Utility Of Morphological Characters Research Articles

Monophyly of Verbascum (Scrophularieae : Scrophulariaceae): evidence from nuclear and plastid phylogenetic analyses

Verbascum is one of the main genera of Scrophulariaceae, but delimitation and phylogenetic relationships of this genus are unclear and have not yet been studied using DNA sequences. Here, using four selected molecular markers (nrDNA ITS and the plastid spacers trnS/G, psbA-trnH and trnY/T), we present a phylogeny of Verbascum and test previous infrageneric taxonomic hypotheses as well as its monophyly with respect to Scrophularia. We additionally discuss morphological variation and the utility of morphological characters as predictors of phylogenetic relationships. Our results show that while molecular data unambiguously support the circumscription of Verbascum inferred from morphology, they prove to be of limited utility in resolving infrageneric relationships, suggesting that Verbascum ‘s high species diversity is due to rapid and recent radiation. Our work provides phylogenetic estimation of the genus Verbascum using molecular data and can serve as a starting point for future investigations of Verbascum and relatives.

Distribution of morphological diversity within widespread Australian species of Poa (Poaceae, tribe Poeae) and implications for taxonomy of the genus

Taxonomic uncertainty exists regarding the circumscription of the following seven phenotypically similar Australian species: Poa crassicaudex Vickery, P. hookeri Vickery, P. labillardierei Steud., P. phillipsiana Vickery, P. poiformis (Labill.) Druce, P. porphyroclados Nees (including P. serpentum Nees) and P. sieberiana Spreng. Multivariate ordination and clustering analyses of morphological data were conducted and the distribution of morphological diversity among taxa was assessed for congruence with current taxonomic boundaries. One-way analyses of variance and Tukey’s honest significant difference tests were applied to identify continuous characters that differentiate taxa. Utility of morphological characters was assessed in light of the distribution of variation among and within taxa. Revisions of P. labillardierei, P. porphyroclados and P. sieberiana circumscriptions are proposed. Accounting for nomenclatural priority, proposed revisions include recognition of P. porphyroclados vars. acris, labillardierei, porphyroclados, and. serpentum, P. sieberiana var. cyanophylla Vickery at species rank, and P. phillipsiana at varietal rank within P. sieberiana. Species boundaries are supported by leaf, culm, panicle, spikelet and floret dimensions. The present study enables increased accuracy in taxonomic identifications for Poa species that are keystones in a range of grassland vegetation types, including critically endangered natural temperate grassland and eucalypt woody grassland ecosystems, therefore contributing to the effective biodiversity monitoring and management of these ecosystems.

Phylogeny of the <I>Bouteloua curtipendula</I> Complex (Poaceae: Chloridoideae) Based on Nuclear Ribosomal and Plastid DNA Sequences from Diploid Taxa

The Bouteloua curtipendula complex (Poaceae: Chloridoideae) has been treated as a group of 12 species distributed from Canada to Argentina. Due to considerable morphological variation, putative hybridization, polyploidy (including aneuploidy), and apomixis, circumscription of and relationships among taxa have been uncertain. To infer the phylogeny of this complex, two non-coding regions, the internal transcribed spacer (nrDNA) and trnT-L-F (cpDNA), were sequenced and analyzed by maximum parsimony and maximum likelihood methods. Character-state reconstruction was carried out to test the utility of morphological characters used for species circumscription. Nuclear and plastid data revealed similar phylogenetic patterns, albeit with a lower level of resolution from the trnT-L-F sequences. Results support monophyly of the Bouteloua curtipendula complex, but not the species monophyly, except for B. triaena, which forms a strongly supported clade in both phylogenies. The origin of the Bouteloua curtipendula complex seems to be recent with low divergence between taxa. All of the morphological characters used to circumscribe species were found to be homoplasious.

Phylogenetic relationships in the species–rich Irano–Turanian genus Alcea (Malvaceae)

AbstractThe genus Alcea (Malvaceae) includes approximately 50 species of mainly Irano–Turanian distribution and is considered one of the most challenging genera of the Middle East, due to its uniformity and pronounced plasticity in morphological traits. Here, using three molecular markers (nrDNA ITS and the plastid spacers psbA–trnH and trnL–trnF), we present a phylogeny of Alcea and test previous infrageneric taxonomic hypotheses as well as its monophyly with respect to Althaea, a genus with which it has often been merged. We additionally discuss morphological variation and the utility of morphological characters as predictors of phylogenetic relationships. Our results show that while molecular data unambiguously support the circumscription of Alcea inferred from morphology, they prove to be of limited utility in resolving interspecific relationships, suggesting that Alcea,s high species diversity is due to rapid and recent radiation. Our work provides the first phylogeny of Alcea and aims to set the scene for the study of processes underlying species radiation in the Irano–Turanian region, a main centre of species diversity for many medium–sized to large genera that remains greatly understudied.

The Power and Utility Of Morphological Characters In Systematics: A Fully Resolved Phylogeny of Xenosaurus and Its Fossil Relatives (Squamata: Anguimorpha)

Abstract Xenosaurus is an enigmatic clade of Mexican and Central American lizards distinguished by knob-like scalation and flattening of the head and body associated with living in cracks within cliff faces. The position of Xenosaurus within the larger clade Anguimorpha is difficult to determine owing to a combination of primitive features and a unique, highly modified anatomy that obscures useful characters. Evidently, the phylogenetic stem of Xenosaurus represents a long independent history of evolution. Fortunately, several fossil taxa exist that can elucidate this history. These taxa include the extinct Exostinus lancensis (Cretaceous), Exostinus serratus (Oligocene), and Restes rugosus (Paleocene), the latter two known from substantial, cranial material (Bhullar, 2007; 2010). Using osteological and alcohol-preserved specimens, fossils, and high-resolution x-ray CT scans thereof, I attempted to reconstruct the relationships of the three fossil taxa and the six extant species of Xenosaurus that are ava...

Molecular phylogeny and species recognition in the mealybug genusFerrisiaFullaway (Hemiptera: Pseudococcidae)

Previous allozyme and DNA nucleotide sequence studies of the mealybug genus Ferrisia Fullaway (Hemiptera: Pseudococcidae), although limited, have suggested greater species diversity than is recognized by the current morphology-based taxonomy. Here we analyse nucleotide sequence data from one mitochondrial (cytochrome oxidase I) and two nuclear (EF-1α and 28S D2D3) genes and recover ten well-supported groups that allow us to reassess the taxonomic utility of morphological characters used for species recognition. We report on previously used morphological characters for which states are highly variable within genetic groups and identify new characters (of the wax-exuding cuticular ducts and pores) with taxonomically informative states. The widespread pest species F. virgata (Cockerell), commonly called the striped mealybug, should be diagnosed more narrowly. From samples identified as F. virgata, we recover six clades that we equate with species and that can be distinguished with the newly identified morphological characters. We determine that five of the ‘electrophoretic species' identified informally by the late Uzi Nur based on electrophoretic mobility of 20 enzymes correlate with four of our genetic groups. This matching of Nur's putative species with ours was possible only because some of Nur's slide-mounted voucher specimens were deposited in a museum and thus available for morphological study. Species confused with F. virgata are either new to science or were placed erroneously in synonymy with F. virgata by earlier authors: they will be described elsewhere. The most important characters of the adult female for distinguishing these species from F. virgata are the positions and characteristics of minute discoidal pore(s) associated both with the ventral oral-collar tubular ducts and with the sclerotized area surrounding each dorsal enlarged tubular duct, and the number of sizes of the ventral oral-collar tubular ducts. In addition, we determine that adult females of F. gilli Gullan from different populations on different host plants vary substantially in the number and size of clusters of small ventral oral-collar ducts on the body margins – features previously suspected to indicate distinct species.

The utility of morphological characters in gastropod phylogenetics: an example from the Calyptraeidae

Organismal taxonomy is often based on a single or a small number of morphological characters. When they are morphologically simple or known to be plastic, we may not have great confidence in the taxonomic conclusions of analyses based on these characters. For example, calyptraeid gastropod shells are well known for their simplicity and plasticity, and appear to be subject to frequent evolutionary convergences, but are nevertheless the basis for calyptraeid taxonomy. In a case like this, knowing how the pattern of relationships inferred from morphological features used in traditional taxonomy compares to the patterns of relationships inferred from other morphological characters or DNA sequence data would be useful. In this paper, I examine the relative utility of traditional taxonomic characters (shell characters), anatomical characters and molecular characters for reconstructing the phylogeny of calyptraeid gastropods. The results of an ILD test and comparisons of the recovered tree topologies suggest that there is conflict between the DNA sequence data and the morphological data. Very few of the nodes recovered by the morphological data were recovered by any other dataset. Despite this conflict, the inclusion of morphological data increased the resolution and support of nodes in the topology recovered from a combined dataset. The RIs and CIs of the morphological data on the best estimate topology were not any worse than these indices for the other datasets. This analysis demonstrates that although analyses can be misled by these convergences if morphological characters are used alone, these characters contribute significantly to the combined dataset.

Molecular phylogeny of Coelogyne (Epidendroideae; Orchidaceae) based on plastid RFLPS, matK, and nuclear ribosomal ITS sequences: evidence for polyphyly

To evaluate the monophyly of Coelogyne (Epidendroideae; Orchidaceae) and reveal sectional relationships and relations to allied genera in subtribe Coelogyninae, we collected PCR (polymerase chain reaction) amplified restriction fragment length polymorphisms (RFLPs) from 11 plastid regions for 42 taxa (28 Coelogyne species and 14 representatives of other genera) and three outgroups from Bletiinae and Thuniinae. We also sequenced a large portion of the plastid trnK intron (mostly matK) and the nuclear ribosomal DNA internal transcribed spacers ITS1 and ITS2 (including the 5.8S gene). Separate phylogenetic analyses on each data set using maximum parsimony produced mainly congruent (except for the position of Panisea) but weakly supported clades. Parsimony analysis of the combined data clearly identified three main clades in Coelogyninae. Whereas Coelogyninae are monophyletic, Coelogyne is polyphyletic, with species falling into at least two well-supported clades. The utility of morphological characters used in previous classifications was explored by reconstructing character state evolution on one of the four molecular trees. Lip base and petal shape were homoplasious, whereas ovary indumentum and flower number were congruent with well-supported groups. The implications of our results for the classification of Coelogyne are discussed, and a reorganization of the genus by including Neogyna and Pholidota and removing several species is proposed.