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Senghore, Alieu

University of British Columbia

The mechanisms driving colour variation in organisms have long fascinated scientists. The occurrence of novel phenotypes through random mutations and other factors has always opened new avenues of research to understand the genetic basis and inheritance patterns of these phenotypes. Studying colour asymmetry is an additional way to account for the diverse colour patterns present in nature. In this thesis, I present an investigation into the inheritance pattern and genetic basis of pigmentation in two related Poeciliid species: (Poecilia wingei and Poecilia picta). Additionally, I conducted an analysis of asymmetry in a third related Poeciliid species, the guppy (Poecilia reticulata). The study on P. wingei aimed to understand the heritability and genetic basis of a mutation affecting melanin pigment production. For P. picta, the focus was on understanding the inheritance pattern and genetic basis of a red phenotype referred to as 'blush'. Breeding experiments were conducted, for both P. picta and P. wingei. Subsequently, genotyping of all offspring was performed to determine the inheritance pattern of the mutation in P. wingei and the inheritance pattern of the blush phenotype in P. picta. The findings revealed that the mutation in P. wingei was autosomal recessive, and the blush phenotype in P. picta was not Y-linked, similar to a previous study. Next, an analysis of colour asymmetry was conducted in P. reticulata artificially selected for a high and low proportion of orange, aiming to better understand colour asymmetry present in orange and black guppy ornaments. Fluctuating asymmetry was found to be the main form of asymmetry present in the selection lines, and orange ornaments were more symmetric than black. Furthermore, I figured out that FA in orange ornaments were weakly correlated with FA in black ornaments, indicating that the traits are differentially sensitive to developmental instability. Moreover, the investigation determined the presence of a sizable, albeit insignificant, effect of FA in orange. Finally, heritability calculations for FA in orange and black ornaments were revealed to be quite low. Overall, this thesis contributes valuable insights into the genetic basis, inheritance patterns, and asymmetry in colour pigmentation in some Poeciliid species.

Text

2023-08-25

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/85634

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/