RESUMO
Carotenoids are important as pigments for bright coloration of animals, and as physiologically active compounds with a wide array of health-related benefits. However, the causes of variation in carotenoid acquisition and physiology among species are poorly known. We measured the concentration of carotenoids in the blood of 80 wild bird species differing in diet, body size and the extent of carotenoid-based traits. Preliminary analyses showed that diet significantly explains interspecific variability in plasma carotenoids. However, dietary influences were apparently overridden by phylogenetic relationships among species, which explained most (65%) of this variability. This phylogenetic effect could be due partly to its covariation with diet, but may also be caused by interspecific differences in carotenoid absorption from food to the blood stream, mediated, for example by endothelial carriers or gut parasites. Carotenoid concentrations also decreased with body size (which may be explained by the allometric relationship between ingestion rate and body mass), and correlated positively with the extent of carotenoid-dependent coloration of plumage and bare parts. Therefore, the acquisition of carotenoids from the diet and their use for both health and display functions seem to be constrained by ecological and physiological aspects linked to the phylogeny and size of the species.
Assuntos
Aves/genética , Carotenoides/sangue , Filogenia , Animais , Aves/sangue , Constituição Corporal , Dieta , México , Pigmentação/fisiologia , Análise de Regressão , EspanhaRESUMO
A survey of blood parasites was conducted in February 1995 on white-crowned sparrows (Zonotrichia leucophrys) wintering in two environmentally different localities of Baja California Sur (Mexico). Blood parasite prevalence was higher in La Purísima (49%) than in San José del Cabo (8%), but there were no differences between ages or sexes within each locality. All haematozoa infections were by Haemoproteus coatneyi, except one bird in each site that were positive for Trypanosoma sp. We found no evidence for the predicted negative relationship between host body condition and intensity of parasitism. The relatively high prevalence in one site suggests that an increase of hematozoa transmission may occur in that area.
Assuntos
Doenças das Aves/epidemiologia , Haemosporida/isolamento & purificação , Infecções Protozoárias em Animais/epidemiologia , Aves Canoras , Animais , Doenças das Aves/parasitologia , Constituição Corporal , Feminino , Masculino , México/epidemiologia , Parasitemia/epidemiologia , Parasitemia/veterinária , Prevalência , Infecções Protozoárias em Animais/parasitologia , Estudos Soroepidemiológicos , Caracteres SexuaisRESUMO
Louse flies were collected from 401 birds of 32 species captured in autumn of 1996 in Baja California Sur (Mexico). Only one louse fly species (Microlynchia pusilla) was found. It occurred in four of the 164 common ground doves (Columbina passerina) collected. This is a new a host species for this louse fly.