Browsing by Author "Ewen, JG"

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Egg Carotenoids in Passerine Birds Introduced To New Zealand: Relations To Ecological Factors, Integument Coloration and Phylogeny
(Wiley, 2005) Cassey, P; Ewen, JG; Boulton, RL; Blackburn, TM; Moller, AP; Biard, C; Karadas, F
1. Carotenoids are a diverse group of organic compounds that function as important antioxidants and immunostimulants and are of particular importance to developing embryos and young birds. In addition, they constitute the majority of yellow to red hues in the integumentary pigments of birds. 2. We investigated the maternally derived carotenoid concentrations and balances in the yolks of eight European passerine species successfully introduced and abundant in New Zealand. Specifically, we addressed whether variation in maternally derived yolk carotenoids were related to phylogeny, integument coloration, native vs introduced distribution, breeding habitat and laying sequence. 3. Across species, the concentration and balance of carotenoids deposited in yolks varied significantly. Egg carotenoid concentration was positively associated with the occurrence of male carotenoid pigmented body regions. Carotenoid concentrations differed between agricultural habitat types within New Zealand but not between samples from New Zealand and Europe. Controlling for the differences among species, and among clutches within species, increased egg carotenoid concentrations were significantly associated with decreasing fresh egg mass and eggs laid earlier in the laying sequence. 4. We conclude that variability in the concentration and balance of carotenoids deposited in the egg yolk imply different relative roles for ecological and phylogenetic factors that warrant further investigation, both within and across species.
Influences of Carotenoid Supplementation on the Integrated Antioxidant System of a Free Living Endangered Passerine, the Hihi (Notiomystis Cincta)
(Elsevier Science inc, 2006) Ewen, JG; Thorogood, R; Karadas, F; Pappas, AC; Surai, PF
The integrated antioxidant system is recognised as an essential component of an organisms self maintenance. Our knowledge of this system, however, is largely restricted to species of economic importance. The health and productivity benefits these dietary based compounds provide make them increasingly relevant for study in wildlife ecology. The aim of this research was to identify numerous components of this integrated system in a free living and endangered passerine bird, the hihi. In addition experimental supplementation with carotenoids was used to investigate the modulatory interactions with other members of the antioxidant system. Our results identified lutein and zeaxanthin as the carotenoids utilised by hihi (82% and 17% of total carotenoids respectively in control samples of egg yolk, 84% and 16% of total carotenoids respectively in control samples of nestling plasma), and that vitamin E was represented by both alpha- and gamma-tocopherol. Retinol was also present, as was selenium in surprisingly high concentrations (599.64, 91.76, 377.72 ng/g fresh weight Se in control samples of yolk, albumin and plasma, respectively). Supplementation of lutein and zeaxanthin not only increased their presence in egg yolk (F-1,(10) = 14.285, P= 0.005 and F-1,F-10 = 9.606, P = 0.015, respectively) and nestling plasma (F-1,F-19=35.126, P<0.001 and F-1,F-19 = 28.597, P<0001, respectively) but also led to increased selenium concentration in egg yolk (F-1.10 = 7.213, P=0.028), increased retinol concentration in nestling plasma (F-1.19=4.272, P=0.054) and decreased alpha-tocopherol concentration in nestling plasma (F-1,F-19=5.122, P=0.037). These results provide detail of the antioxidant system in novel taxa and importantly highlight interaction between these various compounds. Given their increased application in productivity and health in agriculture and human medicine we highlight the potential application of this knowledge in wildlife ecology and conservation. (C) 2005 Elsevier Inc. All rights reserved.