Reproductive variation and the egg size-clutch size trade-off within and among populations of painted turtles (Chrysemys picta bellii)

Abstract

Interpopulation variation in egg size, clutch size and clutch mass was studied 3 years in four populations of painted turtles (Chrysemys picta bellii) from western Nebraska. Body size varied among all populations and was larger in two large (56-110 ha), sandhills lake populations than in two populations in smaller habitats (1.5-3.6 ha) of the Platte River floodplain. Reproductive parameters (egg mass, clutch mass, and clutch size) generally increased with maternal body size within populations. Clutch wet and dry mass varied among populations but largely as a function of maternal body size. Clutch size was largest in the sandhills lake populations, both absolutely and relative to maternal body size. Egg mass was smallest in the sandhills lakes and varied annually in one population. Over all populations, an egg sizeclutch size trade-off was detected (a negative correlation between egg mass and clutch size) after statistically removing maternal body size effects. Egg wet mass and clutch size were negatively correlated over all years within the sandhills populations and in some years in three populations. Although egg size varied within populations, egg size and clutch size covaried as expected by optimal offspring size models. Thus, patterns of egg size variation should be interpreted in the context of proximate or adaptive maternal body size and temporal effects. Comparisons among populations suggest that large egg size relative to maternal body size may occur when juvenile growth potential is poor and mean maternal body size is small.

Overcoming environmental and morphological constraints: egg size and pelvic kinesis in the smallest tortoise, Homopus signatus

“…That is, relative to body size, taxa that invest more resources in individual offspring produce fewer offspring per clutch. A similar trade-off between egg size and number has been shown at the generic and family levels for other chelonians (Elgar and Heaphy 1989;Rowe 1994). Of the few nontestudinid chelonians that produce single-egg clutches, most inhabit humid or tropical regions (e.g., Platemys platycephala (Schneider, 1792), Rhinoclemmys punctularia (Daudin, 1802), and Kinosternon angustipons Legler, 1965;Ernst and Barbour 1989), not arid and unpredictable habitats.…”

Evidence for the Morphological Constraint Hypothesis and Optimal Offspring Size Theory in the Mexican Mud Turtle (Kinosternon integrum)

“…The application of the morphological constraint hypothesis to turtles has been addressed since the seminal publication of Congdon and Gibbons (1987), and most of the empirical evidence to support this hypothesis has come from correlations of reproductive traits to body size (Gibbons et al, 1982;Vogt, 1990;Iverson, 1991Iverson, , 1999Iverson, , 2002Iverson and Smith, 1993;Iverson et al, 1991Iverson et al, , 1997Rowe, 1994;Clark et al, 2001;Wilkinson et al, 2005). Few authors have followed King's (2000) suggestion to analyze life-history-body size relationships using an allometric approach (Lindeman, 2005;Ryan and Lindeman, 2007).…”

Terrestrial habitat requirements of nesting freshwater turtles

“…Similarly, it remains to be seen whether construction of artificial nesting areas near wetlands or away from development may be an effective conservation strategy (Buhlmann and Osborn, 2011). The extent to which turtle populations are able to respond to developmentinduced changes by life-history trait evolution is likewise not yet known (Bowen and Janzen, 2008;Rowe, 1997;Wolak et al, 2010). Although some turtle populations may adapt to the loss of nesting areas (and subsequent reduction in recruitment) or of sexually mature females (Fordham et al, 2007), it is not known if contemporary evolution of life history traits can track the ongoing rate of human conversion of turtle habitats and associated effects on turtle populations (e.g., Gibbs and Steen, 2005).…”