Sökning: "reinforcement in biology"

Visar resultat 1 - 5 av 10 avhandlingar innehållade orden reinforcement in biology.

  1. 1. Reinforcement in Biology : Stochastic models of group formation and network construction

    Författare :Qi Ma; David Sumpter; Edward Codling; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; reinforcement in biology; merge and split model; preferential attachment; reinforced random walk; network construction; shortest path problem; transport networks; ant algorithm; slime mould; physarum polycephalum; speed-accuracy tradeoff.; Mathematics with specialization in Applied Mathematics; Matematik med inriktning mot tillämpad matematik;

    Sammanfattning : Empirical studies show that similar patterns emerge from a large number of different biological systems. For example, the group size distributions of several fish species and house sparrows all follow power law distributions with an exponential truncation. LÄS MER

  3. 2. Sexual Signals and Speciation : A Study of the Pied and Collared Flycatcher

    Författare :Jon Haavie; Glenn-Peter Saetre; Trevor Price; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; Speciation; Sexual signals; Hybridization; Reinforcement; Song; Female preference; Sex-linkage; Biologi; Biology; Biologi;

    Sammanfattning : Speciation is the process in which reproductive barriers evolve between populations. In this thesis I examine how sexual signals contribute to the maintenance, reinforcement or breakdown of reproductive barriers.Male pied flycatchers (Ficedula hypoleuca) and collared flycatchers (F. albicollis) differ in song and plumage traits. LÄS MER

  4. 3. Genetics and the Origin of Two Flycatcher Species

    Författare :Thomas Borge; Glenn-Peter Saetre; Staffan Bensch; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; reinforcement; reproductive isolation; Z chromosome; hybridization; mate-choice; single nucleotide polymorphism; sequence variation; sexual selection; recombination; Biologi; Biology; Biologi;

    Sammanfattning : In this thesis, different genetic tools are used to investigate pre- and postzygotic barriers to gene exchange and their role in speciation in the pied flycatcher (Ficedula hypoleuca) and the collared flycatcher (F. albicollis). This species complex consists of four genetically distinct clades that apparently diverged in allopatry (I). LÄS MER

  5. 4. Speciation - What Can be Learned from a Flycatcher Hybrid Zone?

    Författare :Chris Wiley; Anna Qvarnström; Lars Gustafsson; Roger Butlin; Uppsala universitet; []
    Nyckelord :Biology; speciation; reinforcement; fitness; postzygotic isolation; asymmetrical hybridization; hybrid zone; species recognition; mate choice; sexual selection; direct benefits; parasite resistance; delayed plumage maturation; Ficedula hypoleuca; Ficedula albicollis; flycatcher; Biologi;

    Sammanfattning : Studies of hybrid zones offer important insights into the process of speciation. Much of the knowledge to be gained is dependent on an accurate estimation of the strength of pre- and post-zygotic isolation between hybridizing taxa. My results demonstrate that hybridization can variously affect different components of fitness. LÄS MER

  7. 5. Artificial neural networks in models of specialization and sympatric speciation

    Författare :Niclas Norrström; Högskolan i Skövde; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Biology; Biologi; Naturvetenskap; Natural sciences;

    Sammanfattning : This thesis deals with specialization and how it is linked to sympatric speciation. The trait driving specialization is a cue recognition trait modelled with artificial neural networks that exploiters use to discriminate beneficial resources from detrimental resources based on the signals of the resources. LÄS MER