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