Reproductive strategies in Angiosperms

Reproductive strategies in Angiosperms

Overview
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Self Incompatibility and changes in a mating
system
Types of mixed reproduction strategies
Obligate apomicts
How plants enforce outcrossing

Mechanisms to promote
Outcrossing
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Dioecy – separation of sexes between
individual plants, not hermaphrodite.
Self incompatibility – sometimes too effective
Dichogamy – Male and Female reproductive
parts mature asynchronously
Herkogamy – Spatial separation of sex parts

Arabidopsis Lyrata
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Normally a genetically SI obligate outcrosser
Shift in mating system resulted in loss of
heterozygosity
Low population density and pollinator scarcity drive
loss of SI system
SI will evolve with high inbreeding depression

Why mixed reproduction?
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Perennials have more opportunities to outcross
Resource allocation depends on environment
Most species are hermaphroditic
High seed set versus Inbreeding depression

Viola lanceolata
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Mixed breeding with two flower types
Either Outcrossing chasmogamous flowers or
selfing cleistogamous flowers
Tradeoff between two types
Chasmogamy results from favorable
(Cortes 2006)
environmental factors.

Bulbine vagans
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Hermaphroditic flowers accessible to bees
Spatial separation of pistils and stamens
Sex parts fold together when flower expires
Inbreeding depression observed
Reproductive assurance without wasting ovules
(Vaughton 2007)

Evidence of Inbreeding Depression

Taraxacum officinale
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Polyploid Amomicts
Clonal reproduction results in highly
homogeneous communities.
Numerous hybridization events
Asexual offspring from sexual parents
(Majesky 2012)

Conclusion
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Both autogamy or self incompatibility will evolve
under certain conditions.
Costs associated with reproducing sexually
Mixed reproduction can be accomplished
different ways.
Asexual species arise from hybridization

Works Cited
Majeský L, Vasut RJ, Kitner M, Trávnícek B. The pattern of genetic variability in apomictic clones of taraxacum officinale indicates the
alternation of asexual and sexual histories of apomicts. PLoS One. 2012;7(8).
Aurea CC, Ballard,Harvey E.,,Jr. Influence of annual fluctuations in environmental conditions on chasmogamous flower production in viola
striata1. J Torrey Bot Soc. 2006;133(2):312-320.
Mable BK, Robertson AV, Dart S, Berardo CD, Witham L. Breakdown of self-incompatibility in the perennial ArabidopsisLyrata (brassicaceae)
and its genetic consequences. Evolution. 2005;59(7):1437-1448. http://search.proquest.com/docview/55590502?accountid=14696. doi:
http://dx.doi.org/10.1043/0014-3820(2005)059[1437:BOSITP]2.0.CO;2.
Porcher E, Lande R. Loss of gametophytic self-incompatibility with evolution ofInbreeding depression. Evolution. 2005;59(1):46-60.
http://search.proquest.com/docview/55697690?accountid=14696. doi: 2.0.CO;2" TARGET="_blank">http://dx.doi.org/10.1043/0014-
3820(2005)0592.0.CO;2
Vaughton G, Ramsey M, Simpson I. Does selfing provide reproductive assurance in the perennial herb bulbine vagans (asphodelaceae)? Oikos.
2008;117(3):390-398. http://search.proquest.com/docview/211499354?accountid=14696. doi: http://dx.doi.org/10.1111/j.2007.0030-
1299.16365.x. .