A recent hypothesis for explaining blue-green eggs in birds suggests that they may be a sexually selected signal of female (and thus nestling) quality that males use to make parental investment decisions. Although this hypothesis has found mixed correlational support in a few species, well-controlled experimental support has been lacking in non-cavity-nesting species with vivid blue eggs. In this study, we isolate the influence of egg colour on male behaviour by replacing natural American robin Turdus migratorius clutches with four artificial eggs (all of the same colour) representing extremes in natural colour intensity. After incubation, three unrelated nestlings were fostered into each experimental nest immediately after the normal incubation period and parental behaviour was monitored when nestlings were 3, 6, and 9 days old. For the youngest nestlings, male provisioning rate significantly increased in the dark egg treatment, but the effect of egg colour disappeared at the older nestling stages. This result remains significant when controlling for variation in female behaviour. Male feeding rate at unmanipulated nests was also significantly related to natural egg colour. These results suggest that blue-green egg colour acts as post-mating signal of female quality in at least some cup-nesting species, but does not exclude the possibility that the blue-green pigment also serves other adaptive purposes. / Thesis (Master, Biology) -- Queen's University, 2009-05-28 13:21:06.941

Made available in DSpace on 2016-12-08T16:24:11Z (GMT). No. of bitstreams: 1 PGCA11MA083.pdf: 3400558 bytes, checksum: fedbf896e2daef8109b07884eb122a44 (MD5) Previous issue date: 2011-03-03 / Brazilian Caipira chicken are hardy birds that, it is believed, show high genetic diversity. However, there is almost no scientific studies that prove the alleged high genetic variability of the Caipira chicken. Studies that investigate this issue are very important, because the scientific evidence of this polymorphism makes the maintenance and conservation of these animals essential. The gene polymorphism is fundamental to the perpetuation of the species, besides being a source of alleles for genetic improvement programs for livestock. The commercial birds, for example, have lost much of their genetic variability because they have been through strict selection processes. Even though these animals are highly productive, some features related to production still deserve the attention of breeders, such as disease resistance. Some brazilian (blue-egg Caipira) chicken. This coloration of the egg shell is characteristic of a South American breed of chickens that participated in the formation of the native caipira chicken. This study used fifteen microsatellite loci to assess the genetic variability of brazilian (blue egg caipira) chicken. The animals were from the city of Two Lajeados - RS. By PCR, the amplicons obtained using a primer labeled with fluorophores were genotyped in an automatic sequencer and the results analyzed using the statistical program ARLEQUIN. It was detected a total of 168 alleles with an average of 11.2 alleles per locus, 288 genotypes, HE = 0.76 and HO = 0.49. These results confirmed the suspicion of high genetic variability in brazilian (blue egg Caipira) chicken / Galinhas caipiras brasileiras são aves rústicas, que, acredita-se, apresentam elevada diversidade genética. Entretanto, quase não há trabalhos científicos que comprovem a suposta alta variabilidade genética das aves caipiras. Trabalhos que investiguem esta questão são muito importantes, pois a comprovação científica deste polimorfismo transforma a manutenção e conservação destes animais imprescindível. O polimorfismo gênico é fundamental para a perpetuação da espécie, além de ser fonte de alelos para programas de melhoramento genético de animais de produção. As aves comerciais, por exemplo, perderam muito de sua variabilidade gênica por terem passado por rigorosos processos de seleção. Mesmo que estes animais sejam altamente produtivos, algumas características relacionadas à produção ainda merecem atenção dos melhoristas, como é o caso da resistência a doenças. Algumas galinhas caipiras brasileiras colocam ovos azuis. Esta coloração da casca do ovo é característica de uma raça sul-americana de galinhas que participou da formação das aves caipiras nacionais. Este trabalho utilizou quinze loci de microssatélites para avaliar a variabilidade genética de galinhas caipiras brasileiras de ovos azuis. Os animais foram provenientes do município de Dois Lajeados RS. Através da técnica da PCR, os amplicons obtidos com a utilização de iniciadores marcados com fluoróforos foram genotipados em seqüenciador automático e os resultados obtidos analisados através do programa estatístico ARLEQUIN. Foi detectado um total de 168 alelos, com média de 11,2 alelos por locus, 288 genótipos, HE=0,76 e HO=0,49. Estes resultados comprovaram a suspeita de alta variabilidade genética presente em galinhas caipiras brasileiras de ovos azuis