• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 14
  • 3
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 25
  • 14
  • 9
  • 9
  • 8
  • 7
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Utilisation de l'information sociale, ses effets sur le choix du partenaire et le maintien des couples chez les oiseaux monogames : le cas du diamant mandarin (Taeniopygia guttata)

Drullion, Dominique January 2008 (has links)
Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal
22

Vasodilatory effects of exogenous nitric oxide on the brood patch of the Zebra finch (Taeniopygia guttata)

Södergren, Anna January 2010 (has links)
In birds like the Zebra finch (Taeniopygia guttata) the female, but not the male develop a brood patch upon incubation of eggs. The brood patch functions to increase heat exchange between the bird and the eggs. Development of the brood patch includes de-feathering, increased vascularization and edema formation. The increased vascularization is due to the development of arteriovenous anastomoses, AVA. The AVA are thermoregulatory vessels involved in cold induced vasodilation, CIVD, demonstrated to occur in the brood patch. Nitric oxide, NO, which is a well known vasodilator is a candidate substance for involvement in CIVD. In this study a NO-generating gel was applied to the brood patch of male and female zebra finches. Vasodilation was found to be markedly larger in females than in males. The larger vasodilation in the female brood patch is probably because NO vasodilate AVA selectively more than any other vessels. The study also investigated whether vasodilation would cause an increase in brood patch temperature. No definite changes in brood patch temperature could be observed and no conclusions could be drawn in the matter.
23

Alokace karotenoidů a redoxní homeostáza u ptáků / Carotenoid allocation and redox homeostasis in birds

Mojžišová, Kateřina January 2015 (has links)
In many species carotenoid-based ornaments plays fundamental role in sexual selection. It is believed that carotenoid-based ornaments act as indicators of individual quality and condition during mate-choice, as associations between their expression, individual fintess and various condition indicators were observed. Despite the long-term research, mechanisms ensuring signalling honesty remain unknown. Currently, the most accepted hypothesis suggests antioxidant properties of carotenoids, and, therefore, a trade-off between their allocation to ornamentation or defence against free radicals. The antioxidant function of carotenoids in vivo was challenged in birds, however, and alternative hypotheses were proposed, assuming either carotenoid loss due to free-radical oxidation, or harmful (pro- oxidant) effects of high carotenoid levels in the body, or interconnection of metabolic pathways for both, the carotenoid conversion and homeostatic control of mitochondrial respiration and redox state. These hypotheses assume differing allocation of carotenoids under elevated oxidative stress, which we tested using experimental manipulations of oxidative state and carotenoid intake in adult male zebra finches (Taeniopygia guttata). The results are inconsistent with all the alternative hypotheses, but partly...
24

Vliv stavu a funkce imunitního systému na pohlavní výběr u ptáků / Vliv stavu a funkce imunitního systému na pohlavní výběr u ptáků

Vinkler, Michal January 2011 (has links)
Evolution is a most fascinating feature of all living things in our world. The means of organismal evolution are diverse, comprising mainly of natural and sexual selection. Both of these phenomena may contribute to evolutionary adaptations in health and disease. The questions of immunity impact on the process of sexual selection and sexual selection for increased anti-parasite resistance are wide issues of the present research in natural sciences. Their clarification requires multidisciplinarily-based investigation combining a variety of partial results into a single united paradigm. My co-workers and I have chosen several specific issues to study, in order to fill some of the important gaps of the current knowledge. We proposed the Carotenoid maintenance handicap hypothesis to point out that optimisation instead of maximisation of the carotenoid intake and ornamental display may be physiologically convenient for the individual. In Scarlet rosefinch (Carpodacus erythrinus) we confirmed the role of the carotenoid-based ornamental colouration in the process of sexual selection and investigated several partial aspects of the association between immunogenetics, immune function, health and the ornament expression and mate choice. In Zebra finch (Taeniopygia guttata) we have shown that the present way of...
25

Kondiční závislost pohlavně selektovaných ornamentů u ptáků / Condition dependence of sexually selected ornaments in birds

Tomášek, Oldřich January 2018 (has links)
Sexual ornaments important for mating success in many species are often assumed to evolve as condition-dependent signals of individual quality. Ornament expression can be associated with age and survival, thereby signalling individual viability. Here, we have tested viability signalling function of tail streamers and their importance for within-pair and extra-pair fertilisation success in the European barn swallow (Hirundo rustica rustica). In contrast to previous studies on this subspecies, our data suggest that tail length is not associated with fertilisation success in our population. Instead, the most important predictors of within-pair and extra-pair fertilisation success were female and male age, respectively. Our data supported viability signalling function of male tail streamers, as documented by age-related within- individual increase in their length. There was no evidence for senescence in this trait. Contrary to some previous studies, the viability signalling function of tail streamers was further supported by observed selective disappearance of males with shorter tails. Several physiological mechanisms have been proposed as maintaining signalling honesty. Among them, oxidative stress from highly reactive species (RS), including free radicals, attracted a considerable attention. Given...

Page generated in 0.0534 seconds