Estimate Of Phylogenetic Relationships Research Articles

Dating in the Dark: Elevated Substitution Rates in Cave Cockroaches (Blattodea: Nocticolidae) Have Negative Impacts on Molecular Date Estimates.

Rates of nucleotide substitution vary substantially across the Tree of Life, with potentially confounding effects on phylogenetic and evolutionary analyses. A large acceleration in mitochondrial substitution rate occurs in the cockroach family Nocticolidae, which predominantly inhabit subterranean environments. To evaluate the impacts of this among-lineage rate heterogeneity on estimates of phylogenetic relationships and evolutionary timescales, we analysed nuclear ultraconserved elements (UCEs) and mitochondrial genomes from nocticolids and other cockroaches. Substitution rates were substantially elevated in nocticolid lineages compared with other cockroaches, especially in mitochondrial protein-coding genes. This disparity in evolutionary rates is likely to have led to different evolutionary relationships being supported by phylogenetic analyses of mitochondrial genomes and UCE loci. Furthermore, Bayesian dating analyses using relaxed-clock models inferred much deeper divergence times compared with a flexible local clock. Our phylogenetic analysis of UCEs, which is the first genome-scale study to include all thirteen major cockroach families, unites Corydiidae and Nocticolidae and places Anaplectidae as the sister lineage to the rest of Blattoidea. We uncover an extraordinary level of genetic divergence in Nocticolidae, including two highly distinct clades that separated ~115 million years ago despite both containing representatives of the genus Nocticola. The results of our study highlight the potential impacts of high among-lineage rate variation on estimates of phylogenetic relationships and evolutionary timescales.

Plastome structure and phylogenetic relationships of Styracaceae (Ericales)

BackgroundThe Styracaceae are a woody, dicotyledonous family containing 12 genera and an estimated 160 species. Recent studies have shown that Styrax and Sinojackia are monophyletic, Alniphyllum and Bruinsmia cluster into a clade with an approximately 20-kb inversion in the Large Single-Copy (LSC) region. Halesia and Pterostyrax are not supported as monophyletic, while Melliodendron and Changiostyrax always form sister clades. Perkinsiodendron and Changiostyrax are newly established genera of Styracaceae. However, the phylogenetic relationship of Styracaceae at the generic level needs further research.ResultsWe collected 28 complete plastomes of Styracaceae, including 12 sequences newly reported here and 16 publicly available sequences, comprising 11 of the 12 genera of Styracaceae. All species possessed the typical quadripartite structure of angiosperm plastomes, with sequence differences being minor, except for a large 20-kb (14 genes) inversion found in Alniphyllum and Bruinsmia. Seven coding sequences (rps4, rpl23, accD, rpoC1, psaA, rpoA and ndhH) were identified to possess positively selected sites. Phylogenetic reconstructions based on seven data sets (i.e., LSC, SSC, IR, Coding, Non-coding, combination of LSC + SSC and concatenation of LSC + SSC + one IR) produced similar topologies. In our analyses, all genera were strongly supported as monophyletic. Styrax was sister to the remaining genera. Alniphyllum and Bruinsmia form a clade. Halesia diptera does not cluster with Perkinsiodendron, while Perkinsiodendron and Rehderodendron form a clade. Changiostyrax is sister to a clade of Pterostyrax and Sinojackia.ConclusionOverall, our results demonstrate the power of plastid phylogenomics in improving estimates of phylogenetic relationships among genera. This study also provides insight into plastome evolution across Styracaceae.

Chimaera compacta, a new species from southern Indian Ocean, and an estimate of phylogenetic relationships within the genus Chimaera (Chondrichthyes: Chimaeridae)

Chimaera compacta sp. nov., a new species of shortnose chimaera (Holocephali: Chimaeriformes: Chimaeridae), is described from a single specimen collected at 595–655 m depth, off Amsterdam Island, in the southern Indian Ocean. The species is easily distinguished from its congeners by the combination of the following characters: massive head with short snout; stocky and relatively long trunk 44% BDL, short tail with second dorsal fin base 72% BDL; long pelvic fin anterior margin 26% BDL. Caudal fin dorsal origin slightly posterior to caudal fin ventral origin. Firm, non-deciduous skin; brown color with yellow blotches. Chimaera compacta sp. nov. is morphologically close to Chimaera lignaria Didier 2002 from New Zealand and Chimaera willwatchi Clerkin, Ebert and Kemper 2017 from south western Indian Ocean. The new species can be distinguished from other Chimaera species based on DNA sequences divergence of the COI and NADH2 genes. This species has a nucleotide sequence divergence (uncorrected p distances) for the studied genes of 4.2 and 4.1%, respectively, with its closest relatives. Phylogenetically, Chimaera compacta sp. nov. is nested within a well-supported group including Chimaera carophila Kemper, Ebert, Naylor and Didier 2014, Chimaera didierae Clerkin, Ebert and Kemper 2017, C. lignaria, Chimaera macrospina Didier, Last and White 2008, Chimaera notafricana Kemper, Ebert, Compagno and Didier 2010, Chimaera opalescens Luchetti, Iglesias and Sellos 2011, and C. willwatchi. It is the first Chimaeridae described for the Territory of the French Southern and Antarctic Lands.

Phylogenetic relationships of Podarcis siculus (Rafinesque-Schmaltz, 1810) and Podarcis tauricus (Pallas, 1814) in Turkey, based on mitochondrial DNA

The Italian wall lizard and the Balkan wall lizard have a series of taxonomic revisions. However, their phylogenetic relationships still remain uncertain in Turkey. In the present study, we have assessed taxonomic relationships, both of Podarcis siculus and Podarcis tauricus through estimation of phylogenetic relationships among 43 and 42 specimens, respectively, using mtDNA (16 S rRNA and cytb) from great main populations in Turkey. The genetic distances among the populations of P. siculus in Turkey were very low and they were ranged from 0.2 to 1.6% in 16 S rRNA while they were ranged from 0.0% to 3.3% in cytb. On the other hand, the p-distances among the populations of P. tauricus were ranged from 0.0 to 0.6% in 16 S rRNA while they were 0.2% cytb in Turkey. Finally, most of the topologically identical trees of phylogenetic analyses and p-distances showed that monophyly was found in extant populations of P. siculus and P. tauricus. The nominate subspecies, P. s. siculus and P. t. tauricus are representatives of these lizards in Turkey.

Phylogenetic relationships of D. rudis (Bedriaga, 1886) and D. bithynica(Mehely, 1909) based on microsatellite and mitochondrial DNA in Turkey

The spiny-tailed lizard of the genus Darevskia have a series of taxonomic revisions, but still their phylogenetic relationships remain uncertain. In the present study, we have assessed taxonomic relationships among Darevskia bithynica and Darevskia rudis populations through estimation of phylogenetic relationships among 96 specimens using microsatellite DNA (Du215, Du281, Du323 and Du418 loci) and 53 specimens using mtDNA (16S rRNA and cytb) from main populations in Turkey. Although D. b. bithynica and D. r. mirabilis were separated based on the PCoA analysis at low level from other D. rudis and D. bithynica populations, the distance values of Nei's genetic distance, Nei's unbiased genetic distance, Fst and Linear Fst were not high among taxa in microsatellite DNA. On the other hand, our phylogenetic analyses (NJ, ML, MP and BI) did not separate D. rudis and D. bithynica populations. Finally, most of the topologically identical trees of phylogenetic analyses and microsatellite results showed that the extant populations of D. rudis and D. bithynica were found to be polytomy. Based on our molecular phylogenetic study, D. rudis complex is still ongoing revisions.

Impact of deep coalescence and recombination on the estimation of phylogenetic relationships among species using AFLP markers

Deep coalescence and the nongenealogical pattern of descent caused by recombination have emerged as a common problem for phylogenetic inference at the species level. Here we use computer simulations to assess whether AFLP-based phylogenies are robust to the uncertainties introduced by these factors. Our results indicate that phylogenetic signal can prevail even in the face of extensive deep coalescence allowing recovering the correct species tree topology. The impact of recombination on tree accuracy was related to total tree depth and species effective population size. The correct tree topology could be recovered upon many simulation settings due to a trade-off between the conflicting signals resulting from intra-locus recombination and the benefits of the joint consideration of unlinked loci that better matched overall the true species tree. Errors in tree topology were not only determined by deep coalescence, but also by the timing of divergence and the tree-building errors arising from an insufficient number of characters. DNA sequences generally outperformed AFLPs upon any simulated scenario, but this difference in performance was nearly negligible when a sufficient number of AFLP characters were sampled. Our simulations suggest that the impact of deep coalescence and intra-locus recombination on the reliability of AFLP trees could be minimal for effective population sizes equal to or lower than 10,000 (typical of many vertebrates and tree plants) given tree depths above 0.02 substitutions per site.

Genetic diversity assessment and estimation of phylogenetic relationships among 26 Fagaceae species using ISSRs

The family Fagaceae includes several species and presents huge genetic variability. In the last two decades, several genetic studies about phylogenetics and genetic diversity of Fagaceae have emerged. ISSR markers were used to evaluate the genetic diversity of 26 species of Fagaceae belonging to the genera Castanea, Fagus and Quercus. Among several primers tested, 17 were selected for the evaluation of diversity and estimation of genetic relationships. A total of 371 ISSR markers were produced and each primer revealed high polymorphism. Specific ISSR markers for the Quercus infrageneric groups were amplified. ISSRs proved to be a reliable tool for the discrimination of the analyzed species per genus, infrageneric group and/or ecological origin.

Divergence Times and the Evolutionary Radiation of New World Monkeys (Platyrrhini, Primates): An Analysis of Fossil and Molecular Data.

The estimation of phylogenetic relationships and divergence times among a group of organisms is a fundamental first step toward understanding its biological diversification. The time of the most recent or last common ancestor (LCA) of extant platyrrhines is one of the most controversial among scholars of primate evolution. Here we use two molecular based approaches to date the initial divergence of the platyrrhine clade, Bayesian estimations under a relaxed-clock model and substitution rate plus generation time and body size, employing the fossil record and genome datasets. We also explore the robustness of our estimations with respect to changes in topology, fossil constraints and substitution rate, and discuss the implications of our findings for understanding the platyrrhine radiation. Our results suggest that fossil constraints, topology and substitution rate have an important influence on our divergence time estimates. Bayesian estimates using conservative but realistic fossil constraints suggest that the LCA of extant platyrrhines existed at ca. 29 Ma, with the 95% confidence limit for the node ranging from 27–31 Ma. The LCA of extant platyrrhine monkeys based on substitution rate corrected by generation time and body size was established between 21–29 Ma. The estimates based on the two approaches used in this study recalibrate the ages of the major platyrrhine clades and corroborate the hypothesis that they constitute very old lineages. These results can help reconcile several controversial points concerning the affinities of key early Miocene fossils that have arisen among paleontologists and molecular systematists. However, they cannot resolve the controversy of whether these fossil species truly belong to the extant lineages or to a stem platyrrhine clade. That question can only be resolved by morphology. Finally, we show that the use of different approaches and well supported fossil information gives a more robust divergence time estimate of a clade.

Multilocus phylogeny reveals unexpected diversification patterns inAsian wolf snakes (genusLycodon)

The diverse group of Asian wolf snakes of the genusLycodonrepresents one of many poorly understood radiations of advanced snakes in the superfamilyColubroidea. Outside of three species having previously been represented in higher‐level phylogenetic analyses, nothing is known of the relationships among species in this unique, moderately diverse, group. The genus occurs widely from central to Southeast Asia, and contains both widespread species to forms that are endemic to small islands. One‐third of the diversity is found in thePhilippine archipelago. Both morphological similarity and highly variable diagnostic characters have contributed to confusion over species‐level diversity. Additionally, the placement of the genus among genera in the subfamilyColubrinae remains uncertain, although previous studies have supported a close relationship with the genusDinodon. In this study, we provide the first estimate of phylogenetic relationships within the genusLycodonusing a new multi‐locus data set. We provide statistical tests of monophyly based on biogeographic, morphological and taxonomic hypotheses. With few exceptions, we are able to reject many of these hypotheses, indicating a need for taxonomic revisions and a reconsideration of the group's biogeography. Mapping of color patterns on our preferred phylogenetic tree suggests that banded and blotched types have evolved on multiple occasions in the history of the genus, whereas the solid‐color (and possibly speckled) morphotype color patterns evolved only once. Our results reveal that the colubrid genusDinodonis nested withinLycodon—a clear finding that necessitates the placing of the former genus in synonymy with the latter.

The Pipid Root

The estimation of phylogenetic relationships is an essential component of understanding evolution. Accurate phylogenetic estimation is difficult, however, when internodes are short and old, when genealogical discordance is common due to large ancestral effective population sizes or ancestral population structure, and when homoplasy is prevalent. Inference of divergence times is also hampered by unknown and uneven rates of evolution, the incomplete fossil record, uncertainty in relationships between fossil and extant lineages, and uncertainty in the age of fossils. Ideally, these challenges can be overcome by developing large "phylogenomic" data sets and by analyzing them with methods that accommodate features of the evolutionary process, such as genealogical discordance, recurrent substitution, recombination, ancestral population structure, gene flow after speciation among sampled and unsampled taxa, and variation in evolutionary rates. In some phylogenetic problems, it is possible to use information that is independent of fossils, such as the geological record, to identify putative triggers for diversification whose associated estimated divergence times can then be compared a posteriori with estimated relationships and ages of fossils. The history of diversification of pipid frog genera Pipa, Hymenochirus, Silurana, and Xenopus, for instance, is characterized by many of these evolutionary and analytical challenges. These frogs diversified dozens of millions of years ago, they have a relatively rich fossil record, their distributions span continental plates with a well characterized geological record of ancient connectivity, and there is considerable disagreement across studies in estimated evolutionary relationships. We used high throughput sequencing and public databases to generate a large phylogenomic data set with which we estimated evolutionary relationships using multilocus coalescence methods. We collected sequence data from Pipa, Hymenochirus, Silurana, and Xenopus and the outgroup taxon Rhinophrynus dorsalis from coding sequence of 113 autosomal regions, averaging ∼300 bp in length (range: 102-1695 bp) and also a portion of the mitochondrial genome. Analysis of these data using multiple approaches recovers strong support for the ((Xenopus, Silurana)(Pipa, Hymenochirus)) topology, and geologically calibrated divergence time estimates that are consistent with estimated ages and phylogenetic affinities of many fossils. These results provide new insights into the biogeography and chronology of pipid diversification during the breakup of Gondwanaland and illustrate how phylogenomic data may be necessary to tackle tough problems in molecular systematics. [Coalescence; gene tree; high-throughout sequencing; lineage sorting; pipid; species tree; Xenopus.].

Taxonomic Relationships among Turkish Water Frogs as Revealed by Phylogenetic Analyses using mtDNA Gene Sequences

We assessed taxonomic relationships among Turkish water frogs through estimation of phylogenetic relationships among 62 adult specimens from 44 distinct populations inhabiting seven main geographical regions of Turkey using 2897 bp sequences of the mitochondrial Cytb, 12S rRNA and 16S rRNA genes with equally-weighted parsimony, likelihood, and Bayesian methods of inference. Monophyletic clade (Clade A) of the northwesternmost (Thrace) samples is identified as Pelophylax ridibundus. The other clade (Clade B) consisted of two monophyletic subclades. One of these contains specimens from southernmost populations that are regarded as an unnamed species. The other subclade consists of two lineages, of which one corresponds to P. caralitanus and another to P. bedriagae. Taxonomic relationships of these two species are discussed and recognition of P. caralitanus as a subspecies of P. bedriagae is proposed.

A comparison of information-theoretically optimal classifications with estimates of phylogenetic relationships in the squid family Cranchiidae (Cephalopoda: Oegopsida)

Criteria by which some biological classifications may be judged better or worse than others have been debated for centuries, but since 1859 most systematists have striven to create taxonomies that reflect genealogical relationships, and the familiarity of such terms as “monophyletic”, “paraphyletic” and “polyphyletic” reflects a widespread concern about the nature of correspondences between classifications and phylogenies. Some systematists, however, have expressed pessimism about the ability of modern researchers to discover true phylogenies, and question the utility of phylogenetic classifications even were it possible to ascertain their historical accuracy. J. S. L. GILMOUR, an early and articulate critic of evolutionary taxonomy, proposed that biological classifications be comprised exclusively of “. . . natural groups [that] class together individuals which have a large number of attributes in common” (GILMOUR 1940: 466). The utility of natural groups, so defined, is usually equated with the information about characters conveyed by knowledge of group memberships (SOKAL and SNEATH 1963; FARRIS 1979). That classifications should (1) correspond to known or inferred phylogenies and (2) be maximally informative about characters are both intuitively appealing ideal properties, and it is therefore of interest to inquire whether or not they need be viewed irreconciliable as optimality criteria. In this paper we define ways in which classifications can correspond to tree diagrams of evolutionary history, propose quantitative measures of taxonomic information content and examine the relationships between phylogenetic reconstructions and informative classifications of pelagic squids in the family Cranchiidae.

Pollen and the Evolution of Arctotideae (Compositae)

Recent molecular studies have elucidated the phylogeny of Compositae tribe Arctotideae, and found it to contain two, well supported, monophyletic subtribes, Arctotidineae and Gorteriinae, as well as some polyphyletic and problematic genera. On the basis of this new information, it may now be possible to identify diagnostic characters and synapomorphies to support the groupings defined within Arctotideae. Pollen characters have been shown to be particularly variable in Compositae. This paper aims to investigate the utility of those characters in the context of recent molecular phylogenies, in order to determine synapomorphic and diagnostic characters in Arctotideae. The pollen of each genus is described, illustrated with scanning electron micrographs, and optimised on a phylogeny of the tribe. Many pollen characters were found to be very informative when considered in the context of the current best estimate of phylogenetic relationships. Pollen morphology provides synapomorphies for clades at a number of hierarchical levels within Arctotideae, including the two subtribes, Arctotidinae and Gorteriinae, the grouping of Eremothamnus and Hoplophyllum, and smaller clades. It also supports the exclusion of Platycarpha from the tribe. The plesiomorphic palynological state for the tribe is discussed. Particular attention is paid to the evolution of different patterns of lophae (surface ridges). A single origin for the lophate condition is proposed as the most parsimonious mode of evolution in Arctotideae.

Structural Extremes in a Cretaceous Dinosaur

Fossils of the Early Cretaceous dinosaur, Nigersaurus taqueti, document for the first time the cranial anatomy of a rebbachisaurid sauropod. Its extreme adaptations for herbivory at ground-level challenge current hypotheses regarding feeding function and feeding strategy among diplodocoids, the larger clade of sauropods that includes Nigersaurus. We used high resolution computed tomography, stereolithography, and standard molding and casting techniques to reassemble the extremely fragile skull. Computed tomography also allowed us to render the first endocast for a sauropod preserving portions of the olfactory bulbs, cerebrum and inner ear, the latter permitting us to establish habitual head posture. To elucidate evidence of tooth wear and tooth replacement rate, we used photographic-casting techniques and crown thin sections, respectively. To reconstruct its 9-meter postcranial skeleton, we combined and size-adjusted multiple partial skeletons. Finally, we used maximum parsimony algorithms on character data to obtain the best estimate of phylogenetic relationships among diplodocoid sauropods. Nigersaurus taqueti shows extreme adaptations for a dinosaurian herbivore including a skull of extremely light construction, tooth batteries located at the distal end of the jaws, tooth replacement as fast as one per month, an expanded muzzle that faces directly toward the ground, and hollow presacral vertebral centra with more air sac space than bone by volume. A cranial endocast provides the first reasonably complete view of a sauropod brain including its small olfactory bulbs and cerebrum. Skeletal and dental evidence suggests that Nigersaurus was a ground-level herbivore that gathered and sliced relatively soft vegetation, the culmination of a low-browsing feeding strategy first established among diplodocoids during the Jurassic.

Circumscription and phylogeny of Apiaceae subfamily Saniculoideae based on chloroplast DNA sequences

An estimate of phylogenetic relationships within Apiaceae subfamily Saniculoideae was inferred using data from the chloroplast DNA trnQ- trnK 5′-exon region to clarify the circumscription of the subfamily and to assess the monophyly of its constituent genera. Ninety-one accessions representing 14 genera and 82 species of Apiaceae were examined, including the genera Steganotaenia, Polemanniopsis, and Lichtensteinia which have been traditionally treated in subfamily Apioideae but determined in recent studies to be more closely related to or included within subfamily Saniculoideae. The trnQ- trnK 5′-exon region includes two intergenic spacers heretofore underutilized in molecular systematic studies and the rps16 intron. Analyses of these loci permitted an assessment of the relative utility of these noncoding regions (including the use of indel characters) for phylogenetic study at different hierarchical levels. The use of indels in phylogenetic analyses of both combined and partitioned data sets improves resolution of relationships, increases bootstrap support values, and decreases levels of overall homoplasy. Intergeneric relationships derived from maximum parsimony, Bayesian, and maximum likelihood analyses, as well as from maximum parsimony analysis of indel data alone, are fully resolved and consistent with one another and generally very well supported. We confirm the expansion of subfamily Saniculoideae to include Steganotaenia and Polemanniopsis (as the new tribe Steganotaenieae C.I. Calviño and S.R. Downie) but not Lichtensteinia. Sister group to tribe Steganotaenieae is tribe Saniculeae, redefined to include the genera Actinolema, Alepidea, Arctopus, Astrantia, Eryngium, Petagnaea, and Sanicula. With the synonymization of Hacquetia into Sanicula, all genera are monophyletic. Eryngium is divided into “Old World” and “New World” subclades and within Astrantia sections Astrantia and Astrantiella are monophyletic.

Can microsatellite markers resolve phylogenetic relationships between closely related crested newt species (Triturus cristatus superspecies)?

AbstractTheoretical and empirical studies revealed that fast evolving microsatellite markers might be successfully employed in phylogenetic reconstruction. In this study we used seven highly polymorphic microsatellite loci and six different genetic distances to infer the performance of microsatellites in estimation of phylogenetic relationships between closely related crested newt species (Triturus cristatus superspecies). Many intraspecific distances exceeded interspecific values likely due to loss of genetic distance linearity in time, revealing that none of them was able to estimate divergence between the species. The Neighbor-joining trees constructed on the basis of genetic distances showed trichotomies (three-way polychotomies) and low bootstrap support at the species level. This study thus revealed limits of microsatellites to estimate phylogenetic relationships between the crested newt taxa.

Estimation of phylogenetic relationships within the Ascomycota on the basis of 18S rDNA sequences and chemotaxonomy

Small subunit rRNA gene sequences (18S rDNA), cell wall carbohydrate composition and ubiquinone components were analysed within a larger number of ascomycetous yeasts and dimorphic fungi to validate their congruence in predicting phylogenetic relationships. The glucose-mannose pattern distinguishes the Hemiascomycetes from the Euascomycetes and the Protomycetes which are characterised with the glucose-mannose-galactose-rhamnose-(fucose) profile. The glucose-mannose-galactose pattern was found in the cell walls of all the three classes. Different coenzyme Q component (CoQ5 to CoQ10) were found within the representatives of the Hemiascomycetes. Whereas CoQ9, CoQ10 and CoQ10H2 predominate within the Euascomycetes, CoQ9 and CoQ10 characterise the Protomycetes. Chemotaxonomic studies coupled with additional molecular and co-evolution studies support the idea that the Hemiascomycetes occupy a basal position in the phylogeny of Ascomycota. These results are not in line with the phylogenetic studies based on the sequences of 18S rRNA encoding gene. The maximum parsimony analysis indicated that Hemiascomycetes and Protomycetes might represent sister groups, opposing to the earlier reported results, where the Archiascomycetes (Protomycetes) or the Hemiascomycetes had been considered to be the most primitive ascomycetous fungi. Instead of the class Archiascomycetes, the term Protomycetes was introduced reflecting much better the properties of the whole class.

Divergence patterns of banding sequences in different polytene chromosome arms reflect relatively independent evolution of different genome components

Divergence patterns of the banding sequences from the chromosomal arms A, C, D, E, and F were compared in 63 species of the genus Chironomus. Evaluation of the number of breakpoints between the pairs of inverted banding sequences and the analysis of the lengths of the conserved segments in the chromosomal arms in the chironomid species examined showed that different arms evolved relatively independently and at different rates. No direct correlation between the arm length and the breakpoints number was observed. The length of the conservative segment was not fixed, but was arm-specific. Robustness and fidelity of the estimates of phylogenetic relationships between the species examined increased with the arm number, i.e., with the genome proportion included in the analysis.

Testing geographical pathways of speciation in a recent island radiation

Determining the mode, or geographical context, of speciation is a critical first step to understanding the evolutionary mechanisms that cause new species to arise. In this study, we estimated phylogenetic relationships in the cerasina species group of the Hawaiian cricket genus Laupala (Orthoptera: Gryllidae) to test competing phylogeographical hypotheses and thus infer the mode of speciation. A previous phylogenetic result based on nuclear sequence data suggested that populations of L. cerasina on the Big Island of Hawaii are the result of two independent colonizations from Maui, implying parallel speciation and convergent song evolution, and contradicting systematic hypotheses based on behavioural and morphological data. We used amplified fragment length polymorphisms to investigate further the relationships among species and populations in the cerasina species group. Results of these analyses provide a robust estimate of phylogenetic relationships and support the phylogeographical history indicated by behavioural and morphological data.

Time Flies, a New Molecular Time-Scale for Brachyceran Fly Evolution Without a Clock

The insect order Diptera, the true flies, contains one of the four largest Mesozoic insect radiations within its suborder Brachycera. Estimates of phylogenetic relationships and divergence dates among the major brachyceran lineages have been problematic or vague because of a lack of consistent evidence and the rarity of well-preserved fossils. Here, we combine new evidence from nucleotide sequence data, morphological reinterpretations, and fossils to improve estimates of brachyceran evolutionary relationships and ages. The 28S ribosomal DNA (rDNA) gene was sequenced for a broad diversity of taxa, and the data were combined with recently published morphological scorings for a parsimony-based phylogenetic analysis. The phylogenetic topology inferred from the combined 28S rDNA and morphology data set supports brachyceran monophyly and the monophyly of the four major brachyceran infraorders and suggests relationships largely consistent with previous classifications. Weak support was found for a basal brachyceran clade comprising the infraorders Stratiomyomorpha (soldier flies and relatives), Xylophagomorpha (xylophagid flies), and Tabanomorpha (horse flies, snipe flies, and relatives). This topology and similar alternative arrangements were used to obtain Bayesian estimates of divergence times, both with and without the assumption of a constant evolutionary rate. The estimated times were relatively robust to the choice of prior distributions. Divergence times based on the 28S rDNA and several fossil constraints indicate that the Brachycera originated in the late Triassic or earliest Mesozoic and that all major lower brachyceran fly lineages had near contemporaneous origins in the mid-Jurassic prior to the origin of flowering plants (angiosperms). This study provides increased resolution of brachyceran phylogeny, and our revised estimates of fly ages should improve the temporal context of evolutionary inferences and genomic comparisons between fly model organisms.