Editing Coccolithophore (section)

===Life history strategy===
[[File:Life cycle strategies of phytoplankton.png|thumb|upright=1.7| {{center|Life cycle strategies of phytoplankton}}  (a) [[dinoflagellate]]s tend to utilize a [[haplontic]] (asexual) life cycle, (b) [[diatom]]s tend to utilize a [[diplontic]] (sexual) life cycle, and (c) coccolithophores tend to utilize a haplo-diplontic life cycle. Note that not all coccolithophores calcify in their haploid phase.<ref name="de Vries2021">{{cite journal | last1=de Vries | first1=Joost | last2=Monteiro | first2=Fanny | last3=Wheeler | first3=Glen | last4=Poulton | first4=Alex | last5=Godrijan | first5=Jelena | last6=Cerino | first6=Federica | last7=Malinverno | first7=Elisa | last8=Langer | first8=Gerald | last9=Brownlee | first9=Colin | title=Haplo-diplontic life cycle expands coccolithophore niche | journal=Biogeosciences | publisher=Copernicus GmbH | volume=18 | issue=3 | date=2021-02-16 | issn=1726-4189 | doi=10.5194/bg-18-1161-2021 | pages=1161–1184| bibcode=2021BGeo...18.1161D | s2cid=233976784 | doi-access=free }} [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].</ref>]]

The complex life cycle of coccolithophores is known as a [[Biological life cycle#Haplodiplontic life cycle|haplodiplontic life cycle]], and is characterized by an alternation of both asexual and sexual phases. The asexual phase is known as the [[haploid]] phase, while the sexual phase is known as the [[diploid]] phase. During the haploid phase, coccolithophores produce haploid cells through [[mitosis]]. These haploid cells can then divide further through mitosis or undergo sexual reproduction with other haploid cells. The resulting diploid cell goes through [[meiosis]] to produce haploid cells again, starting the cycle over. With coccolithophores, asexual reproduction by mitosis is possible in both phases of the life cycle, which is a contrast with most other organisms that have alternating life cycles.<ref name="Young2003"/> Both [[abiotic]] and [[biotic factors]] may affect the frequency with which each phase occurs.<ref name=Vardi2012>{{citation |journal=Proceedings of the National Academy of Sciences |volume=109 |issue=47 |year=2012 |pages=19327–19332 |title=Host–virus dynamics and subcellular controls of cell fate in a natural coccolithophore population |first=A. |last=Vardi |doi=10.1073/pnas.1208895109 |pmid=23134731 |display-authors=etal  |bibcode = 2012PNAS..10919327V |pmc=3511156 |doi-access=free }}</ref>

Coccolithophores [[asexual reproduction|reproduce asexually]] through [[Fission (biology)|binary fission.]] In this process the coccoliths from the parent cell are divided between the two daughter cells. There have been suggestions stating the possible presence of a sexual reproduction process due to the diploid stages of the coccolithophores, but this process has never been observed.<ref name=Houdan2006>{{citation |journal=Aquatic Microbial Ecology |volume=44 |year=2006 |pages=291–301 |title=. Ecology of oceanic coccolithophores. I. Nutritional preferences of the two stages in the life cycle of Coccolithus braarudii and Calcidiscus leptoporus |last1=Houdan |doi=10.3354/ame044291|last2=Probert |first2=I |last3=Zatylny |first3=C |last4=Véron |first4=B |last5=Billard |first5=C |display-authors=etal|doi-access=free }}</ref>

[[R/K selection theory|K or r- selected strategies]] of coccolithophores depend on their life cycle stage. When coccolithophores are diploid, they are r-selected. In this phase they tolerate a wider range of nutrient compositions.  When they are haploid they are K- selected and are often more competitive in stable low nutrient environments.<ref name=Houdan2006 /> Most coccolithophores are K strategist and are usually found on nutrient-poor surface waters. They are poor competitors when compared to other phytoplankton and thrive in habitats where other phytoplankton would not survive.<ref name=Hogan2009 /> These two stages in the life cycle of coccolithophores occur seasonally, where more nutrition is available in warmer seasons and less is available in cooler seasons. This type of life cycle is known as a complex heteromorphic life cycle.<ref name=Houdan2006 />