GENETIC VARIATION AND INTROGRESSION ACROSS A HYBRID ZONE OF DIVERGENT PINE SQUIRRELS (TAMIASCIURUS) USING DDRADSEQ DATA
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Date
2019-05
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The Ohio State University
Abstract
The North American tree squirrels Tamiasciurus hudsonicus and Tamiasciurus douglasii are parapatric species that hybridize over a transitional forest zone in the Northern Cascade mountains. In a previous study, Chavez (2011) found pure parental populations at the ends of the transect and found hybrids in a transitional forest habitat with the use of mtDNA and microsatellite data. The levels of hybridization and strength of barriers to gene flow are still unclear. The objective of this study is to use genome-wide SNP data from ddRADseq approach to provide new insight into the dynamics of gene flow and introgression between Tamiasciurus hudsonicus and Tamiasciurus douglasii. Population assignment analyses of SNP DNA generated using ddRADseq allowed the genotyping of individuals in populations, and we found different distributions of hybrids across the transect and different levels of hybridization among hybrids and confirmed the presence of first generation hybrids. The geographical cline shows differential introgression asymmetry of the hybrid zone toward T. douglasii range. Perhaps the Northern Cascade mountains is not providing a significant physical barrier to gene flow and there is movement of Tamiasciurus hudsonicus into the Tamiasciurus douglasii range.
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Hybrid zone