Abstract

Understanding the genetics of a polymorphic trait is important to predict its likely evolution. In Collinsia heterophylla, the upper petal lip colour can be either be white or white with a purple band, while the lower petal lip colour is invariably purple. Because the corolla is only partly polymorphic, the polymorphism can not have evolved due to a mutation where a pigment was lost in the entire plant, which is common in other polymorphic species. In a previous study, high frequency of the purple band was found in populations with darker flowers, indicating possible selection for this trait. In this study, I determined inheritance of the colour polymorphism using two populations (one with only white morph and other with both morphs). I conducted experimental crosses within and between floral morphs to determine whether patterns of segregation in offspring conform to single-gene predictions. Data from F(1), F(2), F(3) and backcross progeny are consistent with a genetic model of one major locus with presence of the band being completely dominant, as indicated in earlier studies using distantly related populations. A novel finding in this study was that the two morphs did not show a difference in seed germination frequency or seedling survival. This trait can thus be valuable as a genetic marker. Even though more thorough ecological data are needed to understand the potential selection pressures on upper petal lip colour in C. heterophylla, its simple inheritance may indicate the possibility of fast evolutionary response to selective forces acting on this trait.

Keywords

early selection; flower colour; genetic marker; inheritance; polymorphism; Collinsia heterophylla

Published in

Journal of Genetics
2009, Volume: 88, number: 2, pages: 205-215
Publisher: INDIAN ACAD SCIENCES

UKÄ Subject classification

Evolutionary Biology
Ecology
Genetics


Publication identifier

DOI: https://doi.org/10.1007/s12041-009-0029-7

Permanent link to this page (URI)

https://res.slu.se/id/publ/42109