title: Thermal fluctuation within nests and predicted sex ratio of Morelet's Crocodile.
abstract: Understanding the interplay between thermal variations and sex ratio in reptiles with temperature-dependent sex determination is the first step for developing long-term conservation strategies. In case of crocodilians, the information is fragmentary and insufficient for establishing a general framework to consider how thermal fluctuation influence sex determination under natural conditions. The main goal of this study was to analyze thermal variation in nests of Crocodylus moreletii and to discuss the potential implications for predicting offspring sex ratio. The study was carried out at the Centro de Estudios Tecnológicos del Mar N° 2 and at the Sistemas Productivos Cocodrilo, Campeche, Mexico. Data was collected in the nesting season of Morelet's Crocodiles during three consecutive seasons (2007-2009). Thermal fluctuations for multiple areas of the nest chamber were registered by data loggers. We calculate the constant temperature equivalent based on thermal profiles among nests to assess whether there are differences between the nest temperature and its equivalent to constant temperature. We observed that mean nest temperature was only different among nests, while daily thermal fluctuations vary depending on the depth position within the nest chamber, years and nests. The constant temperature equivalent was different among and within nests, but not among survey years. We observed differences between constant temperature equivalent and mean nest temperature both at the top and in the middle of the nest cavities, but were not significantly different at the bottom of nest cavities. Our results enable examine and discuss the relevance of daily thermal fluctuations to predict sex ratio of the Morelet's Crocodile.
authors.affiliation: Centro Universitario de la Costa, Universidad de Guadalajara, Av. Universidad 203, 48280 Puerto Vallarta, Jalisco, México. Electronic address: elchorvis@gmail.com.
authors.forename: Armando H
authors.initials: AH
authors.lastname: Escobedo-Galván
authors.affiliation: División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carr. Villahermosa-Cárdenas km.0.5 s/n, Entrq. Bosques de Saloya, 86039 Villahermosa, Tabasco, México.
authors.forename: Marco A
authors.initials: MA
authors.lastname: López-Luna
authors.affiliation: Centro Universitario de la Costa, Universidad de Guadalajara, Av. Universidad 203, 48280 Puerto Vallarta, Jalisco, México.
authors.forename: Fabio G
authors.initials: FG
authors.lastname: Cupul-Magaña
mesh_terms: D000489:Alligators and Crocodiles / Q000502:physiology*; D000818:Animals; D057231:Climate Change; D005260:Female; D008297:Male; D008800:Mexico; D009425:Nesting Behavior; D012098:Reproduction; D019849:Sex Determination Processes; D012744:Sex Ratio; D013696:Temperature
keywords: Climate change; Crocodylus moreletii; Reproductive ecology; Reptiles; Temperature-dependent sex determination