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Hybridization is associated with changes in sexual system in the bryophyte genus Atrichum
Author(s) -
Perley Danielle S.,
Jesson Linley K.
Publication year - 2015
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.1400494
Subject(s) - biology , ploidy , gametophyte , bryophyte , sporophyte , leafy , dioecy , genus , plant evolution , polyploid , evolutionary biology , botany , genetics , gene , genome , pollen
• Premise of the study: Over 50% of bryophytes have separate sexes, and numerous transitions have occurred between combined and separate sexes. Polyploidy and hybridization is one proximate mechanism hypothesized to cause evolutionary transitions to hermaphroditism in bryophytes because sex is expressed at the haploid stage and in nonpolyploid dioecious species males have a single V chromosome and females a U. Hermaphroditism can arise if gametophytes of allopolyploids have both U and V chromosomes. We examined the association between polyploidy and hermaphroditism in the bryophyte genus Atrichum , which has species where gametophytes can be haploid, diploid, or triploid, and some species have hermaphroditic individuals. • Methods: We generated phylogenies of Atrichum from sequences of three plastid regions ( rbcL , rps4 , and trnL‐trnF ) and the second intron for the nuclear gene Leafy/Floricaula to further understand the relationships among haploid, diploid, and triploid species, and those with combined or separate sexes. • Key results: The existence of multiple sequences of Leafy/Floricaula in diploid and triploid, but not haploid, individuals is consistent with independent allopolyploid origins of the diploid and triploid species. Allopolyploidy was associated with a likely gain in hermaphroditism in triploid Atrichum undulatum and possibly diploid A. altecristatum , but not in the allopolyploid A. crispulum (diploid at the gametophyte level). • Conclusions: These results highlight a role for hybridization and polyploidy in sexual system evolution, but the presence of diploid (allopolyploid) dioecious species suggest that other factors may influence the maintenance of sexual systems after an evolutionary transition.