Patterns of DNA Methylation Throughout a Range Expansion of an Introduced Songbird

Document Type

Article

Publication Date

3-27-2013

Publication Title

Integrative and Comparative Biology

DOI

10.1093/icb/ict007

ISSN

1557-7023

Abstract

The spread of invasive species presents a genetic paradox: how do individuals overcome the genetic barriers associated with introductions (e.g., bottlenecks and founder effects) to become adapted to the new environment? In addition to genetic diversity, epigenetic variation also contributes to phenotypic variation and could influence the spread of an introduced species in novel environments. This may occur through two different (non-mutually exclusive) mechanisms. Individuals may benefit from existing (and heritable) epigenetic diversity or de novo epigenetic marks may increase in response to the new environment; both mechanisms might increase flexibility in new environments. Although epigenetic changes in invasive plants have been described, no data yet exist on the epigenetic changes throughout a range expansion of a vertebrate. Here, we used methylation sensitive-amplified fragment length polymorphism to explore genome-wide patterns of methylation in an expanding population of house sparrows (Passer domesticus). House sparrows were introduced to Kenya in the 1950s and have significant phenotypic variation dependent on the time since colonization. We found that Kenyan house sparrows had high levels of variation in methylation across the genome. Interestingly, there was a significant, potentially compensatory relationship between epigenetic and genetic diversity: epigenetic diversity was negatively correlated with genetic diversity and positively correlated with inbreeding across the range expansion. Thus, methylation may increase phenotypic variation and/or plasticity in response to new environments and therefore be an important source of inter-individual variation for adaptation in these environments, particularly over the short timescales over which invasions occur.

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© The Author 2013. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

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