Current Thesis Project
Historical and contemporary gene flow between a cultivated hybrid and native Platanus species along the northern Sacramento River
Hybridization can be a primary source of gene flow between sympatric species and empirically measured rates of allele frequencies in different demographic groups can be used to model the temporal dynamics of gene flow. Introgressive hybridization among historically allopatric, anemophilous populations can contribute to changes in allele frequency within the respective species. The future direction and extent of allelic frequency change through time by introgressive hybridization however, remains largely unknown especially among native and non-native taxa. Historic habitat loss for the native Platanus racemosa (California Sycamore) in northern California riparian woodlands coupled with recent, increased plantings of the non-native, introduced hybrid, Platanus X hispanica (London Plane) have been hypothesized to result in native allelic frequency replacement through introgressive hybridization.
Within the northern California native range of the P. racemosa, seven hundred individual Platanus spp. trees in 23 locations have been sampled for diameter breast height (dbh), mapped via GPS, and had their DNA extracted. Eleven previously established, species-specific genomic microsatellite DNA markers will be used to genotype each tree sampled and dbh measurements will be used as a surrogate for age. The genetic identities of native, introduced, and hybrid populations will be quantified using STRUCTURE, and rates of allelic replacement over time will be estimated for the native P. racemosa lineage.
This work will identify unhybridized native P. racemosa individuals that will be used for future revegetation efforts. The genetic identity (native, introduced, hybrid) and gene flow data will provide empirical data for landscape level models used to predict the consequences of genetic pollution from introduced, conspecific taxa. The significance and extent of the proposed population genetic study of introgressive hybridization will elucidate the impacts that human activities can have on evolutionary processes at the urban-wildlife interface.
Hybridization can be a primary source of gene flow between sympatric species and empirically measured rates of allele frequencies in different demographic groups can be used to model the temporal dynamics of gene flow. Introgressive hybridization among historically allopatric, anemophilous populations can contribute to changes in allele frequency within the respective species. The future direction and extent of allelic frequency change through time by introgressive hybridization however, remains largely unknown especially among native and non-native taxa. Historic habitat loss for the native Platanus racemosa (California Sycamore) in northern California riparian woodlands coupled with recent, increased plantings of the non-native, introduced hybrid, Platanus X hispanica (London Plane) have been hypothesized to result in native allelic frequency replacement through introgressive hybridization.
Within the northern California native range of the P. racemosa, seven hundred individual Platanus spp. trees in 23 locations have been sampled for diameter breast height (dbh), mapped via GPS, and had their DNA extracted. Eleven previously established, species-specific genomic microsatellite DNA markers will be used to genotype each tree sampled and dbh measurements will be used as a surrogate for age. The genetic identities of native, introduced, and hybrid populations will be quantified using STRUCTURE, and rates of allelic replacement over time will be estimated for the native P. racemosa lineage.
This work will identify unhybridized native P. racemosa individuals that will be used for future revegetation efforts. The genetic identity (native, introduced, hybrid) and gene flow data will provide empirical data for landscape level models used to predict the consequences of genetic pollution from introduced, conspecific taxa. The significance and extent of the proposed population genetic study of introgressive hybridization will elucidate the impacts that human activities can have on evolutionary processes at the urban-wildlife interface.
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