Talk:Biological life cycle

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K and r selection[edit]

I think the K and r selection section currently in sexual selection belongs here (ie life history), or in a closely related entry, life history theory?. --Pete Hurd

No, K and r are population biology topis; this is cell biology (perhaps). Dysmorodrepanis (talk) 21:03, 10 April 2009 (UTC)

Rename Page[edit]

If this page were retitled 'Life cycle' it would make for tidier internal links from other pages (DMC)

Not sure why that would be true (please explain), but as the word has more meaning than just as a biological phenomenon, it seems unwise to change it. - Marshman 02:22, 14 February 2006 (UTC)
I would tend to agree that it should redirect here (or rather this page be moved to life cycle with a dab page created, though checking the links at life cycle for context seems to indicate there are a reasonable portion of non-biology links. Richard001 10:14, 11 June 2007 (UTC)


Hydrozoa and "worms" and many others are diplonts as typical for animals, but they differ from the standard strategy in having an asexual cloining phase. This article needs expansion in that direction. 21:03, 10 April 2009 (UTC)

Use of specialized language[edit]

The subject of this article of is of fundamental importance in biology, and as such it is (I presume) well understood by biologists. It gives a concise overview of the subject, but does so by using language foreign to the non-specialist. It is true that dificult terminology is hyperlinked, but this does little to improve readability. I think it would be good to unpack some of the jargon within the article. This would make it more comprehensible to non-specialiststs, who I would presume are the target audience of the article. Tapatio (talk) 07:45, 11 August 2009 (UTC)

Possibly, though it's at a perfect level for undergraduate biology students! Seriously though, I think Alternation of generations provides a pretty good summary of the basic concept of diploid and haploid life phases, and the broader idea of a life history can then be understood by comparing that with mammalian reproduction, which most people are more familiar with. You don't exactly want to be defining words like meiosis or spore in this article, right? Dewert (talk) 22:58, 4 December 2009 (UTC)

life cycle of a bear[edit]

life cycle of a bear —Preceding unsigned comment added by (talk) 01:52, 20 November 2009 (UTC)

seriously? a bear? no way! Dewert (talk) 22:54, 4 December 2009 (UTC)


According to Noctilucales#Characteristics - admittedly after I fixed a probable spelling mistake - these (and speculatively other dinoflagellates) also have gametic meiosis. Is the list supposed to be exhaustive? Should we add Noctoluticales to the list? Cucamber (talk) 19:58, 7 January 2010 (UTC)

Limits of definition of "biological life cycle"[edit]

Just a note that this "life cycle" in this context only refers to passing of one generation to the next. It does NOT refer to life cycle from original conception (the "first") to extinction (the "last"). -- (talk) 02:27, 8 February 2011 (UTC)

Grammatical errors in the first paragraph[edit]

I see many grammatical errors in the first paragraph and some sentences are not even complete. English isn't my native language so I'm not too confident about correcting them myself. — Preceding unsigned comment added by (talk) 17:03, 3 March 2012 (UTC)

Incorrect statement in Haplodiplontic life cycle section?[edit]

The Haplodiplontic life cycle section has this sentence, which appears to have been copy-pasted from the Diplontic life cycle section:

"In the whole cycle, gametes are usually the only haploid cells, and mitosis usually occurs only in the diploid phase."

I'm not an expert on this, but this seems factually incorrect to me, since a Haplodiplontic life cycle would have a multicellular haploid phase, which would necessarily have to undergo mitosis. Could someone more knowledgeable than me correct this if I'm right? Equaaldoors (talk) 22:52, 11 March 2012 (UTC)

Article restructuration[edit]

I think that the article must be restructured, clarifying some concepts, according to Díaz-González [1], the French article [2], and the Dutch article [3]:

  • (1) about the concepts of generation, phase, individual and biont:
    • generation, for geneticists (Simon, 2007 [4]): intervalle de temps séparant l'oeuf de l'oeuf c'est à dire l'ensemble des mitoses, et éventuellement des phases individualisées que sépare deux fécondations. [Interval between an egg and other egg, that is, the set of mitosis, and eventually the individualized phases that separates two fertilizations.]
    • génération (Feldmann, 1978, cf. Simon, 2007, [5]): une génération, chez les végétaux, est une étape du développement d'un organisme débutant par une cellule reproductrice (spore ou zygote) et aboutissant, après une activité végétative marquée, à la production d'autres cellules reproductrices différentes ou non de celle ayant produit la génération envisagée. [A generation in plants is a developmental stage of a organism starting by a reproductive (spore or zygote) cell and ending after a marked vegetative activity, with the production or other different (or not) reproductive cells from that which produced the contemplated generation.]
    • génération (Martens, 1954, cf. Simon, 2007, [6]): pour Martens, au contraire de J. Feldmann, cette activité végétative doit comporter des mitoses. [For Martens, unlike J. Feldmann, this vegetative activity must include mitosis.] So, maybe it is not applicable to some unicellular organisms (do exist unicellular eukaryotes without mitosis, only with meiosis/fertilization?). See also Boudoresque (2015).
I'll start a new section below. Sminthopsis84 (talk) 19:53, 12 November 2014 (UTC)
    • generation and phase (Smith, 1938, [7]): he seems to use "generation" for multi-celled phases and "phase" only for one-celled phases
    • individual or biont (Svedelius, 1915, [8], 1931, [9], Díaz-González [10]): it seems to have a meaning alike that of generation used by Feldmann or Martens, but a generation, to be considered a biont, must be physiologically (nutritionally) independent of other generation.
    • biont (Celakovsky’s, 1874, cf. Haig, 2008 [11])
  • (2) types of life cycle according to the "cytologic alternation of nuclear phases" - i.e., according to the nuclear phases present in the cycle (excluding that in gametes and zygotes); or to the moment when meiosis occur; or to the moment when mitosis occur; cf. Feldmann (1952), [12], Feldmann (1972), [13], [14], Beukeboom & Perrin (2014):
    • haplophasic cycle: haplont organisms, only zygote is diploid; zygotic meiosis; with no diploid mitoses
    • diplophasic cycle: diplont organisms, only gametes are haploid; gametic meiosis; with no haploid mitoses
    • diplohaplophasic cycle: diplohaplont organisms, two vegetative phases, haploid and diploid; sporic meiosis; with both haploid and dilpoid mitoses
      • Note 1: Battaglia (1985) [15] makes a revision of the terminology used to describe life cycles: "As early as 1875, with reference to the sex dimorphism in Juglans regia, Federico Delpino (1875) [cf. Battaglia (2009) [16]] proposed the terms "aplonte", "diplonte" & "triplonte" (= pleionte) whilst in the next century the same terms and very similar ones, without due attention to historical priorities and etymological exactness are universally adopted with regard to the alternation of generations: Haplophase & Diplophase in Vuillemin (1908); Dihaplophase in Bonnet (1912); Haplont, Diplont in Fischer (cf. Goeldi & Fischer, 1916); Haplont, Diplont, Diplohaplont in Hartmann (1918) [17]; Haplobiont, Diplobiont, Haplodiplobiont in Wettstein (1924) [18]; Isohaplont & Miktohaplont in Kniep (1928) [19]; hémiplonte & pseudohaplonte in Dangeard (1947) [20]; Uplont in Widder (1951) [21]; Polyplont in Chapmann & Chapmann (1961) [22], etc."
      • Note 2: South (1987) [23] uses the terms zygotic, gametic, sporic and somatic life cycles; D'Amato (1977) [24] uses the terms haplontic, diplontic and diplohaplontic life cycles, Ruppert (2004) [25] uses the terms asexual haploid cycle, sexual haploid cycle, diploid cycle and haplodiploid cycle.
  • (3) types of life cycle according to the "morphologic alternation of generations" - i.e., according to the number of generations in a cycle, by Feldmann (1952), [26], Chapman (1962), [27], Feldmann (1972), [28], [29], Díaz-González, [30]:
    • monogenetic cycle (no morphological alternatin of generations)
    • digenetic cycle
    • trigenetic cycle
      • Note 1: these terms are also used in zoology to indicate the number of hosts in life cycles of parasites.
      • Note 2: van den Hoek et al. (1972, [31]) prefer the terms monophasic, diphasic and triphasic cycles.
  • (4) types of organisms according to the "alternation of individuals" - i.e., according to the number of individuals (=bionts), except males and females, in nature, according to Svedelius, 1915, [32], 1931, [33], and Díaz-González [34]:
    • haplobiont organisms (they can be either haplont, diplont or diplohaplont organisms)
    • diplobiont organisms
      • Note 1: the bionts or individuals need not necessarily coincide with the cytological generations (nuclear phases) or with the morphological generations.
Proposal, based on Díaz González et al.: PAvdK (talk) 13:30, 30 December 2015 (UTC);
Biological life cycles of sexually reproducing organisms
Organism: Life cycle: Meiosis: Morfological alternation of generations:
haplont haplophasic zygotic monogenetic
× ×
diplont diplophasic gametic monogenetic
digenetic diplont ×
= haplodiplont
= heterophasic
sporic =
× digenetic diplohaplont: trigenetic

Small readability improvement (hopefully) PAvdK (talk) 06:50, 2 June 2016 (UTC)

Alternation of generations
(1 generation)
(2 generations)
(3 generations)
(1 individual)
1 individual
1 individual
1 individual
1 individual
(2 individuals)
1st individual 2nd individual
1st individual 2nd individual


Interesting articles and books[edit]

Some interesting papers and books that may enrich the article:

Zorahia (talk) 15:21, 5 October 2013 (UTC)

As almost an aside, wikipedia is surprisingly deficient, it seems, in a definition of "generation" that would be appropriate here. I've added something to Generation (disambiguation), but it is not in an ideal form. Sminthopsis84 (talk) 21:24, 6 October 2013 (UTC)

It's important also to keep WP:MTAU in mind: no matter what is discussed, it needs to be made understandable to people who don't know or don't care what haplophasic meiosis is. I'm an educated biologist and am familiar with zygotic and gametic meiosis, yet never heard the terms haplontic or diplontic in my life, thus their use as headers may further burden less-famililar readers. The life cycle is a very fundamental concept that needs a thorough yet comprehensible explanation. Rather than potentially overwhelm nonspecialist or non-collegiate readers, this article might better serve as an overview or introduction, with haplodiplonty etc. described in depth in their own article for those interested. Most basic information should be summarized first, leading to more complex discussion or soft redirects when it gets into the nitty gritty. Thus, largely unknown terms like sporocyst and redia should probably not be in the first paragraph of the lead.--Animalparty-- (talk) 03:55, 30 March 2014 (UTC)

Agree. It is also important, I think, to keep this page on life cycles reasonably free of material duplicated from alternation of generations. Sminthopsis84 (talk) 15:06, 30 March 2014 (UTC)


Is anyone able to make a little stub page or a section in another article that defines Biont? I think that would be very helpful. (A wikipedia search at present gives the impression that the term is only used in science fiction.) Sminthopsis84 (talk) 14:05, 4 October 2014 (UTC)

Eukaryotes without mitosis[edit]

It was asked above what this book says about the existence of some eukaryotes that lack mitosis. Origins of Sex: Three Billion Years of Genetic Recombination By Lynn Margulis I don't have access to the whole book either, but here are some intriguing excerpts.

"Unlike animals, fungi, and plants, protoctists may lack mitosis, microtubules, mitochondria, and other common eukaryotic organelles. The distribution, including the absence, of these features considered essential to the sexual meiotic process provides us with fascinating clues to its origins."

"Only recently has comprehensive information about protoctists been available in one source, Handbook of Protoctista (Margulis et al. 1990), comparable to those for bacteria: Bergey's Manual (Buchanan and Gibbons, 1974) and more recently The Prokaryotes (Starr et al., 1983)."

"Karyoblastea (amitotic amoebae) The phylum karyoblastea inclues anaerobic giant amoebae that lack mitochondria, chromosomes, mitotic spindles, mitosis, and meiotic sex. Several types of bacterial endosymbionts have been noted inside karyoblastea, including methanogens, which are anaerobic bacteria capable of produging methane gas. Pelomyza palustris, a pond-water form, is virtually the only species studied. Undulipodia may be present on its surface."

"Dinomastigotes (dinoflagellates) ...The DNA organization is unique in this group. Histones forming nucleosomes are absent. The unit DNA fibril densely packed to make permanently condensed chromosomes is more like that of prokaryotes than like the nucleosome-studded particle of other eukaryotes ..."

"Rhizopods ... Sex is absent. ..."

"Actinopods (radiolarians, acantharians, heliozoans) ... Fusion of products of mitosis within a common cyst interpreted to be sex has been observed in heliozoans. Sexuality is unknown in other groups. ..."

"Hyphochytrids ... Sexuality is absent."

"Xanthophytes (yellow-green algae) ... No sexuality has been described for any members."

"Eustigmatophytes and Raphidiophytes ("chloromonads") ... no sexuality of any kind has been documented in them ..."

"Cryptomonads (cryptophytes) ... Rather than by standard mitosis, these mastigotes divide by an extensive developmental process that involves their undulipodia and the formation of a groove. Sex has never been seen in any of them. ..."

"Apicomplexa ("sporozoans") ... Reproduction is by multiple fission (nuclear mitoses in which several nuclear divisions precede cytoplasmic divisions), and small cells are formed. ..."

"Microsporidians (microsporidian parasites) ... They lack mitochondria and even kinetids and undulipodia are unknown. Sexuality has not been documented in the group, and their ribosomes, resembling those of prokaryotes, are smaller than those in the cytoplasm of other eukaryotes. ..." Sminthopsis84 (talk) 19:53, 12 November 2014 (UTC)

In relation to the lack mitosis:
in the article of Pelomyxa, it is said that it has mitosis; in the case of cryptophytes, I think we could say that they lack standard mitosis, but not mitosis; there is an review about mitosis in protozoa (Raikov, 1994), but I don't have access to it...
In relation to the absence of meiotic sex in eukaryotes:
Lahr et al. (2011) point that many amoeboid groups have sex (cryptic in many); Beukeboom et al. (2014) made a review of the presence of sex in many groups (but not all you listed), see the online material (The diversity of sexual cycles and Eukaryota sexual systems overview). Zorahia (talk) 23:47, 12 November 2014 (UTC)
I don't have access to the Raikov review either. Sminthopsis84 (talk) 17:11, 13 November 2014 (UTC)

Assessment comment[edit]

The comment(s) below were originally left at Talk:Biological life cycle/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Rated "high" as high school/SAT biology content. This article ties in with ploidy. It could use some references/sources. - tameeria 23:17, 18 February 2007 (UTC)

Last edited at 23:17, 18 February 2007 (UTC). Substituted at 09:42, 29 April 2016 (UTC)