Genomic Variation in Diatoms


Microsatellites: short segment of DNA (2 to 50 bases) repeated multiple times. For example, one allele may contain GCGCGC while another might contain GCGCGCGCGC. Microsatellites vary in length and base composition which makes them useful tools for distinguishing members of a population.

How much diversity is present in a population?
How is this diversity maintained?

Samples of D. birghtwellii take from 3 sites in Hood Canal - a very stable body of water.
This diatom species can reproduce sexually and asexually.


Microsatellites used to genotype all isolates.


Based on frequency of homozygotes, it was determined that these organisms were reproducing asexually.

Given that these were mitotic products, the diversity is much higher than expected. Why?


Growth rates at 3 different light levesl.

No correlation between light levels.


By varying one component of the environment, individual strains would predominate quickly.

Therefore, the high genetic diversity is due to rapidly changing selection pressures.

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