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On the evolution of the occurrence of subadult plumage

Vahl, W.K. (1999) On the evolution of the occurrence of subadult plumage. Bachelor's Thesis, Biology.

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Young birds that do not achieve somatic maturation in the same year as they achieve sexual maturation, wear a plumage distinct from that of the definitive adult plumage during their first potential breeding year. This feature has got extensive attention in literature as 'delayed plumage maturation'. This paper argues that the occurrence of subadult plumage is a better name as is does not make any advanced assumptions on the evolutionary development of subadult plumage. Although the occurrence of subadult plumage does not have to be adaptive, most hypotheses on the evolution of subadult plumage assume this trait to be adaptive. In studying the adaptiveness of a trait there are two major approaches. The within species approach considers the adaptiveness of the trait within a single species by relating variation in plumage colour to variation in fitness-related parameters (either natural variation (descriptive approach) or artificial variation (experimental approach)). The comparative approach compares the occurrence of subadult plumage in several species and uses the generality of the trait to get an indication of its adaptiveness. Comparative studies can either use phylogeny or not use phylogeny. The best understanding of the adaptiveness of subadult plumage will follow from the combined use of the comparative approach with phylogeny and of the experimental within species approach. The comparative approach with phylogeny is necessary to identify independent groups and suitable control groups, the experimental within species approach can actually prove whether something is adaptive or not.

Item Type: Thesis (Bachelor's Thesis)
Degree programme: Biology
Thesis type: Bachelor's Thesis
Language: English
Date Deposited: 15 Feb 2018 07:44
Last Modified: 15 Feb 2018 07:44

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