Seasonal changes in biochemical composition of body walls, gonads and pyloric caeca in two populations ofSclerasterias mollis (Echinodermata: Asteroidea) during the annual reproductive cycle

1991 ◽  
Vol 109 (1) ◽  
pp. 27-34 ◽  
Author(s):  
M. F. Barker ◽  
R. A. Xu
Keyword(s):  
Reproductive Cycle ◽  
Seasonal Changes ◽  
Biochemical Composition ◽  
Annual Reproductive Cycle ◽  
Pyloric Caeca ◽  
Two Populations

Geographic and annual variation in reproductive cycles in the Tasmanian spotted snow skink, Niveoscincus ocellatus (Squamata : Scincidae)

1999 ◽  
Vol 47 (6) ◽  
pp. 539 ◽  
Author(s):  
Erik Wapstra ◽  
Roy Swain ◽  
Susan M. Jones ◽  
Julianne O'Reilly
Keyword(s):  
Reproductive Cycle ◽  
Annual Variation ◽  
Thermal Conditions ◽  
Gestation Length ◽  
Annual Reproductive Cycle ◽  
Climatic Range ◽  
Reproductive Cycles ◽  
Reproductive Events ◽  
Two Populations ◽  
Winter Hibernation

We studied the reproductive cycle of two populations of the spotted snow skink, Niveoscincus ocellatus, over a three-year period. This species is widespread in Tasmania and its distribution overlaps those of other species in the genus that show two distinct reproductive strategies: annual reproduction that is completed within one season, and biennial reproduction in which females carry advanced embryos throughout winter hibernation. We chose populations representative of the climatic extremes of the species’ distribution, within these areas of overlap. Niveoscincus ocellatus maintains the same basic reproductive strategy in both populations: summer gestation, primary autumn mating with obligate sperm storage by females, secondary mating in spring, and predominantly spring vitellogenesis and ovulation. In both populations all females reproduce annually, suggesting that reproductive frequency is not constrained by availability of energy. However, we found distinct differences in the timing of ovulation and parturition. Females from our subalpine site ovulated approximately one month later than those from our warmer, lowland site; parturition was delayed by the same period so gestation length was unchanged. The delay in ovulation results in gestation proceeding over the warmest months at the cold site. The annual reproductive cycle of this species appears to constrain its distribution to the lower altitudinal/climatic range of alpine Niveoscincus species. There were minor annual differences in the timing of reproductive events at each site, which we attribute to variation in thermal conditions and the amount of precipitation.

scholarly journals Seasonal changes in the pituitary gonadotrops during tha annual reproductive cycle of the Murrel Channa punctatus (Bloch)

1998 ◽  
Vol 12 (12) ◽  
pp. 17
Author(s):  
S. J. Srivastava ◽  
R. Singh
Keyword(s):  
Reproductive Cycle ◽  
Seasonal Changes ◽  
Channa Punctatus ◽  
Annual Reproductive Cycle

Foram observadas mudanças sazonais na estrutura e comportamento dos hormônios gonadotrópicos pituitários durante o ciclo reprodutivo anual de Channa punctatus. Os hormônios gonadotrópicos demonstram mudanças morfológicas marcantes na forma da granulação, degranulação e vacuolisação com o ciclo sexual sugerindo sua tendência de armazenamento e liberaçào durante atividades gonadais.

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