http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Comparative demography of two viviparous lizards (Sceloporus jarrovi and Sceloporus poinsetti) with consideration of the evolutionary ecology of viviparity in lizards
Population studies of Sceloporus jarrovi using mark-recapture procedures were conducted on two study plots near Portal, Arizona during the summer months of 1969 and 1970. Similar studies of Sceloporus poinsetti were conducted on a single study plot near Mertzon, Texas during the summer months of 1968, 1969 and 1970. Series of these lizards were taken from areas near the study plots and autopsied to determine their reproductive condition. The reproductive cycle of both species involves mating in the fall with parturition occurring the following June. A single litter is produced each year. S. poinsetti attains maturity during the second mating season after birth, at an age of approximately 16-17 months, although approximately 60% of the S. jarrovi females mature in their first mating season at approximately five months of age. Female S. jarrovi, which mature in their first year, produce an average of four young, whereas, older females produce an average of 10.5 young (7-15). There is an increase in litter size as snout-vent length increases which equals one embryo per three millimeters of body length. S. poinsetti produce an average of 10.4 young (6-23) with a similar increase in number of embryos with increasing snout-vent length of the female. Body sizes of young at birth were 29-35 mm in S. poinsetti and 25-32 mm in S. jarrovi. Young of both species are larger than comparable oviparous species of Sceloporus. Newborn of j5. poinsetti from large litters are significantly smaller than newborn from small litters. Such a relationship probably has a negative feedback on litter size of viviparous species particularly if increased hatchling survivorship through increased size at birth is a major advantage of viviparity. ...
Ph. D. in Wildlife and Fisheries Sciences Texas A & M University