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Robust Phylogeny (robust + phylogeny)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

RECONSTRUCTING PLUMAGE EVOLUTION IN ORIOLES (ICTERUS): REPEATED CONVERGENCE AND REVERSAL IN PATTERNS

EVOLUTION, Issue 6 2000
Kevin E. Omland
Abstract. Several empirical studies suggest that sexually selected characters, including bird plumage, may evolve rapidly and show high levels of convergence and other forms of homoplasy. However, the processes that might generate such convergence have not been explored theoretically. Furthermore, no studies have rigorously addressed this issue using a robust phylogeny and a large number of signal characters. We scored the appearance of 44 adult male plumage characters that varied across New World orioles (Icterus). We mapped the plumage characters onto a molecular phylogeny based on two mitochondrial genes. Reconstructing the evolution of these characters revealed evidence of convergence or reversal in 42 of the 44 plumage characters. No plumage character states are restricted to any groups of species higher than superspecies in the oriole phylogeny. The high frequency of convergence and reversal is reflected in the low overall retention index (RI = 0.66) and the low overall consistency index (CI = 0.28). We found similar results when we mapped plumage changes onto a total evidence tree. Our findings reveal that plumage patterns and colors are highly labile between species of orioles, but highly conserved within the oriole genus. Furthermore, there are at least two overall plumage types that have convergently evolved repeatedly in the three oriole clades. This overall convergence leads to significant conflict between the molecular and plumage data. It is not clear what evolutionary processes lead to this homoplasy in individual characters or convergence in overall pattern. However, evolutionary constraints such as developmental limitations and genetic correlations between characters are likely to play a role. Our results are consistent with the belief that avian plumage and other sexually selected characters may evolve rapidly and may exhibit high homoplasy. The overall convergence in oriole plumage patterns is an interesting evolutionary phenomenon, but it cautions against heavy reliance on plumage characters for constructing phylogenies. [source]

The pre-radial history of echinoderms

GEOLOGICAL JOURNAL, Issue 3 2005
Andrew B. Smith
Abstract Gene sequence data now identify a robust phylogeny of deuterostomes and provide a framework within which the evolution of echinoderms can be interpreted. The topology of the molecular tree makes a number of important predictions about the morphological characters of the earliest echinoderm at its split from hemichordates: it possessed gill slits (but not a notochord), had a bilaterally symmetrical body plan in the adult and, less certainly, underwent torsion during development. Carpoids, a highly contentious group of extinct deuterostomes with a plated calcite skeleton that have variously been interpreted as stem- and crown-group chordates, stem-group echinoderms or stem- and crown-group echinoderms, display many of these basal characters and provide critical evidence for how the latest common ancestor of hemichordates and echinoderms was transformed into a pentaradiate crown-group echinoderm. Cinctans have a large atrial opening in addition to mouth and anus, and are interpreted as pharyngeal basket feeders. The paired grooves associated with the mouth indicate the presence of a hydrovascular system, but not necessarily one built along the echinoderm plan (that is, derived from just the left hydrocoel). Stylophorans have a bilateral body plan that is externally masked by torsion and possess gills, either unpaired and external, or paired and internal, opening into an atrial cavity. Their bilateral appendage is a locomotory organ, not an ambulacrum, and there is no evidence that stylophorans ever possessed a well-developed hydrovascular system homologous to the water vascular system of echinoderms and the tentacles of pterobranch hemichordates. Solutes are the most crownward, having a true echinodermal ambulacral system with a single hydropore and no pharyngeal gill openings. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Large subunit rDNA and rbcL gene sequence data place Petrohua bernabei gen. et sp. nov. in the Batrachospermales (Rhodophyta), but do not provide further resolution among taxa in this order

PHYCOLOGICAL RESEARCH, Issue 2 2007
Morgan L. Vis
SUMMARY The phylogenetic relationship among 12 previously described batrachospermalean taxa and a novel member of the order were investigated using the LSU and rbcL genes separately and in combination. The primary goal of this research was to establish the phylogenetic placement of a previously undescribed freshwater red alga from Chile. The results showed that the new entity with pseudoparenchymatous tube morphology is a member of the Batrachospermales and Petrohua bernabei gen. et sp. nov. is described herein. This is the first record to our knowledge of a Lemanea -like alga from Chile. It would appear that this thallus construction has evolved at least three times in the Batrachospermales and that the switch from a Batrachospermum -like construction to a pseudoparenchymatous construction may be a repeated adaptive response to turbulent waterfall habitats. In addition to providing information about a new freshwater red alga, this study sought to determine whether combining the data from two genes would produce a more robust phylogeny, particularly for intermediate nodes, to resolve familial relationships within the order. As with previous analyses, the Batrachospermales was resolved as a clade and support was high for relationships resolved among relatively recent nodes. Unfortunately, combining the LSU and rbcL data did not have the desired effect of more fully resolving intermediate nodes among the Batrachospermales. [source]

A comprehensive phylogeny of the bumble bees (Bombus)

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2007
S. A. CAMERON
Bumble bees (Bombus Latreille) occupy a wide diversity of habitats, from alpine meadows to lowland tropical forest, yet they appear to be similar in morphology throughout their range, suggesting that behavioural adaptations play a more important role in colonizing diverse habitats. Notwithstanding their structural homogeneity, bumble bees exhibit striking inter- and intraspecific variation in colour pattern, purportedly the outcome of mimetic evolution. A robust phylogeny of Bombus would provide the framework for elucidating the history of their wide biogeographical distribution and the evolution of behavioural and morphological adaptations, including colour pattern. However, morphological studies of bumble bees have discovered too few phylogenetically informative characters to reconstruct a robust phylogeny. Using DNA sequence data, we report the first nearly complete species phylogeny of bumble bees, including most of the 250 known species from the 38 currently recognized subgenera. Bayesian analysis of nuclear (opsin, EF-1,, arginine kinase, PEPCK) and mitochondrial (16S) sequences results in a highly resolved and strongly supported phylogeny from base to tips, with clear-cut support for monophyly of most of the conventional morphology-based subgenera. Most subgenera fall into two distinct clades (short-faced and long-faced) associated broadly with differences in head morphology. Within the short-faced clade is a diverse New World clade, which includes nearly one-quarter of the currently recognized subgenera, many of which are restricted to higher elevations of Central and South America. The comprehensive phylogeny provides a firm foundation for reclassification and for evaluating character evolution in the bumble bees. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 161,188. [source]