Date of Award


Document Type

Honors Thesis (Colby Access Only)


Colby College. Biology Dept.


Judy L. Stone

Second Advisor

W. Herbert Wilson, Jr.


Colonization, which is the process of a species spreading to a new habitat, provides species with the opportunity to take advantage of areas in which their niches are either not currently or minimally exploited. To explore the evolutionary genetics of colonization, we examined the population genetics of 16 Iris versicolor (blue flag iris) populations in and around the Bay of Fundy. The use of microsatellites, short segments of DNA composed of one to four base pair repeats, allowed us to analyze relationships in and among iris populations. Multiple primer pairs were developed, including eight primer pairs that showed evidence of fixed heterozygosity, a common characteristic of allopolyploids such as I. versicolor. Three primer pairs were chosen for this study because they consistently amplified genetically variable regions. I. versicolor samples revealed high heterozygosity for all three primer pairs scored. Mainland populations were found to have higher genetic diversity than island populations. Among island populations, genetic diversity increased with island size. Island populations were more genetically diverged than mainland populations. No correlation was found between geographic distance and genetic distance in examined I. versicolor samples. These findings reveal that although island populations experienced a genetic bottleneck following colonization, they were able to retain a large portion of their genetic diversity.


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colonization, genetic diversity, evolutionary ecology

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