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Abstract Detail

Genetics Section

Johnson, Matthew [1], Lang, Kylene [2], Schierenbeck, Kristina [3], Manos, Paul [4].

Evidence for genetic pollution of a California native tree, Platanus racemosa, via recent, ongoing introgressive hybridization with an introduced ornamental species.

When widespread, genetically diverse species are introduced, hybridization may pollute the genetic composition of local, native species, perhaps even resulting in extinction. In the genus Platanus, introgressive hybridization is widespread, and one common ornamental species, introduced to California during the late 19th century, is itself a hybrid. Our microsatellite analysis of more than 400 Platanus trees from north-central California reveals a complex pattern of invasion and hybridization in an age-structured population. By using size as a proxy for age, we have demonstrated that the Platanus population of north-central California has recently gained genetic diversity and effective population size. Principal coordinate analysis (PCoA) and genetic admixture analysis (STRUCTURE) both reveal a strong differentiation of genotypes into two main genetic clusters, with a large number of admixed genotypes. Because trees in one of the genetic cluster are heavily biased towards younger trees, and because this includes sampling locations known to be relatively recently planted ornamental trees likely to be P. x hispanica (formerly known as P. x acerifolia) we conclude that the two genetic clusters correspond to the native P. racemosa and the introduced invasive hybrid species P. x hispanica. Additional hybridization between the invasive ornamental and the native species has occurred in California, and recent hybrid trees are more likely to be younger than trees without admixture. Our findings suggest that the observed increase in genetic diversity among California Platanus is due to rampant ongoing introgression, which may be threatening the continued genetic distinctiveness of the native species.

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1 - Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, ILLINOIS, 60022, United States
2 - California State University Chico, Biological Sciences, Chico, California
3 - California State University Chico, Department Of Biological Sciences, Holt Hall Room 207, California State University Chico, Chico, CA, 95929-0515, USA
4 - Duke


Presentation Type: Oral Paper:Papers for Sections
Session: 17
Location: Salon 15/16/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 2:15 PM
Number: 17004
Abstract ID:1095
Candidate for Awards:Margaret Menzel Award

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