It is widely acknowledged that all opolyploidy via hybridization and genome doubling can easily lead to speciation, as polyploid hybrids can be immediately isolated from diploid parental taxa due to high levels of sterility caused by uneven numbers of chromosome complements in their progeny (Soltis and Soltis,2009;Abbottetal., 2013). However, homoploid hybrid speciation (HHS), in which a hybrid lineage becomes genetically isolated from their parents and functions as a distinct evolutionary unit, has been thought to be fairly uncommon (Chaseetal., 2010; Servedioetal., 2013). Schumeretal. (2014) proposed three criteria for proving HHS: evidence of hybridization in the genome, reproductive isolation (RI) of hybrid lineages from parental species, andevidence that this reproductive isolation is a consequence of hybridization. According to these criteria, only one case of HHS in sunflowers was strictly documented in plants till now (Schumeretal., 2014). These criteria highlight two reasons why HHS is harder to detect and prove than allopolyploid speciation: the first is the lack of chromosome number change, whereas the second is that molecular evidence for hybridization becomes harder to detect as the parent species become more closely related, and it is known that HHS tends to involve more closely related parents pecies than allopolyploidy events (Abbottetal.,2013).
- entomophilous plant
- flower color
- homoploid hybrid speciation
- pollinator mediated isolation
- reproductive isolation