Variation of Reproductive Traits and Female Body Size in the Most Widely-Ranging Terrestrial Reptile: Testing the Effects of Reproductive Mode, Lineage, and Climate

Abstract

The European common lizard, Zootoca vivipara, is the most widespread terrestrial reptile in the world. It occupies almost the entire Northern Eurasia and includes four viviparous and two oviparous lineages. We analysed how female snout-vent length (SVL), clutch size (CS), hatchling mass (HM), and relative clutch mass (RCM) is associated with the reproductive mode and climate throughout the species range and across the evolutionary lineages within Z. vivipara. The studied variables were scored for 1,280 females and over 3,000 hatchlings from 44 geographically distinct study samples. Across the species range, SVL of reproductive females tends to decrease in less continental climates, whereas CS corrected for female SVL and RCM tend to decrease in climates with cool summer. Both relationships are likely to indicate direct phenotypic responses to climate. For viviparous lineages, the pattern of co-variation between female SVL, CS and HM among populations is similar to that between individual females within populations. Consistent with the hypothesis that female reproductive output is constrained by her body volume, the oviparous clade with shortest retention of eggs in utero showed highest HM, the oviparous clade with longer egg retention showed lower HM, and clades with the longest egg retention (viviparous forms) had lowest HM. Viviparous populations exhibited distinctly lower HM than the other European lacertids of similar female SVL, many of them also displaying unusually high RCM. This pattern is consistent with Winkler and Wallin’s model predicting a negative evolutionary link between the total reproductive investment and allocation to individual offspring.

Geographic variation of life‐history traits in the sand lizard,Lacerta agilis: testing Darwin's fecundity‐advantage hypothesis

“…The latter trait is an important variable of reptilian life history that reflects the position of the individual female, population or species along the oviparity–viviparity continuum (Shine, ; Braña et al ., ). Remarkably, within one of these species ( Zootoca vivipara ), which exhibits reproductive bimodality, the pattern of reproductive divergence between viviparous (smaller offspring mass and higher relative clutch mass) vs. oviparous (larger offspring mass and lower RCM) populations (Roitberg et al ., ) is similar to that between L. a. agilis and L. a. exigua (this study). This parallelism lends additional support for the Winkler & Wallin model.…”

“…See Roitberg et al . () for further justifications of using RCM. Second, we used residuals of an ordinary least squares regression of mean clutch size on mean female SVL to measure relative (size‐specific) fecundity.…”

Viviparity does not affect the numbers and sizes of reptile offspring

“…Meiri et al () found that viviparous squamates had lower reproductive output when this was measured as the biomass of offspring produced per year – but attributed this mainly to the higher number of yearly broods in oviparous species. Within a single reproductively bimodal species ( Lerista bougainvillii ), Qualls and Shine () found no differences in offspring size or number (Roitberg et al, reached the same conclusion when comparing oviparous vs. viviparous populations of Zootoca vivipara ), but an increase in RCM in the viviparous lineage.…”

Distinct telomere differences within a reproductively bimodal common lizard population

“…We initially hypothesized that the viviparous mothers would have a higher reproductive investment (Lindtke et al, ) because of the prolonged pregnancy and presumed larger clutch mass in viviparous species (Horváthová et al, ; Qualls & Shine, ; Roitberg et al, ). However, the relative clutch mass (as a proxy for reproductive investment) was similar between the reproductive modes.…”

“…However, it has been suggested that viviparity may incur substantial costs for the mother. Firstly, the prolonged gestational period and presumed larger clutch mass in viviparous individuals (Horváthová et al, ; Qualls & Shine, ; Roitberg et al, ) could carry a greater metabolic cost for the mother. Secondly, viviparity has been linked to the evolution of larger body sizes to counteract the space constraint in utero (Qualls & Shine, ) and there can be costs associated with rapid growth and/or a larger body size (Metcalfe & Monaghan, ).…”