Home About us Contact
|
Home About us Contact | ||
|
|
||
One Clade (one + clade)
Selected AbstractsPhylogenetic relationships within the tropical soft coral genera Sarcophyton and Lobophytum (Anthozoa, Octocorallia)INVERTEBRATE BIOLOGY, Issue 4 2006Catherine S. McFadden Abstract. The alcyonacean soft coral genera Sarcophyton and Lobophytum are conspicuous, ecologically important members of shallow reef communities throughout the Indo-West Pacific. Study of their ecology is, however, hindered by incomplete knowledge of their taxonomy: most species cannot be identified in the field and the two genera cannot always be distinguished reliably. We used a 735-bp fragment of the octocoral-specific mitochondrial protein-coding gene msh1 to construct a phylogeny for 92 specimens identified to 19 species of Lobophytum and 16 species of Sarcophyton. All phylogenetic methods used recovered a tree with three strongly supported clades. One clade included only morphologically typical Sarcophyton species with a stalk distinct from the polypary, poorly formed club-shaped sclerites in the colony surface, and large spindles in the interior of the stalk. A second clade included only morphologically typical Lobophytum colonies with lobes and ridges on the colony surface, poorly formed clubs in the colony surface, and interior sclerites consisting of oval forms with regular girdles of ornamental warts. The third distinct clade included a mix of Sarcophyton and Lobophytum nominal species with intermediate morphologies. Most of the species in this mixed clade had a polypary that was not distinct from the stalk, and the sclerites in the colony surface were clubs with well-defined heads. Within the Sarcophyton clade, specimens identified as Sarcophyton glaucum belonged to six very distinct genetic sub-clades, suggesting that this morphologically heterogeneous species is actually a cryptic species complex. Our results highlight the need for a complete taxonomic revision of these genera, using molecular data to help confirm species boundaries as well as to guide higher taxonomic decisions. [source] When Thailand was an island , the phylogeny and biogeography of mite harvestmen (Opiliones, Cyphophthalmi, Stylocellidae) in Southeast AsiaJOURNAL OF BIOGEOGRAPHY, Issue 6 2010Ronald M. Clouse Abstract Aim, To develop a comprehensive explanation for the biological diversity of Southeast Asia, especially in the Wallacea and Sundaland regions. This study focuses on a group of arachnids, mite harvestmen, which are thought to be an extremely old group of endemic animals that have been present in the region since most of its land supposedly formed part of the northern rim of the supercontinent Gondwana. Location, Eastern Himalayas, Thai-Malay Peninsula, Sumatra, Borneo, Java, Sulawesi, and New Guinea. Methods Approximately 5.6 kb of sequence data were obtained from 110 South-east Asian Cyphophthalmi specimens. Phylogenetic analyses were conducted under a variety of methods and analytical parameters, and the optimal tree was dated using calibration points derived from fossil data. Event based and paralogy-free subtree biogeographical analyses were conducted. Results, The Southeast Asian family Stylocellidae was recovered as monophyletic, arising on what is now the Thai-Malay Peninsula and diversifying into three main clades. One clade (Meghalaya, here formally placed in Stylocellidae) expanded north as far as the eastern Himalayas, a second clade entered Borneo and later expanded back across the Sundaland Peninsula to Sumatra, and a third clade expanded out of Borneo into the entire lower part of Sundaland. Molecular dating suggested that Stylocellidae separated from other Cyphophthalmi 295 Ma and began diversifying 258 Ma, and the lineage that inhabits mostly Borneo today began diversifying between 175 and 150 Ma. Main conclusions, The topology and molecular dating of our phylogenetic hypothesis suggest that Stylocellidae originated on Gondwana, arrived in Southeast Asia via the Cimmerian palaeocontinent, and subsequently diversified north, then south. Their present distribution in the Indo-Malay Archipelago is explained largely by a diversification over the Sundaland Peninsula before western Sulawesi departed and the peninsula was extensively inundated. [source] On the evolution and morphology of the rotiferan trophi, with a cladistic analysis of RotiferaJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 3 2002M. V. SØrensen Abstract The phylogeny of Rotifera was examined in different computer-generated cladistic analyses, including Seisonidea, Bdelloidea, Flosculariacea, Collothecacea and all ploimids treated on family level. The analyses were based on a character matrix solely dealing with morphological characters, primarily based on the trophi morphology. Limnognathia maerski (Micrognathozoa), Rastrognathia macrostoma and Gnathostomula paradoxa (Gnathostomulida) were used as outgroups. The cladistic analysis performed by paup produced 288 most parsimonious trees. peewee analyses produced between 140 and 432 trees, depending on the concavity value. The monophyly of Eurotatoria, Monogononta and Ploima was confirmed in all obtained trees. All analyses suggested a division of Ploima into major clades. One clade corresponded to Transversiramida while the other contained all other ploimid taxa and recognized Antrorsiramida as a monophylum. Based on the obtained results a scenario for the trophi evolution is proposed. The analyses suggested that the presence of an incus is synapomorphic for Gnathifera while mallei are synapomorphic for Micrognathozoa and Rotifera. The ancestral rotifer trophi probably resembled those in Harringia (Asplanchnidae). Zusammenfassung Die Phylogenie der Rotatorien wurde mit verschiedenen kladistischen Computeranalysen, unter Einbezug der Seisonidea, Bdelloidea, Flosculariacea, Collothecacea und aller Taxa von Ploima auf Familienebene, untersucht. Die Analyse basierte auf einer Mekmalsmatrix, die nur morphologische Merkmale, vorwiegend aus der Morphologie der Kiefer, enthielt. Limnognathia maerski (Micrognathozoa), Rastrognathia macrostoma und Gnathostomula paradoxa (Gnathostomulida) wurden als Außengruppe benutzt. Die mit paup durchgeführte Analyse ergab 288 ,,sparsamste'' Kladogramme. PeeWee Analysen produzierten in Abhängigkeit vom Konkavitäts-Wert 140 bzw. 432 Bäume. Die Monophylie der Eurotatoria, Monogononta und Ploima wurde in allen Kladogrammen bestätigt. Alle Analysen schlugen auch eine Teilung von Ploima in zwei große Kladen vor. Eine der Kladen entspricht den Transversiramida, die andere enthält alle anderen Ploima-Taxa und weist Antrorsiramida als Monophylum aus. Gestützt auf die gefundenen Ergebnisse wird ein Szenarium für die Evolution der Kiefer vorgeschlagen. Die Analysen lassen vermuten, daß der Besitz eines Incus eine Synapomorphie der Gnathifera ist, während der eines Malleus eine Synapomorphie der Mikrognathozoa und derRotifera darstellt. Die ursprünglichen Kiefer waren vermutlich dem von Harringia (Asplanchnidae) ähnlich. [source] A molecular assessment of the iron stress response in the two phylogenetic clades of TrichodesmiumENVIRONMENTAL MICROBIOLOGY, Issue 1 2010P. Dreux Chappell Summary Trichodesmium spp. play key roles in global carbon and nitrogen budgets and thus defining what controls their productivity is important for understanding climate change. While iron availability has been shown to be an important chemical factor for controlling both growth and nitrogen fixation rates in Trichodesmium, all culture experiments to date have focused solely on representatives from one clade of Trichodesmium. Genomic sequence analysis determined that the Trichodesmium erythraeum (IMS101) genome contains many of the archetypical genes involved in the prokaryotic iron stress response. Focusing on three of these genes, isiB, idiA and feoB, we found that all three showed an iron stress response in axenic T. erythraeum (IMS101), and their sequences were well conserved across four species in our Trichodesmium culture collection [consisting of two T. erythraeum strains (IMS101 and GBRTRLI101), two Trichodesmium tenue strains (Z-1 and H9-4), Trichodesmium thiebautii and Trichodesmium spiralis]. With clade-specific quantitative PCR (qPCR) primers for one of these genes, isiB, we found that high isiB expression at low Fe levels corresponded to specific reductions in N2 fixation rates in both major phylogenetic clades of Trichodesmium (the T. erythraeum clade and T. tenue clade). With regard to the two clades, the most significant difference determined was temperature optima, while more subtle differences in growth, N2 fixation rate and gene expression responses to Fe stress were also observed. However the apparent conservation of the Fe stress response in the Trichodesmium genus suggests that it is an important adaptation for their niche in the oligotrophic ocean. [source] THE GEOGRAPHICAL PATTERN OF SPECIATION AND FLORAL DIVERSIFICATION IN THE NEOTROPICS: THE TRIBE SINNINGIEAE (GESNERIACEAE) AS A CASE STUDYEVOLUTION, Issue 7 2007Mathieu Perret The geographical pattern of speciation and the relationship between floral variation and species ranges were investigated in the tribe Sinningieae (Gesneriaceae), which is found mainly in the Atlantic forests of Brazil. Geographical distribution data recorded on a grid system of 0.5 × 0.5 degree intervals and a near-complete species-level phylogenetic tree of Sinningieae inferred from a simultaneous analysis of seven DNA regions were used to address the role of geographical isolation in speciation. Geographical range overlaps between sister lineages were measured across all nodes in the phylogenetic tree and analyzed in relation to relative ages estimated from branch lengths. Although there are several cases of species sympatry in Sinningieae, patterns of sympatry between sister taxa support the predominance of allopatric speciation. The pattern of sympatry between sister taxa is consistent with range shifts following allopatric speciation, except in one clade, in which the overlapping distribution of recent sister species indicates speciation within a restricted geographical area and involving changes in pollinators and habitats. The relationship between floral divergence and regional sympatry was also examined by analyzing floral contrasts, phenological overlap, and the degree of sympatry between sister clades. Morphological contrast between flowers is not increased in sympatry and phenological divergence is more apparent between allopatric clades than between sympatric clades. Therefore, our results failed to indicate a tendency for sympatric taxa to minimize morphological and phenological overlap (geographic exclusion and/or character displacement hypotheses). Instead, they point toward adaptation in phenology to local conditions and buildup of sympatries at random with respect to flower morphology. Additional studies at a lower geographical scale are needed to identify truely coexisting species and the components of their reproductive isolation. [source] SOCIALITY IN THERIDIID SPIDERS: REPEATED ORIGINS OF AN EVOLUTIONARY DEAD ENDEVOLUTION, Issue 11 2006Ingi Agnarsson Abstract Evolutionary ,dead ends' result from traits that are selectively advantageous in the short term but ultimately result in lowered diversification rates of lineages. In spiders, 23 species scattered across eight families share a social system in which individuals live in colonies and cooperate in nest maintenance, prey capture, and brood care. Most of these species are inbred and have highly female-biased sex ratios. Here we show that in Theridiidae this social system originated eight to nine times independently among 11 to 12 species for a remarkable 18 to 19 origins across spiders. In Theridiidae, the origins cluster significantly in one clade marked by a possible preadaptation: extended maternal care. In most derivations, sociality is limited to isolated species: social species are sister to social species only thrice. To examine whether sociality in spiders represents an evolutionary dead end, we develop a test that compares the observed phylogenetic isolation of social species to the simulated evolution of social and non-social clades under equal diversification rates, and find that sociality in Theridiidae is significantly isolated. Because social clades are not in general smaller than their nonsocial sister clades, the spindly phylogenetic pattern,many tiny replicate social clades,may be explained by extinction rapid enough that a nonsocial sister group does not have time to diversify while the social lineage remains extant. In this case, this repeated origin and extinction of sociality suggests a conflict between the short-term benefits and long-term costs of inbred sociality. Although benefits of group living may initially outweigh costs of inbreeding (hence the replicate origins), in the long run the subdivision of the populations in relatively small and highly inbred colony lineages may result in higher extinction, thus an evolutionary dead end. [source] Australian biogeographical connections and the phylogeny of large genera in the plant family MyrtaceaeJOURNAL OF BIOGEOGRAPHY, Issue 7 2003Pauline Y. Ladiges Abstract Aim To compare the phylogeny of the eucalypt and melaleuca groups with geological events and ages of fossils to discover the time frame of clade divergences. Location Australia, New Caledonia, New Guinea, Indonesian Archipelago. Methods We compare published molecular phylogenies of the eucalypt and melaleuca groups of the plant family Myrtaceae with geological history and known fossil records from the Cretaceous and Cenozoic. Results The Australasian eucalypt group includes seven genera, of which some are relictual rain forest taxa of restricted distribution and others are species-rich and widespread in drier environments. Based on molecular and morphological data, phylogenetic analyses of the eucalypt group have identified two major clades. The monotypic Arillastrum endemic to New Caledonia is related in one clade to the more species-rich Angophora, Corymbia and Eucalyptus that dominate the sclerophyll vegetation of Australia. Based on the time of rifting of New Caledonia from eastern Gondwana and the age of fossil eucalypt pollen, we argue that this clade extends back to the Late Cretaceous. The second clade includes three relictual rain forest taxa, with Allosyncarpia from Arnhem Land the sister taxon to Eucalyptopsis of New Guinea and the eastern Indonesian archipelago, and Stockwellia from the Atherton Tableland in north-east Queensland. As monsoonal, drier conditions evolved in northern Australia, Arnhem Land was isolated from the wet tropics to the east and north during the Oligocene, segregating ancestral rain forest biota. It is argued also that the distribution of species in Eucalyptopsis and Eucalyptus subgenus Symphyomyrtus endemic in areas north of the stable edge of the Australian continent, as far as Sulawesi and the southern Philippines, is related to the geological history of south-east Asia-Australasia. Colonization (dispersal) may have been aided by rafting on micro-continental fragments, by accretion of arc terranes onto New Guinea and by land brought into closer proximity during periods of low sea-level, from the Late Miocene and Pliocene. The phylogenetic position of the few northern, non-Australian species of Eucalyptus subgenus Symphyomyrtus suggests rapid radiation in the large Australian sister group(s) during this time frame. A similar pattern, connecting Australia and New Caledonia, is emerging from phylogenetic analysis of the Melaleuca group (Beaufortia suballiance) within Myrtaceae, with Melaleuca being polyphyletic. Main conclusion The eucalypt group is an old lineage extending back to the Late Cretaceous. Differentiation of clades is related to major geological and climatic events, including rifting of New Caledonia from eastern Gondwana, development of monsoonal and drier climates, collision of the northern edge of the Australian craton with island arcs and periods of low sea level. Vicariance events involve dispersal of biota. [source] GENETIC VARIATION OF KOGIA SPP.MARINE MAMMAL SCIENCE, Issue 4 2005WITH PRELIMINARY EVIDENCE FOR TWO SPECIES OF KOGIA SIMA Abstract Concordance between mitochondrial DNA (mtDNA) markers and morphologically based species identifications was examined for the two currently recognized Kogia species. We sequenced 406 base pairs of the control region and 398 base pairs of the cytochrome b gene from 108 Kogia breviceps and 47 K. sima samples. As expecred, the two sister species were reciprocally monophyletic to each other in phylogenetic reconstructions, but within K. sima, we unexpectedly observed another reciprocally monophyletic relationship. The two K. sima clades resolved were phylogeographically concordant with all of the haplotypes in one clade observed solely among specimens sampled from the Atlantic Ocean and with those in the other clade observed solely among specimens sampled from the Indo-Pacific Ocean. These apparently allopatric clades were observed in all phylogenetic reconstructions using the maximum parsimony, maximum likelihood, and neighborjoining algorithms, with the mtDNA gene sequences analyzed separately and combined. The nucleotide diversity for the combined gene sequence haplotypes of the two K. sima clades resolved in our analyses was 0.58% and 1.03% for the Atlantic and Indo-Pacific, respectively, whereas for the two recognized sister species, nucleotide diversity was 1.65% and 4.02% for K. breviceps and K. sima, respectively. The combined gene sequence haplotypes have accumulated 44 fixed base pair differences between the two K. sima clades compared to 20 fixed base pair differences between the two recognized sister species. Although our results are consistent with species-level differences between the two K. sima clades, recognition of a third Kogia species awaits supporting evidence that these two apparently allopatric clades represent reproductively isolated groups of animals. [source] Geological history and within-island diversity: a debris avalanche and the Tenerife lizard Gallotia gallotiMOLECULAR ECOLOGY, Issue 12 2006RICHARD P. BROWN Abstract Several processes have been described that could explain geographical variation and speciation within small islands, including fragmentation of populations through volcanic eruptions. Massive landslides, or debris avalanches, could cause similar effects. Here we analyse the potential impact of the 0.8 million-year-ago (Ma) Güimar valley debris avalanche on the phylogeography of the lizard Gallotia galloti on the Canary Island of Tenerife. Distributions of mitochondrial DNA lineages (based on cytochrome b sequences) were analysed on a 60-km southeastern coast transect centred on this area. Three main clades were detected, which can be divided into northern (one clade) and southern (two clades) groups that introgress across the valley. Maximum-likelihood estimates of migration rates (scaled for mutation rate) revealed highly asymmetric patterns, indicating that long-term gene flow into this region from both the northern and the southern populations greatly exceeded that in the opposite directions, consistent with recolonization of the area. The ancestral Tenerife node on the G. galloti tree is estimated at 0.80 Ma, matching closely with the geological estimate for the debris avalanche. Morphological variation (body dimensions and scalation) was also analysed and indicated a stepped cline in female scalation across the valley, although the patterns for male scalation and male and female body dimensions were not as clear. Together these findings provide support for the hypothesis that the debris avalanche has shaped the phylogeography of G. galloti and may even have been a primary cause of the within-island cladogenesis through population fragmentation and isolation. Current estimates of timing of island unification mean that the original hypothesis that within-island diversity is explained by the secondary contact of populations from the two ancient precursor islands of Teno and Anaga is less plausible for this and some other Tenerife species. Large-scale landslides have occurred on many volcanic islands, and so may have been instrumental in shaping within-island diversities. [source] Phylogeography and morphological variability in land snails: the Sicilian Marmorana (Pulmonata, Helicidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2008VIVIANA FIORENTINO Land snails have long been recognized as suitable organisms for studying phenotypic differentiation and phylogeny in relation to geographical distribution. Morphological data (shell and anatomy biometry on different geographical scales) and partial sequences from mitochondrial genes (cytochrome oxidase subunit I, 16S rDNA) were used to test whether morphological patterns match phylogeny in a diversified group of Sicilian rock-dwelling land snails belonging to the genus Marmorana. The taxonomic implications of the three character sets (shell and anatomical biometry and molecular data) were also considered. The inferred phylogenetic relationships do not match morphological (shell and genitalia) patterns. This result may significantly modify the current taxonomy. Mitochondrial based reconstructions define several supported clades well correlated with geographic distribution and populations were found to be distributed parapatrically. The progressive decline in mitochondrial DNA sequence similarity over a distance of 250 km is consistent with a model of isolation by distance, a pattern previously recognized for other groups of land snails. For one clade of Marmorana, colonization along Mediterranean trade routes appears to be a possibility. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 809,823. [source] Phylogenetic relationships of the genera of Theaceae based on morphologyCLADISTICS, Issue 3 2004Isolda Luna This work represents the first phylogenetic analysis of all genera belonging to the plant family Theaceae (sensu lato). The study is based on 60 morphological characters derived from herbarium specimens and an extensive literature review of 37 genera (including the outgroup). In contrast to the results from molecular data, Theaceae is here found to consist of one clade in which the recognition of two families or subfamilies would leave Theaceae s.s. paraphyletic. Within that clade, Ternstroemiaceae is supported as monophyletic and includes Adinandra, Anneslea, Archboldiodendron, Balthasaria, Cleyera, Eurya, Euryodendron, Ficalhoa, Freziera, Symplococarpon, Ternstroemia and Visnea. The paraphyletic Theaceae s.s. includes Apterosperma, Camellia, Dankia, Gordonia, Pyrenaria, Schima, and Stewartia. Tetrameristaceae (Pentamerista and Tetramerista) are supported as a monophyletic family, with Pellicieraceae (Pelliciera) as sister group, and that clade is sister to the rest of the taxa. Bonnetiaceae (Archytaea and Bonnetia) and Kielmeyeroideae of the Clusiaceae (Caraipa, Haploclathra, Kielmeyera, Mahurea, Marila, and Neotatea) are also supported as monophyletic. Given the differences between the results obtained from morphological and molecular data, we consider that there is still a need for further research, including combined analyses. [source] | ||||||||||||||||||||||