G. Sorci et al., QUANTITATIVE GENETICS OF LOCOMOTOR SPEED AND ENDURANCE IN THE LIZARD LACERTA-VIVIPARA, Physiological zoology, 68(4), 1995, pp. 698-720
We used quantitative genetic analyses to test the hypothesis of a trad
e-off between locomotor speed and endurance in a population of the Eur
opean lizard Lacerta vivipara, which is the subject of long-term demog
raphic studies. We estimated the heritability of maximal sprint speed
treadmill endurance and tail length, a morphometric trait that may aff
ect locomotor performance, as well as phenotypic, genetic, and environ
mental correlations between these traits. Gravid females were captured
in the field and held in the laboratory under standardized conditions
until giving birth; traits were then measured on their offspring. Pri
or to ge genetic analyses, we used multiple regressions to remove the
effects of such covariates as body size (mass and snout-vent length),
dam age, and length of time dams were held in captivity prior to partu
rition. When we examined the residual characters, heritability was low
and statistically nonsignificant for speed but relatively high for bo
th endurance (0.46) and tail length (0.51). None of the phenotypic, ge
netic, or environmental correlations between traits was statistically
significant Thus, we found no evidence for a trade-off between speed a
nd endurance; these results are consistent with those reported in two
previous studies of squamate reptiles (the garter snake Thamnophis sir
talis and the fence lizard Sceloporus occidentalis). The lack of a neg
ative genetic correlation between speed and endurance suggests that th
ese aspects of locomotor abilities are relatively free to evolve indep
endently, such that natural selection could increase both speed and en
durance. However, the species studied to date have low to moderate cap
acities for speed and endurance, as compared with other squamates. Phy
siologically based trade-offs-for example, those caused by the composi
tion of muscle fiber types-should be more likely to exist in species t
hat heave high capacities for speed and/or endurance.