XVI International Botanical Congess

According to theory, a tetraploid should have a less negative response to inbreeding relative to a diploid. A tetraploid becomes homozygous at fewer loci and expresses fewer deleterious alleles when selfed. I used a tetraploid (Vaccinium corymbosum) and diploid (V. myrtilloides) to test this theory. Both species responded negatively to inbreeding. The tetraploid had a consistent response to inbreeding across life history stage while inbreeding depression in the diploid appears to decline across life history stage. Estimates of lethal equivalents were higher in the tetraploid. These data suggest, purging of deleterious alleles and greater tolerance of selfing in the diploid and the tolerance of more deleterious alleles in the tetraploid because of polyploidy. I am currently characterizing the mating system and expect to see higher outcrossing rates in the tetraploid.