312:, placental transport accounts for nearly all of the provisioning of nutrients to the embryos before birth. In the uterus, the eggs are very small, about 1 mm in diameter, with very little yolk and very thin shells. The shell membrane is vestigial and transient; its disintegration permits the absorption of nutrients from uterine secretions. The embryo then produces invasive chorionic tissues that grow between the cells of the uterine lining till they can absorb nutrients from maternal blood vessels. As it penetrates the lining, the embryonic tissue grows aggressively till it forms sheets of tissue beneath the uterine epithelium. They eventually strip it away and replace it, making direct contact with maternal capillaries. In several respects, the phenomenon is of considerable importance in theoretical zoology. Blackburn & Flemming (2011) remark that such an endotheliochorial placenta is fundamentally different from that of any known viviparous reptile.
128:
433:
occurrences. Additionally, they state that the previous study does not take into account the morphological and behavioral modifications that would have to occur for reversion to occur. Some of these modifications would be the redevelopment of uterine glands to synthesize and secrete shell fibers, the restoration of the careful timing of oviposition due to eggshell thickness, etc. The degradation and loss of function of oviparous genes during viviparous evolution suggests that these genes would have to re-evolve in order for the reversion of this evolution to occur. Since this re-evolution is near impossible due to the complexity of oviparous reproductive mode, the simple labile characteristic of parity cannot be sufficiently supported.
425:. Advanced ancestral state reconstruction was used to more accurately prove that the reverse evolution of viviparity to oviparity is true. In the analysis, the authors use a maximum likelihood tree to reveal that parity mode is a labile trait in the Squamata order. They also further show through analysis that viviparity is also strongly associated with cooler climates which suggests the previously stated "cold-climate hypothesis" is true.
1725:
49:
399:. Since the developing offspring remains within the mother's body, she becomes, in essence, a walking incubator, protecting the developing young from excessive heat, cold, drought, or flood. This offers powerful options for dealing with excessive changes in climate or when migration events expose populations to unfavourable temperatures or humidities. In
291:, some skinks, and some fish can rely on the placenta for transfer of all necessary nutrients to the offspring and for removal of all the metabolic wastes as well once it has been fully established during the early phases of a pregnancy. In such species, there is direct, intimate contact between maternal and embryonic tissue, though there also is a
403:
reptiles in particular, there is a correlation between high altitudes or latitudes, colder climates and the frequency of viviparity. The idea that the tendency to favour egg-retention selectively under cooler conditions arises from the thermoregulatory benefits, and that it consequently promotes the
373:
In many ways, depending on the ecology and life strategy of the species, viviparity may be more strenuous and more physically and energetically taxing on the mother than oviparity. However, its numerous evolutionary origins imply that in some scenarios there must be worthwhile benefits to viviparous
432:
trait. In their critique, they show that ancestral state reconstruction analyses are reliant on the underlying phylogenetic information provided. The use of a maximum likelihood tree which is vulnerable to phylogenetic error may cause an artificial inflation of the number of viviparity to oviparity
369:
of the mother. Through continued generations of egg retention, viviparous lecithotrophy may have gradually developed; in other words the entire development of the embryo, though still with nutrients provided by the yolk, occurred inside the mother's reproductive tract, after which she would give
381:
There is no one mode of reproduction that is universally superior in selective terms, but in many circumstances viviparity of various forms offers good protection from parasites and predators and permits flexibility in dealing with problems of reliability and economy in adverse circumstances.
1054:
Griffith, O.W.; Blackburn, D.G.; Brandley, M.C.; Dyke, J.U.V.; Whittington, C.M.; Thompson, M.B. (2015). "Ancestral state reconstructions require biological evidence to test evolutionary hypotheses: A case study examining the evolution of reproductive mode in squamate reptiles".
783:
Griffith, OW; Blackburn, DG; Brandley, MC; Van Dyke, JU; Whittington, CW; Thompson, M.B. (2015). "Ancestral state reconstructions require biological evidence to test evolutionary hypotheses: A case study examining the evolution of reproductive mode in squamate reptiles".
365:). One traditional hypothesis concerning the sequence of evolutionary steps leading to viviparity is a linear model. According to such a model, provided that fertilization was internal, the egg might have been retained for progressively longer periods in the
390:
of partly developed embryos in hard times or when they are too numerous for the mother to bring to term, but among the most profoundly advantageous features of viviparity are various forms of physiological support and protection of the embryo, such as
370:
birth to the young as they hatched. The next evolutionary development would be incipient matrotrophy, in which yolk supplies are gradually reduced and are supplemented with nutrients from the mother's reproductive tract.
335:
of the
Cretaceous, use genotypic sex determination (sex chromosomes), much as birds and mammals do. Genotypic sex determination is also found in most reptiles, including many viviparous ones (such as
283:). However, the term is poorly and inconsistently defined, and may be obsolete. This term has been redefined and more commonly referred to as oviparous egg retention or prolonged egg retention.
1162:
96:, where the embryos are developed in eggs that remain carried inside the mother's body until the hatchlings emerge from the mother as juveniles, similar to a live birth.
287:
At least some transport of nutrients from mother to embryo appears to be common to all viviparous species, but those with fully developed placentas such as found in the
247:, are the best-known example, but adaptations in some other animals also have incorporated this principle or close analogies. Other examples include some species of
412:
Through ancestral state reconstruction, scientists have shown that the evolution of viviparity to oviparity may have occurred a maximum of eight times in the genus
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169:; this occurs in all birds, most reptiles, and some fishes. These modes are distinguished from viviparity, which covers all the modes that result in live birth:
1528:
1155:
1518:
127:
319:, which cannot function in an aquatic environment, is seen only in terrestrial viviparous reptiles. Therefore, marine viviparous species, including
860:
Blackburn, Daniel G (2014). "Evolution of vertebrate viviparity and specializations for fetal nutrition: A quantitative and qualitative analysis".
72:
inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives
316:
1407:
1148:
1678:
903:
Lambert, S. M.; Wiens, J. J. (2013). "Evolution of viviparity: a phylogenetic test of the cold-climate hypothesis in phrynosomatid lizards".
642:
Blackburn, D.G.; Flemming, A.F. (2011). "Invasive implantation and intimate placental associations in a placentotrophic
African lizard,
577:
1417:
829:"Convergent evolution of viviparity, matrotrophy, and specializations for fetal nutrition in reptiles and other vertebrates"
1096:
Wang, Y.; Evans, S.E. (2011). "A gravid lizard from the
Cretaceous of China and the early history of squamate viviparity".
689:
Organ, Chris L.; et al. (2009). "Genotypic sex determination enabled adaptive radiations of extinct marine reptiles".
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339:), whilst temperature dependent sex determination is found in some viviparous species, such as the montane water skink (
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There is no relationship between sex-determining mechanisms and whether a species bears live young or lays eggs.
189:
1594:
740:
Robert, Kylie A.; Thompson, Michael B. (2001). "Sex determination: Viviparous lizard selects sex of embryos".
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modes of reproduction; selective pressures have led to its convergent evolution more than 150 times among the
948:"The evolution of oviparity with egg guarding and viviparity in lizards and snakes: A phylogenetic analysis"
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1002:"Early origin of viviparity and multiple reversions to oviparity in squamate reptiles"
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evolution of viviparity as an adaptation, is known as "the cold climate hypothesis".
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Journal of
Experimental Zoology Part B: Molecular and Developmental Evolution
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are believed to have evolved from an ancestral condition of oviparity and
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giving viviparous birth, an unusual mode of reproduction among insects
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of eggs or sibling embryos in some sharks or in the black salamander
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204:: nutrients are provided by the female, often through some form of
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47:
488:"Viviparity and oviparity: Evolution and reproductive strategies"
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Hemotrophic viviparity: a mammal embryo (centre) attached by its
362:
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to control or prevent uncontrolled exchange and the transfer of
219:
84:, where the embryos develop independently outside the mother in
1660:
1144:
610:"Mom Genes: This cockroach species' live births are in its DNA"
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have been differentiated in animals based on relations between
80:
that is at least metabolically independent. This is opposed to
1495:
382:
Variations on the theme in biology are enormous, ranging from
85:
428:
However, others directly refute this notion that parity is a
239:
is arguably the most highly developed form of viviparity.
37:"Viviparous" redirects here. For the gastropod genus, see
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and parents. The five include two nonviviparous modes:
275:, a less developed form of viviparity, occurs in most
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946:Fraipont, M.D.; Clobert, J.; Barbault, R. (1996).
513:. Eagle Mountain, UT: Eagle Mountain Publications.
231:and most mammals exhibit a hemotrophic viviparity.
535:] (in French). Paris, FR: Eds Dunod Sciences.
88:until they are developed enough to break out as
555:. Herpetological Monographs. pp. 371–377.
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533:Reproduction strategies in the animal kingdom
8:
27:Development of the embryo inside the mother
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1665:
1657:
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1141:
529:Les stratégies de reproduction des animaux
218:are fed by the mother through specialized
1017:
963:
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279:, and in most live-bearing bony fishes (
473:
317:Temperature-dependent sex determination
108:form "viviparous" both derive from the
1000:Pyron, R. A.; Burbrink, F. T. (2013).
176:: the zygotes develop in the female's
1534:Hypothalamic–pituitary–prolactin axis
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572:. Springer Reference. p. 3311.
481:
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1529:Hypothalamic–pituitary–gonadal axis
161:, with external fertilisation, and
965:10.1111/j.1558-5646.1996.tb04501.x
76:to a fully or partially developed
25:
1723:
361:(nutrients supplied through the
608:Newbern, E. (26 January 2016).
180:, but find their nutrients by
104:The term "viviparity" and its
1:
597:. Belknap Press. p. 151.
492:Encyclopedia of Reproduction
1711:(Histotrophic, Hemotrophic)
498:. Academic Press: 994–1003.
353:In general, viviparity and
302:In at least one species of
119:, meaning "give birth to".
1868:
1806:Live-bearing aquarium fish
1519:Reproductive endocrinology
595:The Other Insect Societies
569:Encyclopedia of Entomology
566:Capinera, John L. (2008).
337:Pseudemoia entrecasteauxii
228:Pseudemoia entrecasteauxii
142:
36:
29:
1721:
1587:Human reproductive system
1118:10.1007/s00114-011-0820-1
827:Blackburn, D. G. (1992).
582:– via Google Books.
323:and, it now appears, the
190:intra-uterine cannibalism
139:(top) which provides food
593:Costa, James T. (2006).
549:Blackburn, D.G. (2000).
486:Blackburn, D.G. (1999).
115:, meaning "living"; and
30:Not to be confused with
408:Reversion of viviparity
174:Histotrophic viviparity
1747:Internal fertilization
1742:External fertilization
1609:Diseases and disorders
1418:Sexual differentiation
509:Schuett, G.W. (2002).
202:Hemotrophic viviparity
140:
68:is development of the
57:
1801:Gastric-brooding frog
1688:Modes of reproduction
1641:Premature ejaculation
1636:Hard flaccid syndrome
1306:Human sexual activity
862:Journal of Morphology
648:Journal of Morphology
511:Biology of the Vipers
151:modes of reproduction
145:Modes of reproduction
143:Further information:
130:
51:
1770:fish (mouthbrooding)
1631:Erectile dysfunction
846:10.1093/icb/32.2.313
255:, certain genera of
236:Placental viviparity
1410:reproductive system
1398:Vaginal lubrication
1176:sexual reproduction
1110:2011NW.....98..739W
1098:Naturwissenschaften
1077:10.1002/jez.b.22614
1069:2015JEZB..324..493G
806:10.1002/jez.b.22614
798:2015JEZB..324..493G
711:10.1038/nature08350
703:2009Natur.461..389O
306:in the large genus
211:Gastrotheca ovifera
1408:Development of the
1319:Sexual intercourse
874:10.1002/jmor.20272
660:10.1002/jmor.11011
644:Trachylepis ivensi
367:reproductive tract
342:Eulamprus tympanum
141:
58:
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1826:Pregnancy in fish
1654:
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1423:Sexual dimorphism
1388:Postpartum period
1019:10.1111/ele.12168
917:10.1111/evo.12130
748:(6848): 698–699.
697:(7262): 389–392.
293:placental barrier
241:Placental mammals
123:Reproductive mode
16:(Redirected from
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1393:Mechanics of sex
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272:Ovoviviparity
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94:ovoviviparity
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63:
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42:
41:
33:
19:
1796:Adelphophagy
1708:
1508:
1481:Paternal age
1477:Maternal age
1450:Tanner scale
1433:Virilization
1428:Feminization
1378:Implantation
1364:Insemination
1348:Ejaculation
1324:Masturbation
1240:spermatocyte
1212:Luteal phase
1197:Menstruation
1101:
1097:
1060:
1056:
1012:(1): 13–21.
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786:J Exp Zool B
785:
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620:. Retrieved
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384:trophic eggs
380:
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329:ichthyosaurs
314:
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270:
265:velvet worms
243:, including
234:
226:
209:
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193:
186:adelphophagy
173:
148:
116:
112:
103:
65:
59:
45:
39:
1831:Trophic egg
1816:Matrotrophy
1626:Dyspareunia
1621:Dysorgasmia
1567:Development
615:LiveScience
463:Placentalia
453:Livebearers
415:Gerrhonotus
376:vertebrates
355:matrotrophy
333:plesiosaurs
309:Trachylepis
281:Poeciliidae
253:cockroaches
159:ovuliparity
1852:Viviparity
1709:Viviparity
1646:Vaginismus
1616:Anorgasmia
1470:Adrenarche
1465:Spermarche
1445:Gonadarche
622:26 January
469:References
388:resorption
321:sea snakes
90:hatchlings
66:viviparity
18:Viviparous
1704:Oviparity
1572:Lactation
1562:Thelarche
1539:Andrology
1486:Menopause
1383:Pregnancy
1373:Fertility
1328:Erection
1284:Germ cell
1257:Oogenesis
1245:spermatid
1207:Ovulation
982:205780092
952:Evolution
905:Evolution
458:Marsupial
349:Evolution
325:mosasaurs
297:pathogens
249:scorpions
163:oviparity
106:adjective
100:Etymology
82:oviparity
40:Viviparus
1846:Category
1509:Vivipary
1479: /
1460:Menarche
1455:Pubarche
1337:Clitoral
1289:gonocyte
1262:oogonium
1192:Menarche
1126:21766177
1085:25732809
1028:23953272
974:28568867
925:24033171
882:24652663
833:Am. Zool
814:25732809
762:11507628
719:19759619
668:21956253
527:(2001).
443:Apomixis
437:See also
401:squamate
206:placenta
178:oviducts
137:placenta
78:juvenile
32:vivipary
1821:Oophagy
1780:mammals
1544:Hormone
1440:Puberty
1134:8017857
1106:Bibcode
1065:Bibcode
933:3890276
794:Bibcode
770:4420854
699:Bibcode
676:5191828
618:. Purch
423:lizards
378:alone.
216:embryos
182:oophagy
62:animals
1775:humans
1600:Female
1554:Breast
1357:Female
1344:Orgasm
1332:Penile
1294:gamete
1267:oocyte
1132:
1124:
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1026:
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742:Nature
727:351047
725:
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691:Nature
674:
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576:
430:labile
420:anguid
331:, and
289:Theria
277:vipers
263:, and
261:snakes
257:sharks
245:humans
222:. The
155:zygote
92:; and
70:embryo
1765:birds
1696:Modes
1272:ootid
1250:sperm
1130:S2CID
978:S2CID
929:S2CID
886:S2CID
766:S2CID
723:S2CID
672:S2CID
531:[
304:skink
224:skink
220:gills
149:Five
135:to a
117:pario
113:vivus
110:Latin
74:birth
54:aphid
1595:Male
1504:Ovum
1352:Male
1277:ovum
1122:PMID
1081:PMID
1024:PMID
970:PMID
921:PMID
878:PMID
810:PMID
758:PMID
715:PMID
664:PMID
624:2016
574:ISBN
395:and
363:yolk
259:and
251:and
167:yolk
86:eggs
1496:Egg
1174:of
1114:doi
1073:doi
1061:324
1014:doi
960:doi
913:doi
870:doi
866:276
841:doi
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184:or
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