The location of the polymorphism in the Quercus COL gene and given the potential role of COL genes in adaptive divergence and reproductive isolation makes this a promising candidate speciation gene. Further investigation of the phenological characteristics of both species and flowering time pathway genes is suggested in order to elucidate the importance of phenology genes for the maintenance of species integrity. Next-generation sequencing in multiple population pairs in combination with high-density genetic linkage maps could reveal the genome-wide distribution of outlier genes and their potential role in reproductive isolation between these species.

Oaks provide a model system to study maintenance of species identity by divergent selection since they maintain morphological differences and ecological adaptations despite interspecific hybridization. The genome of closely related interfertile oak species was shown to be largely homogeneous, with a few genomic areas exhibiting high interspecific differentiation possibly as result of strong divergent selection. Previously, a genic microsatellite was identified as under strong divergent selection, being nearly fixed on alternative alleles in the two interfertile North American red oak species: Quercus rubra L. and Quercus ellipsoidalis E.J. Hill. Further genotyping in two other red oak species-Quercus velutina Lam. and Quercus coccinea Münchh.-revealed a similar bias for the Q. ellipsoidalis-specific allele. To further elucidate the basis of this differentiation, we sequenced the microsatellite in individuals from all four red oak species. Sequence variability was observed in the microsatellite motif which encodes a poly-Q repeat in a COL gene involved in phenology and growth. Furthermore, in neighboring (parapatric) Q. rubra/Q. ellipsoidalis populations, introgression of the Q. ellipsoidalis-specific allele into Q. rubra occurred at a lower rate than introgression of the Q. rubra-specific allele into Q. ellipsoidalis despite symmetric interspecific gene flow, indicating potential adaptive introgression. Introgression of adaptive alleles can be an important mechanism for rapid adaptation to new environmental conditions (e.g., climate change).

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Abstract:Coordinating forest management across thousands of nonindustrial private forest (NIPF) owners is a difficult yet necessary task for state land management agencies. Voluntary Incentive Programs (VIPs) can coordinate the decentralized activities of these owners in return for services or financial incentives. However, many VIPs typically have low enrollment. Our study investigates the implementation of VIPs to increase forest management coordination among NIPFs in Michigan. We present findings from 20 semi-structured interviews with leaders of state and local land management organizations, and government officials at state natural resource agencies, and contrast their answers with those recorded from 37 interviews of NIPF owners regarding their knowledge and attitudes toward VIPs. Our interviews highlight a critical disconnect between NIPF owner motivations and VIP incentives, as well as misallocated resources for VIP promotion by state agencies, driving low enrollment. At the core, low enrollment in VIPs is generated by inadequate communication between NIPF owners and program managers, along with distrust of government agency objectives. Viewing managers as "street level bureaucrats", civil servants whose job discretion is impacted heavily by available resources, may increase our understanding of the issues plaguing VIPs and help identify improvements to VIP design and implementation.