e. does not contain all descendants of a single common ancestor). Furthermore, one family of Psocoptera, Liposcelididae, is identified as the sister taxon to the louse suborder Amblycera, making parasitic lice (Phthiraptera) a polyphyletic order (i.e. descended from two separate ancestors). We infer from these results that parasitism of vertebrates arose twice independently within Psocodea, once in the common ancestor of Amblycera and once in the common ancestor of all other parasitic lice.     

Early origins of modern birds and mammals: molecules vs. morphology

Recent claims from molecular evidence that modern orders of birds and mammals arose in the Early Cretaceous, over 100 million years (Myr) ago, are contrary to palaeontological evidence. The oldest fossils generally fall in the time range from 70-50 Myr ago, with no earlier finds. If the molecular results are correct, then the first half of the fossil record of modern birds and mammals is missing. Suggestions that this early history was played out in unexplored parts of the world, or that the early progenitors were obscure forms, are unlikely. Intense collecting over hundreds of years has failed to identify these missing fossils. Control experiments, in the form of numerous Cretaceous-age fossil localities which yield excellently preserved lizards, salamanders, birds, and mammals, fail to show the modern forms. The most likely explanation is that they simply did not exist, and that the molecular clock runs fast during major radiations.     

Phylogenetic position of Phthiraptera (Insecta: Paraneoptera) and elevated rate of evolution in mitochondrial 12S and 16S rDNA

Phthiraptera (chewing and sucking lice) and Psocoptera (booklice and barklice) are closely related to each other and compose the monophyletic taxon Psocodea. However, there are two hypotheses regarding their phylogenetic relationship: (1) monophyletic Psocoptera is the sister group of Phthiraptera or (2) Psocoptera is paraphyletic, and Liposcelididae of Psocoptera is the sister group of Phthiraptera. Each hypothesis is supported morphologically and/or embryologically, and this problem has not yet been resolved. In the present study, the phylogenetic position of Phthiraptera was examined using mitochondrial 12S and 16S rDNA sequences, with three methods of phylogenetic analysis. Results of all analyses strongly supported the close relationship between Phthiraptera and Liposcelididae. Results of the present analyses also provided some insight into the elevated rate of evolution in mitochondrial DNA (mtDNA) in Phthiraptera. An elevated substitution rate of mtDNA appears to originate in the common ancestor of Phthiraptera and Liposcelididae, and directly corresponds to an increased G+C content. Therefore, the elevated substitution rate of mtDNA in Phthiraptera and Liposcelididae appears to be directional. A high diversity of 12S rDNA secondary structure was also observed in wide range of Phthiraptera and Liposcelididae, but these structures seem to have evolved independently in different clades.     

A new Early Permian reptile and its significance in early diapsid evolution

The initial stages of evolution of Diapsida (the large clade that includes not only snakes, lizards, crocodiles and birds, but also dinosaurs and numerous other extinct taxa) is clouded by an exceedingly poor Palaeozoic fossil record. Previous studies had indicated a 38 Myr gap between the first appearance of the oldest diapsid clade (Araeoscelidia), ca 304 million years ago (Ma), and that of its sister group in the Middle Permian (ca 266 Ma). Two new reptile skulls from the Richards Spur locality, Lower Permian of Oklahoma, represent a new diapsid reptile: Orovenator mayorum n. gen. et sp. A phylogenetic analysis identifies O. mayorum as the oldest and most basal member of the araeoscelidian sister group. As Richards Spur has recently been dated to 289 Ma, the new diapsid neatly spans the above gap by appearing 15 Myr after the origin of Diapsida. The presence of O. mayorum at Richards Spur, which records a diverse upland fauna, suggests that initial stages in the evolution of non-araeoscelidian diapsids may have been tied to upland environments. This hypothesis is consonant with the overall scant record for non-araeoscelidian diapsids during the Permian Period, when the well-known terrestrial vertebrate communities are preserved almost exclusively in lowland deltaic, flood plain and lacustrine sedimentary rocks.     

New dinosaurs link southern landmasses in the Mid-Cretaceous

Abelisauroid predators have been recorded almost exclusively from South America, India and Madagascar, a distribution thought to document persistent land connections exclusive of Africa. Here, we report fossils from three stratigraphic levels in the Cretaceous of Niger that provide definitive evidence that abelisauroid dinosaurs and their immediate antecedents were also present on Africa. The fossils include an immediate abelisauroid antecedent of Early Cretaceous age (ca. 130-110 Myr ago), early members of the two abelisauroid subgroups (Noasauridae, Abelisauridae) of Mid-Cretaceous age (ca. 110 Myr ago) and a hornless abelisaurid skull of early Late Cretaceous age (ca. 95 Myr ago). Together, these fossils fill in the early history of the abelisauroid radiation and provide key evidence for continued faunal exchange among Gondwanan landmasses until the end of the Early Cretaceous (ca. 100 Myr ago).     

Phylogeny of the lice (Insecta, Phthiraptera) inferred from small subunit rRNA

There has been much argument about the phylogenetic relationships of the four suborders of lice (Insecta: Phthiraptera). Lyal's study of the morphology of lice indicated that chewing/biting lice (Mallophaga) are paraphyletic with respect to sucking lice (Anoplura). To test this hypothesis we inferred the phylogeny of 33 species of lice from small subunit (SSU) rRNA sequences (18S rRNA). Liposcelis sp. from the Liposcelididae (Psocoptera) was used for outgroup reference. Phylogenetic relationships among the four suborders of lice inferred from these sequences were the same as those inferred from morphology. The Amblycera is apparently the sister-group to all other lice whereas the Rhynchophthirina is apparently sister to the Anoplura; these two suborders are sister to the Ischnocera, i.e. (Amblycera (Ischnocera (Anoplura, Rhynchophthirina))). Thus, the Mallophaga (Amblycera, Ischnocera, Rhynchophthirina) is apparently paraphyletic with respect to the Anoplura. Our analyses also provide evidence that: (i) each of the three suborders of lice that are well represented in our study (the Amblycera, Ischnocera, and Anoplura) are monophyletic; (ii) the Boopiidae is monophyletic; (iii) the genera Heterodoxus and Latumcephalum (Boopiidae) are more closely related to one another than either is to the genus Boopia (also Boopiidae); (iv) the Ricinidae and Laemobothridae may be sister-taxa; (v) the Philopteridae may be paraphyletic with respect to the Trichodectidae; (vi) the genera Pediculus and Pthirus are more closely related to each other than either is to the genus Pedicinus ; and (vii) in contrast to published data for mitochondrial genes, the rates of nucleotide substitution in the SSU rRNA of lice are not higher than those of other insects, nor do substitution rates in the suborders differ substantially from one another.     

A new, nearly complete stem turtle from the Jurassic of South America with implications for turtle evolution

Turtles have been known since the Upper Triassic (210Myr old); however, fossils recording the first steps of turtle evolution are scarce and often fragmentary. As a consequence, one of the main questions is whether living turtles (Testudines) originated during the Late Triassic (210Myr old) or during the Middle to Late Jurassic (ca 160Myr old). The discovery of the new fossil turtle, Condorchelys antiqua gen. et sp. nov. from the Middle to Upper Jurassic (ca 160-146Myr old) of South America (Patagonia, Argentina), presented here sheds new light on early turtle evolution. An updated cladistic analysis of turtles shows that C. antiqua and other fossil turtles are not crown turtles, but stem turtles. This cladistic analysis also shows that stem turtles were more diverse than previously thought, and that until the Middle to Upper Jurassic there were turtles without the modern jaw closure mechanism.     

Haemothermia or Archosauria? The interrelationships of mammals,birds and crocodiles

The recently proposed hypothesis that the living birds and the living mammals are sister groups, together forming a natural taxon Haemothermia, is contrasted with the more traditional view, that birds and crocodiles are living sister groups within the taxon Archosauria. Of the 28 or so characters claimed to be unique to the Haemothermia, several are found to be structurally or developmentally different in birds compared to mammals. Others are found to occur also in crocodiles. In either case the status of the characters as homologues categorizing the group becomes doubtful, and only about eight characters remain as potentially acceptable. In contrast, some 24 characters are identified as potential homologues of birds plus crocodiles and therefore categorizing the group Archosauria, and this hypothesis must be judged preferable. The evidence of the characters of fossils can be used legitimately to test cladograms, but only to a limited extent. Nevertheless, the relevant fossils do support the Archosauria rather than the Haemothermia hypothesis. Cladograms logically may, and methodologically should, be taken as theories of phylogenetic relationships, and are potentially subject to independent evolutionary tests. A priori character weighting is sound in principle but cannot be applied in practice for want of the necessary, independently acquired knowledge of how characters change in evolution. The relative dates of the fossils is shown to be more compatible with the Archosauria than the Haemothermia classification. Finally, the hypothetical common ancestors that are implied by the two respective cladograms are compared. That shared by mammals and birds, as implied by the Haemothermia theory, would have been functionally incongruent, and therefore less probable than that shared by birds and crocodiles. These several lines of evidence all lead to the conclusion that the traditional theory of a relationship between birds and crocodiles, vis à vis mammals is substantially the better supported.     

Multiple lineages of lice pass through the K-Pg boundary

For modern lineages of birds and mammals, few fossils have been found that predate the Cretaceous-Palaeogene (K-Pg) boundary. However, molecular studies using fossil calibrations have shown that many of these lineages existed at that time. Both birds and mammals are parasitized by obligate ectoparasitic lice (Insecta: Phthiraptera), which have shared a long coevolutionary history with their hosts. Evaluating whether many lineages of lice passed through the K-Pg boundary would provide insight into the radiation of their hosts. Using molecular dating techniques, we demonstrate that the major louse suborders began to radiate before the K-Pg boundary. These data lend support to a Cretaceous diversification of many modern bird and mammal lineages.     

AMNIOTE PHYLOGENY AND THE IMPORTANCE OF FOSSILS

Abstract— Several prominent cladists have questioned the importance of fossils in phylogenctic inference, and it is becoming increasingly popular to simply fit extinct forms, if they are considered at all, to a cladogram of Recent taxa. Gardiner's (1982) and Løvtrup's (1985) study of amniote phylogeny exemplifies this differential treatment, and we focused on that group of organisms to test the proposition that fossils cannot overturn a theory of relationships based only on the Recent biota. Our parsimony analysis of amniote phylogeny, special knowledge contributed by fossils being scrupulously avoided, led to the following best fitting classification, which is similar to the novel hypothesis Gardiner published: (lepidosaurs (turtles (mammals (birds, crocodiles)))). However, adding fossils resulted in a markedly different most parsimonious cladogram of the extant taxa: (mammals (turtles (lepidosaurs (birds, crocodiles)))). That classification is like the traditional hypothesis, and it provides a better fit to the stratigraphic record. To isolate the extinct taxa responsible for the latter classification, the data were successively partitioned with each phylogenetic analysis, and we concluded that: (1) the ingroup, not the outgroup, fossils were important; (2) synapsid, not reptile, fossils were pivotal; (3) certain synapsid fossils, not the earliest or latest, were responsible. The critical nature of the synapsid fossils seemed to lie in the particular combination of primitive and derived character slates they exhibited. Classifying those fossils, along with mammals, as the sister group to the lineage consisting of birds and crocodiles resulted in a relatively poor fit to data; one involving a 2—4 fold increase in evolutionary reversals! Thus, the importance of the critical fossils, collectively or individually, seems to reside in their relative primitive-ness, and the simplest explanation for their more conservative nature is that they have had less time to evolve. While fossils may be important in phylogenetic inference only under certain conditions, there is no compelling reason to prejudge their contribution. We urge systematists to evaluate fairly all of the available evidence.     

Phosphatized multicellular algae in the Neoproterozoic Doushantuo Formation, China, and the early evolution of florideophyte red algae

Phosphatic sediments of the Late Neoproterozoic (ca. 600 million years old [Myr]) Doushantuo Formation at Weng'an, South China, contain fossils of multicellular algae preserved in anatomical detail. As revealed by light microscopy and scanning electron microscopy, these fossils include both simple pseudoparenchymatous thalli with apical growth but no cortex-medulla differentiation and more complex thalli characterized by cortex-medulla differentiation and structures interpretable as carposporophytes, suggesting a multiphasic life cycle. Simple pseudoparenchymatous thalli, represented by Wengania, Gremiphyca, and Thallophycoides, are interpreted as stem group florideophytes. In contrast, complex pseudoparenchymatous thalli, such as Thallophyca and Paramecia, compare more closely to fossil and living corallinaleans than to other florideophyte orders, although they also differ in some important aspects (e.g., lack of biocalcification). These more complex thalli are interpreted as early stem group corallinaleans that diverged before Paleozoic stem groups such as Arenigiphyllum, Petrophyton, Graticula, and Archaeolithophyllum. This phylogenetic interpretation implies that (1) the phylogenetic divergence between the Florideophyceae and its sister group, the Bangiales, must have taken place before Doushantuo time-an inference supported by the occurrence of bangialean fossils in Mesoproterozoic rocks; (2) the initial diversification of the florideophytes occurred no later than the Doushantuo time; and (3) the corallinalean clade had a "soft" (uncalcified) evolutionary history in the Neoproterozoic before evolving biocalcification in the Paleozoic and undergoing crown group diversification in the Mesozoic.     

A new Late Cretaceous family of Hymenoptera, and phylogeny of the Plumariidae and Chrysidoidea (Aculeata)

The taxonomic placement of an enigmatic species of wasp known from two specimens in Late Cretaceous New Jersey amber is investigated through cladistic analyses of 90 morphological characters for 33 terminals ranging across non-Aculeata, non-Chrysidoidea, most subfamilies of Chrysidoidea and all genera of Plumariidae (the family to which the fossils were initially assigned), based on use of exemplars. The fossil taxon is apparently basal in Chrysidoidea, most likely sister to Plumariidae, but perhaps sister to the remaining chrysidoids, or even sister to Chrysidoidea as a whole. It is described as representing a new family, Plumalexiidaefam. n., containing a single species, Plumalexius rasnitsynigen. et sp. n. Previous estimates of relationships for the genera of Plumariidae and for the higher taxa of Chrysidoidea are mostly confirmed. The importance of outgroup choice, and additivity and weighting of characters are demonstrated.     

Phylogeny and classification, origins, and evolution of host associations of lice

Lice are highly successful ectoparasites. Most species of mammals and birds are infested by at least 1 but up to 6 species of lice. Current opinion is that lice evolved from free-living Psocoptera (booklice, barklice and psocids). It is generally agreed that there are 4 main groups of lice: Anoplura, Amblycera, Ischnocera and Rhyncophthirina. In contrast, there is no agreement on the phylogenetic relationships of these groups and their classification. In particular, there is much debate over the validity of the taxon Mallophaga, which is almost certainly paraphyletic. For many years the sister-group of the Boopiidae, which almost exclusively infest Australasian marsupials, was thought to be a group of lice that now infest marsupials in South America. This, however, is almost certainly incorrect; the sister-group of the Boopiidae probably contains bird-infesting lice from the Menoponidae (Amblycera). Thus, menoponid lice transferred from birds to mammals and from these arose the Boopiidae. Transfers of lice between mammals and birds have occurred on other occasions during the evolution of the lice; 2 of the 4 main groups of lice, the Ischnocera and Amblycera, contain families that infest birds and families that infest mammals. Strict cospeciation and coevolution was thought to predominate among the lice; however, detailed studies indicate this to be incorrect. Consequently, the axiom that lice and their hosts invariably coevolve should be abandoned. Ironically, biologists may learn more about the evolutionary biology of hosts when host-switching has occurred. Some evidence exists for competition between species of lice; this interaction may determine whether or not the transfer of a species of louse to an atypical hose (a potential host-switch) is successful. Thus, the extincion of populations of lice (that result in uninfested hosts) may facilitate host-switching and perhaps the evolution of new taxa of lice. In contrast, extinction of hosts unfortunately often leads to the extinction of species of lice.     

New fossil Progonocimicidae (Hemiptera: Coleorrhyncha: Progonocimicoidea) from the Upper Mesozoic of northeastern China,with a phylogeny of Coleorrhyncha

A new Progonocimicidae species, Cicadocoris anisomeridis sp.n. , with asymmetrical tegmina is described from the Middle Jurassic Jiulongshan Formation in northeastern China. This is the fifth report of Coleorrhyncha from China. A cladistic analysis based on a combination of fossil and extant taxa clarifies the phylogenetic status of the new fossils and allows the reconstruction of inter‐subfamily relationships within the suborder Coleorrhyncha. Coleorrhyncha is monophyletic and divided into two main clades. Progonocimicidae comprises a monophyletic lineage, to which the new fossils belong. The broadly conceived Progonocimicinae and Cicadocorinae, as recognized by earlier authors, are not supported. The monophyly of the family Karabasiidae is also not supported, and its two constituent subfamilies Hoploridiinae and Karabasiinae are raised to family rank. Hoploridiidae is found to be sister group to all extant moss bugs, and Karabasiidae is found to be the monophyletic sister group to Hoploridiidae + all extant moss bugs. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:30BC0498‐3B8A‐4650‐BC9D‐02A0C8D870B2 .     

Evolution of the angiosperms: calibrating the family tree.

Growing evidence of morphological diversity in angiosperm flowers, seeds and pollen from the mid Cretaceous and the presence of derived lineages from increasingly older geological deposits both imply that the timing of early angiosperm cladogenesis is older than fossil-based estimates have indicated. An alternative to fossils for calibrating the phylogeny comes from divergence in DNA sequence data. Here, angiosperm divergence times are estimated using non-parametric rate smoothing and a three-gene dataset covering ca. 75% of all angiosperm families recognized in recent classifications. The results provide an initial hypothesis of angiosperm diversification times. Using an internal calibration point, an independent evaluation of angiosperm and eudicot origins is performed. The origin of the crown group of extant angiosperms is indicated to be Early to Middle Jurassic (179-158 Myr), and the origin of eudicots is resolved as Late Jurassic to mid Cretaceous (147-131 Myr). Both estimates, despite a conservative calibration point, are older than current fossil-based estimates.     

†Cormopsocidae: A new family of the suborder Trogiomorpha (Insecta: Psocodea) from Burmese amber

Cormopsocidae n. fam . of the psocid suborder Trogiomorpha was proposed for a fossil species from mid‐Cretaceous Burmese amber, Cormopsocus groehni n. gen . & n. sp . This family was estimated to be the sister group of all other trogiomorphan taxa, but the possibility of much deeper divergence (i.e. placement as a sister group of all Psocodea) could not be excluded. Cormopsocus groehni retains many plesiomorphic features, which will contribute greatly to elucidating the ancestral state of Psocodea.     

Complete mitochondrial DNA genome sequences show that modern birds are not descended from transitional shorebirds

To test the hypothesis put forward by Feduccia of the origin of modern birds from transitional birds, we sequenced the first two complete mitochondrial genomes of shorebirds (ruddy turnstone and blackish oystercatcher) and compared their sequences with those of already published avian genomes. When corrected for rate heterogeneity across sites and non-homogeneous nucleotide compositions among lineages in maximum likelihood (ML), the optimal tree places palaeognath birds as sister to the neognaths including shorebirds. This optimal topology is a re-rooting of recently published ordinal-level avian trees derived from mitochondrial sequences. Using a penalized likelihood (PL) rate-smoothing process in conjunction with dates estimated from fossils, we show that the basal splits in the bird tree are much older than the Cretaceous-Tertiary (K-T) boundary, reinforcing previous molecular studies that rejected the derivation of modern birds from transitional shorebirds. Our mean estimate for the origin of modern birds at about 123 million years ago (Myr ago) is quite close to recent estimates using both nuclear and mitochondrial genes, and supports theories of continental break-up as a driving force in avian diversification. Not only did many modern orders of birds originate well before the K-T boundary, but the radiation of major clades occurred over an extended period of at least 40 Myr ago, thus also falsifying Feduccia's rapid radiation scenario following a K-T bottleneck.     

A Gondwanan origin of passerine birds supported by DNA sequences of the endemic New Zealand wrens

Zoogeographic, palaeontological and biochemical data support a Southern Hemisphere origin for passerine birds, while accumulating molecular data suggest that most extant avian orders originated in the mid-Late Cretaceous. We obtained DNA sequence data from the nuclear c-myc and RAG-1 genes of the major passerine groups and here we demonstrate that the endemic New Zealand wrens (Acanthisittidae) are the sister taxon to all other extant passerines, supporting a Gondwanan origin and early radiation of passerines. We propose that (i) the acanthisittids were isolated when New Zealand separated from Gondwana (ca. 82-85 Myr ago), (ii) suboscines, in turn, were derived from an ancestral lineage that inhabited western Gondwana, and (iii) the ancestors of the oscines (songbirds) were subsequently isolated by the separation of Australia from Antarctica. The later spread of passerines into the Northern Hemisphere reflects the northward migration of these former Gondwanan elements.     

HAEMATOTHERMIA: WARM-BLOODED AMNIOTES

Abstract— An exhaustive parsimony analysis of amniote phylogeny using 97 characters has substantiated the hypothesis that mammals and birds are sister groups. This deduction is further supported by parasitological and molecular evidence.
The presumed importance of "synapsid" fossils in amniote phylogeny is questioned and it is concluded that they represent a transformation series which when broken down into constit uent, monophyletic groups does not support the separation of the Mammalia from the remainder of the amniotes.
Fossil members of the Haematothermia include pterosaurs and "dinosaurs" (both stem-group birds) and Dinocephalia, Dicynodontia, Gorgonopsida and Therocephalia (all stem-group mammals). The Dromaeosauridae are the most crownward stem-group birds and the Morganucodontidae the most crownward stem-group mammals.
"Criticism of our conjectures is of decisive importance: by bringing out our mistakes it makes us understand the difficulties of the problem which we are trying to solve." (K. R. Popper, 1972)     

Phylogeny and evolution of Mesozoic and extant lineages of Histeridae (Coleoptera), with discovery of a new subfamily Antigracilinae from the Lower Cretaceous

In order to place a newly discovered species Antigracilus costatus gen. sp. n. from the Lower Cretaceous Yixian Formation (China) and to assess previously unplaced fossil taxa, we investigated the relationships of extant and extinct lineages of Histeridae based on three data sets: (i) 69 morphological characters belonging to 48 taxa (representing all 11 subfamilies and 15 of 17 tribes of modern Histeridae); (ii) partitioned alignment of 6030 bp from downloaded nucleotide sequences (28S, CAD, COI, 18S) of 50 taxa (representing 10 subfamilies and 15 of 17 tribes of modern Histeridae); and (iii) a combined morphological and molecular dataset for 75 taxa. Phylogenetic analyses of the morphology and combined matrices recovered the new Lower Cretaceous taxon as a sister group to remaining Histeridae and it is placed in †Antigracilinae subfam. n. †Antigracilinae constitutes the earliest record of Histeridae from the Lower Cretaceous Yixian Formation (∼125 Myr), backdating the minimum age of the family by 25 Myr from the earliest Cenomanian (~99 Myr) to the Barremian of the Cretaceous Period. Our molecular phylogeny supports Histeridae to be divided into seven different clades, with currently recognised subfamilies Abraeinae (sensu lato), Saprininae, Chlamydopsinae, and Histerinae (sensu lato) recovered as monophyletic, while Dendrophilinae, Onthophilinae, and Tribalinae are polyphyletic taxa. The Burmese amber species †Pantostictus burmanicus Poinar & Brown is placed as a sister group to the tribe Plegaderini (Abraeinae) and was assigned as a new tribe Pantostictini trib. n. Both molecular and combined phylogenies recovered the subfamilies Trypanaeinae and Trypeticinae deeply within the subfamily Abraeinae (sensu lato), and they are downgraded into Trypanaeini stat. n. and Trypeticini stat. n.