monoecy
{{Short description|Sexual system in seed plants}}
{{Distinguish|Monoicy}}
Monoecy ({{IPAc-en|m|ə|ˈ|n|iː|s|i}}; adj. monoecious {{IPAc-en|m|ə|ˈ|n|iː|ʃ|ə|s}}){{Cite dictionary |url=http://www.lexico.com/definition/monoecious |archive-url=https://web.archive.org/web/20210905101905/https://www.lexico.com/definition/monoecious |url-status=dead |archive-date=September 5, 2021 |title=monoecious |dictionary=Lexico UK English Dictionary |publisher=Oxford University Press}} is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant.{{Cite book|last=Batygina|first=T. B.|url=https://books.google.com/books?id=4VOWDwAAQBAJ&q=monoecy&pg=PA43|title=Embryology of Flowering Plants: Terminology and Concepts, Vol. 3: Reproductive Systems|date=2019-04-23|publisher=CRC Press|isbn=978-1-4398-4436-6|pages=43|language=en}} It is a monomorphic sexual system comparable with gynomonoecy, andromonoecy and trimonoecy, and contrasted with dioecy where individual plants produce cones or flowers of only one sex and with bisexual or hermaphroditic plants in which male and female gametes are produced in the same flower.{{Cite journal|last1=Torices|first1=Rubén|last2=Méndez|first2=Marcos|last3=Gómez|first3=José María|date=2011|title=Where do monomorphic sexual systems fit in the evolution of dioecy? Insights from the largest family of angiosperms|journal=New Phytologist|language=en|volume=190|issue=1|pages=234–248|doi=10.1111/j.1469-8137.2010.03609.x|pmid=21219336|issn=1469-8137|doi-access=free|bibcode=2011NewPh.190..234T }}
Monoecy often co-occurs with anemophily, because it prevents self-pollination of individual flowers and reduces the probability of self-pollination between male and female flowers on the same plant.{{Cite book|last=Karasawa|first=Marines Marli Gniech|url=https://books.google.com/books?id=prsDCwAAQBAJ&dq=monoecy+not+in+animals&pg=PA32|title=Reproductive Diversity of Plants: An Evolutionary Perspective and Genetic Basis|date=2015-11-23|publisher=Springer|isbn=978-3-319-21254-8|language=en}}{{Rp|32}}
Monoecy in angiosperms has been of interest for evolutionary biologists since Charles Darwin.{{Cite journal|last1=Nozaki|first1=Hisayoshi|last2=Mahakham|first2=Wuttipong|last3=Heman|first3=Wirawan|last4=Matsuzaki|first4=Ryo|last5=Kawachi|first5=Masanobu|date=2020-07-02|title=A new preferentially outcrossing monoicous species of Volvox sect. Volvox (Chlorophyta) from Thailand|journal=PLOS ONE|language=en|volume=15|issue=7|pages=e0235622|doi=10.1371/journal.pone.0235622|issn=1932-6203|pmc=7332039|pmid=32614898|bibcode=2020PLoSO..1535622N|doi-access=free}}
Terminology
Monoecious comes from the Greek words for one house.{{Cite book|last1=Purves|first1=William K.|url=https://books.google.com/books?id=kS-h84pMJw4C&q=monoecious+means+one+house|title=Life: The Science of Biology|last2=Sadava|first2=David E.|last3=Orians|first3=Gordon H.|last4=Heller|first4=H. Craig|date=2001|publisher=Macmillan|isbn=978-0-7167-3873-2|pages=192|language=en}}
History
The term monoecy was first introduced in 1735 by Carl Linnaeus. Darwin noted that the flowers of monoecious species sometimes showed traces of the opposite sex function, suggesting that they evolved via hermaphroditism.{{Cite book|first1=Roger A. |last1=Pedersen |first2=Gerald P. |last2=Schatten|url=https://books.google.com/books?id=ZsMhkZpUkO4C&q=how+Gynomonoecious+evolved&pg=PA180|title=Current Topics in Developmental Biology|date=1998-02-03|publisher=Academic Press|isbn=978-0-08-058461-4|pages=180|language=en}} Monoecious hemp was first reported in 1929.{{Cite book|last1=Rowell|first1=Roger M.|url=https://books.google.com/books?id=V79kbwVW1wQC&q=dioecy+first+discovered&pg=PA49|title=Paper and Composites from Agro-Based Resources|last2=Rowell|first2=Judith|date=1996-10-15|publisher=CRC Press|isbn=978-1-56670-235-5|pages=49|language=en}}
Occurrence
Monoecy is most common in temperate climates{{Cite book|last=Willmer|first=Pat|url=https://books.google.com/books?id=1_eWTM2_kfcC&q=Monoecy&pg=PA85|title=Pollination and Floral Ecology|date=2011-07-05|publisher=Princeton University Press|isbn=978-1-4008-3894-3|pages=85|language=en}} and is often associated with inefficient pollinators or wind-pollinated plants.{{Cite book|last=Glover|first=Beverley|url=https://books.google.com/books?id=uXMVDAAAQBAJ&q=monoecy+oxford&pg=PA139|title=Understanding Flowers and Flowering Second Edition|date=February 2014|publisher=Oxford University Press|isbn=978-0-19-966159-6|pages=139|language=en}}{{cite journal|last1=Friedman|first1=Janice|last2=Barrett|first2=Spencer C. H.|date=January 2009|title=The Consequences of Monoecy and Protogyny for Mating in Wind-Pollinated Carex|journal=The New Phytologist|volume=181|issue=2|pages=489–497|doi=10.1111/j.1469-8137.2008.02664.x|jstor=30224692|pmid=19121043|doi-access=free|bibcode=2009NewPh.181..489F }} It may be beneficial to reducing pollen-stigma interference,{{clarify|reason=how does this work? and why is it important?|date=August 2021}} thus increasing seed production.{{Cite book|last=Patiny|first=Sébastien|url=https://books.google.com/books?id=lOMT3R2EpMIC&q=Monoecy&pg=PA33|title=Evolution of Plant-Pollinator Relationships|date=2011-12-08|publisher=Cambridge University Press|isbn=978-1-139-50407-2|pages=33|language=en}}
Around 10% of all seed plant species are monoecious. It is present in 7% of angiosperms.{{rp|8}} Most Cucurbitaceae are monoecious{{Cite book|last=Pessarakli|first=Mohammad|url=https://books.google.com/books?id=jnGmCwAAQBAJ&q=plant+sex+organs|title=Handbook of Cucurbits: Growth, Cultural Practices, and Physiology|date=2016-02-22|publisher=CRC Press|isbn=978-1-4822-3459-6|pages=171|language=en}} including most watermelon cultivars.{{Cite book|last1=Prohens-Tomás|first1=Jaime |url=https://books.google.com/books?id=GehFAAAAQBAJ&q=monoecy+in+watermelon&pg=PA390 |title=Vegetables I: Asteraceae, Brassicaceae, Chenopodicaceae, and Cucurbitaceae|last2=Nuez|first2=Fernando|date=2007-12-06|publisher=Springer Science & Business Media|isbn=978-0-387-30443-4|pages=390|language=en}} It is prevalent in Euphorbiaceae.{{cite book | editor-last=Kubitzki | editor-first=Klaus | title=The Families and Genera of Vascular Plants - Volume XI - Flowering Plants, Eudicots - Malpighiales | publisher=Springer | publication-place=Heidelberg | year=2014 | isbn=978-3-642-39416-4 | oclc=868922400 | pages=51–216/x+331 | last=Webster | first=G. L. | chapter=Euphorbiaceae}} {{ISBN|978-3-642-39417-1}}. {{ISBN|3642394167}}.{{Cite book|last1=Bahadur|first1=Bir|url=https://books.google.com/books?id=TAQMI-ikrvYC&q=Monoecy&pg=PA27|title=Jatropha, Challenges for a New Energy Crop: Volume 2: Genetic Improvement and Biotechnology|last2=Sujatha|first2=Mulpuri|last3=Carels|first3=Nicolas|date=2012-12-14|publisher=Springer Science & Business Media|isbn=978-1-4614-4915-7|pages=27|language=en}} Dioecy is replaced by monoecy in polyploid populations of Mercurialis annua.{{cite journal |title= Hybridization, polyploidy and evolutionary transitions between monoecy and dioecy in Bryonia (Cucurbitaceae) |first1=Stefanie M. |last1=Volz |first2=Susanne S. |last2=Renner |journal=American Journal of Botany |volume=95 |issue=10 |pages=1297–1306 |date=2008 |doi=10.3732/ajb.0800187 |pmid=21632334 |url=https://epub.ub.uni-muenchen.de/14650/ |url-access=subscription }}
=Maize=
Maize is monoecious since both pistillate (female) and stamenate (male) flowers occur on the same plant. The pistillate flowers are present on the ears of corn and the stamenate flowers are in the tassel at the top of the stalk. In the ovules of the pistillate flowers, diploid cells called megaspore mother cells undergo meiosis to produce haploid megaspores. In the anthers of the stamenate flowers, diploid pollen mother cells undergo meiosis to produce pollen grains. Meiosis in maize requires gene product RAD51, a protein employed in recombinational repair of DNA double-strand breaks.{{cite journal |vauthors=Li J, Harper LC, Golubovskaya I, Wang CR, Weber D, Meeley RB, McElver J, Bowen B, Cande WZ, Schnable PS |title=Functional analysis of maize RAD51 in meiosis and double-strand break repair |journal=Genetics |volume=176 |issue=3 |pages=1469–82 |date=July 2007 |pmid=17507687 |pmc=1931559 |doi=10.1534/genetics.106.062604 }}
Evolution
{{Main|Evolution of sexual reproduction}}
The evolution of monoecy has received little attention.
Male and female flowers evolve from hermaphroditic flowers{{Cite book|last1=Núñez-Farfán|first1=Juan|url=https://books.google.com/books?id=iF70DwAAQBAJ&q=consensus+unisexual&pg=PA177|title=Evolutionary Ecology of Plant-Herbivore Interaction|last2=Valverde|first2=Pedro Luis|date=2020-07-30|publisher=Springer Nature|isbn=978-3-030-46012-9|pages=177|language=en}} via andromonoecy or gynomonoecy.{{Cite book|last=Das|first=Saubhik|url=https://books.google.com/books?id=X0S8DAAAQBAJ&dq=Monoecy&pg=PA148|title=Amaranthus: A Promising Crop of Future|date=2016-07-25|publisher=Springer|isbn=978-981-10-1469-7|pages=|language=en}}{{Rp|148}}
In amaranths monoecy may have evolved from hermaphroditism through various processes caused by male sterility genes and female fertility genes.{{Rp|150}}
Monoecy may be an intermediate state between hermaphroditism and dioecy.{{cite journal |last1=Kinney |first1=M.S. |last2=Columbus |first2=J.T. |last3=Friar |first3=E.A. |title=Dicliny in Bouteloua (Poaceae: Chloridoideae): Implications for the evolution of dioecy |journal=Aliso: A Journal of Systematic and Floristic Botany |volume=23 |issue=1 |pages=605–614 |date=2007 |url=https://scholarship.claremont.edu/cgi/viewcontent.cgi?article=1100&context=aliso}} Evolution from dioecy to monoecy probably involves disruptive selection on floral sex ratios.{{Cite book|last=Avise|first=John|url=https://books.google.com/books?id=OGGsAgAAQBAJ&dq=Monoecy&pg=PA65|title=Hermaphroditism: A Primer on the Biology, Ecology, and Evolution of Dual Sexuality|date=2011-03-15|publisher=Columbia University Press|isbn=978-0-231-15386-7|language=en}}{{Rp|65}} Monoecy is also considered to be a step in the evolutionary pathway from hermaphroditism towards dioecy.{{Cite book |last=Leonard |first=Janet L. |url=https://books.google.com/books?id=0rWZDwAAQBAJ&q=Monoecy&pg=PA91 |title=Transitions Between Sexual Systems: Understanding the Mechanisms of, and Pathways Between, Dioecy, Hermaphroditism and Other Sexual Systems |date=2019-05-21 |publisher=Springer |isbn=978-3-319-94139-4 |language=en}}{{Rp|page=91}} Some authors even argue monoecy and dioecy are related. But, there is also evidence that monoecy is a pathway from sequential hermaphroditism to dioecy.{{Rp|8}}