Viviparity

Amphibians. Amphibians are highly susceptible to endocrine disruption during development of the larval form and during metamorphosis. The action of metamorphosis is triggered and controlled by the thyroid gland via an increase in triiodothyronine and a decrease in thyroxine, and differs greatly between oviparous and viviparous species. Experimentally, it has been shown that disruption during this sensitive period can lead to malformations and adverse impacts on immune and reproductive functions. 

Adults exposed to 1, 2, 5, or 10 During exposure for 80 days, there was a significant reduction in reproductive lifespan at 2, 5, and 10 pg/L. Nauplii produced viviparously by mated pairs were comparable to controls — except for the 10-pg/L group, which produced fewer nauplii. Cysts produced oviparously by treated pairs, however, had lower mean hatchability 19... 

Schultz, M.E. and J.R. Schultz. 1982. Induction of hepatic tumors with 7,12-dimethylbenz(a)anthracene in two species of viviparous fishes (genus Poeciliopsis). Environ. Res. 271 337-351. 

The tsetse flies are viviparous. The egg is retained and hatched in the body of the female fly, where it is nourished until full grown, then it is deposited on loose or sandy soil in a shaded place. The larva pupates within a few hours and after several weeks an adult fly emerges. The gestation period in the fly is about 10 days, and the flies may reproduce over a period of several months. Most of the species are limited to fly belts within their respective ranges. Shade and abundant ground cover characterize typical fly belts. 

McCarty, D.R. et al., The Viviparous-1 developmental gene of maize encodes a novel transcriptional activator. Cell, 66, 895, 1991. 

Hattori, T. et al., The Viviparous-1 gene and abscisic acid activate the Cl regulatory gene for anthocyanin biosynthesis during seed maturation in maize. Genes Dev., 6, 609, 1992. 

Some cockroach species exhibit obligatory or facultative parthenogenesis, but most species reproduce sexually with reproductive modes that include oviparity, ovo-viviparity, and viviparity (Roth, 1970). Oviparous females oviposit their eggs inside a protective egg case (ootheca), which is either deposited soon after being produced or carried by the mother until the nymphs hatch. In ovoviviparous and viviparous species, the egg case is reduced and remains unsclerotized it is incubated within a brood sac or uterus and live nymphs hatch from the female. At least one species, Diploptera punctata (Eschscholtz), is viviparous and the embryos receive nutrients directly from the mother in the form of milk (Evans and Stay, 1995). 

Kriz, A.R., Wallace, M.S. Paiva, R. (1990). Globulin gene expression in embryos of maize viviparous mutants. Plant Physiology 92, 538-42. 

McCarty, D.R., Carson, C.B., Stinard, P.S. Robertson, D.S. (1989). Molecular cloning of viviparous-1 An abscisic acid-insensitive mutant in maize. The Plant Cell 1, 523-32. 

Wilson, G.F., Rhodes, A.M. Dickinson, D.B. (1973). Some physiological effects of viviparous genes Vpl and Vp5 on developing maize kernels. Plant Physiology 52, 350-6. 

Constantz, G.D. (1980). Energetics of viviparity in the gila topminnow Pisces Poeciliidae. Copeia 1980 (4), 876-878. 

Turbot, Black Sea Vermilion rockfish Viviparous blenny Wall-eye pollock West Pacific sardine Whitefish White sea flounder Whiting, Black Sea Whiting, North Sea White perch Wolf-fish Yellowfin sole Yellowfin tuna Yellowfish... 

The demosponge subclasses Tetractinomorpha and Ceractinomorpha are primarily defined by oviparous or viviparous larval development, respectively. This division is the subject of some dispute as there have been indications that the reproductive mode may be ecologically dependent and thus not a stable character for classification. There are 12 orders in the subclasses Tetractinomorpha and Ceractinomorpha, with the largest number of metabolites reported from the orders Halichondrida (424), Haplosclerida (489), and Dictyoceratida (663). 

Aphids exhibit vivipary and ovipary, depending on environmental conditions. Oviparous aphids are sex pheromone competent, and females attract males with sex pheromonal signals in contrast, viviparous females are unable to produce pheromone (Crema and Bergamini, 1985). The pheromone is produced in tibial plaques, which are absent in viviparous females. The occurrence of vivipary and loss of tibial plaques is triggered by juvenile hormone, under conditions that stimulate vivipary. 

Youngsteadt, E., Fan, Y., Stay, B. and Schal, C. (2005). Cuticular hydrocarbon synthesis and its maternal provisioning to embryos in the viviparous cockroach Diploptera punctata. J. Insect Physiol., 51, 803-809. 

Most arthropods lay eggs, which hatch into larvae. Some are viviparous, like scorpions, and bear live young. As most arthropods grow, they shed or molt their outer skin covering a number of times before becoming adults. There are some groups that metamorphose from larva to adult inside a cocoon or pupa of their own making. 

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