Diapause

In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.^[1]^[2] It is a physiological state with very specific initiating and inhibiting conditions. The mechanism is a means of surviving predictable, unfavorable environmental conditions, such as temperature extremes, drought, or reduced food availability. Diapause is observed in all the life stages of arthropods, especially insects.

Activity levels of diapausing stages can vary considerably among species. Diapause may occur in a completely immobile stage, such as the pupae and eggs, or it may occur in very active stages that undergo extensive migrations, such as the adult monarch butterfly, Danaus plexippus. In cases where the insect remains active, feeding is reduced and reproductive development is slowed or halted.

Embryonic diapause, a somewhat similar phenomenon, occurs in over 130 species of mammals, possibly even in humans,^[3] and in the embryos of many of the oviparous species of fish in the order Cyprinodontiformes.^[4]

^ The Insects; Structure and Function, 4th Edition. R.F. Chapman, Cambridge University Press, 1998. ISBN 0-521-57048-4, p 403.
^ Tauber, M.J., Tauber, C.A., Masaki, S. (1986) Seasonal Adaptations of Insects. Oxford University Press^{[page needed]}
^ Fenelon, Jane C.; Renfree, Marilyn B. (2017-09-15). "The enigma of embryonic diapause". Development. 144 (18): 3199–3210. doi:10.1242/dev.148213. ISSN 1477-9129. PMID 28928280.
^ Glen E. Collier; William J. Murphy (August 1997). "A molecular phylogeny for aplocheiloid fishes (Atherinomorpha, Cyprinodontiformes): the role of vicariance and the origins of annualism". Mol. Biol. Evol. 14 (8): 790–9. doi:10.1093/oxfordjournals.molbev.a025819. PMID 9254916. Annual aplocheiloid killifish embryos possess a rare ability among vertebrates to enter stages of developmental arrest (diapause) when subjected to adverse environmental conditions.

[1] The Insects; Structure and Function, 4th Edition. R.F. Chapman, Cambridge University Press, 1998. ISBN 0-521-57048-4, p 403.

[Tauber-2] Tauber, M.J., Tauber, C.A., Masaki, S. (1986) Seasonal Adaptations of Insects. Oxford University Press^{[page needed]}

[3] Fenelon, Jane C.; Renfree, Marilyn B. (2017-09-15). "The enigma of embryonic diapause". Development. 144 (18): 3199–3210. doi:10.1242/dev.148213. ISSN 1477-9129. PMID 28928280.

[4] Glen E. Collier; William J. Murphy (August 1997). "A molecular phylogeny for aplocheiloid fishes (Atherinomorpha, Cyprinodontiformes): the role of vicariance and the origins of annualism". Mol. Biol. Evol. 14 (8): 790–9. doi:10.1093/oxfordjournals.molbev.a025819. PMID 9254916. Annual aplocheiloid killifish embryos possess a rare ability among vertebrates to enter stages of developmental arrest (diapause) when subjected to adverse environmental conditions.

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