Covariation of Life-History Traits in Lacertid Lizards: A Comparative Study

Abstract

We analyzed patterns of life-history covariation within a clade of lacertid lizards, using the method of phylogenetically independent contrasts. Examination of allometric relations and correlations among life-history traits showed that species within this clade can be arranged along a single, multivariate axis. At one end of this continuum are small-sized species that mature early, have small clutches of relatively large young, may have multiple broods per year, and have short adult lives. At the other extreme are the larger lacertids with the opposite suite of traits. Much of this pattern can be deduced from two relations: the increase of adult life span with adult body size and the negative allometry of offspring size. After the effects of body size were statistically removed, residuals of adult life span and age at sexual maturity were positively correlated, whereas residuals of the number and size of offspring were negatively correlated. The detection of these size-free relations supports an interpretation of coadaptive adjustments among life-history variables. The pattern of life-history covariation in lacertid lizards differs fundamentally from the "fast-slow" continuum. This gradient reflects a negative association between adult life span and fecundity, whereas both variables are positively correlated among species of lacertid lizards.