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Title: Genetic variation and distribution of Pacific crabapple

Author
item ROUTSON, KANIN - University Of Arizona
item Volk, Gayle
item Richards, Christopher
item SMITH, STEVEN - University Of Arizona
item NABHAN, GARY - University Of Arizona
item DE ECHEVERRIA, VICTORIA - University Of Victoria

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2012
Publication Date: 9/12/2012
Citation: Routson, K.J., Volk, G.M., Richards, C.M., Smith, S.E., Nabhan, G.P., De Echeverria, V.W. 2012. Genetic variation and distribution of Pacific crabapple. Journal of the American Society for Horticultural Science. 137(5):325-332.

Interpretive Summary: The Pacific crabapple is found in moist coastal habitats in the Pacific Northwest of the United States. It is one of four apple species native to North America. Malus fusca is culturally important to First Nations of the region who value and use the fruits of this species as food, the bark and leaves for medicine, and the wood for making tools and in construction. Little is known about either distribution or genetic diversity of this species. We used modeling methods to map the habitat types which M. fusca occupies. It currently is found in a colder, drier northern region and a warmer, wetter southern region. A total of 239 M. fusca individuals sampled from across its native range were genetically compared to determine their diversity. There were higher within population genetic differences than those found among populations, with greater differences in diversity observed between populations that were far apart. These results may help establish priorities for in situ and ex situ M. fusca conservation for USDA.

Technical Abstract: The Pacific crabapple (Malus fusca (Raf.) C.K. Schneid.) is found in moist coastal habitats in the Pacific Northwest. It is one of four apple species native to North America. Malus fusca is culturally important to First Nations of the region who value and use the fruits of this species as food, bark and leaves for medicine, and the wood for making tools or constructing buildings. Little is known about either distribution or genetic diversity of this species. To correct this deficiency, we used habitat suitability modeling to map M. fusca habitat types using species occurrence records. The species apparently occupies at least two distinct climate regions: a colder, drier northern region and a warmer, wetter southern region. Total area of modeled habitat encompasses approximately 356,780 square kilometers of low-lying areas along the Pacific coast. A total of 239 M. fusca individuals sampled from across its native range were genetically compared using six microsatellite markers to assess geographic structuring of genotypes associated with different climate regions. The primers amplified 50 alleles. Significant isolation by distance was identified across the approximately 2600 (straight line) kilometers where samples were distributed. Low but significant Chi-square tests for two markers may indicate some natural selection occurring between the two climate regions. These results may help establish priorities for in situ and ex situ conservation of M. fusca.