Maternal effects influence phenotypes and survival during early life stages in an aquatic turtle

Abstract

Summary1. Offspring phenotypic variation can be substantially influenced by non-genetic factors such as maternal effects, which ultimately can influence organismal fitness. For oviparous organisms that lack parental care, oviposition-site choice and egg size are maternal effects that can greatly affect offspring traits. Yet, few studies examine the consequences of these traits in the wild. 2. We manipulated the contents of natural painted turtle nests such that offspring spent two life stages (incubation and hibernation) in either maternally selected nest sites or randomly selected nest sites and quantified treatment differences in environmental parameters and offspring phenotypes. Additionally, we tracked the fates of individual eggs and hatchlings, which allowed us to quantify the strength and form of selection acting on egg size during incubation and, for the first time, body size during hibernation. 3. Maternally selected nest sites were warmer and produced offspring that were longer and hatched earlier than their siblings emerging from cooler, randomly selected nests. Treatments did not affect any measured traits during hibernation. 4. We detected no selection on egg size during the incubation stage, but significant linear selection favouring larger hatchlings during hibernation. 5. Our results suggest that nest-site choice allows mothers to partially control the environment of their incubating eggs, but is less effective at controlling hatchling environments during hibernation. Additionally, we provide novel support for the 'bigger-is-better' hypothesis in turtles by showing a positive relationship between size and survival during the hibernation stage.

Latitudinal differences in temperature effects on the embryonic development and hatchling phenotypes of the Asian yellow pond turtle,Mauremys mutica

“…Therefore, similarly to posthatching individuals, embryos of oviparous reptiles from different populations might have evolved diverse strategies to benefit from the thermal environment in which they complete development (Denno & Dingle, ; Warkentin, ; Colbert, Spencer & Janzen, ; Sun et al ., ). In addition, maternal behaviours also provide an important mechanism for organisms to adapt to changing climatic conditions, and enhance the survival of embryos and the fitness of offspring (Mitchell, Maciel & Janzen, , ). For example, females may shift the timing of nesting and actively select nest sites and depths with a suitable thermal environment for embryonic development to reduce the negative effects imposed by changing climatic conditions (Ewert et al ., ; Doody et al ., ; Telemeco, Elphick & Shine, ).…”

Female lizards choose warm, moist nests that improve embryonic survivorship and offspring fitness

“…The importance of maternal effects in the processes of ecological adaptation and evolutionary change has attracted increasing attention since maternal effects can influence offspring fitness, the evolution of life‐history traits and population dynamics (Mousseau & Fox, ; Mousseau, Uller, Wapstra, & Badyaev, ; Murphy, Goedert, & Morris, ; Plaistow & Benton, ). In heterogeneous environments, maternal effects can increase offspring fitness by mediating changes in offspring phenotypes (Bernardo, ; Galloway, ; Ghalambor, McKay, Carroll, & Reznick, ), and the selection of nest sites in oviparous species is a mechanism by which females can regulate the developmental environment of embryos and, therefore, influence the development and phenotypes of their offspring (Bernardo, ; Mitchell, Maciel, & Janzen, ; Refsnider & Janzen, ; Spencer, Blaustein, & Cohen, ).…”

Preovulatory Maternal Effects on Intra- and Interpopulation Variation in Sex Ratios and Phenotypic Characteristics of Magdalena River Turtles (Podocnemis lewyana)

“…Phenotypic Characteristics One ubiquitous maternal effect commonly demonstrated in studies on freshwater turtle species is the importance of egg mass on multiple hatchling phenotypic characteristics (Congdon et al 1983;Congdon and Gibbons 1985;Ashmore and Janzen 2003;Mitchell et al 2015). Most studies fail to quantify fine-scale differences in yolk composition, however, and simply measure egg mass before assuming that effects on hatchling phenotypes are mediated by differences in energetic investment in yolk volume.…”

“…Thus, the date when, and the site where, a female chooses to nest constitute strong epigenetic effects that influence the phenotype of the offspring beyond simple nuclear genetic effects (Mitchell et al 2015). In oviparous species in general, the greater phenotypic resemblance among siblings (as compared to members of other clutches) results from (1) higher genetic relatedness; (2) shared maternal effects; and (3) similar environmental conditions experienced during incubation.…”

“…Size at hatching is an important trait not only from a life-history perspective (Vogt and Bull 1984), but also from ecological and evolutionary perspectives (Bernardo 1996b). Studies of some turtle species have shown that larger hatchlings have higher probabilities of survival because smaller individuals either move slower or are otherwise easier for predators to capture (Janzen et al 2000(Janzen et al , 2007, or have lower chances of surviving hibernation (Mitchell et al 2015). Furthermore, growth in hatchling turtles is influenced by yolk composition (the proportion of protein and polar vs. nonpolar lipids, as well as steroid hormonal concentrations; Congdon and Gibbons 1985;Nagle et al 2003).…”