Search results for "phylogenetic"
showing 10 items of 1179 documents
New Algorithms for Computing Phylogenetic Biodiversity
2014
A common problem that appears in many case studies in ecology is the following: given a rooted phylogenetic tree \(\mathcal{T}\) and a subset R of its leaf nodes, we want to compute the distance between the elements in R. A very popular distance measure that can be used for this reason is the Phylogenetic Diversity (PD), which is defined as the cost of the minimum weight Steiner tree in \(\mathcal{T}\) that spans the nodes in R. To analyse the value of the PD for a given set R it is important also to calculate the variance of this measure. However, the best algorithm known so far for computing the variance of the PD is inefficient; for any input tree \(\mathcal{T}\) that consists of n nodes…
Polyphasic taxonomy of a novel yeast isolated from antarctic environment; description of Cryptococcus victoriae sp. nov.
1999
In 1992 some samples of mosses, lichens and soils were collected from Botany Bay, Southern Victoria Land (77 degrees 01' S 162 degrees 32' E) and, as a result of a routine screening programme some yeasts were isolated. One of them, designated as strain G5, showed marked differences when compared to other antarctic yeasts. According to morphological and physiological characteristics, we were able to identify the strain G5 as a yeast belonging to the genus Cryptococcus. Some characteristics of this genus are the growth response to myo-inositol, celobiose, raffinose and D-glucuronate, no-fermentation, the absence of mycelium and pseudomycelium, asexual reproduction, Diazolium blue B test (DBB)…
New findings of Setaria tundra and Setaria cervi in the red deer (Cervus elaphus) in Poland
2019
AbstractOur study aimed at examining the phylogenetic position of the newly-found Setaria nematodes obtained from the red deer (Cervus elaphus) based on sequences of the mitochondrial cytochrome c oxidase subunit 1 (COX-1). Alignment and phylogenetic analyses, as well as SEM microscopic analysis, revealed the presence of two Setaria species: S. cervi and S. tundra. Setaria tundra was noted in only one individual, a calf of the red deer, while S. cervi was observed in three stages, two hinds and one calf of the red deer. According to our knowledge, it is the first case of S. cervi in the red deer in Poland confirmed in molecular studies and also the first case of S. tundra infection in the r…
Chloroplast DNA evidence for introgression and long distance dispersal in the desert annualSenecio flavus (Asteraceae)
1995
Phylogenetic analysis of chloroplast DNA (cpDNA) restriction site variation supports a close genetic relationship between the Southwest AsianSenecio flavus subsp.breviflorus and the North AmericanS. mohavensis. The intercontinental disjunct distribution of these two desert annuals may have originated via long distance dispersal. The chloroplast genomes of the Southern and North AfricanS. flavus subsp.flavus and subsp.breviflorus differ by at least ten restriction sites, while at most two restriction sites differentiate the cpDNA genomes of subsp.breviflorus and the outgroupS. squalidus. This suggests that the cpDNA genome ofS. flavus subsp.breviflorus may have resulted from introgression an…
Molecular phylogeny of the freshwater sponges in Lake Baikal
2003
The phylogenetic relationship of the freshwater sponges (Porifera) in Lake Baikal is not well understood. A polyphyletic and/or monophyletic origin have been proposed. The (endemic) Baikalian sponges have been subdivided into two families: endemic Lubomirskiidae and cosmopolitan Spongillidae. In the present study, two new approaches have been made to resolve the phylogenetic relationship of Baikalian sponges; analysis of (1) nucleotide sequences from one mitochondrial gene, the cytochrome oxidase subunit I (COI) and of (2) one selected intron from the tubulin gene. Specimens from the following endemic Baikalian sponge species have been studied; Lubomirskia baicalensis, Baikalospongia interm…
Is mate fidelity related to site fidelity? A comparative analysis in Ciconiiforms
2000
We tested for an association between divorce rate and site fidelity in 42 avian species belonging to the order Ciconiiforms, using comparative methods that account for the influences of phylogenetic relationships on the data. Our methods enabled us to detect evidence of correlated evolution and provided information on the temporal ordering of evolutionary changes in these two variables. We found a significant correlation between divorce rate and site fidelity, indicating that species with little or no site fidelity are more likely to divorce. Our data suggest that the coupled evolution of divorce and site fidelity can be summarized by three major events. The first event corresponds to a tra…
ECOLOGICAL LIMITS ON DIVERSIFICATION OF THE HIMALAYAN CORE CORVOIDEA
2012
Within regions, differences in the number of species among clades must be explained by clade age, net diversification rate, or immigration. We examine these alternatives by assessing historical causes of the low diversity of a bird parvorder in the Himalayas (the core Corvoidea, 57 species present), relative to its more species rich sister clade (the Passerida, ∼400 species present), which together comprise the oscine passerines within this region. The core Corvoidea contain ecologically diverse species spanning a large range of body sizes and elevations. Despite this diversity, on the basis of ecological, morphological, and phylogenetic information, we infer that the best explanation for t…
Ancient recruitment by chromists of green algal genes encoding enzymes for carotenoid biosynthesis.
2008
Chromist algae (stramenopiles, cryptophytes, and haptophytes) are major contributors to marine primary productivity. These eukaryotes acquired their plastid via secondary endosymbiosis, whereby an early-diverging red alga was engulfed by a protist and the plastid was retained and its associated nuclear-encoded genes were transferred to the host genome. Current data suggest, however, that chromists are paraphyletic; therefore, it remains unclear whether their plastids trace back to a single secondary endosymbiosis or, alternatively, this organelle has resulted from multiple independent events in the different chromist lineages. Both scenarios, however, predict that plastid-targeted, nucleus-…
Disentangling composite colour patterns in a poison frog species
2008
A phylogenetic approach was performed to infer whether variation in conspicuous colour-patterns of a poison frog (Dendrobatidae: Dendrobates tinctorius) has evolved neutrally or under selection. Colour and pattern were split into components that were separately analysed and subsequently re-grouped via principal component analysis. This revealed four different ‘displayed’ factors on the dorsal and lateral views versus one ‘concealed’ factor on the ventral view. Based on the assumption that current patterns of trait variation contain information about the evolutionary history of the phenotype, we correlated these trait components to a neutrally evolving gene fragment (cytochrome b). The conce…
Range size: Disentangling Current Traits and Phylogenetic and Biogeographic Factors
2006
The range size of a species can be determined by its current traits and by phylogenetic and biogeographic factors. However, only rarely have these factors been studied in combination. We use data on the geographic range sizes of all 26 Sylvia warblers to explicitly test whether range size was determined by current species-specific traits (e.g., body size, dispersal ability), phylogenetic factors (e.g., age of the lineage), or environmental, biogeographic factors (e.g., latitudinal position of the range). The results demonstrated that current traits and phylogenetic and biogeographic factors were interrelated. While a number of factors were significant in simple regression analyses, only one…