Sökning: "new species"

Visar resultat 11 - 15 av 1349 avhandlingar innehållade orden new species.

  1. 11. Interaction strength and responses of ecological communities to disturbances

    Författare :Maria Christianou; Bo Ebenman; Peter de Ruiter; Linköpings universitet; []
    Nyckelord :Species deletion; secondary extinctions; keystone species; keystone links; species reintroductions; Lotka-Volterra models; local stability; permanence; resilience; sensitivity analysis; diversity; complexity; food webs; competition communities; NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : Ecological communities are continuously exposed to natural or anthropogenic disturbances of varied intensity and frequency. The way communities respond to disturbances can depend on various factors, such as number of species, structural characteristics of the community, stability properties, species characteristics and the nature of the disturbance. LÄS MER

  3. 12. Species extinctions in food webs : local and regional processes

    Författare :Anna Eklöf; Bo Ebenman; Peter Münger; Marcel Holyoak; Linköpings universitet; []
    Nyckelord :Extinction; food web; metacommunity; dispersal; species loss; migration; habitat fragmentation; connectance; NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : Loss of biodiversity is one of the most severe threats to the ecosystems of the world. The major causes behind the high population and species extinction rates are anthropogenic activities such as overharvesting of natural populations, pollution, climate change and destruction and fragmentation of natural habitats. LÄS MER

  4. 13. Gastrotricha of Sweden - Biodiversity and Phylogeny

    Författare :Tobias Kånneby; Ulf Jondelius; M. Antonio Todaro; Sven Boström; Rick Hochberg; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; taxonomy; systematics; phylogeny; new species; cryptic species; Chaetonotidae; Dasydytidae; Thaumastodermatidae; Systematic Zoology; zoologisk systematik och evolutionsforskning; Livets mångfald;

    Sammanfattning : Gastrotricha are small aquatic invertebrates with approximately 770 known species. The group has a cosmopolitan distribution and is currently classified into two orders, Chaetonotida and Macrodasyida. The gastrotrich fauna of Sweden is poorly known: a couple of years ago only 29 species had been reported. LÄS MER

  5. 14. Instrumental and methodological developments for isotope dilution analysis of gaseous mercury species

    Författare :Tom Larsson; Erik Björn; Holger Hintelmann; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mercury; gas; species; speciation analysis; isotope dilution analysis; permeation tubes; Analytical chemistry; Analytisk kemi;

    Sammanfattning : This thesis deals with instrumental and methodological developments for speciation analysis of gaseous mercury (Hg(g)), based on isotope dilution analysis (IDA). The studied species include Hg0, (CH3)2Hg, CH3HgX and HgX2 (where X symbolises a negatively charged counter ion in the form of a halide or hydroxyl ion). LÄS MER

  7. 15. Species Delimitation and Phylogenetic Relationships. A study of Silene sections Atocion and Cryptoneurae

    Författare :Zeynep Aydin; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Caryophyllaceae; Silene; Section Atocion; S. ertekinii; S. cryptoneura; S. aegyptiaca; SystematicsPhylogenetics; Species delimitation; Multispecies coalescent; Marginal likelihood; Species tree; DISSECT.;

    Sammanfattning : Abstract The existence of conflicting genealogies of different genes through the evolution of species complicates the inference of phylogenetic relationships. The Multispecies Coalescent (MSC) model provides a theoretical background that account for the stochasticity in the genealogical process, thus providing systematists with a potentially objective way of testing alternative hypotheses of putative species. LÄS MER