Maternal investment in reproduction and its consequences in leatherback turtles

Abstract

Maternal investment in reproduction by oviparous non-avian reptiles is usually limited to pre-ovipositional allocations to the number and size of eggs and clutches, thus making these species good subjects for testing hypotheses of reproductive optimality models. Because leatherback turtles (Dermochelys coriacea) stand out among oviparous amniotes by having the highest clutch frequency and producing the largest mass of eggs per reproductive season, we quantified maternal investment of 146 female leatherbacks over four nesting seasons (2001-2004) and found high inter- and intra-female variation in several reproductive characteristics. Estimated clutch frequency [coefficient of variation (CV) = 31%] and clutch size (CV = 26%) varied more among females than did egg mass (CV = 9%) and hatchling mass (CV = 7%). Moreover, clutch size had an approximately threefold higher effect on clutch mass than did egg mass. These results generally support predictions of reproductive optimality models in which species that lay several, large clutches per reproductive season should exhibit low variation in egg size and instead maximize egg number (clutch frequency and/or size). The number of hatchlings emerging per nest was positively correlated with clutch size, but fraction of eggs in a clutch yielding hatchlings (emergence success) was not correlated with clutch size and varied highly among females. In addition, seasonal fecundity and seasonal hatchling production increased with the frequency and the size of clutches (in order of effect size). Our results demonstrate that female leatherbacks exhibit high phenotypic variation in reproductive traits, possibly in response to environmental variability and/or resulting from genotypic variability within the population. Furthermore, high seasonal and lifetime fecundity of leatherbacks probably reflect compensation for high and unpredictable mortality during early life history stages in this species.

Pleated turtle escapes the box – shape changes in Dermochelys coriacea

“…These approximate calculations suggest that the distended shell accommodates approximately three-quarters of the accumulated fat. It is already well known that female D. coriacea demonstrate the highest maternal investment of all living reptiles (for reviews, see Wallace et al, 2006;Wallace et al, 2007). They lay multiple (normally seven to eight, but <11) large egg clutches (approximately 65 eggs per clutch) of the largest eggs (80-90g each and approximately 53mm diameter) of any sea turtle and do so every 2-4years for decadal periods (Spotila et al, 1996).…”

“…From the data of Miller (Miller, 1997) and Reina et al (Reina et al, 2002b) it can be estimated that a female may lay approximately 35kg of eggs (equivalent to approximately 37l volume) per breeding season. Unlike all other turtles, leatherback females also lay very variable numbers of shelled albumen gobs (formerly known as yolkless eggs) that have an uncertain function (Wallace et al, 2007). Hence it is probable that a female will deposit approximately 40kg (ca.…”

Maternal transfer of trace elements in leatherback turtles (Dermochelys coriacea) of French Guiana

“…Leatherback females come ashore at night around the high tide to lay an average of 7 clutches with an interval between nesting events of 10 days (Girondot and Fretey, 1996). They have the biggest eggs (∼80 g) and the largest clutches by weight (∼5-10 kg) among sea turtles; egg production represents the highest reproductive out-put in reptiles (Miller, 1997;Wallace et al, 2007). Finally, at the end of the breeding season leatherbacks undertake long migrations to feed upon gelatinous zooplankton in rich North Atlantic waters (Davenport, 1998).…”

Life-history costs of reproductive behaviors in a wetland-breeding amphibian

“…Traditionally, life-history studies have examined demographic traits intimately tied to fitness such as body size, age at maturity, and number of offspring (e.g., Stearns 1983Stearns , 1984Roff 1992;Bernardo 1996;Wallace et al 2007; Lee et al 2012). Such factors are major components of life-history theory; however, a focus on these demographic traits means less attention has been paid to the relationship between reproductive behaviors (e.g., reproductive migrations) and life-history theory.…”