Literaturdatenbank
Literaturdatenbank |
|
 |
|
Carthy, R. R. (1996). The role of the eggshell and nest chamber in loggerhead turtle (caretta caretta) egg incubation. Unpublished thesis PhD, University of Florida.
Added by: Admin (13 Sep 2009 10:11:06 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: Carthy1996 View all bibliographic details  |
Categories: General Keywords: Caretta, Caretta caretta, Cheloniidae, Schildkröten = turtles + tortoises, Zeitigung = incubation Creators: Carthy Publisher: University of Florida |
Views: 7/609
Views index: 11% Popularity index: 2.75% |
| Abstract |
|
Abstract (Summary) The traditional view of parental investment in offspring has concentrated on energy expenditure by the parent in preparing propagules and nurturing the young. This study sought to expand that definition by examining aspects of nurturing that are overlooked in the traditional model, but are important in oviparous reptiles because of their life history traits. The role of the eggshell during incubation was studied as a characteristic of maternal investment. Ultrastructure of fresh and spent eggshells of the loggerhead turtle (Caretta caretta) was described using scanning electron microscopy, and a pattern of basal calcium carbonate dissolution was proposed that is consistent with known changes in developmental physiology and physical attributes of incubated eggs. Initial calcium investment in eggshells differed among females, and incubation in media extremes of air and sand affected dissolution of eggshell calcium (P $<$ 0.05) without appearing to influence calcium incorporation into the egg contents. Nest casting studies examined maternal investment in the nesting environment. Analysis of nest chamber size and structure revealed significant correlations of maternal body size and clutch size with nest size parameters. Nests dug on a renourished beach exhibited skewed variances in actual depth, potential air space and several shape parameters influenced by mechanics of excavation. Nests from the natural beach showed normal distributions of size variances. The size of a chamber constructed by a female appears linked to selective pressures exerted by body and clutch size and is sensitive to variation in the density of the nesting medium. Effects of egg position within the chamber were examined by excavation of nests at 8 time intervals throughout incubation and by classification of eggs as top, side, bottom or inner based on location and contacts. Egg position in the nest had significant effects on egg mass, egg density, incubation time, hatchling mass, and hatchling sex; significant effects of clutch on these parameters were attributed primarily to location of the nests on the beach and the accompanying thermal and hydric conditions. These findings elucidate the contribution of factors previously overlooked as important components of maternal investment and have critical implications for sea turtle nesting beach conservation measures.
Added by: Admin |