Sökning: "Character divergence"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden Character divergence.

1. 1. Competition, Coexistence and Character Displacement : In a Young Avian Hybrid Zone

   Författare :Niclas Vallin; Anna Qvarnström; Andrew Hendry; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Competition; coexistence; hybridization; ecological speciation; character displacement; pied flycatcher; collared flycatcher; Biology; Biologi; Animal Ecology; Zooekologi;

   Sammanfattning : This thesis investigates the ecological and evolutionary implications of a recent secondary contact between two closely related bird species: collared (Ficedula albicollis) and pied (F. hypoleuca) flycatchers. LÄS MER

3. 2. Interplay Between Environment and Genes on Morphological Variation in Perch – Implications for Resource Polymorphisms

   Författare :Jens Olsson; Peter Eklöv; Mats Björklund; Richard Svanbäck; Andrew P. Hendry; Uppsala universitet; []
   Nyckelord :Ecology; Perch; Resource polymorphism; Genetic differentiation; Phenotypic plasticity; Morphology; Competition; Character divergence; Behavior; Growth rate; Resource level; Gut lenght; Ekologi;

   Sammanfattning : Recent research has suggested that individual specialization within populations could be substantial and more common than previously acknowledged. Eurasian perch is one of many species of fish in lakes of postglacial origin that displays a morphological and dietary variation tightly coupled to the littoral and pelagic habitats of the lake. LÄS MER

4. 3. On Speciation in Birds – Genomic Signatures across Space and Time

   Författare :Martin Stervander; MEMEG; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; colonization; islands; isolation; introgressive hybridization; sympatry; natural selection; bill morphology; coalescence-based analyses; DNA sequencing; birds; divergence; Speciation;

   Sammanfattning : The process of speciation is a cornerstone in evolutionary biology. In Darwin’s On the Origin of Species, he described how he imagined that a new species would evolve to fill an empty niche. This focus on ecology shifted with Mayr towards the importance of isolation, and for many decades the geographic modes of speciation were debated. LÄS MER

5. 4. The evolutionary ecology of niche separation : Studies on the sympatric butterflies Leptidea sinapis and Leptidea reali

   Författare :Magne Friberg; Wiklund Christer; John N. Thompson; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Lepidoptera; ecological character displacement; reproductive isolation; species discrimination; habitat; host plant; life history; sexual selection; female choice; Biology; Biologi; zoologisk ekologi; Animal Ecology;

   Sammanfattning : Studies of ecology and evolution have become largely integrated, and increasing attention is paid to the role of ecology for speciation and post speciation divergence. In this thesis I have applied an in-depth approach studying the ecology of a butterfly species pair; the morphologically virtually identical sister-species, the Wood white (Leptidea sinapis) and Reál’s wood white (Leptidea reali). LÄS MER

7. 5. Phylogeny and Signal Diversity in Widowbirds and Bishops (Euplectes spp.)

   Författare :Maria Prager; Göteborgs universitet; []
   Nyckelord :Ploceidae; weaverbirds; stochastic character mapping; phylogenetic uncertainty; mate choice; status signalling; sexual dichromatism; C4-oxygenation; status signalling;

   Sammanfattning : Although sexual selection for elaborate signals is well documented in numerous species, the extreme diversity in signal design and expression in many taxa is largely unexplained. This thesis explores phylogenetic, mechanistic and ontogenetic explanations for divergence in two classic condition-dependent signal traits in the African widowbirds and bishops (Euplectes spp. LÄS MER