Groundplans and exemplars: Paths to the tree of life

During cladistic analysis of a diverse higher taxon it is impractical to code every species as a separate terminal. In such cases, workers proceed in one of two distinct ways: (1) examine a number of member species in order to deduce groundplan character states of the higher group before the analysis is begun, here called the intuitive method, or (2), code a number of real species belonging to the group as terminals in the analysis, called the exemplar method. Both methods have the same aim, to estimate the groundplan of the higher taxon concerned. Both groundplan estimation methods will lead to identical results when the character in question has the same state in all members of the terminal group, however when the character has two or more states, the two methods may give different results. The precise methods employed in the intuitive approach have not been articulated in the literature, but possible techniques may result in non-parsimonious ancestral state assignments, even in simple cases. Groundplan estimation in the exemplar method is an extension of parsimony. The exemplar method allows groundplan state/s at internal nodes to be calculated during tree search. In many cases the exemplar method assigns a number of possible states to the groundplan, and the state assignment is therefore equivocal. This is not a deficiency of the method but reflects the notion that the parsimony criterion alone cannot always distinguish a single state present in a hypothetical ancestor. The optimal choice of exemplars required to estimate the groundplan most efficiently is discussed under a simple and common hypothesis of character transformation. For complex character distributions up to three exemplars may be required, each from a separate lineage of the group close to its hypothetical common ancestral node

The evolution and biogeography of the austral horse fly tribe Scionini (Diptera: Tabanidae: Pangoniinae) inferred from multiple mitochondrial and nuclear genes

Phylogenetic relationships within the Tabanidae are largely unknown, despite their considerable medical and ecological importance. The first robust phylogenetic hypothesis for the horse fly tribe Scionini is provided, completing the systematic placement of all tribes in the subfamily Pangoniinae. The Scionini consists of seven mostly southern hemisphere genera distributed in Australia, New Guinea, New Zealand and South America. A 5757. bp alignment of 6 genes, including mitochondrial (COI and COII), ribosomal (28S) and nuclear (AATS and CAD regions 1, 3 and 4) genes, was analysed for 176 taxa using both Bayesian and maximum likelihood approaches. Results indicate the Scionini are strongly monophyletic, with the exclusion of the only northern hemisphere genus Goniops. The South American genera Fidena, Pityocera and Scione were strongly monophyletic, corresponding to current morphology-based classification schemes. The most widespread genus Scaptia was paraphyletic and formed nine strongly supported monophyletic clades, each corresponding to either the current subgenera or several previously synonymised genera that should be formally resurrected. Molecular results also reveal a newly recognised genus endemic to New Zealand, formerly placed within Scaptia. Divergence time estimation was employed to assess the global biogeographical patterns in the Pangoniinae. These analyses demonstrated that the Scionini are a typical Gondwanan group whose diversification was influenced by the fragmentation of that ancient land mass. Furthermore, results indicate that the Scionini most likely originated in Australia and subsequently radiated to New Zealand and South American by both long distance dispersal and vicariance. The phylogenetic framework of the Scionini provided herein will be valuable for taxonomic revisions of the Tabanidae

Phylogeny and systematics of Diptera: Two decades of progress and prospects

Zootaxa1668565-59

Revisão de Euprepina Hull (Diptera, Bombyliidae, Bombyliinae) Revision of Euprepina Hull (Diptera, Bombyliidae, Bombyliinae)

<abstract language="eng">Euprepina Hull, 1971 (Diptera, Bombyliidae, Bombyliinae) a neotropical genus with ten species is revised. Redescriptions of eight species were made: E. nuda Hull, 1971, E. amabilis (Wulp, 1881), E. beckeri Lamas & Couri, 1998, E. bicincta (Wiedemann, 1830), E. caminaria (Wiedemann, 1830), E. knutsoni Hull, 1971, E. maracajula Hull, 1971 and E. truxalia Hull, 1971, with illustrations of the types, male terminalia and spermathecae. Two synonymies - E. bicincta (Wiedemann, 1830), syn.: E. bicincta Hull, 1971; and E. nuda Hull, 1971, syn.: E. shannoni Hull, 1971 - are proposed. A key to species are presented except to E. goyaz (Macquart, 1840) and E. aperta (Macquart, 1847), which were not included in this study, as no material was examined

A dated molecular perspective of eucalypt taxonomy, evolution and diversification

The eucalypts, which include Eucalyptus, Angophora and Corymbia, are native to Australia and Malesia and include over 800 named species in a mixture of diverse and depauperate lineages. We assessed the fit of the eucalypt taxonomic classification to a phylogeny of 711 species scored for DNA sequences of plastid matK and psbA–trnH, as well as nuclear internal transcribed spacer and external transcribed spacer. Two broadly similar topologies emerge from both maximum likelihood and Bayesian analyses, showing Angophora nested within Corymbia, or Angophora sister to Corymbia. The position of certain species-poor groups on long branches fluctuated relative to the three major Eucalyptus subgenera, and positions of several closely related species within those subgenera were unstable and lacked statistical support. Most sections and series of Eucalyptus were not recovered as monophyletic. We calibrated these phylogenies against time, using penalised likelihood and constraints obtained from fossil ages. On the basis of these trees, most major eucalypt subgenera arose in the Late Eocene and Early Oligocene. All Eucalyptus clades with taxa occurring in south-eastern Australia have crown ages <20 million years. Several eucalypt clades display a strong present-day geographic disjunction, although these clades did not have strong phylogenetic statistical support. In particular, the estimated age of the separation between the eudesmids (Eucalyptus subgenus Eudesmia) and monocalypts (Eucalyptus subgenus Eucalyptus) was consistent with extensive inland water bodies in the Eocene. Bayesian analysis of macroevolutionary mixture rates of net species diversification accelerated in five sections of Eucalyptus subgenus Symphyomyrtus, all beginning 2–3 million years ago and associated with semi-arid habitats dominated by mallee and mallet growth forms, and with open woodlands and forests in eastern Australia. This is the first time that a calibrated molecular study has shown support for the rapid diversification of eucalypts in the recent past, most likely driven by changing climate and diverse soil geochemical conditions.Andrew H. Thornhill, Michael D. Crisp D, Carsten Külheim D E, Kristy E. Lam A, Leigh A. Nelson F, David K. Yeates F and Joseph T. Mille

The phylogenetic relationships among infraorders and superfamilies of Diptera based on morphological evidence

10.1111/j.1365-3113.2012.00652.xSystematic Entomology381164-179SYEN

Phylogenetics of Australasian gall flies (Diptera: Fergusoninidae): evolutionary patterns of host-shifting and gall morphology

This study investigated host-specificity and phylogenetic relationships in Australian galling flies, Fergusonina Malloch (Diptera: Fergusoninidae), in order to assess diversity and explore the evolutionary history of host plant affiliation and gall morphology. A DNA barcoding approach using COI data from 203 Fergusonina specimens from 5 gall types on 56 host plant species indicated 85 presumptive fly species. These exhibited a high degree of host specificity; of the 40 species with multiple representatives, each fed only on a single host genus, 29 (72.5%) were strictly monophagous, and 11 (27.5%) were reared from multiple closely related hosts. COI variation within species was not correlated with either sample size or geographic distance. However variation was greater within oligophagous species, consistent with expectations of the initial stages of host-associated divergence during speciation. Phylogenetic analysis using both nuclear and mitochondrial genes revealed host genus-restricted clades but also clear evidence of multiple colonizations of both host plant genus and host species. With the exception of unilocular peagalls, evolution of gall type was somewhat constrained, but to a lesser degree than host plant association. Unilocular peagalls arose more often than any other gall type, were primarily located at the tips of the phylogeny, and did not form clades comprising more than a few species. For ecological reasons, species of this gall type are predicted to harbor substantially less genetic variation than others, possibly reducing evolutionary flexibility resulting in reduced diversification in unilocular gallers