The sex comb an array of specialized bristles on the foreleg, is a highly
variable male trait of Drosophila that provides an ideal system for integrative
studies of morphological evolution. Here, studies of the genetic and
developmental architecture of sex comb bristle number variation in Drosophila
melanogaster are described. Analysis of the response to twenty-four generations
of divergent artificial selection indicated high genetic variance underlying this
trait, and demonstrated a weak relationship with other, developmentally related
non-sex bristle systems. I also present evidence showing bristle number is
associated with mating success. Manipulation of diet in full-sib families
confirmed that this trait is condition dependent, and that there is a genetic basis
for condition dependence. Further partitioning of variance components using a
half-sib mating design revealed a strong maternal, dominance and/or X
chromosome effect on sex comb bristle number variation. Finally, sex comb
bristle number was not correlated with comb orientation in wild type, High and
Low artificial selection lines, or the mutant strain bric a brac PR72. Analysis of
patterns of variation in comb orientation over ontogeny in these lines showed that
this aspect of the sex comb phenotype is highly canalized. This body of work
provides important insight into D. melanogaster sex comb evolvability, and
represents a timely approach to bridging the gap between population genetics and
development in studies of phenotypic evolution. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/21098 |
| Date | 02 1900 |
| Creators | Ahuja, Abha |
| Contributors | Singh, Rama, Biology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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