Matthew S. Olson

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Patterns of reproductive isolation between species may provide insight into the mechanisms and evolution of barriers to interspecific gene exchange. We used data from published interspecific hybridization experiments from 14 genera of angiosperms in order to test for the presence of asymmetrical barriers to gene exchange. Reproductive isolation was examined(More)
*Current perceptions that poplars have high levels of nucleotide variation, large effective population sizes, and rapid decay of linkage disequilibrium are based primarily on studies from one poplar species, Populus tremula. *We analysed 590 gene fragments (average length 565 bp) from each of 15 individuals from different populations from throughout the(More)
Analyses among animal species have found that reproductive isolation increases monotonically with genetic distance, evolves more quickly for prezygotic than postzygotic traits, and is stronger among sympatric than allopatric species pairs. The latter pattern is consistent with expectations under the reinforcement hypothesis. To determine whether similar(More)
We examined patterns of mitochondrial polymorphism and divergence in the angiosperm genus Silene and found substantial variation in evolutionary rates among species and among lineages within species. Moreover, we found corresponding differences in the amount of polymorphism within species. We argue that, along with our earlier findings of rate variation(More)
Rapid range expansions can cause pervasive changes in the genetic diversity and structure of populations. The postglacial history of the Balsam Poplar, Populus balsamifera, involved the colonization of most of northern North America, an area largely covered by continental ice sheets during the last glacial maximum. To characterize how this expansion shaped(More)
Identifying the signature and targets of local adaptation is an increasingly important goal in empirical population genetics. Using data from 443 balsam poplar Populus balsamifera trees sampled from 31 populations, we tested for evidence of geographically variable selection shaping diversity at 27 homologues of the Arabidopsis flowering-time network. These(More)
The macroevolutionary consequences of recent climate change remain controversial, and there is little paleobotanical or morphological evidence that Pleistocene (1.8-0.12 Ma) glacial cycles acted as drivers of speciation, especially among lineages with long generation times, such as trees. We combined genetic and ecogeographic data from 2 closely related(More)
The psbA-trnH intergenic region is among the most variable regions in the angiosperm chloroplast genome. It is a popular tool for plant population genetics and species level phylogenetics and has been proposed as suitable for DNA barcoding studies. This region contains two parts differing in their evolutionary conservation: 1) the psbA 3′UTR (untranslated(More)
Foliar fungal communities of plants are diverse and ubiquitous. In grasses endophytes may increase host fitness; in trees, their ecological roles are poorly understood. We investigated whether the genotype of the host tree influences community structure of foliar fungi. We sampled leaves from genotyped balsam poplars from across the species' range, and(More)
PREMISE OF THE STUDY During past episodes of climate change, many plant species experienced large-scale range expansions. Expanding populations likely encountered strong selection as they colonized new environments. In this study we examine the extent to which populations of the widespread forest tree Populus balsamifera L. have become locally adapted as(More)