Rm. Andrews et al., Effect of incubation temperature on morphology, growth, and survival of juvenile Sceloporus undulatus, HERPETOL M, (14), 2000, pp. 420-431
Incubation temperature affects a wide range of phenotypic traits of hatchli
ng reptiles. The main objective of this research was to determine if such p
henotypic traits persist long enough in the field to have an effect on fitn
ess. Eggs of Sceloporus undulatus lizards were incubated at six temperature
regimes, five constant and one fluctuating, with means ranging from 23-33
C. Hatchlings were measured and their subsequent morphology, growth, and su
rvival were monitored for 7-9 months, one to two months before individuals
reached adult size. Phenotypic traits of lizards that hatched at the field
site were used for comparative purposes. Morphological trails persisted for
7-9 mo. In contrast, growth rates did not differ among incubation temperat
ure treatments after individuals were released in the field. Overall, 29 (2
7%) of 107 individuals that were released survived to the spring following
hatching, and individuals from eggs incubated at the lowest temperature had
higher survival than individuals from all other groups. The phenotypes of
lizards incubated at intermediate temperatures tended to be most similar to
those of field hatched lizards. We rejected two predictions about phenotyp
ic responses to incubation temperature. The first prediction was that extre
me incubation temperatures would be associated with the most deviant phenot
ypes. Observed phenotypic responses to temperature were either linear or, o
nly one extreme temperature produced a deviant phenotype. The second predic
tion was that hatchlings incubated at warm temperatures and that hatched ea
rly in the season would have higher survival in general and higher overwint
er survival in particular than hatchlings incubated at cool temperatures an
d that hatched later in the season. The reverse was true; observed survival
was greatest for hatchlings from the coolest incubation treatment that hat
ched last.