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Faunal Groups (faunal + groups)
Selected AbstractsExisting in plenty: abundance, biomass and diversity of ciliates and meiofauna in small streamsFRESHWATER BIOLOGY, Issue 4 2008JULIA REISS Summary 1. The ciliate and metazoan meiofaunal assemblages of two contrasting lowland streams in south-east England were examined over the period of a year, using a high taxonomic resolution. Monthly samples were taken from an oligotrophic, acid stream (Lone Oak) and a circumneutral, nutrient-rich stream (Pant) between March 2003 and February 2004. 2. We assessed the relative importance of ciliates and rotifers within the small-sized benthic assemblage with respect to their abundance, biomass and species richness. In addition, we examined the influence of abiotic and biotic parameters and season on the assemblage composition at two levels of taxonomic resolution (species and groups). 3. Ciliates dominated the assemblages numerically, with maximum densities of over 900 000 and 6 000 000 ind. m,2 in Lone Oak and Pant respectively. Rotifers and nematodes dominated meiofaunal densities, although their contribution to total meiofaunal biomass (maxima of 71.9 mgC m,2 in Lone Oak and of 646.8 mgC m,2 in the Pant) was low and rotifer biomass equalled that of ciliates. 4. Although the two streams differed in terms of total abundance of ciliates and meiofauna and shared only 7% of species, the relative proportion of groups was similar. Sediment grain size distribution (the percentile representing the 0.5,1 mm fraction) was correlated with assemblage structure at the species level, revealing the tight coupling between these small organisms and their physical environment. Seasonal changes in the relative abundance of groups followed similar patterns in both streams, and were correlated with the abundance of cyclopoid copepods and temperature. 5. Information on these highly abundant but often overlooked faunal groups is essential for estimates of overall abundance, biomass, species richness and productivity in the benthos, and as such has important implications for several areas of aquatic research, e.g. for those dealing with trophic dynamics. [source] Diversity patterns amongst herbivorous dinosaurs and plants during the Cretaceous: implications for hypotheses of dinosaur/angiosperm co-evolutionJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2009R. J. BUTLER Abstract Palaeobiologists frequently attempt to identify examples of co-evolutionary interactions over extended geological timescales. These hypotheses are often intuitively appealing, as co-evolution is so prevalent in extant ecosystems, and are easy to formulate; however, they are much more difficult to test than their modern analogues. Among the more intriguing deep time co-evolutionary scenarios are those that relate changes in Cretaceous dinosaur faunas to the primary radiation of flowering plants. Demonstration of temporal congruence between the diversifications of co-evolving groups is necessary to establish whether co-evolution could have occurred in such cases, but is insufficient to prove whether it actually did take place. Diversity patterns do, however, provide a means for falsifying such hypotheses. We have compiled a new database of Cretaceous dinosaur and plant distributions from information in the primary literature. This is used as the basis for plotting taxonomic diversity and occurrence curves for herbivorous dinosaurs (Sauropodomorpha, Stegosauria, Ankylosauria, Ornithopoda, Ceratopsia, Pachycephalosauria and herbivorous theropods) and major groups of plants (angiosperms, Bennettitales, cycads, cycadophytes, conifers, Filicales and Ginkgoales) that co-occur in dinosaur-bearing formations. Pairwise statistical comparisons were made between various floral and faunal groups to test for any significant similarities in the shapes of their diversity curves through time. We show that, with one possible exception, diversity patterns for major groups of herbivorous dinosaurs are not positively correlated with angiosperm diversity. In other words, at the level of major clades, there is no support for any diffuse co-evolutionary relationship between herbivorous dinosaurs and flowering plants. The diversification of Late Cretaceous pachycephalosaurs (excluding the problematic taxon Stenopelix) shows a positive correlation, but this might be spuriously related to poor sampling in the Turonian,Santonian interval. Stegosauria shows a significant negative correlation with flowering plants and a significant positive correlation with the nonflowering cycadophytes (cycads, Bennettitales). This interesting pattern is worthy of further investigation, and it reflects the decline of both stegosaurs and cycadophytes during the Early Cretaceous. [source] On the genetic diversity in the mitochondrial 12S rRNA gene of Platymantis frogs from Western New Guinea (Anura: Ceratobatrachidae)JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 2 2008F. Köhler Abstract Platymantis is a group of neobatrachian frogs that occurs from the Philippines to New Guinea , an area situated at the interface between the Australian and Asian biogeographical region that is highly fragmented by stretches of open sea. Partial sequences of the mitochondrial 12S rRNA gene are herein used to infer the relationships of species from the Indonesian part of New Guinea (Papua and West Papua Province). The phylogenetic trees reveal a deep bifurcation between the Asian and Western New Guinean clades being consistent with phylogeographic patterns observed in various other faunal groups. While most species are well differentiated in the examined locus, low interspecific genetic distances between one and three percent were observed in the New Guinean species Platymantis papuensis and P. cryptotis as well as P. pelewensis from Palau. Platymantis papuensis and P. pelewensis are geographically separated from each other by a 1100 km stretch of open sea. The minor degree of genetic differentiation between both species points to a recent event of transmarine dispersal as causation for the occurrence of P. pelewensis on Palau. The low genetic differentiation between P. cryptotis and the sympatric P. papuensis, two species that are bioacoustically and morphologically distinct, may indicate its possibly recent evolutionary origin or, alternatively, yet undetected hybridization between the two species. The same may also hold true for frogs from Yapen that exhibit calls different from the sympatric P. papuensis. Tentatively referred to as Platymantis spec., these frogs are also genetically not well differentiated. It is furthermore concluded that the partly low genetic differentiation of the New Guinean Platymantis species render this group one of the cases in which DNA barcoding would likely fail to produce reliable results. Zusammenfassung Arten der Gattung Platymantis besiedeln ein Gebiet, das sich von den Philippinen bis nach Papua-Neuguinea erstreckt. Dieses stark fragmentierte Areal befindet sich an der Nahtstelle zwischen der australischen und asaitischen biogeographischen Region. Wir analysiereten Sequenzfragmente des mitochondrialen Gens der 12S rRNA, um die phylogenetische Verwandtschaft dieser Frösche aus dem indonesischen Teil von Neuguinea zu erhellen (Provinzen Papua und West-Papua). Die phylogenetischen Bäume zeigen übereinstimmend eine tiefe Zweigliederung zwischen den Linien auf den Philippinen und Neuguinea. Obwohl die meisten Arten in bezug auf den untersuchten Marker gut voneinander zu differenzieren sind, werden zwischen einigen nur niedrige genetische Distanzen von 1,3% beobachtet. Im Falle von P. papuensis und P. pelewensis, die durch etwa 1100 km offenen Ozean voneinander getrennt sind, wird die geringe Differenzierung als Hinweis dafür gedeutet, dass beide erst seit relativ kurzer Zeit voneinander getrennt sind. Im Falle der beiden sympatrisch vorkommend Arten P. cryptotis und P. papuensis (letztere charakterisiert durch bioakustische und morphometrische Merkmale) deutet die geringe genetische Differenzierung entweder darauf hin, dass es sich um relativ junge Arten handelt oder dass beide miteinander hybridisieren. Gleiches gilt für die von P. papuensis bioakustisch differenzierbaren Fr,sche von P. spec. [source] Habitat heterogeneity and its influence on benthic biodiversity in oxygen minimum zonesMARINE ECOLOGY, Issue 1 2010Andrew J. Gooday Abstract Oxygen minimum zones (OMZs; midwater regions with O2 concentrations <0.5 ml l,1) are mid-water features that intercept continental margins at bathyal depths (100,1000 m). They are particularly well developed in the Eastern Pacific Ocean, the Arabian Sea and the Bay of Bengal. Based on analyses of data from these regions, we consider (i) how benthic habitat heterogeneity is manifested within OMZs, (ii) which aspects of this heterogeneity exert the greatest influence on alpha and beta diversity within particular OMZs and (iii) how heterogeneity associated with OMZs influences regional (gamma) diversity on continental margins. Sources of sea-floor habitat heterogeneity within OMZs include bottom-water oxygen and sulphide gradients, substratum characteristics, bacterial mats, and variations in the organic matter content of the sediment and pH. On some margins, hard grounds, formed of phosphorites, carbonates or biotic substrata, represent distinct subhabitats colonized by encrusting faunas. Most of the heterogeneity associated with OMZs, however, is created by strong sea-floor oxygen gradients, reinforced by changes in sediment characteristics and organic matter content. For the Pakistan margin, combining these parameters revealed clear environmental and faunal differences between the OMZ core and the upper and lower boundary regions. In all Pacific and Arabian Sea OMZs examined, oxygen appears to be the master driver of alpha and beta diversity in all benthic faunal groups for which data exist, as well as macrofaunal assemblage composition, particularly in the OMZ core. However, other factors, notably organic matter quantity and quality and sediment characteristics, come into play as oxygen concentrations begin to rise. The influence of OMZs on meiofaunal, macrofaunal and megafaunal regional (gamma) diversity is difficult to assess. Hypoxia is associated with a reduction in species richness in all benthic faunal groups, but there is also evidence for endemism in OMZ settings. We conclude that, on balance, OMZs probably enhance regional diversity, particularly in taxa such as Foraminifera, which are more tolerant of hypoxia than others. Over evolutionary timescales, they may promote speciation by creating strong gradients in selective pressures and barriers to gene flow. [source] The importance of bare marine sedimentary habitats for maintaining high polychaete diversity and the implications for the design of marine protected areasAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2009Christopher R. S. Barrio Froján Abstract 1.Bare intertidal sedimentary habitats have received relatively little attention compared with their neighbouring vegetated habitats. An ecological comparison of benthic faunal assemblages inhabiting tropical intertidal seagrass beds and bare sediments has been made to assess the faunal similarity between the two habitats in south-east Asia. 2.The poorly developed taxonomy of most invertebrate taxa in the region precluded the full identification of many faunal groups. Only the polychaetes , which accounted for 76% of all the macrofaunal organisms collected , were identified to the lowest possible taxonomic level, yielding 177 nominal species belonging to 35 families. Ecological analyses suggested that although each habitat had a distinct polychaete assemblage, there were few differences between habitats based on a range of calculated assemblage diversity metrics. 3.Further analyses were applied to the data to test the performance of three strategies for optimizing the selection of sites for inclusion in potential marine protected areas. Strategies were based either on the total number of species, the number of rare or endemic species, or on the level of species richness (used as a surrogate for community structure). 4.All three strategies consistently captured above average numbers of species at most levels of conservation intensity. The merits of each strategy are considered in turn. Copyright © 2009 John Wiley & Sons, Ltd. [source] Phyllostomid Bat Community Structure and Abundance in Two Contrasting Tropical Dry Forests,BIOTROPICA, Issue 4 2005Kathryn E. Stoner ABSTRACT Although tropical wet forests are generally more diverse than dry forests for many faunal groups, few studies have compared bat diversity among dry forests. I compared ground level phyllostomid bat community structure between two tropical dry forests with different precipitation regimes. Parque National Palo Verde in northwestern Costa Rica represents one of the wettest tropical dry forests (rainfall 1.5 m/yr), whereas the Chamela-Cuixmala Biosphere Reserve on the Pacific coast of central Mexico represents one of the driest (750 mm/yr). Mist net sampling was conducted at the two study sites to compare changes in ground level phyllostomid bat community structure between regions and seasons. Palo Verde was more diverse than Chamela and phyllostomid species showed low similarity between sites (Classic Jaccard = 0.263). The distinct phyllostomid communities observed at these two dry forest sites demonstrates that variants of tropical dry forest can be sufficiently different in structure and composition to affect phyllostomid communities. At both dry forest sites, abundance of the two most common foraging guilds (frugivores and nectarivores) differed between seasons, with greatest numbers of individuals captured coinciding with highest chiropterophilic resource abundance. RESUMEN A pesar de que los bosques tropicales húmedos, en general, son más diversos que los bosques tropicales secos para muchos grupos de fauna, pocos estudios han comparado la diversidad de murciélogos en los bosques tropicales secos. El presente estudio compara la estructura de la comunidad de los murciélagos filostómidos a nivel del suelo entre dos tipos de bosque tropical seco con diferentes regimenes de precipitación. El parque Nacional Palo Verde esta localizado en el Noroeste de Costa Rica y representa uno de los bosques tropicales secos mas húmedos (con una precipitación de 1.5 m/año), mientras que la Reserva de la Biosfera Chamela-Cuixmala esta localizada en la costa oeste del pacífico de México y representa uno de los bosques más secos (750 mm/año). Se realizó un muestreo con redes de niebla en los dos sitios para comparar los cambios en la estructura de la comunidad de murciélagos filostómidos a nivel de suelo. Palo Verde fue más diverso que Chamela y se encontró la simultud de las especies filostomidos entre los dos sitio fue bajo (Classic Jaccard = 0.263). Las comunidades distintas de filostomidos observado en estos dos sitios de bosque seco demuestra que las variantes en el bosque tropical seco pueden ser suficientemente diferentes en estructura y composición para poder afectar la comunidad de filostomidos. En ambos bosques secos la abundancia de lo dos gremios tróficos más comunes (frugívoros y nectarívoros) fue diferente en las estaciones, con un mayor número de individuos capturados coincidiendo con una mayor abundancia de recursos quiropterofílicos. [source] | ||||||||||