Hybridization and polyploidy as drivers of continuing evolution and speciation in Sorbus

Ashley Robertson, Timothy C. G. Rich, Alexandra M. Allen, Libby Houston, Cat Roberts, Jon R. Bridle, Stephen A. Harris, Simon J. Hiscock

Research output: Contribution to journalArticle (Academic Journal)peer-review

87 Citations (Scopus)

Abstract

Interspecific hybridization and polyploidy are pivotal processes in plant evolution and speciation. The fate of new hybrid and polyploid taxa is determined by their ability to reproduce either sexually or asexually. Hybrids and allopolyploids with odd chromosome numbers are frequently sterile but some establish themselves through asexual reproduction (vegetative or apomixis). This allows novel genotypes to become established by isolating them from gene flow and leads to complex patterns of variation. The genus Sorbus is a good example of taxonomic complexity arising from the combined effects of hybridization, polyploidy and apomixis. The Avon Gorge in South-west Britain contains the greatest diversity of Sorbus in Europe, with three endemic species and four putative endemic novel hybrids among its 15 native Sorbus taxa. We used a combination of nuclear microsatellite and chloroplast DNA markers to investigate the evolutionary relationships among these Sorbus taxa within the Avon Gorge. We confirm the genetic identity of putative novel taxa and show that hybridization involving sexual diploid species, primarily S. aria and S. torminalis and polyploid facultative apomictic species from subgenus Aria, has been responsible for generating this biodiversity. Importantly our data show that this creative evolutionary process is ongoing within the Avon Gorge. Conservation strategies for the rare endemic Sorbus taxa should therefore consider all Sorbus taxa within the Gorge and must strive to preserve this evolutionary process rather than simply the individual rare taxa that it produces.

Translated title of the contributionHybridisation and polyploidy as drivers of continuing evolution and speciation in Sorbus
Original languageEnglish
Pages (from-to)1675-1690
Number of pages16
JournalMolecular Ecology
Volume19
Issue number8
DOIs
Publication statusPublished - Apr 2010

Bibliographical note

Publisher: Wiley (formerly Blackwell)

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