The primrose, Primula kewensis, has 36 chromosomes that are similar in appearance to the chromosomes in two related species, P. floribunda (2n=18) and P. verticillata (2n=18). How could P. kewensis arise from these species? How would you describe P. kewensis in genetic terms?

Key Concepts

Polyploidy

Polyploidy is a condition in which an organism has more than two complete sets of chromosomes. In the case of Primula kewensis, it likely arose through polyploidy, specifically through hybridization between the two related species, P. floribunda and P. verticillata, followed by chromosome doubling. This process can lead to the formation of new species with increased genetic diversity and adaptability.

Hybridization

Hybridization is the process where two different species interbreed to produce hybrid offspring. In the context of P. kewensis, it suggests that this species originated from the mating of P. floribunda and P. verticillata, resulting in a hybrid with a unique combination of traits. This can contribute to speciation, especially when combined with polyploidy.

Chromosome Number and Structure

The chromosome number and structure are critical for understanding genetic relationships and species classification. P. kewensis has 36 chromosomes, indicating it is likely a hexaploid (6n) derived from the diploid parents (2n=18). This increase in chromosome number can affect gene expression and phenotypic traits, making it distinct from its parent species.