Latitudinal and seasonal variation in reproductive effort of the eastern fence lizard (Sceloporus undulatus)

Abstract

Geographic variation in life-history traits among populations of wide-ranging species is influenced by both spatial and temporal aspects of the environment. Rarely, however, are the effects of both aspects examined concurrently. We collected gravid female lizards (Sceloporus undulatus) from northern (Indiana), central (Mississippi) and southern (Florida) populations, spanning nearly the full latitudinal range of the species, to examine among population differences in strategies of reproductive energy allocation. Adult females from the southern population were smaller, and produced fewer and smaller eggs in their first clutches than did females from the more northern populations. Southern females were more likely to produce a second clutch, and second clutches were smaller than first clutches for females from the 2 northern populations. Together these trends eliminated population differences in overall reproductive output after accounting for body size. The trend for greater reproductive energy to be allocated to first clutches at higher latitudes, and to later clutches at lower latitudes is corroborated by published data from field studies on multiple populations. Distributing reproductive effort by producing more clutches of smaller eggs may be an adaptive response to the long season available for egg incubation and lizard activity in sub-tropical southern environments. In contrast, allocating greater resources to early reproduction may enhance maternal fitness in the relatively short activity seasons that characterize more northern sites.

Maternal stress alters the phenotype of the mother, her eggs and her offspring in a wild‐caught lizard

“…Body condition was calculated as the residuals of the log mass on log SVL, and relative HL was calculated as the residuals of hindlimb length on SVL (Du, Robbins, Warner, Langkilde, & Shine, ; Graham et al., ; Langkilde, ; Schulte‐Hostedde, Zinner, Millar, & Hickling, ). Maternal behaviours were analysed as individual data points (hourly point samples) and plotted as per cent of observations determined from multiple point observations (averaged across all observations; Figure ), while hatchling behaviour was analysed as timed duration as recorded from video footage and plotted as minutes (Figure ).…”

The genetic sex-determination system predicts adult sex ratios in tetrapods

“…For birds, we used body mass dimorphism (data available for n 5 181 species) 39 owing to the lack of sex-specific body length data. The results of the multivariate PGLS model of tetrapods presented in Table 2 Third, we included breeding latitude 40,41 as the geographic coordinates of the ASR studies for amphibians and reptiles, taking absolute values to represent distance from the Equator in latitudinal degree. When the authors did not report latitude, we used Google Earth to estimate it on the basis of the description of the study site.…”

Reproductive cycles and reproductive strategies among populations of the Rose‐bellied Lizard Sceloporus variabilis (Squamata: Phrynosomatidae) from central Mexico

“…undulatus , Du et al. ; Phrynocephalus przewalskii , Wang et al. ; Zootaca vivipara , Horváthová et al.…”