The Melithaeidae (Cnidaria: Octocorallia) of the Ryukyu Archipelago: molecular and morphological examinations

The family Melithaeidae (Octocorallia: Alcyonacea) is distributed in the West Pacific, Indian Ocean and the Red Sea. They are most abundant in warmer waters but can also be found in temperate waters. At present six genera are assigned to this family (Melithaea, Mopsella, Clathraria, Acabaria, Wrightella and Asperaxis), however overlapping characteristics make this group's taxonomic identification difficult and their relationships unclear. There are only a few reports from the Ryukyu Archipelago in southern Japan of melithaeids and most other octocorals, despite the islands being an area of high octocoral diversity. To help resolve the taxonomic confusion in this family, samples from various Ryukyu Archipelago locations were collected and DNA sequences of nuclear 28S ribosomal DNA and mitochondrial cytochrome oxidase I (COI) were obtained. Additionally, SEM micrographs of the sclerites of specimens were taken to further confirm the molecular results. Three strongly supported clades were recovered from the COI and 28S rDNA analyses, corresponding to Melithaea, Acabaria, and Mopsella, and in most cases clades were clearly related with the sclerite shape reported for each genus. These results show clearly that molecular differences are present between the three genera, and also demonstrates the strong need of other molecular markers for resolving intra-generic phylogenies. Our results provide baseline data for future studies of this octocoral family, not only on taxonomy, but also with regards to their distribution in the Ryukyu Islands.     

Elevated feeding rates of fishes within octocoral canopies on Caribbean reefs

Increasing abundance of arborescent octocorals (often referred to as gorgonians) on Caribbean reefs raises the question of whether habitat structure provided by octocorals can mediate a transition between coral- and algal- dominated states by increasing fish abundance and herbivory. This study tested the hypotheses that feeding rates and densities of demersal reef fishes are affected by the habitat structure provided by dense octocoral communities. Surveys of fishes on coral reefs in St John, US Virgin Islands, found 1.7-fold higher densities, and 2.4-fold higher feeding rates within versus outside of dense octocoral canopies. This difference, however, was only seen at sites with octocoral densities > 8 colonies m⁻². Furthemore, the proximity of octocoral colonies to fish had an effect on the grazing rate of key herbivores (surgeonfishes and parrotfishes), with a 53% higher feeding rate (1.90 ± 0.11 bites min⁻¹ m⁻²) near octocorals (< 20 or 30 cm, depending on the site) versus farther from them (1.24 ± 0.09 bites min⁻¹ m⁻²). Finally, within the canopy of dense octocoral communities (17 colonies m⁻²), reef fishes fed at a rate that was 2.2-fold higher within the community than at the edge of the community that faced an adjacent sand patch. Fish abundance, however, was not uniformly higher within versus at the edge of the octocoral community, as ecotone specialists such as gobiids, blennioids, ostraciids, holocentrids, labrids, and pomacentrids were 1.3—2.3 times more abundant at the edge. In contrast, other taxa of demersal fishes, notably herbivores, were twice as abundant within octocoral communities than at the edges. Together, these results reveal an association between habitat structure created by octocorals on shallow reefs and increased feeding rates of demersal fishes (including those of herbivores). The potential of octocorals to increase herbivory that could mediate stony coral recovery is therefore worthy of further study.

     

Octocoral Tissue Provides Protection from Declining Oceanic pH

Increase in anthropogenic pCO₂ alters seawater chemistry and could lead to reduced calcification or skeleton dissolution of calcifiers and thereby weaken coral-reef structure. Studies have suggested that the complex and diverse responses in stony coral growth and calcification, as a result of elevated pCO₂, can be explained by the extent to which their soft tissues cover the underlying skeleton. This study compared the effects of decreased pH on the microstructural features of both in hospite (within the colony) and isolated sclerites (in the absence of tissue protection) of the zooxanthellate reef-dwelling octocoral Ovabunda macrospiculata. Colonies and isolated sclerites were maintained under normal (8.2) and reduced (7.6 and 7.3) pH conditions for up to 42 days. Both in hospite and isolated sclerites were then examined under SEM and ESEM microscopy in order to detect any microstructural changes. No differences were found in the microstructure of the in hospite sclerites between the control and the pH treatments. In stark contrast, the isolated sclerites revealed dissolution damage related to the acidity of the water. These findings suggest a protective role of the octocoral tissue against adverse pH conditions, thus maintaining them unharmed at high pCO₂. In light of the competition for space with the less resilient reef calcifiers, octocorals may thus have a significant advantage under greater than normal acidic conditions.     

Phylogenetic analyses among octocorals (Cnidaria): mitochondrial and nuclear DNA sequences (lsu-rRNA, 16S and ssu-rRNA, 18S) support two convergent clades of branching gorgonians

Gorgonian octocorals lack corroborated hypotheses of phylogeny. This study reconstructs genealogical relationships among some octocoral species based on published DNA sequences from the large ribosomal subunit of the mitochondrial RNA (lsu-rRNA, 16S: 524bp and 21 species) and the small subunit of the nuclear RNA (ssu-rRNA, 18S: 1815bp and 13 spp) using information from insertions-deletions (INDELS) and the predicted secondary structure of the lsu-rRNA (16S). There were seven short (3-10bp) INDELS in the 18S with consistent phylogenetic information. The INDELS in the 16S corresponded to informative signature sequences homologous to the G13 helix found in Escherichia coli. We found two main groups of gorgonian octocorals using a maximum parsimony analysis of the two genes. One group corresponds to deep-water taxa including species from the suborders Calcaxonia and Scleraxonia characterized by an enlargement of the G13 helix. The second group has species from Alcyoniina, Holaxonia and again Scleraxonia characterized by insertions in the 18S. Gorgonian corals, branching colonies with a gorgonin-containing flexible multilayered axis (Holaxonia and Calcaxonia), do not form a monophyletic group. These corroborated results from maternally inherited (16S) and biparentally inherited (18S) genes support a hypothesis of independent evolution of branching in the two octocoral clades.     

Molecular phylogenetic evidence supports a new family of octocorals and a new genus of Alcyoniidae (Octocorallia,Alcyonacea)

Molecular phylogenetic evidence indicates that the octocoral family Alcyoniidae is highly polyphyletic, with genera distributed across Octocorallia in more than 10 separate clades. Most alcyoniid taxa belong to the large and poorly resolved Holaxonia–Alcyoniina clade of octocorals, but members of at least four genera of Alcyoniidae fall outside of that group. As a first step towards revision of the family, we describe a new genus, Parasphaerasclera gen. n., and family, Parasphaerascleridae fam. n., of Alcyonacea to accommodate species of Eleutherobia Pütter, 1900 and Alcyonium Linnaeus, 1758 that have digitiform to digitate or lobate growth forms, completely lack sclerites in the polyps, and have radiates or spheroidal sclerites in the colony surface and interior. Parasphaerascleridae fam. n. constitutes a well-supported clade that is phylogenetically distinct from all other octocoral taxa. We also describe a new genus of Alcyoniidae, Sphaerasclera gen. n., for a species of Eleutherobia with a unique capitate growth form. Sphaerasclera gen. n. is a member of the Anthomastus–Corallium clade of octocorals, but is morphologically and genetically distinct from Anthomastus Verrill, 1878 and Paraminabea Williams & Alderslade, 1999, two similar but dimorphic genera of Alcyoniidae that are its sister taxa. In addition, we have re-assigned two species of Eleutherobia that have clavate to capitate growth forms, polyp sclerites arranged to form a collaret and points, and spindles in the colony interior to Alcyonium, a move that is supported by both morphological and molecular phylogenetic evidence.     

Diversity of algal endosymbionts (zooxanthellae) in octocorals: the roles of geography and host relationships

The presence, genetic identity and diversity of algal endosymbionts (Symbiodinium) in 114 species from 69 genera (20 families) of octocorals from the Great Barrier Reef (GBR), the far eastern Pacific (EP) and the Caribbean was examined, and patterns of the octocoral-algal symbiosis were compared with patterns in the host phylogeny. Genetic analyses of the zooxanthellae were based on ribosomal DNA internal transcribed spacer 1 (ITS1) region. In the GBR samples, Symbiodinium clades A and G were encountered with A and G being rare. Clade B zooxanthellae have been previously reported from a GBR octocoral, but are also rare in octocorals from this region. Symbiodinium G has so far only been found in Foraminifera, but is rare in these organisms. In the Caribbean samples, only Symbiodinium clades B and C are present. Hence, Symbiodinium diversity at the level of phylogenetic clades is lower in octocorals from the Caribbean compared to those from the GBR. However, an unprecedented level of ITS1 diversity was observed within individual colonies of some Caribbean gorgonians, implying either that these simultaneously harbour multiple strains of clade B zooxanthellae, or that ITS1 heterogeneity exists within the genomes of some zooxanthellae. Intracladal diversity based on ITS should therefore be interpreted with caution, especially in cases where no independent evidence exists to support distinctiveness, such as ecological distribution or physiological characteristics. All samples from EP are azooxanthellate. Three unrelated GBR taxa that are described in the literature as azooxanthellate (Junceella fragilis, Euplexaura nuttingi and Stereonephthya sp. 1) contain clade G zooxanthellae, and their symbiotic association with zooxanthellae was confirmed by histology. These corals are pale in colour, whereas related azooxanthellate species are brightly coloured. The evolutionary loss or gain of zooxanthellae may have altered the light sensitivity of the host tissues, requiring the animals to adopt or reduce pigmentation. Finally, we superimposed patterns of the octocoral-algal symbiosis onto a molecular phylogeny of the host. The data show that many losses/gains of endosymbiosis have occurred during the evolution of octocorals. The ancestral state (azooxanthellate or zooxanthellate) in octocorals remains unclear, but the data suggest that on an evolutionary timescale octocorals can switch more easily between mixotrophy and heterotrophy compared to scleractinian corals, which coincides with a low reliance on photosynthetic carbon gain in the former group of organisms.     

A new gorgonian genus from deep-sea Antarctic waters (Octocorallia, Alcyonacea, Plexauridae)

Mesogligorgia scotiae gen. nov., sp. nov. is described and illustrated from a colony collected in the Scotia Sea, 2,201–2,213 m in depth, on the ANDEEP-I cruise. The new taxon is placed in the family Plexauridae because of: 1) the presence of a horny axis with a cross-chambered central core and numerous loculi, 2) retractile polyps in calyces with distinct spicular components, and 3) armed polyps with large sclerites with a poorly- developed collaret and eight well-developed points. The irregularly distributed sclerites running along the axis, into a thick mesogloeal coenenchyme, and the elongated spindles with irregular ends are the most distinctive characters of the newly proposed genus.     

Functional analysis of internal transcribed spacer 2 of Saccharomyces cerevisiae ribosomal DNA.

Using the previously described "tagged ribosome" (pORCS) system for in vivo mutational analysis of yeast rDNA, we show that small deletions in the 5'-terminal portion of ITS2 completely block maturation of 26 S rRNA at the level of the 29 SB precursor (5.8 S rRNA-ITS2-26 S rRNA). Various deletions in the 3'-terminal part, although severely reducing the efficiency of processing, still allow some mature 26 S rRNA to be formed. On the other hand, none of the ITS2 deletions affect the production of mature 17 S rRNA. Since all of the deletions severely disturb the recently proposed secondary structure of ITS2, these findings suggest an important role for higher order structure of ITS2 in processing. Analysis of the effect of complete or partial replacement of S. cerevisiae ITS2 with its counterpart sequences from Saccharomyces rosei or Hansenula wingei, points to helix V of the secondary structure model as an important element for correct and efficient processing. Direct mutational analysis shows that disruption of base-pairing in the middle of helix V does not detectably affect 26 S rRNA formation. In contrast, introduction of clustered point mutations at the apical end of helix V that both disrupt base-pairing and change the sequence of the loop, severely reduces processing. Since a mutant containing only point mutations in the sequence of the loop produces normal amounts of mature 26 S rRNA, we conclude that the precise (secondary and/or primary) structure at the lower end of helix V, but excluding the loop, is of crucial importance for efficient removal of ITS2.     

The genetic identity of dinoflagellate symbionts in Caribbean octocorals

Many cnidarians (e.g., corals, octocorals, sea anemones) maintain a symbiosis with dinoflagellates (zooxanthellae). Zooxanthellae are grouped into clades, with studies focusing on scleractinian corals. We characterized zooxanthellae in 35 species of Caribbean octocorals. Most Caribbean octocoral species (88.6%) hosted clade B zooxanthellae, 8.6% hosted clade C, and one species (2.9%) hosted clades B and C. Erythropodium caribaeorum harbored clade C and a unique RFLP pattern, which, when sequenced, fell within clade C. Five octocoral species displayed no zooxanthella cladal variation with depth. Nine of the ten octocoral species sampled throughout the Caribbean exhibited no regional zooxanthella cladal differences. The exception, Briareum asbestinum, had some colonies from the Dry Tortugas exhibiting the E. caribaeorum RFLP pattern while elsewhere hosting clade B. In the Caribbean, octocorals show more symbiont specificity at the cladal level than scleractinian corals. Both octocorals and scleractinian corals, however, exhibited taxonomic affinity between zooxanthella clade and host suborder.Communicated by R.C. Carpenter     

Mitogenomic phylogenetic analyses of Leptogorgia virgulata and Leptogorgia hebes (Anthozoa: Octocorallia) from the Gulf of Mexico provides insight on Gorgoniidae divergence between Pacific and Atlantic lineages

The use of genetics in recent years has brought to light the need to reevaluate the classification of many gorgonian octocorals. This study focuses on two Leptogorgia species—Leptogorgia virgulata and Leptogorgia hebes—from the northwestern Gulf of Mexico (GOM). We target complete mitochondrial genomes and mtMutS sequences, and integrate this data with previous genetic research of gorgonian corals to resolve phylogenetic relationships and estimate divergence times. This study contributes the first complete mitochondrial genomes for L. ptogorgia virgulata and L. hebes. Our resulting phylogenies stress the need to redefine the taxonomy of the genus Leptogorgia in its entirety. The fossil‐calibrated divergence times for Eastern Pacific and Western Atlantic Leptogorgia species based on complete mitochondrial genomes shows that the use of multiple genes results in estimates of more recent speciation events than previous research based on single genes. These more recent divergence times are in agreement with geologic data pertaining to the formation of the Isthmus of Panama.     

Structural investigations of octocoral sclerites

A common structural pattern (as observed under the SEM) in the main body of sectioned sclerites of the family Alcyoniidae, and octocorals in general, is the arrangement of acicular crystals in concentric layers. The crystals roughly follow the direction of the spicule axis, however, the sectioned tubercles of large Sinularia spicules have the acicular crystals oriented in the direction of the tubercles (i.e. perpendicular to the spicule axis), contrary to the sectioned tubercles of Sarcophyton and Lobophytum spicules. They reveal some rod-like structures, furcating the acute processes at the top of the tubercles. Sectioned small, club-like Sinularia sclerites show numerous tiny acicular crystals, oriented with their long axes at a fairly constant degree of inclination around a central axis. SEM studies of sectioned Cladiella sclerites show a granulate structure organized in concentric layers, but lacking acicular crystals. The Silurian Atractosella cataractaca show important characters in common with Recent alcyoniid species.     

Identification of European diplozoids (Monogenea, Diplozoinae) by restriction digestion of the ribosomal RNA internal transcribed spacer

The second internal transcribed spacer (ITS2) of the ribosomal RNA genes of Diplozoon paradoxum and Paradiplozoon nagibinae were amplified and sequenced. The polymerase chain reaction product of D. paradoxum was bigger (840 bp) than that of P. nagibinae (820 bp). There was no intraspecific variability recorded in sequences from either species. Sequence comparisons and ITS2 restriction fragment length polymorphism (RFLP) pattern of 8 European diplozoid species aimed to resolve their identification and amend the previous studies. RFLP was used to distinguish the 2 species from each other and from P. bliccae, P. homoion, P. megan, P. pavlovskii, P. sapae, and Eudiplozoon nipponicum, using restriction enzymes AluI, HaeIII, HinfI, RsaI, and SphI. The criteria for morphological identification of 8 European diplozoids are also included, with the main morphological characters of clamps, trapeze spur, and anterior joining sclerites of 8 diplozoid species being illustrated. Combination of the shape and comparison of length of the trapeze spur and anterior joining sclerites could lead to accurate identification of diplozoid species.     

Global habitat suitability of cold‐water octocorals

Aim Three‐quarters of Octocorallia species are found in deep waters. These cold‐water octocoral colonies can form a major constituent of structurally complex habitats. The global distribution and the habitat requirements of deep‐sea octocorals are poorly understood given the expense and difficulties of sampling at depth. Habitat suitability models are useful tools to extrapolate distributions and provide an understanding of ecological requirements. Here, we present global habitat suitability models and distribution maps for seven suborders of Octocorallia: Alcyoniina, Calcaxonia, Holaxonia, Scleraxonia, Sessiliflorae, Stolonifera and Subselliflorae. Location Global. Methods We use maximum entropy modelling to predict octocoral distribution using a database of 12,508 geolocated octocoral specimens and 32 environmental grids resampled to 30 arc‐second (approximately 1 km²) resolution. Additionally, a meta‐analysis determined habitat preferences and niche overlap between the different suborders of octocorals. Results Suborder Sessiliflorae had the widest potential habitat range, but all records for all suborders implied a habitat preference for continental shelves and margins, particularly the North and West Atlantic and Western Pacific Rim. Temperature, salinity, broad scale slope, productivity, oxygen and calcite saturation state were identified as important factors for determining habitat suitability. Less than 3% of octocoral records were found in waters undersaturated for calcite, but this result is affected by a shallow‐water sampling bias. Main conclusions The logistical difficulties, expense and vast areas associated with deep‐sea sampling leads to a gap in the knowledge of faunal distributions that is difficult to fill without predictive modelling. Global distribution estimates are presented, highlighting many suitable areas which have yet to be studied. We suggest that approximately 17% of oceans are suitable for at least one suborder but 3.5% may be suitable for all seven. This is the first global habitat suitability modelling study on the distribution of octocorals and forms a useful resource for researchers, managers and conservationists.     

Environmental filtering and neutral processes shape octocoral community assembly in the deep sea

The ecological and evolutionary processes that interact to shape community structure are poorly studied in the largest environment on earth, the deep sea. Phylogenetic data and morphological traits of octocorals were coupled with environmental factors to test hypotheses of community assembly in the deep (250–2500 m) Gulf of Mexico. We found lineage turnover at a depth of 800–1200 m, with isidids and chrysogorgiids at deeper depths and a diversity of species from across the phylogeny occupying shallower depths. Traits, including axis type, polyp shape, and polyp retraction, differed among species occupying the shallowest (250–800 m) and deepest (1200–2500 m) depths. Results also indicated that octocoral species sort along an environmental gradient of depth. Closely related octocoral species sorted into different depth strata on the upper to middle slope, likely due to barriers imposed by water masses followed by adaptive divergence. Within any given depth zone down to 2000 m, the phylogenetic relatedness of co-existing octocorals was random, indicating that stochastic processes, such as recruitment, also shape community structure. At depths >2000 m, octocorals were more closely related than expected by chance due to the diversification of chrysogorgiids and isidids, which retain conserved traits that impart survival at deeper and/or colder depths. Polyp density, size, and inter-polyp distance were significantly correlated with depth, particularly in plexaurids and isidids, highlighting trait lability across depth and supporting that environmental gradients influence octocoral morphology. Our community phylogenetics approach indicates that both environmental filtering and neutral processes shape community assembly in the deep sea.     

Higher species richness of octocorals in the upper mesophotic zone in Eilat (Gulf of Aqaba) compared to shallower reef zones

Mesophotic coral-reef ecosystems (MCEs), which comprise the light-dependent communities of corals and other organisms found at depths between 30 and ~ 150 m, have received very little study to date. However, current technological advances, such as remotely operated vehicles and closed-circuit rebreather diving, now enable their thorough investigation. Following the reef-building stony corals, octocorals are the second most common benthic component on many shallow reefs and a major component on deep reefs, the Red Sea included. This study is the first to examine octocoral community features on upper MCEs based on species-level identification and to compare them with the shallower reef zones. The study was carried out at Eilat (Gulf of Aqaba, northern Red Sea), comparing octocoral communities at two mesophotic reefs (30–45 m) and two shallow reef zones (reef flat and upper fore-reef) by belt transects. A total of 30 octocoral species were identified, with higher species richness on the upper MCEs compared to the shallower reefs. Although the MCEs were found to host a higher number of species than the shallower reefs, both featured a similar diversity. Each reef zone revealed a unique octocoral species composition and distinct community structure, with only 16% of the species shared by both the MCEs and the shallower reefs. This study has revealed an almost exclusive dominance of zooxanthellate species at the studied upper MCE reefs, thus indicating an adequate light regime for photosynthesis there. The findings should encourage similar studies on other reefs, aimed at understanding the spatiotemporal features and ecological role of octocorals in reef ecosystems down to the deepest limit of the MCEs.     

3D chemoecology and chemotaxonomy of corals using fatty acid biomarkers: Latitude,longitude and depth

With the objective of uncovering differences in the fatty acid (FA) composition of hexa- and octocorals from different climatic zones (equatorial, subtropical and tropical) and distinct habitats (e.g. rock and coral reefs; intertidal to deep-sea environments), the FA composition of 36 hexa- and octocoral species (132 specimens) was analysed (including the first characterization of organisms from the order Zoantharia and deep-sea gorgonians). PCA was applied in a FA matrix of the ten major PUFAs to detect differences among coral groups. Fatty acid profile analysis confirmed that C24 polyunsaturated FAs are suitable chemotaxonomic biomarkers to separate hexa- and octocorals. The polyunsaturated FA 22:6n-3 was identified as a useful biomarker to distinguish between zoantharians and scleractinians. Also, we discuss the role of food availability (type of phytoplankton assemblage) in relation to autotrophic carbon significance and in the establishment of FA profiles of octocorals from the West and East coasts of the Atlantic Ocean. Furthermore, we show that the occurrence of high levels of primary productivity hinder the use of FA profiles to distinguish between zooxanthellate and azooxanthellate octocorals. Finally, we present and discuss the particular traits of the FA profile of deep-sea gorgonians while comparing it with that of shallow species.     

The ITS region of groundwater amphipods: length,secondary structure and phylogenetic information content in Crangonyctoids and Niphargids

The phylogenetic analysis of groundwater amphipods is challenging due to the lack of suitable morphological characters. However, molecular phylogenies based on the 18S and 28S nuclear genes of two Crangonyctoidea species endemic to Iceland, Crymostygius thingvallensis and Crangonyx islandicus, support the taxonomy of these species on the basis of morphological characters. Molecular analyses suggest that the genus Crangonyx is paraphyletic, with the species that is found in Eurasia being highly divergent genetically from the species present in North America and Iceland. Studies of the phylogenetic relationships within the genus Niphargus also warrant further work. The nuclear ITS2 region has recently been proposed as a barcoding marker for plants and animals. In addition, ITS2 has been used to build phylogenies at high taxonomic levels by including its secondary structure. In this study, we want to evaluate the applicability of the ITS region for this group of species and describe its characteristics. The taxonomy of C. thingvallensis, as well as the paraphyly of the genus Crangonyx, is supported herein by phylogenies based on the ITS2 variation. The secondary structure and the length of the ITS2 sequences of the Crangonyctoidea and the Niphargidae species studied are highly variable and are characterized by duplications. The ITS2 sequence of Niphargus plateaui is the longest metazoan sequence deposited in the ITS2 database so far. Although saturation was observed in the nucleotide variation of this marker, the addition of the secondary structure information for the reconstruction of the phylogeny did not add support to the phylogenetic trees. The ITS1 region, which is known to be more variable than ITS2 and bears a large duplication within C. islandicus, was found to be less useful for phylogenetic reconstruction.     

Molecular phylogeny of the Pooideae (Poaceae) based on nuclear rDNA (ITS) sequences

Phylogenetic relationships of the Poaceae subfamily, Pooideae, were estimated from the sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA. The entire ITS region of 25 species belonging to 19 genera representing seven tribes was directly sequenced from polymerase chain reaction (PCR)-amplified DNA fragments. The published sequence of rice, Oryza saliva, was used as the outgroup. Sequences of these taxa were analyzed with maximum parsimony (PAUP) and the neighbor-joining distance method (NJ). Among the tribes, the Stipeae, Meliceae and Brachypodieae, all with small chromosomes and a basic number more than x=7, diverged in succession. The Poeae, Aveneae, Bromeae and Triticeae, with large chromosomes and a basic number of x=7, form a monophyletic clade. The Poeae and Aveneae are the sister group of the Bromeae and Triticeae. On the ITS tree, the Brachypodieae is distantly related to the Triticeae and Bromeae, which differs from the phylogenies based on restriction-site variation of cpDNA and morphological characters. The phylogenetic relationships of the seven pooid tribes inferred from the ITS sequences are highly concordant with the cytogenetic evidence that the reduction in chromosome number and the increase in chromosome size evolved only once in the pooids and pre-dated the divergence of the Poeae, Aveneae, Bromeae and Triticeae.This paper reports factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitableThis paper is a cooperative investigation of USDA-ARS and the Utah Agricultural Experiment Station. Logan, Utah 84322. Journal Paper No. 4581