Sökning: "eye evolution"

Visar resultat 1 - 5 av 31 avhandlingar innehållade orden eye evolution.

1. 1. Evolution of Vertebrate Eyes: a study on lens suspension and optical proterties

   Författare :Ola Gustafsson; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; evolution; eye; fish; crystalline lens; lens suspension; multifocal optical systems; Agnatha; Actinopterygii; Chondrichthyes; Vertebrate; Sarcopterygii;

   Sammanfattning : Many fishes have well-developed visual systems with color vision capabilities. The crystalline lens is the major refractive element in a fish eye since the cornea is optically inactive underwater. A typical fish eye has a large pupil and a lens of short focal length, features that increase light gathering ability. LÄS MER

3. 2. Comparative optics of prosobranch eyes

   Författare :Jan-Olof Seyer; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ampularia; Littorina; Strombus; evolution; visual ecology; summation; convergence; optic nerve; resolution; sensitivity; optics; eye; gastropod; prosobranch; Animal anatomy; animal morphology; Djurs anatomi och morfologi;

   Sammanfattning : Functional aspects of the large diversity of eye design in prosobranch molluscs was investigated using morphological and optical methods. Three species from different habitats were investigated. Littorina littorea from Scandinavian intertidal rock habitats, Strombus raninus and S. gigas from tropical sand-flats and Ampularia sp. LÄS MER

4. 3. Evolution of eyes: Pax, gene duplications & morphology

   Författare :Karin Nordström; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; animal morphology; Djurs anatomi och morfologi; Animal anatomy; tetraploidization; planula; phototransduction; pax; paired domain; mutagenesis; cnidaria; eye evolution;

   Sammanfattning : During the course of evolution animal complexity and diversity is generated. The last couple of years it has become increasingly clear that morphologically diverse animals share a great deal of their genomic contents, and it must be the expression of regulatory genes in new setting, rather than the generation of new genes, that are fundamental for the generation of diversity. LÄS MER

5. 4. Visual ecology of insect superposition eyes

   Författare :Pär A Brännström; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Animal physiology; tiger beetle; hawkmoth; mayfly; insect; visual ecology; eye design; vision; compound eye; Djurfysiologi;

   Sammanfattning : In the superposition compound eye each rhabdom (light sensitive unit) receives light through many ommatidial facets, while in the apposition compound eye every rhabdom receives light from a single facet. The superposition design increases photon capture, which is an advantage in dark environments. LÄS MER

7. 5. Defence on Demand : A physiological perspective on phenotypic plasticity in anti-predator traits

   Författare :Jerker Vinterstare; Enhet akvatisk ekologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Phenotypic plasticity; inducible defences; stress physiology; cortisol; immune function; trade-offs; sexual dimorphism; crucian carp; visual ecology; predator-prey interactions; POMC pro-opiomelanocortin ; colour change; eco-immunology; Anti-predator defences; Inducible morphological defence; Phenotypic plasticity; Stress physiology; Cortisol; Immune function; Crucian carp; Predator-prey interactions; Trade-offs; Sexual dimorphism; POMC; Pro-opiomelanocortin; Visual ecology; Eye evolution; Melanin; Eco-immunology; Pace-of-life; Behavioural plasticity;

   Sammanfattning : Almost all species face some degree of predation risk, and, hence, evolution has produced a plethora of anti-predator defences. However, anti-predator strategies require resources, and the prevailing risk of becoming prey is influenced by many factors and rarely constant across time and space. LÄS MER