Intraspecific Variation in demography and Life History of the Lizard, Sceloporus Jarrovi, Along an Altitudinal Gradient in Southeastern Arizona

Abstract

Mark—recapture studies were conducted on a low (1675 m) and high (2542 m) altitude population of Sceloporus jarrovi in southeastern Arizona, USA from 1973 through 1976. Average age—specific mortality rates differed between altitudes only in the 0—1 yr age class. The increased mortality of neonates are low altitude was correlated with an increased number of potential predators and a significantly greater frequency of natural tail—breaks. Tail—break frequency did not differ between sites for older age classes. Survivorship and age at maturity were greater at high altitude. Low—altitude females mature in their first reproductive season. Transfer of neonates between altitudes indicate that high—altitude females do not mature in their first season even if raised at low altitude. Age at maturity appears to be adaptively adjusted by the demographic environment. Fertility schedules indicate that °40% of the replacement of low—altitude populations results from reproduction by 1st yr animals. There was a greater variation in replacement rate and population size at low than at high altitude.

Testosterone has opposite effects on male growth in lizards(Sceloporusspp.) with opposite patterns of sexual size dimorphism

“…4 months winter dormancy in S. virgatus), roughly coincident with the onset of their respective mating seasons. On our study plot, most males and some females of each species attain sexual maturity as yearlings (Ballinger, 1973(Ballinger, , 1979Ballinger and Ketels, 1983;Smith et al, 1995). However, while yearling males of S. virgatus grow only half as fast as females during their spring mating season, yearling males of S. jarrovii grow more quickly than females during their fall mating season (Cox, 2005; R. M. Cox and H. B. John-Alder, manuscript submitted).…”

“…Both species are primarily saxicolous, employ sit-and-wait foraging tactics, share common prey and predators, attain sexual maturity as yearlings (i.e. within 12 months of birth), reproduce only once annually, and exhibit polygynous mating systems characterized by aggressive intrasexual male competition for breeding females (Ballinger, 1973(Ballinger, , 1979Ballinger and Ketels, 1983;Rose, 1981;Ruby, 1978;Ruby and Dunham, 1984;Smith, 1985;Smith et al, 1995;Vinegar, 1975b). However, while adult females of S. virgatus average 10% larger than adult males (longer in snout-vent length, SVL), adult males of S. jarrovii average 10% larger than adult females (Cox et al, 2003;Cox, 2005; R. M. Cox and H. B. John-Alder, manuscript submitted).…”

Autotomy in Blue Crab (Callinectes sapidus Rathbun) Populations: Geographic, Temporal, and Ontogenetic Variation

“…Autotomy is an effective escape response to predators (Robinson et al, 1970;Congdon et al, 1974;Medel et al, 1988;Smith, 1990a). Variation in injury levels in populations may indicate differential predation pressure (e.g., Shaffer, 1978;Ballinger, 1979;Schall and Pianka, 1980;McCallum et al, 1989) or predator efficiency (Schoener, 1979;Schoener and Schoener, 1980;Jaksic and Fuentes, 1980). In the Rhode River, significantly higher levels of limb loss were recorded in blue crabs in 1986 (250/0) than in three subsequent years (18-190/0).…”

“…Variation in injury levels among populations and species has been thought to reflect differences in predation intensity and efficiency over altitudinal gradients (Ballinger, 1979;Shaffer, 1978), ecological habitats (Schoener and Schoener, 1980); biogeographic regions (Vermeij, 1976); geologic time (Vermeij, 1977(Vermeij, , 1983, life histories (Vitt et al, 1977), and behaviors (Jaksic and Fuentes, 1980;Schall and Pianka, 1980). Although specific agents responsible for autotomy in nature are rarely identified (cl, Robinson et aI., 1970;Jaeger, 1981;Smith, 1990a), such information is needed to understand the patterns and impact of injury in populations.…”

Mudanças climáticas e os lagartos brasileiros sob a perspectiva da história de vida.

“…Em ambientes mais quentes (como baixas latitudes), a reprodução é em geral igualmente antecipada (Fitch, 1970;Goldberg, 1974;Duvall e col., 1982) e, em consequência, viabiliza a produção de mais de uma ninhada por ano (Goldberg, 1974;Jones e col., 1987;James e Shine, 1988). Além disso, as taxas de sobrevivência anual também guardam relação com a temperatura, sendo mais altas em regimes térmicos mais frios (Tinkle, 1969;Pianka, 1970;Ballinger, 1979;James e Shine, 1988). Assim como nos adultos, os efeitos descritos da temperatura no desenvolvimento embrionário parecem bastante sólidos.…”