Intraspecific Variation of Reproductive Traits in a Mediterranean Lizard: Clutch, Population, and Lineage Effects

Widely distributed terrestrial ectotherms from the southern European peninsulas show patterns of subdivision (related to isolation in temperate refugia) that allow us to test the relative importance of phylogeographic lineage, population of origin and familial effects as sources of variation for life-history traits. We collected gravid females from 15 geographically separated populations of the lacertid lizard Psammodromus algirus, a widely distributed species with well differentiated eastern and western lineages. We incubated eggs under two treatments of constant (28A degrees C) and fluctuating (28 +/- A 4A degrees C) temperature, and we examined clutch, population, and lineage effects on several traits of females, eggs, and hatchlings. Incubation time was mainly explained by differences between lineages, but it was also influenced by population and female effects. Within each lineage, incubation was shorter at cooler and wetter sites, and for a given climate it was shorter for eastern than for western populations, suggesting that countergradient variation has evolved independently in the two lineages. Female size, clutch size, and relative fecundity were primarily influenced by inter-population differences, a pattern that seemed attributable to environmental differences in productivity, because mean female size was positively correlated with a gradient of increasing precipitation and decreasing temperature. Clutch size was mainly, but not entirely, dependent on female SVL, suggesting both a proximate effect of local conditions and intrinsic differences among populations. Females from drier and warmer sites produced larger hatchlings. Mean egg mass was mainly determined by familial effects. Eggs incubated at a constant temperature hatched earlier than did their siblings incubated at fluctuating temperatures, a fact that could be explained by considering that in Mediterranean environments developmental rate might increase at a lower speed above average incubation temperature than it does decrease below it.