Abstract Detail

Systematics Section/ASPT

Zarrei, Mehdi [1], Talent, Nadia [1], Coughlan, Jen [1], Stefanovic, Sasa [2], Dickinson, Tim [1].

Nuclear ribosomal ITS2 DNA sequences illuminate hybridization in a diploid-polyploid agamic complex of Crataegus (Rosaceae).

The common North American black-fruited hawthorns (Crataegus section Douglasianae) were chosen as a geographically and morphologically identifiable subset of this genus in order to (i) establish their phylogentic relationships, (ii) investigate the history of hybridization and ploidy - level changes, and (iii) discover the impact of hybridization and polyploidy on nuclear ribosomal ITS2. Eleven species (61 accessions) of C. section Douglasianae of known ploidy (2n = 2x, 3x, 4x, and 5x) were cloned for nrITS2. This marker was also cloned for thirty more outgroup accessions comprising thirteen species from C. sections Coccineae, Sanguineae, Crataegus, and Mespilus, as well as the hybrids C. monogyna × C. punctata and C. monogyna × C. suksdorfii. Diploid and autotriploid C. suksdorfii maintain only the C. section Douglasianae haplotypes of nrITS2. Both black-fruited C. section Douglasianae and red-fruited C. section Coccineae haplotypes were represented in the genome of tetraploid and pentaploid C. section Douglasianae taxa. The hybrid taxa studied here maintained the sequences of both progenitors, with homogenization of nrITS2 sequences biased towards the maternal sequence (C. monogyna in the case of C. monogyna × C. punctata). This suggests that intersectional gene flow is common in hawthorns and can explain much of the taxonomic complexity found in the genus.

Broader Impacts:

1 - University of Toronto, Department of Ecology and Evolutionary Biology, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
2 - University of Toronto Mississauga, Department of Biology, 3359 Mississauga Rd N, Mississauga, ON, L5L 1C6, Canada

Keywords:
Crataegus
Nuclear ribosomal ITS2
hybridization.

Presentation Type: Oral Paper:Papers for Sections
Session: 45
Location: Delaware D/Hyatt
Date: Wednesday, July 11th, 2012
Time: 10:30 AM
Number: 45010
Abstract ID:536