View source for Biology:Monoicy

{{Short description|Characteristic of species that produce gametes of both sexes on the same gametophyte}}
 <!--Monoecious and Monoicous are not identical concepts -->

'''Monoicy''' ({{IPAc-en|m|ɒ|ˈ|n|oʊ|ə|s|i}}) is a [[Biology:Sexual system|sexual system]] in [[Biology:Haploid|haploid]] plants (mainly [[Biology:Bryophyte|bryophyte]]s) where both sperm and eggs are produced on the same [[Biology:Gametophyte|gametophyte]], in contrast with [[Biology:Dioicy|dioicy]], where each gametophyte produces only sperm or eggs but never both.<ref name=Crandall-Stotler>Crandall-Stotler, B.J. & Bartholomew-Began, S.E. (2007). ''Morphology of Mosses (Phylum Bryophyta)''. In: Flora of North America Editorial Committee, eds. (1993+).  ''Flora of North America North of Mexico''.  16+  vols.  New York and Oxford. Volume 27, 2007.</ref><ref name=BellHelmsley>Bell, P.R. & Helmsley, A.R. (2000). ''Green plants, their origin and diversity'' (2nd ed.). Cambridge University Press.</ref>   Both '''monoicous''' ({{IPAc-en|m|ɒ|ˈ|n|oʊ|ə|k|ə|s}})<ref>{{Cite dictionary |url=http://www.lexico.com/definition/monoicous |archive-url=https://web.archive.org/web/20211221101533/https://www.lexico.com/definition/monoicous |url-status=dead |archive-date=December 21, 2021 |title=monoicous |dictionary=Lexico UK English Dictionary |publisher=[[Organization:Oxford University Press|Oxford University Press]]}}</ref> and '''dioicous''' gametophytes produce gametes in gametangia by [[Biology:Mitosis|mitosis]] rather than [[Biology:Meiosis|meiosis]], so that sperm and eggs are genetically identical with their parent gametophyte.

It has been suggested that monoicy may have benefits in dry habitats where the ability to produce sporophytes is limited due to lack of water.<ref>{{Cite book|last=Windsor|first=Jon and Lesley Lovett-Doust Professor of Biology the University of|url=https://books.google.com/books?id=Yjv1woP0QtYC&dq=Monoicy&pg=PA292|title=Plant Reproductive Ecology : Patterns and Strategies: Patterns and Strategies|date=1988-07-07|publisher=Oxford University Press, USA|isbn=978-0-19-802192-6|language=en}}</ref>{{Rp|page=292}}

Monoicy is similar to, and often conflated with, [[Biology:Monoecy|monoecy]], which applies to seed plants (spermatophytes) and refers to separate male and female cones or flowers on the same plant.

==Etymology and history==
The word '''monoicous''' and the related forms '''mon(o)ecious''' are derived from the Greek mόνος (''mónos''), ''single'', and οἶκος (''oîkos'') or οἰκία (''oikía''), ''house''.  The words '''dioicous''' and '''di(o)ecious''' are derived from οἶκος or οἰκία and δι- (di-), twice, double. (''(o)e'' is the Latin way of transliterating Greek οι, whereas ''oi'' is a more straightforward modern way.) Generally, the terms "monoicous" and "dioicous" have been restricted to description of haploid sexuality (gametophytic sexuality), and are thus used primarily to describe bryophytes in which the gametophyte is the dominant generation.  Meanwhile, "monoecious" and "dioecious" are used to describe diploid sexuality (sporophytic sexuality), and thus are used to describe tracheophytes (vascular plants) in which the [[Biology:Sporophyte|sporophyte]] is the dominant generation.<ref name="Villareal">{{cite journal|last1=Villarreal|first1=J.C. |last2=Renner |first2=S.S. |title=Correlates of monoicy and dioicy in hornworts, the apparent sister group to vascular plants |journal=BMC Evolutionary Biology |volume=13 |issue=239 |pages=1471–2148 |date=2013 |doi=10.1186/1471-2148-13-239 |pmid=24180692 |pmc=4228369 |doi-access=free }}</ref><ref name=Shaw&Goffinet>{{cite book |editor=Shaw AJ & Goffinet B |date=2000 |author=Buck WR & Goffinet B |title=Bryophyte Biology |chapter=Morphology and classification of mosses |location=New York |publisher=Cambridge University Press |isbn=978-0-521-66794-4}}</ref>{{rp|82}} However, this usage, although precise, is not universal, and "monoecious" and "dioecious" are still used by some bryologists for the gametophyte.<ref>See e.g. {{Harvnb|Taylor|Eppley|Jesson|2007}}.</ref>

== Occurrence ==
40% of mosses are monoicious.<ref>{{Cite book|url=https://books.google.com/books?id=LlfBBwAAQBAJ&dq=dioicy+evolved+in+liverworts&pg=PA109|title=Genomes and Evolution of Charophytes, Bryophytes, Lycophytes and Ferns|date=2016-03-23|publisher=Academic Press|isbn=978-0-12-801324-3|pages=109|language=en}}</ref>

==Bryophyte sexuality==

Bryophytes have life cycles that are [[Biology:Gametophyte|gametophyte]] dominated. The longer lived, more prominent autotrophic plant is the gametophyte. The sporophyte in mosses and liverworts consists of an unbranched stalk (a seta) bearing a single [[Biology:Sporangium|sporangium]] or spore-producing capsule. Even when capable of photosynthesis, as in mosses and hornworts, bryophyte sporophytes require additional photosynthate from the gametophyte to sustain growth and spore development and are dependent on the gametophyte for their supplies of water, mineral nutrients and nitrogen.<ref name=Thomas1978>{{cite journal | last1 = Thomas | first1 = R.J. | last2 = Stanton | first2 = D.S. | last3 = Longendorfer | first3 = D.H. | last4 = Farr | first4 = M.E. | year = 1978 | title = Physiological evaluation of the nutritional autonomy of a hornwort sporophyte | journal = Botanical Gazette | volume = 139 | issue = 3| pages = 306–311 | doi=10.1086/337006| s2cid = 84413961 }}</ref><ref name=Glime2007>Glime, J.M. (2007). ''Bryophyte Ecology''. Vol. 1.  ''Physiological Ecology''. Ebook sponsored by Michigan Technological University and the International Association of Bryologists. Accessed on 4 March 2013 at http://www.bryoecol.mtu.edu/chapters/5-9Sporophyte.pdf {{Webarchive|url=https://web.archive.org/web/20130326072218/http://www.bryoecol.mtu.edu/chapters/5-9Sporophyte.pdf |date=2013-03-26 }}.</ref>

Antheridia and archegonia are often clustered. A cluster of antheridia is called an androecium while a cluster of archegonia is called a gynoecium. (Note these terms have a different meaning when used to refer to flower structures.)

Bryophytes have the most elaborate gametophytes of all living land plants, and thus have a wide variety of gametangium positions and developmental patterns.

Gametangia are typically borne on the tips of shoots, but may also be found in the axils of leaves, under thalli or on elaborate structures called gametangiophores.

Bryophyte species may be:

* '''Autoicous''' meaning that androecia and gynoecia are found on the same individual (monoicous) but in distinctly separate locations. If these are on separate branches, the term '''cladautoicous''' can be applied.
* '''Synoicous''' (also called '''androgynous''') bryophytes produce antheridia and archegonia interspersed in the same cluster.
*'''Paroicous''' bryophytes produce antheridia and archegonia in separate clusters in different leaf axils.
* '''Heteroicous''' bryophyte species may be either monoicous or sequentially dioicous depending on environmental conditions.  This condition is also called '''polygamous''' or '''polyoicous'''.

==Role in survival==
There can be both selective advantages and selective disadvantages for organisms that are monoicous or dioicous.  Monoicous bryophytes can easily reproduce sexually, since both sexes can be found on the same organism.  On the other hand, this can lead to [[Biology:Inbreeding|inbreeding]] and reduce genetic variation within populations.<ref>{{Cite journal |last1=Taylor |first1=P.J. |last2=Eppley |first2=S.M. |last3=Jesson |first3=L.K. |year=2007 |title=Sporophytic inbreeding depression in mosses occurs in a species with separate sexes but not in a species with combined sexes |journal=American Journal of Botany |volume=94 |issue=11 |pages=1853–9 |name-list-style=amp | doi = 10.3732/ajb.94.11.1853 |pmid=21636380|doi-access=free }}</ref>  Dioicous organisms necessarily exchange genes with other organisms of the species during sexual reproduction, increasing [[Biology:Zygosity|heterozygosity]] and variability (given a sufficiently large variable mating population).  If isolated, however, organisms may only reproduce asexually, which could present a severe selective disadvantage over time.  Bryophyte sperm dispersal can therefore be key to species longevity, particularly in dioicous species.  While sperm dispersal is typically passive, with sperm dispersing through water, certain species exhibit very active dispersal mechanisms, such as aerial dispersal recently described in the liverwort ''[[Biology:Conocephalum conicum|Conocephalum conicum]]''.<ref name=Shimamuraetal>{{cite journal | last1 = Shimamura | first1 = Masaki | last2 = Yamaguchi | first2 = Tomio | last3 = Deguchi | first3 = Hironori | year = 2007 | title = Airborne sperm of ''Conocephalum conicum'' (Conocephalaceae)" | journal = Journal of Plant Research | volume = 121 | issue = 1| pages = 69–71 | doi=10.1007/s10265-007-0128-6| pmid = 18058191 | s2cid = 37902329 }}</ref>

== Evolution ==
{{Main|Biology:Evolution of sexual reproduction}}
The ancestral sexual system in bryophytes is unknown but it has been suggested monoicy and dioicy evolved several times.<ref>{{Cite journal|last1=McDaniel|first1=Stuart F.|last2=Perroud|first2=Pierre-François|date=2012|title=Invited perspective: bryophytes as models for understanding the evolution of sexual systems|url=https://www.jstor.org/stable/41486736|journal=The Bryologist|volume=115|issue=1|pages=1–11|doi=10.1639/0007-2745-115.1.1|jstor=41486736|s2cid=85943617|issn=0007-2745|access-date=2021-08-23|archive-date=2021-08-23|archive-url=https://web.archive.org/web/20210823133614/https://www.jstor.org/stable/41486736|url-status=live}}</ref>

In the liverwort genus ''[[Biology:Radula (plant)|Radula]]'' it was found that monoicy was a recent evolutionary acquisition connected to epiphytism, arising 6 times.<ref>{{Cite book|last1=Ramawat|first1=Kishan Gopal|url=https://books.google.com/books?id=qXvSBQAAQBAJ&dq=monoicy+evolved+in+liverworts&pg=PA72|title=Reproductive Biology of Plants|last2=Merillon|first2=Jean-Michel|last3=Shivanna|first3=K. R.|date=2016-04-19|publisher=CRC Press|isbn=978-1-4822-0133-8|language=en}}</ref>{{Rp|page=72}}

==References==
{{reflist}}


[[Category:Plant morphology]]
[[Category:Plant reproduction]]
[[Category:Plant sexuality]]

{{Sourceattribution|Monoicy}}